US20090107503A1 - Nebulizing catheter system and methods of use and manufacture - Google Patents

Abstract

A method and apparatus for delivering a medicine to a patient via the patient's respiratory system with control and efficiency. A nebulization catheter is positioned in the patient's respiratory system so that a distal end of the nebulization catheter is in the respiratory system and a proximal end is outside the body. In a first aspect, the nebulization catheter may be used in conjunction with an endotracheal tube and preferably is removable from the endotracheal tube. The nebulization catheter conveys medicine in liquid form to the distal end at which location the medicine is nebulized by a pressurized gas or other nebulizing mechanism. The nebulized medicine is conveyed to the patient's lungs by the patient's respiration which may be assisted by a ventilator. By producing the aerosol of the liquid medicine at a location inside the patient's respiratory system, the nebulizing catheter provides for increased efficiency and control of the dosage of medicine being delivered. In further aspects of the nebulizing catheter apparatus and method, alternative tip constructions, flow pulsation patterns, centering devices, sensing devices, and aspiration features afford greater efficiency and control of aerosolized medicine dosage delivery.

Description

REFERENCE TO RELATED APPLICATION
• The present application incorporates by reference the copending application entitled “IMPROVED CATHETER SYSTEM FOR DELIVERY OF AEROSOLIZED MEDICINE FOR USE WITH PRESSURIZED PROPELLANT CANISTER” filed by the same inventor of the present application and on even date herewith.
BACKGROUND OF THE INVENTION
• The present invention relates to aerosol delivery of medication to the lungs and more particularly, the present invention relates to delivery systems for application of nebulized medication to the lungs with improved delivery rates, efficiencies, and control.
• Many types of medication can be administered to a patient via the respiratory tract. Medication delivered through the respiratory tract may be carried with a patient's inhalation breath as airborne particles (e.g. an aerosol or nebula) into the lungs where the medication can cross through the thin membrane of the alveoli and enter the patient's bloodstream. Delivery of medication via the respiratory tract may be preferred in many circumstances because medication delivered this way enters the bloodstream very rapidly. Delivery of medication to the lungs may also be preferred when the medication is used in a treatment of a disease or condition affecting the lungs in order to apply or target the medication as close as physically possible to the diseased area.
• Although delivery of medication via the respiratory tract has been used for many years, there are difficulties associated with prior systems that have limited their use and application. For example, conventional methods have provided for only limited medication delivery rates, efficiency, and control. Conventional methods for aerosol delivery result in a substantial portion of the medicine failing to be delivered to the lungs, and thereby possibly being wasted, or possibly being delivered to other parts of the body, e.g. the trachea.
• Aerosols in general are relatively short-lived and can settle out into larger particles or droplets relatively quickly. Aerosols can also impact each other or other objects, settle out as sediment, diffuse, or coalesce. Aerosol particles can also be subject to hydroscopic growth as they travel. Delivery of medicine as airborne particles requires conversion of the medicine, which may be in liquid form, to an aerosol followed relatively quickly by application of the aerosol to the respiratory tract. One such device that has been utilized for this purpose is an inhaler. Inhalers may atomize a liquid to form an aerosol which a person inhales via the mouth or nose. Inhalers typically provide only limited delivery of medication to the lungs since most of the medication is deposited on the linings of the respiratory tract. It is estimated that as little as 10-15% of an aerosol inhaled in this way reaches the alveoli.
• Aerosol delivery of a medication to a patient's respiratory tract also may be performed while the patient is intubated, i.e. when an endotracheal tube is positioned in the patient's trachea to assist in breathing. When an endotracheal tube is positioned in a patient, a proximal end of the endotracheal tube may be connected to a mechanical ventilator and the distal end is located in the trachea. An aerosol may be added to the airflow in the ventilator circuit of the endotracheal tube and carried by the patient's inhalation to the lungs. A significant amount of the aerosolized medication may be deposited inside the endotracheal tube and the delivery rate of the medicine to the lungs also remains relatively low and unpredictable.
• The low and unpredictable delivery rates of prior aerosol delivery systems have limited the types of medications that are delivered via the respiratory tract. For new medications that are relatively expensive, the amount of wasted medicine may be a significant cost factor in the price of the therapy. Therefore, it would be advantageous to increase the delivery rate or efficiency of a medicine delivered to the lungs.
• Another consideration is that some aerosols delivered to the lungs may have adverse side effects, e.g. radioactive tracers used for lung scans. Therefore, it would be advantageous to minimize the overall amount of medication delivered while maintaining the efficacy of the medication by providing the same or a greater amount of the medication to the desired site in the respiratory tract.
• Further, some medications may be more effective when delivered in certain particle sizes. Accordingly, an improved aerosol delivery system may provide for improved rates and efficiencies of delivery also taking into account the aerosol particle size.
• It may also be important to administer certain medications in specific, controlled dosages. The prior methods of aerosol delivery not only were inefficient, but also did not provide a reliable means to control precisely the dosage being delivered.
• It may also be advantageous to be able to target medication to a specific bronchus, or specific groups of bronchia, as desired, while avoiding delivery of medication to other portions of the lungs.
• Taking into account these and other considerations, aerosol delivery via the respiratory tract could become an even more widely used and effective means of medication delivery if the delivery rate and efficiency of the delivery could be improved.
SUMMARY OF THE INVENTION
• According to an aspect of the present invention, there is provided a method and apparatus for delivering a drug with control and efficiency to a patient via the patient's respiratory system. A nebulization catheter is positioned in the patient's respiratory system so that a distal end of the nebulization catheter is in the respiratory system and a proximal end is outside the body. According to a first aspect, the nebulization catheter may be used in conjunction with an endotracheal tube and preferably is removable from the endotracheal tube. The nebulization catheter conveys medicine in liquid form to the distal end at which location the medicine is nebulized by a pressurized gas or other nebulizing agent. The nebulized medicine is conveyed to the patient's lungs by the patient's respiration which may be assisted by a ventilator. The nebulizing catheter incorporates alternative constructions taking into account anatomical considerations and the properties of the medicine being nebulized to provide delivery of medicine with control and efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 shows an exploded view of a first embodiment of the present invention.
• FIG. 2 shows an assembled view of the embodiment ofFIG. 1.
• FIG. 2A is a sectional view of the nebulization catheter ofFIGS. 1 and 2.
• FIG. 3 is a plan view of an alternative embodiment of the endotracheal tube shown inFIGS. 1 and 2.
• FIG. 4 is a cross sectional view taken along the line a-a′ of the alternative embodiment of the endotracheal tube shown inFIG. 3 without the nebulizing catheter in place.
• FIG. 5 is a cross sectional view taken along the line b-b′ of the alternative embodiment of the endotracheal tube shown inFIG. 3 with the nebulizing catheter in place.
• FIG. 6 is a plan view of an embodiment of the nebulizing catheter ofFIGS. 1 and 2 shown in place in the trachea of a patient who is not intubated.
• FIG. 7 is a view similar to that ofFIG. 6 showing an alternative embodiment of the nebulization catheter.
• FIG. 8 is a cross section taken along lines a-a′ of the nebulization catheter ofFIG. 7.
• FIG. 9 is a view similar to that ofFIG. 7 showing an alternative embodiment of the nebulizing catheter shown inFIG. 7.
• FIG. 10 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 11 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 12 is a perspective view of an alternative embodiment ofFIG. 11 with the liquid lumen shown in a closed condition.
• FIG. 13 is a perspective view of the embodiment ofFIG. 12 with the liquid lumen shown in an open condition.
• FIG. 14 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 15 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 16 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 17 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 10.
• FIG. 18 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 19 is a sectional view of the distal end of the embodiment of the nebulization catheter shown inFIG. 18.
• FIG. 20 is a sectional view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 21 is a sectional view similar to that ofFIG. 20 showing an alternative embodiment of the nebulization catheter shown inFIG. 20.
• FIG. 22 is a perspective view partially in section of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 23 is a view similar to that ofFIG. 22, showing an alternative embodiment of the nebulization catheter shown inFIG. 22.
• FIG. 24 is a perspective view partially in section of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 25 is sectional view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 25.
• FIG. 26 is sectional view similar to that ofFIG. 25 showing the embodiment ofFIG. 25 during an exhalation stage of the patient.
• FIG. 27 is a perspective view of alternative embodiments of the nebulization catheter and endotracheal tube shown inFIG. 1.
• FIG. 28 is a perspective view of alternative embodiments of the nebulization catheter and endotracheal tube shown inFIG. 27.
• FIG. 29 is a perspective view of an alternative embodiment of the nebulization catheter shown inFIGS. 27 and 28.
• FIG. 30 is a perspective view of the embodiment of the nebulization catheter shown inFIG. 29 shown with an endotracheal tube in a patient's trachea.
• FIG. 31 is sectional view of a distal end and a diagrammatic view of a proximal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 32 is a cross section view of the embodiment of the nebulization catheter shown inFIG. 31 taken along the line a-a′.
• FIG. 33 is sectional view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 34 is sectional perspective view of a distal end of an alternative embodiment of the nebulization catheter and endotracheal tube shown inFIG. 2.
• FIG. 35 is sectional view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 37 is a cross section view of the embodiment of the nebulization catheter shown inFIG. 36 taken along the line a-a′.
• FIG. 38 is a perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIGS. 36 and 37.
• FIG. 39 is a perspective view of alternative embodiments of the nebulization catheter and endotracheal tube shown inFIGS. 37 and 38.
• FIG. 40 is sectional perspective view of a distal end of an alternative embodiment of the nebulization catheter shown inFIG. 1.
• FIG. 41 is a perspective view of alternative embodiments of the nebulization catheter and endotracheal tube ofFIG. 1 shown in a patient's trachea.
• FIG. 42 is a side view of an another embodiment of the nebulization catheter ofFIG. 1 showing an alternative centering device.
• FIG. 43 is a side view of an another embodiment of the nebulization catheter ofFIG. 1 showing another alternative centering device.
• FIG. 44 is a side view of an another embodiment of the nebulization catheter ofFIG. 1 showing yet another alternative centering device.
• FIG. 45 is a side view of the embodiment ofFIG. 44 shown in another stage of operation.
• FIG. 46 is a side view of a distal end of a nebulization catheter positioned in a patient's trachea illustrating an undesirable condition.
• FIG. 47 is a perspective view similar to that ofFIG. 40 of alternative embodiments of the nebulization catheter and endotracheal addressing the condition shown inFIG. 46.
• FIG. 48 shows an alternative embodiment of the nebulizing catheter and endotracheal tube ofFIG. 47 positioned in a patient's trachea.
• FIG. 49 shows an alternative embodiment of the nebulizing catheter ofFIG. 6.
• FIG. 50 is a diagram illustrating an embodiment of a drug reservoir and pressurization assembly that can be utilized in connection with the embodiment of the nebulization catheter ofFIG. 1.
• FIG. 51 is a diagram similar to that ofFIG. 50 illustrating an alternative embodiment of the drug reservoir and pressurization assembly.
• FIG. 52 is a sectional view along line c-c′ ofFIG. 51.
• FIG. 53 is a side view of an alternative embodiment ofFIG. 1 including an optional humidification and heating arrangement.
• FIG. 54 is a side view of a flow control system used in connection with the embodiment ofFIG. 1 used for pressuring the liquid flow lumen.
• FIG. 55 is a view similar to that ofFIG. 54 showing the flow control system ofFIG. 54 in another stage of operation.
• FIG. 56 is a perspective view of an alternative embodiment of the present invention illustrating an alternative method of use.
• FIG. 57 is a perspective view illustrating an entire nebulization catheter system including sensors.
• FIG. 58 shows a sectional view of an embodiment of a nebulizing catheter including a sensor.
• FIG. 59 shows an alternative embodiment of the nebulizing catheter shown inFIG. 58.
• FIG. 60 is a sectional view of a distal end of an alternative embodiment of the nebulizing catheter ofFIG. 1.
• FIG. 61 is a sectional view of an embodiment of the present invention that incorporates a baffle to generate a secondary aerosol.
• FIG. 62 is a sectional view of another embodiment of the present invention that incorporates a baffle to generate a secondary aerosol.
• FIG. 63 is a sectional view of yet another embodiment of the present invention that incorporates a baffle to generate a secondary aerosol.
• FIG. 64 is a sectional view of still another embodiment of the present invention that incorporates a baffle to generate a secondary aerosol.
• FIG. 65 is a diagram illustrating an embodiment of the present invention that incorporates a pressurized drug/propellant mixture canister.
• FIG. 66 is a side view of an embodiment of a nebulizing catheter incorporated into of a suction catheter.
• FIG. 67 is a detailed sectional view of the tip portion of the suction catheter—nebulizing catheter embodiment ofFIG. 66.
• FIG. 68 is a perspective view of the embodiment ofFIG. 66 positioned in an endotracheal tube in a patient's respiratory system.
• FIG. 69 is cross sectional view of the embodiment ofFIG. 66 taken along lines a-a′.
• FIG. 70 is a perspective view similar toFIG. 68 showing the suction catheter advanced during an further stage of operation.
• FIG. 71 is a side view of a proximal end of an endotracheal tube illustrating an arrangement of receiving a suction catheter and a nebulization catheter into the endotracheal tube.
• FIG. 72 is an alternative embodiment of the arrangement shown inFIG. 71.
• FIG. 73 is another alternative embodiment of the arrangement shown inFIG. 71.
• FIG. 74 is another embodiment of a suction catheter incorporating aerosol delivery by nebulization.
• FIG. 75 is still another embodiment of a suction catheter incorporating aerosol delivery by nebulization.
• FIG. 76 is a sectional view of a distal end of an embodiment of a nebulizing catheter also incorporating a vibrating tip.
• FIG. 77 is a sectional view of another embodiment of the nebulizing catheter incorporating micropulsation of the liquid supply.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
• The present invention provides for the controlled and efficient delivery of an aerosolized medication to the lungs of a patient by nebulization of a medication at a distal end of a catheter positioned in the respiratory tract. Throughout this specification and these claims, the nebulization catheter is described as used for the delivery of medicine or medication. It is intended that the terms “medication”, “medicine”, and “drug” should be understood to include other agents that can be delivered to the lungs for diagnostic or therapeutic purposes, such as tracers, or for humidification.
I. Nebulizing Catheter—Basic Configuration
• Referring toFIGS. 1 and 2, there is depicted a first embodiment of the present invention.FIGS. 1 and 2 show anendotracheal tube10 which may be a conventional endotracheal tube. Theendotracheal tube10 may have aninflatable cuff12 located close to its distal end to facilitate positioning thetube10 in the patient's trachea, or alternatively theendotracheal tube10 may be of a type without an inflatable cuff. Theinflatable cuff12 is connected via a separate inflation lumen in theendotracheal tube10 to aproximal fitting13 for connection to a source of inflating gas (not shown). Theendotracheal tube10 has a proximal end connected to amanifold fitting14. The fitting14 has aport15 suitably adapted for connection to a ventilator circuit (not shown). The fitting14 also includes anotherport16 that permits the introduction of a separate catheter into the endotracheal tube from the proximal end. The fitting14 may be similar in construction to the elbow fitting described in U.S. Pat. No. 5,078,131 (Foley), the entire disclosure of which is incorporated herein by reference. InFIG. 1, anebulizing catheter20 is located in a position ready to be inserted into aventilation lumen22 of theendotracheal tube10 via theproximal fitting14. InFIG. 2, thenebulizing catheter20 is positioned fully in theendotracheal tube10 with a proximal end extending out of theport16 of theproximal fitting14.
• At a proximal end of thenebulizing catheter20 is a manifold24. The manifold24 includes at least agas port28 and a liquid (medicine)port32. Theseports28 and32 may include conventional attaching means, such as luer lock type fittings. In addition, theseports28 and32 may also include closure caps31 that may be used to close the ports when not in use and may be popped open when connection to a gas source or a liquid source is desired. Optionally, the manifold24 may also include a filter located in-line with either thegas port28 or theliquid port32 or both ports to prevent lumen blockages by particulate matter. Thenebulization catheter20 includes at least two separate lumens (as shown inFIG. 2A). Afirst lumen33 is used for conveyance of a liquid medicine and communicates with theport32 on themanifold24. Theother lumen34 is used for conveyance of a pressurized gas and communicates with theport28 on themanifold24. Theliquid lumen33 communicates with a distalliquid orifice35 and thegas lumen34 communicates with adistal gas orifice36 near adistal end37 of thenebulization catheter20. Thedistal opening36 of thepressurized gas lumen34 directs pressurized gas across the distalliquid lumen opening35 thereby nebulizing the liquid medication so that it can be delivered to the patient's lungs. The distalliquid orifice35 may be open or may be provided with a porous material plug or a sponge-like or felt-like material plug which may extend slightly from the distal orifice and that allows liquid to flow from the orifice yet reduces the likelihood of liquid drooling from the tip.
• The length of thenebulization catheter20 should be sufficient so that thedistal end37 can be located in the desired location in the respiratory system while the proximal end (i.e., including the manifold24) is accessible to the physician or other medical personnel for connection to suitable gas and liquid supplies external of the patient's body. Accordingly, the length of the nebulization catheter is dependent upon the size of the patient in which it is being used. A shorter nebulization catheter may be preferred in smaller patients, such as infants or children, and a longer nebulization catheter may be needed for adults. For example, a nebulization catheter suitable for adults may have a length of approximately 45 cm. In one embodiment, approximately 30 cm of thenebulizing catheter20 is in theendotracheal tube10. The nebulization catheter may be introduced into the respiratory system through a patient's mouth or via a tracheostomy tube or through the nasal passages. The nebulization catheter may also be used to deliver an aerosol to a patient's nasal passages in which case the length may be correspondingly shorter.
• As explained in more detail below, the generation of an aerosol plume with the desired geometry, particle size, velocity, etc., requires that the distal gas and liquid orifices have small dimensions. Also as explained below, thedistal gas orifice36 and the distalliquid orifice35 should be in close proximity to each other in order to produce an aerosol with the desired characteristics and efficiency. Further, in order to provide the desired medicine delivery rates and to operate with reasonably available pressure sources, the liquid and gas lumens in the nebulizing catheter should be as large as possible, consistent with anatomical requirements. Accordingly, thenebulization catheter20 has a multiple stage construction with a larger shaft size and larger lumens in a main shaft section and a smaller shaft size and smaller lumens in a distal shaft section.
• As shown inFIG. 2A, thenebulizing catheter20 is composed of ashaft38 having amain section39 and adistal section40. In themain shaft section39 of the nebulization catheter, the liquid andgas lumens33 and34 have a larger size than in thedistal shaft section40. For example, in themain shaft section39, the liquid and gas lumens each may have an I.D. of approximately 0.010 to 0.030 inches. At a most proximal end where themain shaft section39 connects to the manifold24, the lumens may be even larger. In thedistal shaft section40, the liquid and gas lumens taper to a much smaller I.D. with the liquid lumen approximately 0.002 to 0.008 inches or even smaller and the gas lumen 0.002 to 0.020 inches. In a preferred embodiment, the liquid andgas orifices35 and36 are less than 0.125 inches apart, and more preferably less than 0.030 inches apart, and in a most preferred embodiment less than 0.001 inches apart. In a nebulizing catheter having an overall length of 45 cm, themain shaft section39 may be approximately 25 cm and thedistal shaft section40 may be approximately 20 cm. Also, although the liquid and gas lumens are shown to be side by side inFIG. 2A, they may also be constructed to have an coaxial or other arrangement. Further, although themain shaft section39 is shown to be of a uniform diameter and profile, alternatively it may also have a tapered diameter and profile such that theentire shaft38 is tapered along its length.
• In a first preferred embodiment of the invention, as shown inFIGS. 1 and 2, thenebulizing catheter20 is removable, and replaceable with respect to theendotracheal tube10. This provides several significant advantages. First, thenebulizing catheter20 may be specifically adapted and chosen to have the desired operating characteristics suitable for delivery of the particular medication being administered to the patient. In addition, the fact that thenebulizing tube20 is removable and replaceable provides versatility and flexibility regarding the therapy and dosage regime that can be chosen by the physician. For example, a decision by the physician whether to deliver a medication to the respiratory tract, and the selection of the type and dosage of the medication to be delivered, need not be made by the physician until after the endotracheal tube is already in place in the patient. When the physician determines the proper type of medication to the delivered to the patient via the respiratory tract, the appropriate nebulization catheter can be selected and inserted into the endotracheal tube. Further, thenebulizing catheter20 can be removed after it is used and therefore it is not necessary for the nebulization catheter to be left in the patient and occupy space in the patient's respiratory tract or in theendotracheal tube10 when it is no longer needed. In addition, the decision regarding the proper type of medication can be revisited again at any time after the endotracheal tube is in place. If a different type of nebulizing catheter is required, such as for sterility purposes, the endotracheal tube need not be replaced as well.
• Another advantage of providing the nebulization catheter as a separate, removable device is that it can be accommodated in a variety of other instruments and/or devices. For example, the nebulization catheter ofFIGS. 1-5 is shown used in an endotracheal tube; however, the nebulization catheter could also be positioned inside of a bronchoscope, such as in a working channel of a bronchoscope. The nebulizing catheter could be positioned in any instrument that is positioned in the respiratory tract and that can accommodate the nebulizing catheter size.
• The nebulizing catheter may be provided withradiopaque markings41 to facilitate positioning and placement. Theradiopaque markings41 may be provided by radiopaque bands of metal or heat shrunk bands of doped radiopaque plastic that are attached to the nebulizing catheter, or alternatively the markings may be provided by doping the plastic material of the nebulizing catheter with a radiopaque material. Alternatively, a radiopaque dye may be added to the liquid being delivered by the nebulization catheter to assist observation. Themarkings41 may be graduated to facilitate recognition, or alternatively may extend over a portion or all of the nebulizing catheter. In still a further embodiment, the markings may be formed of a ultrasonic reflectors, e.g. textured material, that are visible by means of ultrasonic imaging. The nebulization catheter may also include astripe43 extending along a side of the shaft (as shown inFIGS. 5 and 6). Thestripe43 may be radiopaque or ultrasonically visible and may be used to determine the rotational orientation of the shaft. The stripe may be formed by a coextrusion process or by embedding a wire in the wall of the nebulization catheter.
• One method that may be employed to facilitate positioning of the nebulization catheter is to monitor the pressure at the distal end of the endotracheal tube as the nebulization catheter is being advanced. Monitoring the pressure at the end of the endotracheal tube may be accomplished through one of the endotracheal tube lumens. The gas source connected to the proximal end of the nebulization catheter may be operated so as to expel a gas from the distal end of the nebulization catheter as it is being advanced. The gas being expelled from the distal end of the nebulization catheter affects the pressure being detected through the endotracheal tube. When the distal end of the nebulization catheter passes the distal end of the endotracheal tube, the pressure being measured through the endotracheal tube abruptly changes thereby providing a clear indication of the location of the distal end of the nebulization catheter relative to the endotracheal tube.
• The nebulizing catheter may also include asafety stop44 located along a proximal portion that engages a portion of the endotracheal tube proximal portion or a fitting thereon, as shown inFIG. 2. Thesafety stop44 ensures that the distal end of thenebulizing catheter20 is correctly positioned with respect to thedistal end46 of theendotracheal tube10 and prevents thedistal end37 of the nebulizing catheter from extending too far into the trachea. In addition to thesafety stop44, the proximal portion of thenebulizing catheter20 may also have graduatedmarkings48 that would be visible to the physician handling the proximal end of the nebulizing catheter to enable a determination of the position of thedistal end37 of thenebulizing catheter20 relative to adistal end46 of theendotracheal tube10.
• Thenebulizing catheter20 may also include acritical orifice49 located at a proximal portion of the nebulizing catheter. Thecritical orifice49 may be formed by a small critical opening located in line with thegas pressurization lumen34 of the nebulizing catheter shaft close to themanifold24. Thecritical orifice49 is sized so that if the nebulization catheter is supplied with a flow in excess of its designed operating flow, the critical orifice will allow only the designed operating flow to pass through to the distal gas orifice. Alternatively, a safety valve may be located in the proximal portion of the catheter shaft. The safety valve would be designed to open if supplied with an excess of pressure.
• In addition, the nebulizing catheter may include a centeringdevice50. The centeringdevice50 is located close to a distal end of the nebulizing catheter shaft and helps to center and align the distal end of the nebulizing catheter for improved performance, as explained in more detail below.
• According to one embodiment, theremovable nebulization catheter20 is enclosed in astorage sheath51. Thestorage sheath51 may be similar to the type of storage sheaths used in conjunction with suction catheters. The storage sheath is preferably flexible, collapsible, or extendable to accommodate insertion of the catheter. Thestorage sheath51 may be connected to the fitting14. Thestorage sheath51 can be used to receive thenebulizing catheter20 when it is being withdrawn from theendotracheal tube10. Thestorage sheath51 is sealed and can maintain the withdrawn nebulizing catheter in an isolated condition when it is temporarily removed from the patient's respiratory system. Thestorage sheath51 also allows the physician to re-insert the nebulization catheter into the patient. In this manner, the nebulization catheter can be reused in a limited way with respect to a patient and can be maintained in a sterile condition while withdrawn from the patient. Thestorage sheath51 may have adistal sleeve53 that can slide along the shaft of the nebulization catheter so that the nebulization catheter may be advanced into the ventilation lumen of the endotracheal tube or withdrawn into thestorage sheath51. Thesleeve53 may have a closefitting seal55 located therein which is designed to clean and/or wash the nebulization catheter when it is withdrawn into the sheath. Alternatively, a cleaningseal55 may be located in theport16 ofmanifold fitting14.
• Another feature that may be used in conjunction with certain procedures is radiation shielding. Some procedures for which the nebulization catheter may be used may involve the delivery of radioactive agents, e.g. tracers to the lungs. To minimize exposure to radioactive materials, the nebulizing catheter may be provided with shielding over all or a significant portion of the overall length of the catheter. Shielding may also be provided at the liquid source reservoir.
• The nebulizing catheter is preferably constructed of a biocompatible, chemically resistant polymer in order that it is suitable for use with a wide variety of drugs. The catheter shaft is preferably clear to allow visualization of contaminants or blockages of the interior lumens. Also, the portion of the catheter shaft that forms theliquid lumen33 is preferably composed of a relatively non-compliant material. In a present embodiment, the catheter shaft is composed of a polymer such as polyethylene or nylon. A polymer tubing is extruded with multiple lumens to be used for the separate gas and liquid lumens. In order to produce a nebulization catheter with the tapereddistal section40, a multi-lumen extruded tubing may be drawn down in a portion thereof to form the tapereddistal section40. The draw down ratio may be selected to provide a nebulization catheter shaft with the desired dimensions. The draw down process serves to make the lumens smaller in size distally as well as closer together while maintaining the proximal cross sectional profile of the multi-lumen tubing. The larger proximal profile provides for greater pushability in the catheter shaft and facilitates manufacturing by making the manifold connection easier. The draw down ratio used on the extruded polymer tubing may be on the order of 2-to-1, 5-to-1, or even as high as 20-to-1 or higher. Prior to drawing down, the extruded polymer tubing is preferably exposed to high energy radiation to crosslink the polymer molecules to provide for favorable material properties, such as the ability to maintain orifice dimensions and tolerances. The radiation may have an energy of approximately 10-700 kgy. After the crosslinking step, the tubing is heated to its transition temperature between its melt and glass states, and is drawn down by the desired ratio.
• As an alternative to drawing down the extruded tubing, the multi-stage nebulization catheter shaft may be formed by a bubble extrusion process wherein the desired tapered distal section is formed directly in the shaft as it is being extruded. Again, this process may be used for manufacturing efficiency and convenience. As another alternative, the multi-stage shaft may be formed by a combination of both bubble extrusion and drawing down. Still another alternative for forming the desired tapered profile for the nebulizing catheter shaft is to use a material that can be cold drawn in order to cause a sharp neck down in diameter, such as a linear low density polyethylene. Although the process for forming the tubing is particularly suited for producing a nebulization catheter shaft for use in delivering medicine to the respiratory tract, it should be understood that the process could be used to produce aerosol nozzles for non-medical purposes as well.
• Alternatively, all or part of the nebulization catheter shaft can be molded, especially at locations where close tolerances are preferred such as at the tip.
• After the shaft is formed with the desired stages, it is cut and assembled with the other components of the nebulizing catheter. Although the nebulization catheter is preferably constructed of a polymer, in an alternative embodiment it could be formed of other materials such as a metal, especially a malleable metal to facilitate drawing, shaping or forming orifices. During the manufacturing process, the nebulizing catheter may be pre-sterilized by means of a conventional process, such as a gamma ray or electron beam. The nebulizing catheter is preferably disposable after use with a single patient, but may be reused to a limited extent with a single patient provided that contamination can be prevented such as through the use of thesheath51, described above. The nebulizing catheter shaft preferably possesses torsional rigidity so that rotation of the proximal end is transmitted at a 1:1 ratio to the distal end. The nebulizing catheter may also be provided with an antiseptic coating.
• Drug delivery rates are closely related to the particle size with larger particles providing greater delivery rates. The embodiments of the nebulization catheter described herein have the capability of generating particle distributions with a GSD between 2 and 2.5. Drug delivery rates in a range between approximately 5 and 1000 mg (0.005-1.0 ml) per minute may be obtained. A variety of particle size distributions can be generated at most flow rates through selection of the catheter type and aerosol volume output. An aerosol of this type can be generated with the nebulization catheter using a gas flow rate as low as 0.1 liter/minute.
• There are a number of factors that affect the particle size generated. These factors include: (1) the gas orifice diameter, (2) the liquid orifice diameter, (3) the liquid delivery tube outer diameter and geometry, (4) the distance between the gas and liquid orifices, (5) the rate of gas delivery, and (6) the pressure of the liquid. Of course, the size of the solid particles in suspension, if present, in the liquid are a defining aspect of the aerosol particle size generated. In addition, there are other factors that affect the aerosol particle size such as the characteristics of the liquid, e.g. viscosity, suspension, surface tension and the composition of the driving gas, however, these factors affect the particle size of the aerosol generated to a lesser degree. By selectively varying these parameters, the size and size distribution of the aerosol particles can be changed from less than a micron to at least 10 microns.
• The embodiments of the present invention, described herein are suitable for delivery of an aerosol by nebulization with a volumetric particle size distribution comparable to other nebulization systems. Further, by generating an aerosol at a location in the trachea or even deeper in the bronchi, impaction losses in tract can be avoided. By reducing impaction losses, it may be acceptable to use larger particle sizes (e.g. greater than 5 microns). The combination of lower impaction losses and larger particle sizes may provide higher effective delivery rates than prior systems. Reducing impaction losses would enable an embodiment of the nebulization catheter to provide acceptable delivery rates with aerosol particle sizes greater than 5 microns.
• Referring toFIGS. 3-5, there is depicted a further embodiment of the present invention. According to the embodiment ofFIGS. 3-5, there is provided anendotracheal tube52 and a nebulizing catheter. The nebulizing catheter may be similar to thenebulizing catheter20 shown inFIGS. 1 through 3. In the embodiment ofFIGS. 3-5, theendotracheal tube52 has anauxiliary lumen56 in addition to itsmain ventilation lumen60. Some endotracheal tubes provide auxiliary lumens through the shaft wall. Theauxiliary lumen56 is preferably sized and adapted to receive theseparate nebulization catheter20. This embodiment provides many of the same advantages as the embodiment ofFIGS. 1 through 3. In addition, in this embodiment, theauxiliary lumen56 may be provided with adistal aperture64 that facilitates locating and aligning the distal end of37 thenebulizing catheter20 at a desired location for nebulization purposes.
• In the embodiments of the invention shown inFIGS. 1-5, thenebulizing catheter20 is shown used in conjunction with an endotracheal tube either of aconventional type10, as inFIGS. 1 and 2, or of a type especially designed for use with the nebulizing catheter such asendotracheal tube52 ofFIGS. 3-5. Thenebulizing catheter20 according to an embodiment of the present invention may also be used without a separate endotracheal tube, i.e. the nebulizing catheter may be used on a patient who is not intubated, as shown inFIG. 6. If used on a spontaneously breathing patient (without an endotracheal tube), the patient should be properly anesthetized and/or that the airway passage of the patient be topically anesthetized. Thenebulizing catheter20 is positioned in the respiratory system of a patient directed past thecarina68 into one of thebronchi72 of the lungs. Alternatively, thenebulizing catheter20 may also be positioned proximal of the carina in the trachea, as desired. Embodiments of the nebulizing catheter may also be used on patients who have had tracheotomies or who have tracheotomy tubes.
• In the embodiment ofFIG. 6, a guidingsheath73 is used. The guidingsheath73 is used to help position thenebulizing catheter20 in the respiratory system of the patient. The guidingsheath73 includes a lumen through which thenebulization catheter20 can be advanced into a desired bronchi site. To facilitate positioning the nebulization catheter, the guidingsheath73 may have a pre-shaped distal end to facilitate locating the sheath in the desired airway passage. Alternatively, the guidingsheath73 may have a distal end that can be formed into a desired shape by the physician just prior to insertion. The guidingsheath73 differs from theendotracheal tube10 ofFIGS. 1-5 in that it may have a smaller outside diameter so that it can be advanced into smaller airway passages deep in the patient's bronchi past thecarina68. The inside diameter of thesheath73 is large enough to advance the nebulization catheter. The guidingsheath73 is particularly useful when thenebulization catheter20 is being located deep in the patient's lungs, or when the nebulization catheter is used without an endotracheal tube. The guidingsheath73 may also be used with an endotracheal tube through the ventilation lumen thereof. The guiding sheath is preferably composed of a torsionally rigid material so that the distal end of the guiding sheath is responsive to rotation at the proximal end.
• Referring toFIGS. 7 and 8, there is shown another embodiment of the nebulizing catheter. In the embodiment ofFIG. 7, anebulizing catheter76 includes anocclusion balloon80 located on a distal exterior surface of the nebulizingcatheter shaft body84. Thenebulizing catheter76 may include anadditional lumen88, as shown inFIG. 8, located therethrough and communicating with the interior of theballoon80 for providing inflation fluid, i.e. preferably gas, to expand theocclusion balloon80. Thislumen88 for inflation fluid is in addition to thelumens92 and96 in thecatheter shaft84 used for conveyance of the liquid medicine and pressurized gas, respectively. Theocclusion balloon80 may be used to position the nebulizing catheter in the appropriaterespiratory branch100, center the nebulizing catheter tip for proper orientation, and isolate a particular bronchus, as needed. The embodiment of thenebulizing catheter76 shown inFIG. 7 may be used with an endotracheal tube in a manner similar to that shown inFIGS. 1-3, or alternatively it may be used without a separated endotracheal tube, similar to the embodiment ofFIG. 6. When used without a separate endotracheal tube, thenebulizing catheter76 ofFIG. 7 could be used for the purpose of selective ventilation of one of the bronchi of the lungs even without providing aerosolization. Alternatively, thenebulization catheter76 could provide aerosolization on an intermittent basis with continuous ventilation. If the nebulization catheter is used to provide ventilation as well as aerosolized medication, the ventilation regime can be tailored to maximize aerosol transport.
• In addition, to further facilitate positioning and placement, thenebulizing catheter76 may be used with aguide wire104. The nebulizing catheter may be provided with a separateguide wire lumen108 to receive theguide wire104, or alternatively, the guide wire may use one of the existing lumens that is also used for either the pressurized gas or the liquid or alternatively the guide wire may be incorporated and fixed into the nebulizing catheter so that it is non-removable. The guide wire, whether of the removable type of the type that is fixed to the nebulizing catheter, may also be steerable, i.e. so that it can be guided from a proximal end to access the appropriate location in the lungs. The steering apparatus may utilize selective tensioning of a pull wire, etc. from a proximal end. If the guide wire is of the separate removable type, it may be withdrawn after it has been used to position the distal tip of the nebulizing catheter so as to avoid interfering with aerosol delivery. In addition, the distal tip of the guide wire or nebulization catheter may be pre-shaped or shapable by the physician so as to impart an appropriate curve or bend to facilitate access to the desired airway.
• Referring toFIG. 9, there is shown another embodiment of a nebulizing catheter ofFIG. 7. The embodiment ofFIG. 9 is similar to the embodiment ofFIG. 7 with the exception that theseparate guide wire104 is received in aloop106 located close to a distal end of thenebulizing catheter76. Proximal of theloop106, theguide wire104 is positioned adjacent to theshaft84 of thenebulizing catheter76. Instead of aloop106, the guide wire may be received in a short lumen located in the distal end of the nebulizing catheter.
II. Generation of Aerosol Plume
• It has been discovered that the shape of the aerosol plume can be a significant factor affecting the rate and efficacy of the delivery of medication by an aerosol. In general, it is preferable to generate an aerosol that has a shape that minimizes particle impaction near the distal tip of the nebulizing catheter, given the location of the tip and the airflow conditions around it. For example, if the aerosol plume is wide, a portion of the drug may be wasted in the end of the endotracheal tube or on the wall of the trachea or other airway passage. On the other hand, if the plume is too narrow or the velocity too high, a portion of the drug may impact excessively on the patient's carina. In general, a low aerosol particle velocity is desirable. One of the reasons for this is to avoid impacting the carina with the discharge of high velocity aerosol particles. In addition, it is also generally desirable to have as wide an aerosol plume as possible while avoiding significant impact with the walls of either the endotracheal tube or the respiratory airway passage. The effects of aerosol plume velocity and geometry are related to anatomical factors. In some circumstances, e.g. away from the carina, a narrow, fast aerosol plume may be preferable to a slower, wider plume.
• Regarding the embodiments described below, certain of the embodiments may be preferable from the standpoint of versatility, i.e. they may be able to deliver a variety of medications having different viscosities, suspensions, surface tensions, etc. Others of the embodiments may be more suitable for the delivery of specific types of medications or the delivery of particles of certain sizes.
• Referring toFIG. 10, there is shown a tip configuration for anebulizing catheter112. Thenebulizing catheter112 may be either a stand alone-type of nebulizing catheter, similar to the catheters shown inFIGS. 6 and 10, or may be incorporated into an endotracheal tube either removably, as inFIGS. 1-5, or non-removably. In the embodiment ofFIG. 10, thenebulizing catheter112 has a coaxial configuration. Specifically, thenebulizing catheter112 includes an outertubular member116 defining alumen120 and an innertubular member124 also defining alumen128. The innertubular member124 is located in thelumen120 of the outertubular member116. According to the embodiment shownFIG. 6, pressurized gas is conveyed in the annular region defined between the inner and outer tubular members. Liquid medication is conveyed in thelumen128 of theinner member124. As shown in the embodiment ofFIG. 10, a distal end of the outertubular member116 is approximately adjacent to a distal end of the innertubular member124. In the embodiment ofFIG. 10, the outertubular member116 has an O.D. of approximately 0.008 inches and an I.D. of approximately 0.006 inches. The innertubular member124 has an O.D. of approximately 0.003 inches and I.D. of approximately 0.0015 inches. Both the innertubular member124 and the outertubular member116 have larger dimensions proximal of the distal tip portion. Along a main shaft portion proximal of the distal tip, the outertubular member116 has an O.D. of approximately 0.115 inches and an I.D. of 0.080 inches and the innertubular member124 has an O.D. of approximately 0.060 inches and an I.D. of 0.050 inches.
• The embodiment ofFIG. 11 shows a tip of anebulizing catheter132. This embodiment is similar to the embodiment ofFIG. 10. Thetip133 is formed with a plurality of lumens terminating in a plurality of orifices. Aninner lumen134 is used to convey the liquid medication and the surroundinglumens135 convey the pressurized gas used to nebulize the liquid. This embodiment has the advantage that the orifice of theliquid lumen134 is centered with a fixed spacing relative to the orifices of thegas lumens135 around it. In the embodiment ofFIG. 11, the multiple lumen construction may extend all the way back to the proximal end of thenebulizing catheter132 or alternatively, only a distal segment may have the multiple gas lumen configuration in which case the pressurized gas may be conveyed through a single proximal lumen that connects to the multiple distal lumens.
• FIGS. 12 and 13 show analternative embodiment136 of the multiple lumen nebulization catheter inFIG. 11. The embodiment inFIGS. 12 and 13 is useful when it is desired to provide the aerosol medicine with a pulsed delivery. The pulsed delivery may be timed to coincide with the inhalation of the patient so that aerosol is not wasted when the patient is exhaling. A potential drawback with pulsed delivery is that the aerosol may drool from the tip of the nebulizing catheter when the pressure being applied to the liquid is reduced to effect the pulsation. To avoid this potential problem, thenebulizing catheter136 provides for closure of the liquid lumen when the pressure being applied to it is reduced. As in the previously described embodiment, thenebulization catheter136 inFIGS. 13 and 14, has a centrally locatedlumen137 for delivery of a liquid medicine and a plurality oflumens138 surrounding thecentral lumen137 for conveyance of a pressurized gas to nebulize the liquid at thedistal orifice139. In this embodiment, thecatheter137 is formed of a low compliance material in the outer wall area140 and a relatively high compliance material in thearea141 surrounding the centrally locatedliquid lumen137. These differing compliance characteristics may be formed in the catheter shaft by coextruding a single tube with different materials. When using the embodiment ofFIGS. 12 and 13, a constant, relatively high pressure is applied to the gas in thelumens138. Liquid medicine is delivered via thelumen137 and pressure pulses are applied to the liquid from an external delivery source, such as a pump. When the pressure in theliquid lumen137 is low, the high pressure in thegas lumens138 deform the compliantinner material141 thereby compressing theliquid lumen137 and closing it off, as shown inFIG. 12. When a pressure pulse is applied to the liquid in thelumen137, it overcomes the compressive forces from thegas lumens138 allowing thelumen137 to open and permitting the liquid medicine to be delivered to thedistal orifice139 to be nebulized, as shown inFIG. 13. In this manner, the embodiment ofFIGS. 12 and 13 provides for pulsed liquid nebulization with reduced possibility of drooling.
• Another feature shown inFIGS. 11 and 12 is a porous plug142 located in theliquid orifice139. This porous plug may be made of a felt-like material and may assist in the production of fine aerosol particles.
• The embodiment ofFIG. 14 shows a distal tip of another embodiment of the nebulizing catheter. In this embodiment, anebulizing catheter148 includes amain shaft section152 and adistal shaft section156. Thedistal shaft section156 is tapered to atip160. At thetip160, aliquid orifice164 is surrounded by a plurality ofgas orifices168. In a preferred embodiment, there are six gas lumens terminating in the sixorifices168. In this embodiment, theliquid orifice164 has a diameter of approximately 0.002 inches and thegas orifices168 each have a diameter of approximately 0.002 inches. This embodiment is similar to the embodiment ofFIG. 11 except that thedistal section156 provides for a reduction in the tip size and corresponding modification of the nebulization plume properties. This reduction is preferable as it provides a smaller orifice size.
• The embodiment ofFIG. 15 shows a distal portion of anebulizing catheter172. In this embodiment, the nebulizing catheter includes aproximal shaft section176 and adistal shaft section180. Theproximal shaft section176 includes a plurality oflumens184. Acentral one188 of the plurality oflumens184 is used to convey liquid medicine and the remainder of the lumens surrounding it are used to convey gas. Thedistal shaft section180 connects to the distal end of theproximal shaft section176 and defines atapered cavity192 between the distal end of theproximal shaft section176 and adistal orifice196. At least one of the plurality oflumens184 is used to convey a pressurized gas that is discharged into thecavity192. Atubular extension200 extends the liquid lumen through thecavity192 and distally out theorifice196. Theorifice196 is sized to provide an annular region around thetubular extension200 to permit the pressurized gas to flow through to nebulize the liquid medication that exits adistal orifice204 of thetubular extension200. In a preferred embodiment, thedistal shaft section180 is composed of stainless steel and the orifice has an I.D. of 0.025 inches. Thetubular extension200 has an O.D. of 0.012 inches and an I.D. of 0.007 inches. This embodiment has the advantage of combining a relatively small distal profile with a relatively large proximal flow channel. Another advantage of this embodiment it that it provides for a balanced airflow around theliquid orifice204.
• FIG. 16 shows yet another embodiment for a tip for a nebulizing catheter. InFIG. 16, anebulizing catheter208 has a coaxial configuration similar to the embodiment ofFIG. 10 (although it could also have a configuration similar to that of other coaxial embodiments, e.g.FIG. 11,14, or15). InFIG. 16, a thin solid wire or filament212 is located at a distal end of aliquid orifice216 located at a distal end of an innertubular member220. The tapered wire212 extends a short distance distally from the distal end of the innertubular member220. The tapered wire212 is located with respect to the liquid orifice212 so that liquid being conveyed through theinner member220 continues to flow distally of thedistal orifice216 along the wire212, i.e. adhering to it by surface tension. Of course, once the liquid reaches a distal tip224 of the wire212, it is entrained and nebulized by the gas flow from the annular region228 defined between the innertubular member220 and an outertubular member232. As mentioned above, one of the factors that affects the nebulization plume particle size and geometry is the size of the distal liquid orifice. In general, a smaller liquid orifice produces smaller particles and a narrow aerosol plume cone. In the embodiment ofFIG. 16, the thin wire212 carries only a small amount of liquid along it so that it functions similarly to an orifice of a very small size. Accordingly, the embodiment ofFIG. 16 has the potential for producing an aerosol of very fine particles. In the embodiment ofFIG. 16, the outer tubular member has an I.D. of approximately 0.020 inches. The inner tubular member has an I.D. of approximately 0.006 inches. The thin wire has an O.D. of approximately 0.002 inches. The wire or filament212 may be composed of a metal wire or a polymer wire, such as a polyolefin fiber like Spectra fiber. Alternatively, the filament212 may be composed of a porous or felt-like material, such as nylon or Porex, in which case it may be wider in diameter than if made of a solid material.
• FIG. 17 shows an alternative embodiment of the embodiment ofFIG. 16. InFIG. 17, there is a distal end of anebulizing catheter236 having a tapered wire orfilament240 located at the distal end of a lumen of an innertubular member244. The taperedwire240 in this embodiment has a curved shape that is designed to whip in a spiral when it is in a flow of air. In the embodiment ofFIG. 17, when pressurized gas flows through theannular region248, it causes the taperedwire240 to whip around with a spiral motion. The length of thewire240 is chosen so that it does not impact the wall of the trachea or other airway passage when it moves in a spiral whipping motion. In one embodiment, thewire240 has a length of approximately 1-2 mm. The taperedwire240 carries the liquid out to its tip for entrainment, and the nebulization plume is formed with a conical shape. The width of the plume may be changed by changing the length of thefilament240. The speed of the spiral motion can be controlled by appropriate selection of wire stiffness and air foil shape. In general, the spiral plume produced by the embodiment ofFIG. 17 will be wider than the embodiment ofFIG. 16 and have less forward velocity. Both these characteristics may be favored in a nebulization catheter.
• FIGS. 18 and 19 show another embodiment of the nebulization catheter. In this embodiment, anebulization catheter252 has a coaxial configuration formed of an outertubular member256 and an innertubular member260. Adistal plug264 fits into a distal end of theannular region268 forming the gas lumen. A plurality ofapertures272 extend through theplug264 to form distal gas orifices. Located in alumen276 defined by the innertubular member260 is a retractable wire orpin280. Thewire280 is preferably a solid wire of a rigid material. For example, the wire may be composed of a metal, such as stainless steel, a polymer, or a radiopaque material. Adistal end284 of theinner member260 is tapered and may extend distally of theplug264 or alternatively may extend only to the distal end of the innertubular member260 or even proximally thereof. The distal end of theinner member260 terminates in a distalliquid orifice285. Adistal end286 of thewire280 may also be tapered. Thewire280 is sized with respect to the innertubular member260 so that the tapereddistal portion286 of thewire280 seats against the tapereddistal portion284 of the innertubular member260 and thereby seals a distal end of theliquid lumen276 in a manner similar to a needle valve. Thewire280 is retractable and in a preferred embodiment is operated to reciprocate back and forth to pulse the delivery of liquid out the distal end of thenebulizing catheter252. The pulsing of aerosol delivery may be adjusted to any suitable time period. In one preferred mode of operation, the aerosol may be delivered only during inhalation by the patient. If thenebulizing catheter252 is being used with an endotracheal tube and a ventilator, the pulsing of the aerosol delivery may be timed to coincide with the patient's inhalation by an appropriate connection with the ventilator. By limiting the delivery of medicine to only the period of time when the patient is inhaling, the medicine can be delivered more efficiently and with less waste.
• One preferred way to generate the pulsed aerosol plume with the embodiment ofFIGS. 18 and 19 is with amanifold arrangement287. A proximal end of thewire280 is fixed to anextendable section288 of themanifold287. Thewire280 may be fixed by means of anelastomeric seal289. Pressurized gas is delivered to aport290 of the manifold that communicates with the outertubular member256 and liquid medicine to be nebulized is delivered to asecond port291 that communicates with the innertubular member260. The liquid medicine also fills thevolume292 proximal of theport291 in theexpandable section288. Thewire280 is connected to the manifold so that the distal end of the wire is biased against the distal end of the inner tubular member by the resilience of the innertubular member260 and/or theexpandable section288. Pulsed pressurization of the liquid medicine from the source causes theextendable section288 to reciprocate back and forth as shown by the arrow293. Since the proximal end of thewire280 is attached to theexpandable section288 proximal of theport291, application of pressure pulses to the liquid causes the proximal end of thewire280 to reciprocate back and forth as well. This causes the distal end of thewire280 to reciprocate back and forth in theseat284. Application of pressure pulses to the liquid medicine can be timed to coincide with the patient's inhalation. Alternatively, instead of forming an expandable or compressible section at the manifold, the shaft of the innertubular member260 may be formed of a stretchable material so that pressurization of the liquid causes retraction of the wire as the entire shaft elongates. Other alternatives for effecting reciprocating operation of thewire280 are use of an electro-mechanical, mechanical, hydraulic, or pneumatic actuator to drive the wire. Aside from providing for pulsed delivery of the aerosol, this embodiment of the nebulization catheter has the further advantage that the reciprocating action of the wire may assist in keeping the orifice free of any blockages which may occur, especially with some viscous solutions or suspensions.
• In a manner similar to theembodiments208 and236 ofFIGS. 16 and 17, in theembodiment252 ofFIGS. 18 and 19, the distal tip of theretractable wire292 can extend distally from the distalliquid orifice288 in order to minimize particle size, or alternatively may not extend distally of the distalliquid orifice292. In one embodiment, the distal tip of the retractable wire may extend distally of theliquid orifice288 by approximately 0.2 mm.
• FIG. 20 shows another embodiment of a nebulizing catheter. In this embodiment, anebulizing catheter296 has amain shaft portion300 with agas lumen304 adjacent to aliquid lumen308. The gas andliquid lumens304 and308 flow into adistal cavity312. Thedistal cavity312 is formed by an outertubular extension316 that extends distally over and past adistal end320 of themain shaft portion300. Afilter324 is located in theliquid lumen308 to filter out any particles in the liquid. Theliquid lumen308 has a step down in diameter immediately distal of the location of thefilter324. Aninsert plug328 is located in a distal end of the outertubular extension316. The insert plug328 (which may be a sapphire jewel, for example) has anaperture332 through it that forms an exit orifice from thecavity312. Theinsert plug328 has a conical shaped proximal profile facing thecavity312. An innertubular extension336 fits into the stepped down portion of theliquid lumen308 and extends theliquid lumen308 into thecavity312. Adistal end340 of the innertubular extension336 terminates in thecavity312. Since thegas lumen304 exits into thecavity312, nebulization of the liquid takes place at the tip of the innertubular extension336 inside thecavity312. This region of thecavity312 is a positive pressure region due to the relative sizes and locations of the apertures. The positive pressure in this region may have the effect of reducing drooling of the liquid medicine as it leaves the orifice of thetubular extension336. The aerosol exits thecatheter296 via theaperture332 and the aerosol plume is defined in part by the positive pressure in thecavity312 and the aperture size. In this embodiment, the main shaft portion and the tubular extension are composed of a suitable plastic such as polyethylene. The filter is composed of multiple 50 μm I.D. tubes or similar course filter material. The gas and liquid lumens may each have an I.D. of 0.010 to 0.015 inches. The innertubular extension336 may be formed of polyimide tubing with an I.D. of 0.004 inches and an O.D. of 0.010 inches. The outertubular extension316 may be formed of a heat shrunk tubing, such as polyethylene. Theplug328 may have an O.D. 0.087 inches and theaperture332 in theplug328 may have a diameter of 0.007 inches.
• FIG. 21 shows another embodiment of the nebulizing catheter. This embodiment is similar to theembodiment296 shown inFIG. 20 and accordingly the components are numbered similarly. The embodiment ofFIG. 21 differs from the embodiment ofFIG. 20 in that the distal end of the innertubular extension312 is located in theaperture332 of theinsert plug328. In the embodiment ofFIG. 21, theorifice332 at the distal end of thetubular extension336 is in a low pressure, high velocity region as compared to the embodiment ofFIG. 20. This has a corresponding effect on plume size and shape as well as possible particle size.
• FIG. 22 shows yet another embodiment for the nebulizing catheter. In this embodiment, anebulizing catheter340 has amain shaft portion344 that has agas lumen348 and aliquid lumen352. Thegas lumen348 terminates distally in a gas orifice356. Located in the distal end of theliquid lumen352 is a liquidtubular extension360. The liquidtubular extension360 forms an angle so that a distalliquid orifice364 is in alignment with the flow of gas out the distal gas orifice356. In this embodiment, theliquid lumen352 has an I.D. in the range of 0.010 to 0.020 inches. Thegas lumen348 has an I.D. of approximately 0.10 to 0.020 inches. The liquidtubular extension360 is formed of a stainless steel tube with an O.D. of 0.018 inches and an I.D. of 0.012 inches. The distal gas orifice356 has an I.D. of 0.010 inches. The stainlesssteel extension tube360 forms a right angle so that the distalliquid orifice364 is at a right angle and aligned with the distal gas orifice356. The distal gas orifice356 and the distalliquid orifice364 are positioned as close together as possible, and in one embodiment, these orifices are approximately 0.010 inches apart.
• FIG. 23 shows an alternative embodiment of the nebulization catheter shown inFIG. 22. In this embodiment, thenebulization catheter340 has an additional lumen365. This additional lumen365 may have an I.D. of approximately 0.020 inches. This additional lumen365 may be used for an optical fiber viewing scope366 for illumination and visualization of the distal end of thenebulization catheter340. The optical viewing scope366 may be permanently installed in thecatheter340 or preferably may be removable. A distal end367 of the lumen365 is open or covered with a transparent lens so that the area distal of thecatheter340 can be observed via an optical viewing device connected to a proximal end of the optical fiber366. This enables a physician to observe the alignment of the distal end of the nebulization catheter and also observe the nebulization when it occurs. The gas orifice356 may be located so that the pressurized gas that is expelled helps to keep the distal end of the viewing lumen365 clear. An optical fiber viewing channel may be incorporated into any of the embodiments of the nebulization catheter disclosed herein. When the additional lumen365 is occupied by a removable viewing scope, it may be used for other purposes such as pressure sensing, gas sampling, over pressure relief, or other diagnostic or therapeutic purposes. Alternatively, another lumen may be provided for these purposes.
• The embodiment ofFIG. 23 also shows opposing orifices. As in the embodiment ofFIG. 22, atubular extension360 extends distally of the end of the catheter shaft and is oriented at an angle, e.g. 90 degrees, to the direction of the axis if the catheter shaft. Thetubular extension360 opens to a distalliquid orifice364 from which the liquid being conveyed in thelumen352 exits. In this embodiment, a second tubular extension363 communicates with thegas lumen348 and opens to a distal gas orifice367. The second tubular extension363 is also oriented relative to the axis of the catheter shaft, e.g. by 90 degrees, so that is aimed toward the distalliquid orifice364 in order to nebulize the liquid exiting from the liquid orifice367.
• FIG. 24 shows still another embodiment of the nebulizing catheter. In this embodiment, anebulizing catheter368 has amain shaft section372 with agas lumen376 and aliquid lumen380.Tubular extensions384 and388 extend the gas andliquid lumens376 and380 from themain shaft section372 to a distal tip of thecatheter368. The distal portion of the shaft forms a taperedregion392 that surrounds thetubular extensions384 and388 and causes them to be angled toward each other. Thetubular extension388 for theliquid lumen380 extends slightly distally of the distal end of thetubular extension384 of thegas lumen376 so that a distal liquid orifice396 is in alignment with the flow of gas from a distal gas orifice400. In this embodiment, the distal liquid orifice396 has an O.D. of 150 microns and an I.D. of 20 microns. The gas orifice400 has an I.D. of approximately 0.018 inches.
• FIGS. 25 and 26 show an alternative embodiment of thenebulizing catheter368 shown inFIG. 24. InFIGS. 25 and 26, thetubular extensions384 and388 of thegas lumen376 and theliquid lumen380 are formed with sealable tips. Specifically, thegas tubular extension384 has asealable tip408 and the liquidtubular extension388 has asealable tip412. Alternatively, only theliquid lumen380 has the sealedtip412 and thegas lumen376 has an open distal orifice. The sealable tips may be formed by heating the material from which the tubular extensions are made to reform the walls of the plastic material so as to form a closed slit. This is represented inFIG. 26. When pressurized gas and liquid are conveyed through thelumens376 and380, the slits forming thetips408 and412 dilate thereby permitting the gas and liquid to exit to from the aerosol, as illustrated inFIG. 25. However, when the pressure in thelumens376 and380 falls below a threshold, thetips408 and412 close thereby sealing off the lumens, as illustrated inFIG. 26. The embodiment404 of the nebulizing catheter is used with pulsation of the gas and/or liquid supplies. In order to pulse the generation of aerosol to coincide with a patient's inhalation, the pressure to the gas and/or the liquid lumens can also be pulsed. When the pressure in either of the lumens falls below a threshold, thetips408 or412 close. By closing off the flow of liquid at thetip412 during the period when the aerosol is not being generated, it is possible to reduce any drooling from the tip of the catheter.
III. Nebulization with Counterflow
• As mentioned above, control of nebulized particle size and plume shape are important considerations affecting the efficacy of the therapy. In many applications, it is preferable to have as small a particle size as possible combined with as little forward velocity as possible. Some of the embodiments described below accomplish these objectives through use of counterflow arrangements.
• FIG. 27 shows a nebulization catheter416 that can be located inside of an endotracheal tube as in the previously described embodiments. The nebulization catheter416 has a coaxial tubular arrangement with an outer tube417 surrounding aninner tube418 so that a liquid delivered from a distal liquid orifice419 of theinner tube418 is nebulized by the flow of a pressurized gas delivered in a distal direction from the annular region between the inner and outer tubes at the distal orifice420 of the outer tube417. In addition, anotherlumen428 extends through the shaft of the nebulization catheter416. Thisadditional lumen428 connects to a distaltubular extension432. Thetubular extension432 extends distally of the distal end of the nebulization catheter416. A distal end436 of the distaltubular extension432 curves back on itself so that adistal orifice440 of thetubular extension432 is oriented in a proximal direction back at the orifices419 and420 of the inner and outer tubes. Theadditional lumen428 also carries a pressurized gas which is directed in a proximal direction by theorifice440 against the direction of the aerosol plume generated by the gas and liquid exiting the orifices419 and420. The gas from theadditional lumen428 presents a counterflow to the gas from these orifices thereby slowing down the velocity of the particles generated from these orifices. In a preferred embodiment, the distaltubular extension432 may be formed of a suitable material such as stainless steel needle stock. The O.D. of the nebulization catheter in this embodiment may be similar to the other nebulization catheter embodiments described above, e.g. O.D of approximately 0.038 inches. The distaltubular extension432 may have an O.D. of approximately 0.013 inches and an I.D. of approximately 0.009 inches. In this embodiment, the outer tubular member of the nebulization catheter may have an O.D. of approximately 0.013 inches and an I.D. of approximately 0.009 inches and the inner tubular member may have an O.D. of approximately 0.003 inches and an I.D. of approximately 0.0015 inches.
• FIG. 28 shows another embodiment of the present invention for a nebulizing catheter448 that incorporates a counterflow arrangement. Like the embodiments described above, in this embodiment the nebulizing catheter448 may be located in an endotracheal tube (not shown). The nebulization catheter448 has adistal section452 that curves back on itself. The nebulization catheter448 hasdistal orifices453 and454 that generate a plume of nebulized particles in a reverse, i.e. proximal, direction. Also located in the nebulization catheter448 is anotherlumen456 for carrying a pressurized gas. Theadditional lumen456 has adistal orifice460 oriented in a distal direction. Thedistal orifice460 of theadditional lumen456 is aligned with respect to thedistal orifices452 and453 of the nebulization catheter448 so that the flow of gas from theadditional lumen456 slows down the velocity of the nebulization plume generated from the nebulization catheter448. The aerosol plume generated by the nebulization catheter reverses direction and is delivered to the lungs carried by the inhalation of air through the endotracheal tube or by the flow of gas from theadditional lumen456 or a combination thereof.
• FIGS. 29 and 30 show another embodiment of a counterflow nebulization catheter arrangement. InFIGS. 29 and 30, anebulizing catheter464 is used with anendotracheal tube468. Anebulization catheter464 has adistal tip472 from which a liquid medicine delivered from a distal liquid orifice is nebulized by a flow of pressurized gas from a gas orifice located adjacent to the liquid orifice. Thenebulizing catheter464 shown inFIG. 30 extends distally of theendotracheal tube468 and has adistal section476 that curves back on itself. Thenebulization catheter464 has distal orifices that generate a plume of nebulized particles in a reverse, i.e. proximal, direction back toward the distal opening of theendotracheal tube464. In order to maintain a proper reverse orientation and to prevent snagging, thenebulization catheter464 includes awire480 that extends from thetip472 of thenebulization catheter464. Thewire480 is secured to a portion of the shaft of the nebulization catheter proximal of the tip. Thewire480 can be secured by means of a heat shrunktube484 located on ashaft488 of the catheter to hold the end of thewire480. Although some aerosol may impact thewire480, a wire having a small diameter is used to minimize losses due to such impaction. Moreover, the overall improved efficiency due to reduction in aerosol impaction on the walls of the trachea or other airway passage is expected to more than compensate for any losses due to impaction on thewire488.
• In the embodiment shown inFIG. 30, thenebulization catheter464 directs a nebulization plume in a reverse direction back toward the distal opening of theendotracheal tube468. The nebulization plume from the nebulization catheter encounters the flow of air from theendotracheal tube468 during the inhalation phase of the patient. The inhalation of air through theendotracheal tube468 causes the nebulized medicine to reverse direction and carries it to the lungs. It is noted that the reversal of direction of the nebulization plume has the effect of minimizing the aerosol particle velocity. It is also noted in the embodiment shown inFIG. 30 that theendotracheal tube468 is provided with aninflatable cuff492 located around the distal portion.
IV. Other Nebulization Catheter Embodiments
• In the embodiments described above, the velocity of the nebulization plume was reduced by use of a counterflow of gas in an opposite direction. In the embodiment ofFIGS. 31 and 32, the velocity of the nebulization particles is reduced in another manner. InFIG. 31 a nebulization catheter496 has aliquid lumen500 terminating in a distalliquid orifice504 and a one ormore gas lumens508 terminating in one or moredistal gas orifices512. The liquid delivered through theliquid lumen500 is nebulized by the pressurized gas flowing out the plurality ofgas orifices512. The nebulization catheter496 also includes one or moreadditional lumens516 that terminate in additionaldistal orifices520. Theselumens516 are used to deliver a vacuum (negative pressure) at thedistal orifices520. The vacuum is provided by a suitable vacuum source (not shown) connected to proximal ends of theadditional lumens516. The vacuum delivered by theadditional lumens516 helps withdraw the pressurized gas delivered by thelumen508 after it has nebulized the liquid delivered by theliquid lumen500. Without the vacuum provided by theadditional lumens516, the pressurized gas delivered by thedistal gas orifices512 may continue to impart energy to the nebulized liquid particles delivered by the distalliquid orifice504 thereby causing them to be propelled with a forward velocity. Instead, the vacuum scavenges at least some of the pressurized gas after it has nebulized the liquid so that the forward velocity of the liquid particles can be reduced. In order to facilitate scavenging of the pressurized gas, the distalliquid orifice504, thedistal gas orifices512, and thedistal vacuum orifices520 all open into adistal cavity524 formed by an outertubular extension528 of the nebulizing catheter496. Thedistal extension528 has a closeddistal end532 with asmall aperture536 located therein to emit the nebulized liquid particles with a low forward velocity. With the nebulizing gas removed, the aerosol particles are carried forward primarily only by their inertia.
• The embodiment of the nebulization catheter496 shown inFIG. 31 includes avacuum line516 as a means to reduce the forward velocity of the nebulization plume. Provision ofvacuum line516 to the tip of a nebulization catheter496 can serve an additional function of balancing the gas flow and pressure delivered to the airway in which the nebulization catheter is located. This may be useful to prevent excess airway pressure generated by the catheter flow particularly in smaller airways or where a neutral flow balance may be desired. This may particularly be desired when the nebulization catheter is provided with an inflatable cuff that occludes the airway passage at the distal end of the nebulization catheter. The flow balance may be controlled with a closed or partially closed pumping system where agas pump537 with a single intake and outlet would be connected to the respective vacuum andgas supply lumens516 and508 of the catheter. Both the driving gas and vacuum would be balanced and regulated by the pump speed. A vacuum orpressure vent port538 could be incorporated into the respective vacuum or pressure lines if a positive or negative flow balance was desired. If flow balance is a concern, but not velocity reduction, it is not important where the air flow is removed at the distal tip of the catheter and accordingly, thedistal end extension532 may not be needed. Alternatively, a flow balance may be maintained with separate a pressure and vacuum source through the use of regulators, restrictive capillary tubes or orifices, or flow sensors and flow control valves incorporated into the pressure and vacuum supply lines.
• FIG. 33 shows another embodiment of anebulization catheter540 that incorporates a feature to reduce the forward velocity of the nebulized liquid particles. Thenebulization catheter540 has amain shaft portion544 having aliquid lumen548 and apressurized gas lumen552. Thelumens548 and552 terminate indistal orifices556 and560. The pressurized gas flow from theorifice560 nebulizes the liquid exiting from theorifice556. Thenebulization catheter540 includes adistal spacer tube564. Thespacer tube564 has a length of approximately 2-3 mm and an inside diameter larger than the outside diameter of thenebulization catheter shaft544. Because the inside diameter of thespacer tube564 is larger than the airflow lumen and orifice, the velocity of air and entrained particles is reduced as they pass through thespacer tube564 and out adistal opening568 thereof. In addition, thespacer tube564 may have one or more apertures or holes572 through a wall thereof close to the proximal end of the spacer tube at its connection to themain shaft544. Theseholes572 draw in air to the inside of thespacer tube564 thereby causing drag due to turbulence and reducing the velocity of the aerosol as it exits the spacer tube. Theholes572 may also slow the flow of particles through the spacer tube by causing drag turbulence.
• Thespacer tube564 also serves to protect thedistal orifices556 and560 of the nebulization catheter from coming into contact with any part of the endotracheal tube, trachea, or other airway passage thereby helping to maintain optimum tip operation and to prevent damage to it during handling and insertion. In an alternative embodiment, if only the tip protection feature is desired, thespacer tube564 ofFIG. 33 may be provided without theapertures572. In such an alternative embodiment, thespacer tube564 may be provided in a shorter length, e.g. 1 mm.
• FIG. 34 shows another embodiment of anebulization catheter576 used with anendotracheal tube580. Theendotracheal tube580 may be a conventional endotracheal tube. Thenebulization catheter576 provides for a nebulization plume with a reduced forward velocity by imparting a spiral component to the liquid particle flow. Thenebulization catheter576 has adistal tip584 from which a liquid medicine delivered from a distal liquid orifice is nebulized by a flow of pressurized gas from a gas orifice located adjacent to the liquid orifice. Thenebulization catheter576 is positioned coaxially in theendotracheal tube580. A centeringdevice585 may be used to aid in centering thenebulization catheter576. Located along a portion of thenebulization catheter576 proximal from thetip584 is asecond gas orifice588. Thissecond gas orifice588 may open to the same gas lumen that communicates with the nebulizing gas orifice at thedistal tip584 or alternatively, thesecond gas orifice588 may connect to another, separate gas lumen. Thesecond gas orifice588 is oriented to direct a pressurized flow of gas in a spiral, distal direction along the distal end of thenebulization catheter576. To accomplish this, thesecond gas orifice588 may be formed by an inclined opening or with a deflection foil to direct the flow of gas in the appropriate spiral direction. The spiral flow of pressurized gas travels along the distal portion of thenebulizing catheter576 inside theendotracheal tube580. The spiral flow of gas entrains the aerosol generated from thedistal end584 of the nebulizing catheter imparting a spiral flow component to the aerosol plume. This has the effect of reducing the forward velocity component of the liquid particle flow as it leaves theendotracheal tube580.
• FIG. 35 shows an alternative method for using thenebulization catheter576 ofFIG. 34. InFIG. 35, thenebulization catheter576 is shown extended distally of the distal end of theendotracheal tube580 so that the distal portion of thenebulization catheter576 including thesecond gas orifice588 is located in an airway passage. Taking into account the size of the airway passage, thenebulization catheter576 with thesecond gas orifice588 would operate similarly to the method shown inFIG. 34 and generate a spiral gas flow to reduce the forward velocity of the aerosol plume.
• Another embodiment of anebulizing catheter592 is shown inFIGS. 36 and 37. This embodiment of thenebulizing catheter592 can be used with a separate endotracheal tube (not shown). Thenebulizing catheter592 includes amain shaft596 having a central lumen600 and one or moreadditional lumens604 located around the central lumen600. In this embodiment, the central lumen600 is used for the flow of a pressurized gas and the additionalperipheral lumens604 are used for the delivery of the liquid medicine. Thelumens600 and604 terminate distally inorifices608 and612, respectively. Located at a distal end of thenebulizing catheter592 and immediately adjacent theorifices608 and612 is adiffuser616. In one embodiment, thediffuser616 is composed of a generally disk-shaped body that is sized to deflect the flow of gas from theorifice608 of the central lumen600 past theliquid orifices612 thereby nebulizing the liquid medicine. A small gap (or venturi area)620 between thediffuser616 and the distal end of themain shaft section596 of thecatheter92 provides favorable flow characteristics for generating the aerosol. Thediffuser616 may be connected to aretaining wire624 that is located in the central lumen600. Theretaining wire624 may be used to secure thediffuser616 to the distal end of thenebulizing catheter592. Also, theretaining wire624 may be used to pulse the generation of aerosol by reciprocation of the diffuser. It is noted that the aerosol produced by this embodiment has a substantially radial velocity component and may have only a small forward velocity component. In addition, a centering device, such aswings625, may be attached to thediffuser616.
• FIG. 38 shows an alternative embodiment of thediffuser616. InFIG. 38, thediffuser616 is formed of a loop that has its ends located in two apertures in the nebulization catheter shaft tip and a middle portion directly in front of thedistal gas orifice608. The loop may be formed of a metal or polymer wire or other material. The loop could be formed by an extrusion method or molded.
• Referring toFIG. 39, there is an alternative embodiment of the nebulization catheter system. A nebulization catheter627 is located in anendotracheal tube628. The nebulization catheter627 includes a coaxially arranged outer tube629, amiddle tube630, and aninner tube631. Liquid delivered through a lumen of theinner tube631 is nebulized by pressurized gas delivered in theannular region632 between theinner tube631 and themiddle tube630. In addition, pressurized gas is also delivered from a secondary gas supply that communicates with theannular region633 between themiddle tube630 and the outer tube629. The secondary gas supply may be used to help provide the desired plume shape and velocity. For example, the secondary gas supply delivered from the outer tube629 can be used to provide a coaxial sheath of air that helps minimize impaction of the nebulized aerosol on the walls of the trachea or other airway passage. Alternatively, the secondary air supply may be used to impart additional forward velocity to the aerosol plume. With the embodiment ofFIG. 39, the additional air flow can be provided by the secondary gas supply viaregion633.
• In the embodiments discussed above, nebulization is provided at a distal tip of a catheter by directing a pressurized gas from a distal orifice across another distal orifice from which the liquid medicine is delivered. As shown in several of the embodiments above, one way to deliver the liquid from the distal orifice is via a lumen that extends through the catheter to a proximal end. This construction provides efficient operation for many types of medication delivery. In many cases, the distal liquid medicine orifice is subject to a negative pressure due to the pressurized gas flow across it. This negative pressure may in many applications be sufficient to draw the liquid out of the orifice in order to nebulize it. If pulsing of the aerosol is desired, the pressure of the gas lumen can be pulsed thereby resulting in pulsed generation of the aerosol. By increasing the gas pressure, it may be possible to also increase the aerosol output.
• In other situations, it may be preferable to apply a positive pressure to the liquid, such as at the proximal end of the liquid lumen, in order to deliver liquid from the distal liquid orifice, it is necessary. This positive pressure applied to the liquid lumen may be the same as that applied to the gas lumen (e.g. 35-50 psi) or alternatively may be different (less than the gas lumen). If it is desired to pulse the nebulization of the liquid, this can be accomplished by applying pulses of pressure to the column of liquid via the proximal end of the liquid lumen or reservoir. It may also be preferred to synchronize the pressurization of the gas in the gas lumen with the pressurization of the liquid lumen. In addition to applying the positive pressure to the liquid lumen in pulses to generate a pulsed aerosol from the distal orifice, if it may be preferred in an alternative embodiment to apply a small negative pressure immediately after each positive pressure pulse in order to draw the liquid at the distal orifice back into the liquid lumen to thereby avoid drooling. In a preferred embodiment, the portion of the nebulization catheter in which the liquid lumen is formed may be composed of a relatively low compliance material to transmit pressure pulses to the distal end with minimum attenuation.
• A full length liquid lumen may have disadvantages in certain situations. For example, pulsing of the liquid from the distal orifice may not correspond to or follow closely with the application of pressure to the proximal end due to attenuation of the pressure pulse over the length of the catheter. In addition, applying pressure to the proximal end of the liquid lumen in order to transmit pressure to discharge the liquid from a distal orifice requires that the lumen be filled with the liquid. In some situations, this is more medicine than would be required by the patient and might result in waste.
• The embodiment inFIG. 40 addresses these concerns by controlling the pressurization of the liquid as close as possible to the distal liquid orifice, thereby reducing the effects of catheter compliance and attenuation. InFIG. 40, anebulization catheter652 has amain body656 having agas lumen660 that extends from a proximal end (not shown) to adistal gas orifice664. Themain body656 also includes a distal liquid medicine reservoir668. In the embodiment shown inFIG. 40, the liquid reservoir668 is located in a distal portion of themain shaft656 of thecatheter652. The liquid reservoir668 is preferably close to the distal tip of thenebulizing catheter652. The liquid reservoir668 is filled with the medicine to be delivered. If the amount of medicine is small in volume, the liquid reservoir may also be correspondingly small. This embodiment is especially suitable for the delivery of small volumes of medicine such as 0.1 to 0.5 ml, e.g. single use. The reservoir668 may be pre-filled during the manufacturing stage of the catheter. The reservoir668 may be formed by plugging a lumen of the catheter at a distal location. Alternatively, the liquid reservoir668 may also extend back to the proximal end of the catheter, thereby forming a liquid lumen, and communicate with a proximal port as described with respect to the other embodiments discussed herein. This may be required if the lumen is made of a non-compliant material. In yet another alternative embodiment, the liquid reservoir may be formed in a balloon located externally of thecatheter shaft656.
• Afilter672 and plug676 occupy positions in the distal end of the liquid lumen/reservoir668. A distaltubular extension680 extends from theplug676 and communicates with the liquid lumen/reservoir668. Thetubular extension680 has adistal orifice684 aligned with thedistal gas orifice664 so that a pressurized gas exiting thegas orifice664 nebulizes the liquid exiting theliquid orifice684. The distal liquid orifice may have a sealable cap or wax-like covering associated therewith that can be opened when the nebulization catheter is put into use. In a distal section of themain shaft656 of thecatheter652, thegas lumen660 and the liquid lumen668 are separated by a flexible, distendable wall ormembrane688. In the embodiment ofFIG. 40, pulsing of the aerosol is accomplished by pulsing of the gas pressure in thegas lumen660. When the pressure in thegas lumen660 is high, it causes theflexible wall688 between the gas andliquids lumens660 and668 to distend into the liquid lumen668. This is represented by the dashed line inFIG. 40. When this occurs, the pressure from thegas lumen660 is transmitted to the liquid lumen668 and liquid medicine is forced out the distalliquid orifice684. When the pressure applied to thegas lumen660 is low, thedistendable wall688 recovers its original position. It is noted that when thedistendable wall680 recovers its original position, it may cause a negative pressure at the distalliquid orifice684 which may cause the liquid to withdraw slightly into thetubular extension680 thereby reducing the occurrence of liquid drooling at the tip. In addition, it is noted that the delivery of liquid from the distalliquid orifice680 may not occur immediately upon application of a high gas pressure to the gas orifice since it will take some time for thebladder688 to distend. This means that gas will be flowing steadily at a high pressure from the distal gas orifice when the liquid begins to flow from the distal liquid orifice. This also may provide cleaner aerosol delivery and reduce the occurrence of drooling of liquid at the tip.
• An alternative embodiment of thenebulization catheter652 shown inFIG. 40 may be made using a flexible, but inelastic material for thebladder wall688. If thebladder wall688 were flexible, but inelastic, the pressurized gas passing past theliquid orifice684 would create a negative pressure (venturi effect) thereby drawing out the liquid and nebulizing it. A continuous or preferably an intermittent gas supply to the venturi area would provide this negative pressure. The bladder wall may be provided with a vent to facilitate discharge.
• In order to manufacture a nebulization catheter with compliant and non-compliant regions, as described above, the catheter may be co-extruded using different compounds or polymers to optimize the physical properties of the different wall sections. It may be preferred to use high energy radiation to crosslink the polymer material in the formation of the bladder wall.
V. Alignment of the Aerosol Plume
• The embodiments described above are directed to developing an optimum nebulization plume. It is further recognized that another factor that contributes to the efficiency of the nebulization is the position of the nebulization catheter relative to the anatomical environment. For example, even if the nebulization catheter being used develops an optimal plume, the delivery efficiency of the catheter may be significantly impaired if the plume is directed into the wall of the endotracheal tube, the trachea or other airway passage. Accordingly, proper location, orientation, and alignment of the nebulization catheter in the anatomy can be an important factor contributing the delivery of medicine via a nebulization catheter. In general, it is preferable to align the catheter coaxially in the airway passage in which it is located.
• It is also noted that an endotracheal tube, if present, can adversely effect delivery of aerosol from a separate nebulization catheter. For example, an endotracheal tube has an inner diameter that is smaller than the diameter of the trachea so that if the nebulization takes place inside the endotracheal tube, a portion of the aerosol may impact the inner wall of the endotracheal tube and thereby be wasted. Most conventional endotracheal tubes have a curved distal end that is relatively rigid so that when it is in place in the trachea of a patient, the distal end of the endotracheal tube is oriented off center. This can affect the orientation of a nebulization catheter located in the endotracheal tube causing it direct its aerosol into the trachea wall even if the nebulization catheter is positioned so that its distal end is located distally of the endotracheal tube. In general, it is desirable to allow the aerosol particles to avoid impaction for several centimeters after the aerosol is produced so that the aerosol particles can lose their velocity and become entrained in the inspiratory airflow.
• The embodiment of the invention inFIG. 41 is directed at providing improved alignment of a nebulization catheter in a patient's trachea. InFIG. 41, anendotracheal tube700 is positioned in atrachea704 of a patient. Theendotracheal tube700 is of a type that has an inflatable cuff708 located around a distal exterior side to facilitate positioning and alignment of theendotracheal tube700 in thetrachea696. Extending through and out of a distal end of theendotracheal tube700 is anebulization catheter712. Thenebulization catheter712 may be similar to any of the embodiments of the nebulization catheter described above. Located around adistal portion716 of thenebulization catheter712 is aspring centering apparatus720. Thespring centering apparatus720 includes aretainer ring724 fixed to the shaft of thenebulization catheter712 and a plurality ofarms728 connected to thering724. In one embodiment, there are threearms726. Thearms726 are flexible and resilient. Thearms726 may be made of a spring tempered metal or a suitable plastic. Located at the end of each of thearms726 opposite its connection to thering724 is aball727. Thespring centering apparatus720 is deployed by first positioning thenebulizing catheter712 including the spring centering apparatus in thelumen728 of theendotracheal tube700. Thearms726 are formed so that they assume a size larger than the diameter of the trachea or airway passage. Accordingly, when the centering device is positioned in theendotracheal tube700, the arms are resiliently deformed into a compressed configuration with theballs727 close to the shaft of thenebulizing catheter712. To deploy the centering device, thenebulizing catheter712 is advanced out the distal end of theendotracheal tube700. When theballs727 are advanced out theendotracheal tube700, they spring out to an expanded size and engage the walls of the trachea or other airway passage. Theballs727 provide a relatively smooth surface to limit irritation or injury to the trachea walls or other airway passage. With the arms expanded, the nebulizing catheter is centered in the trachea or other airway passage so that a plume discharged from a distal end of the nebulizing catheter has minimal contact with the walls of the trachea or other airway passage. When it is necessary to remove thenebulizing catheter712, it can be withdrawn in a proximal direction back into theendotracheal tube700. In a preferred embodiment, the arms are formed of a thin resilient wire or polymer, preferably less than approximately 0.015 inches in diameter. The arms and/or the balls may be made of, or coated with, a radiopaque material. It is an advantage of the embodiment of the centering device shown inFIG. 41 that it is located somewhat in advance of the distal end of the nebulization catheter. This positions thearms726 of the centering device in the portion of the trachea or other airway passage into which the aerosol will be initially flowing. Thus, the centering device orients the distal tip of the nebulization catheter relative to the portion of the trachea or other airway passage beyond the distal tip thereby helping to reduce impaction along this portion.
• FIG. 42 shows an alternative embodiment of the nebulization catheter. A nebulization catheter729 is used with an endotracheal tube as described above. The nebulization catheter729 includes a centering device730. The centering device730 includes a plurality of arms731 that are formed to resiliently extend outward from the axis of the catheter shaft to engage the wall of the patient's trachea or airway passage or the interior of an endotracheal tube depending upon the desired location of the distal end of the nebulization catheter. At the ends of each of the arms731 areballs732. The proximal ends of the arms731 are formed ofwires733 that extend throughlumens734 in the shaft of the catheter729. Each of thelumens734 has adistal opening735 from which an arm can extend. The distal openings are approximately 0.10-1 cm from the distal end of the catheter shaft. The proximal ends of thewires733 exit thelumens734 of the nebulization catheter viaopenings736 that are close to the proximal end of the catheter in a portion of the catheter that would normally be outside the patient's body during use. Thus, the proximal ends of thewires733 are accessible to the physician during use. By pulling and pushing on the proximal ends of thewires733, the portion of the arms731 that extend from theopenings735 can be adjusted. Thus, the arms731 can be adjusted from a fully retracted to a fully advanced position by pulling or pushing on the proximal ends of thewires733. In addition, since the proximal ends can of thewires733 be adjusted in any intermediate position between the fully retracted and fully advanced positions, the physician can adjust the size of the centering device730 to any appropriate size, as desired. Because thewires733 should assume a desired shape when advanced out of the lumens in which they are contained during positioning, it is preferable that they be formed of a material that has shape memory properties so that the desired expanded shape can be imparted to the wires during manufacture. In one embodiment, the wires may be formed of nitinol.
• In one preferred embodiment, a second centering device737 is also provided. The second centering device737 is located on the shaft of the nebulization catheter729 proximally from the first centering device730. The second centering device737 may be formed of resilient wings formed of a material such as plastic or metal that extend radially outward from the shaft. The second (or proximal) centering device737 helps keep the distal portion of the catheter729 in alignment.
• FIG. 43 shows another alternative embodiment of the present invention. Anebulizing catheter738 is shown which may be similar to thecatheter20 ofFIG. 1. Thenebulizing catheter738 includes a centeringdevice739. The centeringdevice739 includes awire loop740 located at a distal end of the catheter. Oneend741 of theloop740 connects to the distal end of the nebulizing catheter shaft. Theother end742 of thewire loop740 enters anopening743 in the shaft that communicates with alumen744 that extends to a proximal end of thecatheter738. Aproximal end745 of the wire exits thelumen744 via anopening746 in a proximal portion of the nebulizing catheter which is normally outside the patient's body during use. The size of thewire loop740 can be adjusted by advancing or withdrawing theproximal end745 of the wire. In this embodiment, it can be determined that the centering device is fully retracted when thewire745 cannot be withdrawn any further. The position of the distal end of the nebulization catheter can also be determined by the resistance to further retraction caused when the loops or arms engage the distal end of the endotracheal tube. When in an expanded size, thewire loop740 engages the walls of the trachea or airway passage or the interior of the endotracheal tube depending upon where the distal end of the nebulizing catheter is positioned. The size of thewire loop740 can be adjusted from a fully reduced size to a fully expanded size as well as intermediate sizes. With the embodiment ofFIG. 43, the size of the loop can be adjusted to different size airway passages in different patients or alternatively the size of the loops can be adjusted to different airway passages in the same patient if the physician desires relocating the nebulizing catheter to different locations in a patient's respiratory tract. In a one preferred embodiment, more than one wire loop may be provided at the distal end of the nebulizing catheter. It is noted that thewire loop740 of this embodiment may also be used in for facilitating positioning over a guide wire in a manner similar toloop106 shown inFIG. 9.
• FIGS. 44 and 45 show another alternative embodiment of the present invention. Anebulizing catheter747 has ashaft portion748 and awire loop749 extending from a distal end of theshaft748. In this embodiment, thewire loop749 is connected at eachend750 and751 to the distal end of thecatheter shaft748. Aretractable sheath752 is positioned over thenebulizing catheter shaft748. Thesheath752 can be advanced and withdrawn relative to thecatheter shaft748. When it is desired to maneuver the nebulizing catheter into a desired position in the respiratory tract of a patient, thesheath752 is advanced over theloop749 to maintain a low profile, as shown inFIG. 45. When the distal end of the nebulizing catheter is suitably positioned, thesheath752 is then retracted, as shown inFIG. 44, allowing theloop749 to expand to its expanded size to center and align the distal end of the nebulizing catheter in the respiratory tract. In one embodiment, theloop749 is formed of a superelastic material such as nitinol.
• As noted above, proper positioning and alignment of the nebulization catheter can be an important factor affecting drug delivery efficiency. In general, it is preferable to position the tip of the nebulizing catheter as closely to the central region of the trachea (or other respiratory passage, such as the bronchi) as possible. It is further noted that even if the catheter can be centered relative to the trachea, if a section proximal to a centering device is misaligned, it can affect the directional orientation of the tip. This situation is represented inFIG. 46 in which anebulizing catheter753 is centered, but the tip is not properly aimed to provide an optimum plume. This potential problem can be overcome by using an embodiment of the invention shown inFIG. 47. InFIG. 47, anebulizing catheter754 is located in atrachea755 of a patient. Thenebulizing catheter754 extends out the end of anendotracheal tube756. A first centeringapparatus757 is located on amain shaft760 of thenebulizing catheter754 close to thedistal end764. The first centeringdevice757 may be similar to the centering devices shown inFIGS. 41-45. A second centeringdevice768 is located axially along thenebulizing catheter shaft760 proximally from the first centeringdevice757. The second centeringdevice768 may be the same as the first centeringdevice757. As shown inFIG. 47, the two centeringdevices757 and768 not only serve to position the nebulization catheter7754 centrally in the trachea, but also serve to align the nebulizing catheter tip to expel the plume along a central axis of the trachea.
• The proximal centeringdevice768 may be substituted by another type of centering device or may employ theendotracheal tube756 for this purpose, as shown inFIG. 48. If the endotracheal tube is used to assist in centering the nebulization catheter, it may incorporate a distal, elongated occlusion cuff772 or balloon to coaxially align it accurately in the trachea. Most conventional endotracheal tubes are provided with a curvature to facilitate positioning the trachea of a patient. In addition, most conventional endotracheal tubes are relatively stiff. These factors may result in the misalignment of the distal end of the endotracheal tube relative to a patient's trachea as illustrated inFIGS. 46 and 47. In order to use the endotracheal tube for centering of the nebulization catheter, it is preferable to make the tip of the endotracheal tube straighter and/or more flexible than in conventional endotracheal tubes to ensure proper concentricity with the occlusion balloon and the trachea. An endotracheal tube with a straighter and more flexible tip is shown inFIG. 48. In addition, the endotracheal tube may be provided with a centering or aimingdevice776 for aligning thenebulization catheter754. In the embodiment ofFIG. 48, the aimingdevice776 is formed by a plurality of flexible or resilient wings the extend from the wall of theendotracheal tube756 toward an axially central position.
• Appropriate centering and aiming of the nebulization catheter can be affected by anatomical factors. It is noted that in some circumstances, it is preferable to position the distal tip of the nebulization catheter into either bronchus of the lungs or even into separate bronchia. Positioning of the nebulizing tip closer to the alveoli may enhance drug delivery efficiency. In a situation in which it is desired to place the nebulizer tip in both bronchi of the lungs, anebulizing catheter780 with dual tips can be employed, as shown inFIG. 49. When using a dual tip catheter such as shown inFIG. 49, centering and aiming can be important considerations because of the narrower air passages in each of the bronchi. To provide for centering and aiming of a dual tip nebulizing catheter, each of thetips784 and788 may be provided with its own centering apparatus, such as792 and796. These centering devices may be similar to the centering devices described above. Alternatively, the centeringdevices792 and796 may be formed of arms or struts, made of a flexible or resilient material, that bow out from the shafts of each of thetips784 and788, as shown. These struts may be formed with a shorter length in order to fit into smaller airway passages or alternatively they may be made to provide a range of deployment sizes to accommodate different airway passages.
• As an alternative to providing a nebulizing catheter withdual tips784 and788 as shown inFIG. 49, if delivery of aerosolized medicine into separate branches of the lungs is desired, it may be preferred to use a nebulizing catheter with a single nozzle tip that has multiple orifices or jets aimed toward the desired branches.
• With respect to all the centering devices described above, it is noted that some aerosol may impact the wires or loops that form the centering devices and accordingly, the centering devices are preferably constructed of wires or other materials having a small diameter or cross section to minimize losses due to such impaction. Moreover, the overall improved efficiency due to the reduction in aerosol impaction on the walls of the trachea or other airway passage is expected to more than compensate for any losses due to impaction on the centering device.
• Another alternative means for centering the distal end of a nebulization catheter in the air passage is to use part of the pressurized gas for a pneumatic centering device. Air jets generated from two or more outward directed orifices spaced evenly around the outer circumference of the nebulizing catheter near the tip can be used to center the catheter in the airway. This alternative may help avoid irritation and provide additional advantages compared to physical centering devices.
• Another alternative way to help center the nebulizing catheter in the patient's airway passage is to use a balloon or wire centering device placed near the nebulizing catheter tip. The balloon or wire centering device can be temporarily inflated to double check the placement of the nebulizing catheter tip in relation to the endotracheal tube tip. To use this feature the nebulizing catheter is advanced beyond the endotracheal tube tip using markings on the proximal shaft to judge the distance. The centering device or balloon would then be expanded to a diameter larger than the endotracheal tube and the catheter retracted until the centering device or balloon could be felt engaging with the endotracheal tube tip or until the endotracheal airflow was obstructed.
VI. Operation and Flow Control
• As mentioned above, the driving gas used to pressurize the gas lumen may be pure (e.g. 100%) oxygen at a pressure of 35-50 psi. Other gases and pressures may be used with suitable adjustments to provide for the desired particle size. The pressurized gas also may be humidified by a bubbler or other suitable means and warmed, if necessary.
• Regarding the liquid lumen, one way to deliver the liquid drug through the nebulizing catheter is by a manually operated syringe. To delivery a liquid drug in this manner, a syringe containing the liquid medicine to be nebulized is connected to the liquid port on the manifold connected to a proximal end of the nebulizing catheter. Then, the liquid is injected while the pressuring gas is being supplied to the nebulizing catheter via the gas inlet port on the nebulizing catheter manifold. Using a manually operated syringe is reliable, easy to use, and may be preferred when it is desired to deliver only a small amount of medication.
• In a preferred embodiment, the liquid drug is delivered to the nebulizing catheter from a pressurized source. A pressurized source for the liquid medicine can provide for a generally higher and more uniform pressure. A high pressure assists in clearing any blockages that may occlude the liquid lumen. Pressurization of the liquid lumen also can ensure that all the liquid drug is evacuated from the catheter tip. In addition, use of a liquid pressurization source can provide for drug delivery for a longer period of time or a drug delivery that is timed or pulsed to coincide with operation of a ventilator, if used. In a preferred embodiment, the same pressure source (at 50 psi) that is used to provide the gas pressurization can also be used to provide for pressurization of the liquid. Some ventilators have an auxiliary port that are used for externally located nebulizers. The pressure flow from this auxiliary port may be used as a pressure source to drive the liquid and gas supplies of the embodiments of the nebulizing catheter considered herein. Alternatively, a sensor located in the flow from this auxiliary port may be used to trigger another control device that operates the pressurized liquid and gas supplies.
• In a preferred embodiment, the generation of the aerosol can be synchronized with the inhalation of the patient. In one embodiment, this can be accomplished with a manually operable control gas valve on the gas pressure line to the liquid input port. This may be suitable when the medicine can be delivered in a short period of time, e.g. a few respiratory cycles. Alternatively, when it is preferred to deliver the medicine for an extended period of time, it may be preferred to employ a system that can automatically deliver medicine via the nebulizer from a source of liquid medicine. In such a system, the gas and/or liquid flow are triggered by the patient's respiratory cycle with the use of an electronic pressure sensor and relay actuator.
• An important factor relating to effective delivery of medication via a nebulizing catheter is the flow control system for pressurizing and supplying the gas and liquid to the proximal end of the nebulization catheter. In many circumstances, it is envisioned that medication will be delivered to the patient via a nebulization catheter that is in place in the patient over an extended period of time, such as several hours or days. In such circumstances, it would be preferred to use a system that automatically delivers the proper dosage of medication from a supply of the medicine to the patient at the proper rate, and further that can operate automatically and unattended. Further, it would be preferred to provide a means to detect when the supply is running low so that either the nebulization catheter can be disconnected or a new supply provided.FIGS. 50 and 51 show several embodiments of a reservoir and pressurization system for use with a nebulizing catheter.
• Referring toFIG. 50, a reservoir andpressurization assembly800 is connected to a proximal end of a nebulization catheter. The nebulization catheter may be similar to any of the embodiments described above. Theassembly800 has agas inlet port804 that can connect to an external pressurized gas supply. The external pressurized gas supply may be the main gas supply of the hospital or may be provided by another unit. The external gas supply may provide oxygen at 50 psi. Thegas inlet port804 communicates with anairflow passageway808 defined by and extending through theassembly800. Theassembly800 includes agas output port812 that communicates with thefluid flow passageway808 and which connects to a gas inlet port of the nebulization catheter (not shown). Thegas output port812 is located immediately downstream of thegas inlet port804. Located in thefluid flow passageway808 downstream of thegas outlet port812 is a filter816. The filter816 is preferably a hydrophobic filter that allows the passage of gas but which would prevent the backflow of any liquid. Located downstream of the filter816 in thefluid flow passageway808 is an injection port andreservoir820. Thisport820 communicates with a supply of the liquid fluid medication to be supplied to the nebulizing catheter. Located next in thefluid flow passageway808 is a capillarytube drug reservoir824. Thecapillary tube reservoir824 is comprised of a length of plastic tubing adapted to hold a supply of the liquid medication to be delivered. In the embodiment shown, the capillary tube reservoir consists of a helical coil of transparent tubing. Located downstream of thecapillary tubing reservoir824 is aliquid outlet828 that connects to a liquid inlet port of the nebulization catheter (not shown). With the embodiment shown inFIG. 50, the transparentcapillary tubing824 provides a convenient and reliable way to ascertain the supply of medication to the nebulizing catheter. The capillary tubing because of its length is capable of containing a suitable supply of the medication. When the attending medical personnel observe that the medication is about to run out, a new supply can be readily provided. The clear capillary tube allows easy visualization of the drug flow by watching the gas-drug meniscus travel down the tube. Instead of relying on direct observation by medical personnel, the capillary tubing may be used with an automatic detection device, e.g. a photocell, that provides an alarm to the medical personnel upon detection that the medication is running out in the capillary tubing or that the meniscus has ceased moving due to a blockage. A blockage may also be detected by detection of an increase in pressure.
• FIGS. 51 and 52 show another embodiment of a fluid reservoir andpressurization assembly832. This embodiment includes agas inlet836, afluid flow passageway840, a liquidmedicine supply vent844, afilter848, acapillary channel section852, and anoutlet port856. In this embodiment, thefilter848 is located downstream of the fillingvent844. Thefilter848 allows the pressurized gas to push the liquid drug during use but prevents the liquid drug from backing up to the vent during filling. In this embodiment, asecond injection port860 is provided downstream of thecapillary section852 and asecond filter864 is located downstream of thesecond injection port860. Thesecond filter864 is preferably a filter having approximately a 20 μm retention. Also, in this embodiment, thecapillary section852 may be composed of aplanar section865. Theplanar section865 may be a piece of plastic having a winding channel molded, routed or otherwise formed therein. The planar section868 is preferably colored to provide suitable contrast with the liquid solution flowing therethrough. A transparent flat plastic cover is positioned over the winding channel of theplanar section865 to form the closed channel of the capillary section. The fluid channel in the capillary section preferably has an I.D. of approximately 2 mm. Thesecond inlet port864 provides an additional means to add medication to the nebulizing catheter liquid flow. When the capillary channel in thesection852 has been filled, the gas is used to pressurize the tube and force the fluid to the catheter tip. Thesecond filter864 acts as a restrictive orifice to precisely meter the flow to the nebulizing catheter. The clear capillary channel allows easy visualization of the drug flow by watching the gas-drug meniscus travel down the tube. The narrow tube makes the flow appear to move quickly even at slow delivery rates. Thus, any flow interruption can be easily observed. The capillary tubing section also ensures that almost 100% of the drug is delivered to the catheter tip since there is no dead space in the line except at theinjection port860.
• During ventilation of a patient with an endotracheal tube, especially when intubation that takes place for a long period of time, it is considered desirable to humidify the air being delivered. When a nebulization catheter is used for delivery of medicine, either in conjunction with an endotracheal tube or even without an endotracheal tube, it is possible to utilize the nebulization catheter for providing humidification in addition to medicine delivery. An embodiment of a flow delivery system for a nebulizing catheter incorporating humidification is shown inFIG. 53. A suitablylarge reservoir866 holds sterile water or saline. Thereservoir866 is connected to theliquid supply lumen867 of a nebulization catheter868. Solution is drawn into the nebulization catheter868 from thereservoir866 by negative pressure at the catheter tip, gravity, a pump in the solution supply line distal of the reservoir, or by pressurizing the reservoir by a suitable means.
• Medicine may be added to the humidification water in at the following ways. In a first alternative, the medicine is added to the isotonic saline in thesolution reservoir866 thereby providing for high dilution and slow, continuous delivery of the medicine along with the water. In second alternative, the medicine is introduced into thesolution supply line867 via aninjection port869 between thereservoir866 and the liquid lumen of the catheter868. The medicine may be delivered to the injection port of the solution supply line from a solution reservoir system such assystem800 ofFIG. 50. Using this latter alternative, a more concentrated dose of the medicine can be delivered at the specific time preferred by the physician. It may also be preferable to include a molecular sieve, check valve orair trap870 between thereservoir866 and the injection port to the to ensure that the medicine cannot flow or diffuse backwards into thereservoir866.
• When delivering medicine to the lungs or when delivering water for humidification, it may be desired to heat the liquid prior to delivery. This may especially be appropriate since expanding gases which are associated with the nebulization of liquids may remove heat from the body. In order to address this concern, aheating element871 may be associated with theliquid supply line867 to the nebulizing catheter868. Thisheating element871 may include an electric coil wound around thesupply line867 or may use a heated water flow in a tubing wound around thesupply line867. Theheating element871 may be used in embodiments that provide for humidification as well as those that do not. Alternatively, theheating element871 may be associated with the gas supply line or with theliquid reservoir866,
• It is generally considered preferable to operate the nebulizing catheter so as to generate an aerosol that is carried by a patient's inhalation to the lungs. This requires a pulsing of the aerosol generation so that it is timed to coincide with the inhalation of the patient. If the patient is intubated, the timing of the nebulization can be synchronized with the operation of the ventilator. It is recognized that it may be preferable to begin the nebulization slightly in advance of, at, or slightly after, the beginning of the inhalation period in order to account for the distance between the nebulization tip and the alveoli. Also, it may be preferable to stop the nebulization slightly before the end of the inhalation period in order to avoid wasting aerosol after the inhalation flow has stopped.
• This continuous pulsing of the aerosol can be accomplished by asystem872 as shown inFIGS. 54 and 55.FIGS. 54 and 55 show a portion of the flow control system for a nebulizing catheter. Aflow line876 has aninlet880 and anoutlet884. Theflow line876 may be formed of a soft (e.g. compliant) tube. Theinlet880 connects to the source of liquid medicine and in particular may attach to the liquid outlet (828 or856) of the liquid reservoirs shown inFIGS. 50-52. Theflow line outlet884 inFIGS. 54 and 55 connects to the liquid inlet port on the manifold of the nebulizing catheter, such asport32 inFIGS. 1 and 2. Located around a portion of theflow line876 is anactuator piston888. Theactuator piston888 includes asolenoid pinch valve892 that can impinge upon the portion of theliquid flow line876 extending therethrough thereby pinching it off. Theactuator piston888 is connected to and operated by a controller that receives input from the ventilator (such as from the auxiliary port used for an external nebulizer) so that theactuator piston888 is operated to open and close the flow line synchronous with the inhalation and exhalation phases of the ventilator. Instead of a solenoid piston, a metering valve or reversible syringe pump may be used.
• In a preferred embodiment, theflow control system872 uses a dual solenoid arrangement to provide a draw-back feature. Pulsing of the liquid flow by actuation of theactuator piston888 may result in some liquid being left at the distal nebulizer liquid orifice when the pressure is turned off. This may result in small amounts of liquid drooling from the distal liquid orifice tip since the liquid is not being expelled under controlled pressure conditions. In order to limit the occurrence of such drooling, a draw back feature is provided in the flow control system. The draw back feature is provided by asecond solenoid896 which is associated with abladder900 that communicates with theflow line876. Thebladder900 communicates with theflow control line876 downstream of theactuator piston888. A small amount of fluid (liquid/air) occupies thebladder900. The bladder is composed of an elastic material that is formed with a tendency to recover to an expanded size. When theactuator piston888 opens to allow the flow of fluid to the distal end of the nebulizing catheter, thesecond solenoid896 moves to a closed position thereby compressing thebladder900 and squeezing fluid out of it into thefluid flow line876, as shown inFIG. 54. During the exhalation stage of the ventilation cycle, theactuator piston888 closes to shut off the flow of fluid to the distal end of the nebulizing catheter. When theactuator piston888 closes, thesecond solenoid896 opens, as shown inFIG. 55. This allows thebladder900 to resiliently recover to its expanded size, and when it does, it draws fluid into it from thefluid flow line876. Because thefluid flow line876 is closed proximally at theactuator piston888, when the bladder draws fluid into it from thefluid flow line876, it draws fluid from the distal end of the fluid flow line that connects to the nebulizing catheter liquid lumen. This causes the entire column of liquid in the liquid lumen of the nebulizing catheter to move slightly in a reverse direction (i.e. proximally) thereby moving the liquid away from the distal orifice. In this manner, the flow control system ofFIGS. 54 and 55 allows the draw back of liquid in the flow line in a reverse direction during the exhalation phase of the ventilator when the liquid flow line is shut off.
VII. Selective Nebulization Therapy Delivery
• When delivering medication with a nebulizing catheter, it may be desirable to deliver the medication to only one of the bronchi of the lungs and not the other or to only certain bronchia and not others. A reason for this type of selective therapy may be that only one area of the lungs requires medication. An embodiment of the invention shown inFIG. 56 facilitates selective delivery of a medication via a nebulizing catheter to only one bronchus. InFIG. 56, anendotracheal tube904 is positioned in atrachea908 of a patient. Anebulizing catheter912 is positioned in theendotracheal tube904. Thisnebulizing catheter904 may be similar to the embodiments described above. Thisnebulizing catheter904 may even be of the type that is non-removably incorporated into the endotracheal tube. Asecond catheter916 extends distally of theendotracheal tube904. Thesecond catheter916 may be positioned in theventilation lumen920 of theendotracheal tube904. Thesecond catheter916 includes a lumen through which a low flow pressurized gas can be conveyed. A proximal end of thesecond catheter916 extends out of the proximal end of theendotracheal tube904 through a suitable fitting, such as the fitting described in U.S. Pat. No. 5,078,131 (Foley). A suitable source of pressurized gas is attached to a proximal end of thesecond catheter916. This gas source may be the same gas source used for the pressurized gas lumen of thenebulization catheter912. Adistal end928 of thesecond catheter916 is positioned in thebronchus932 other than the bronchus to which it is desired to deliver nebulized medication. Pressurized gas is delivered through thesecond catheter916 out anorifice936 in the distal end thereof. The delivery of pressurized gas out thedistal end936 of thesecond catheter916 causes the pressure level in thebronchus932 to be slightly greater than in the other bronchus. Accordingly, when thenebulizing catheter912 generates an aerosol of liquid medicine, it will tend to flow with the inhalation stream from theendotracheal tube904 to the bronchus other than the one with thesecond catheter916. In this manner, one of the bronchi of the lungs, or even selected bronchia, can be selectively medicated using a single nebulization catheter positioned in the endotracheal tube.
VIII. Timing of Nebulization
• As mentioned before, in order to deliver the nebulized medicine to the lungs, it is preferred that the medicine is carried by the inhalation of the patient. A number of factors affect the efficiency of the medicine delivered this way. The following embodiments are directed to improving drug delivery efficiency taking into account some of these factors.
• If the patient is intubated, it may be possible to synchronize the timing of the nebulization pulse with the patient's ventilation. In one embodiment, this may be accomplished by providing an interface between the ventilator and the nebulizer. In some circumstances it may be preferred to provide other means for triggering the nebulization. For example, the ventilator being used may not provide a suitable interface. Also, the ventilator may not provide sufficiently accurate information concerning the patient's respiration to enable the nebulization catheter to operate with highest efficiency. In such situations, it may be preferred to utilize one or more separate sensors to obtain information that can be used to trigger and operate the nebulization catheter.
• Referring toFIG. 57, there is anebulizing catheter944 positioned in anendotracheal tube948 located in thetrachea952 of a patient. A proximal end of theendotracheal tube948 is connected to aventilator956. In order to obtain physiological information concerning the patient's respiration for use in timing the generation of nebulization pulses by thenebulization catheter944, one or more sensors may be used. For example, afirst sensor960 may be located on a distal end of theendotracheal tube948. In addition, asensor964 may be positioned on thenebulization catheter944. Anothersensor968 may be positioned on a separate device, such as aseparate catheter972 which is located further distally in the respiratory system. In addition, asensor976 may be positioned in the ventilator circuit of theventilator956 or in a ventilator auxiliary port, if available, or elsewhere on the patient. Thesesensors960,964,968, and976 may be types of sensors that measure pressure, flow or a physiological parameter of the patient, such as muscle contraction, electophysiological activity, etc. In alternative embodiments, one or more of these sensors may be used.
• FIGS. 58 and 59 show alternative embodiments of nebulization catheters that incorporate sensors. InFIG. 58, anebulization catheter980 is shown. Thisnebulization catheter980 may be similar to the nebulization catheter inFIG. 11. InFIG. 58, amain shaft984 includes a plurality of lumens with a centrally locatedlumen988 used to deliver a liquid medicine and a plurality oflumens992 located peripherally around it used to deliver a pressurized gas. One of theperipheral lumens996 is not used for pressurized gas delivery, but instead is used for sensing purposes. This may be accomplished by forming anaperture1000 through a wall of themain shaft984. The aperture communicates with thesensing lumen996. Theaperture1000 may be open or may be covered with a flexible diaphragm that permits transmission of pressure across it. A pressure sensing device may be located at a proximal end of the nebulizing catheter. The pressure at the distal end of the nebulizing catheter can be sensed by the proximally located sensing device via thesensing lumen996. This could rely on pneumatic sensing of the distal air pressure. Because of the effect of the distal gas pressurization orifice, pressure sensing through thesensing lumen996 may be used for purposes of gross overpressure for safety purposes. Alternatively, thepressure sensing lumen996 may be used during periods of time when a pressurizing gas is not being delivered to sense the patient's physiological airway pressure.
• FIG. 59 shows another embodiment of a pressure sensing nebulization catheter. This embodiment is similar to the embodiment ofFIG. 58 except that asensor1004 is located at a distal end of thecatheter980, specifically in theaperture1000. In this embodiment, thesensor1004 is a pressure transducer. Wire leads1008 extend proximally from thesensor1004 via thelumen996. Instead of measuring pressure, thesensor1004 could measure the flow at the distal end of the catheter. This may be accomplished by piezoelectric, optical, Hall effect, or other types of sensor technologies. The sensor may also be of a fiber optic type.
• Although the embodiments ofFIGS. 58 and 59 show sensing apparatuses associated with a nebulization catheter, these same types of sensors could also be used in theendotracheal tube948, theseparate catheter972, or theventilator956 ofFIG. 57 or the ventilator circuit.
• The sensor outputs information to acontroller1012 that operates theflow control portion1013 of the nebulization catheter system. The flow control portion may include the flow control assembly872 (shown inFIG. 55) as well as include the control functions for gas pressurization. Thecontroller1012 may have preset triggering parameters or may be user adjustable. Thecontroller1012 may use airway flow, pressure, or physiological activity as a basis for controlling theflow control assembly1013. Thecontroller1012 may provide for pulsing based upon any one of the following modes: (1) a controlled volume (bolus) of medicine is delivered with each pulse; (2) medicine is delivered until a physiological condition is sensed, e.g. exhalation; or (3) medicine is delivered for a fixable time interval, e.g. 2 seconds. These modes of operation may be selectable by the physician based upon the preferred treatment taking into account the patient's condition, the type of medicine being delivered, etc.
• It may also be desired to regulate the delivery of aerosol so that it is not delivered with every inhalation. As mentioned above, one concern with delivery of an expanding gas is the cooling effect that it may have on the body. This can be a factor with high gas flow rates. Accordingly, it may be preferable to deliver aerosol on every other inhalation or every third inhalation, and so on. Alternatively, it may be preferred to deliver aerosol for certain periods of time, e.g. 5 minutes every hour. Therefore, by alternating aerosol delivery, the cooling effect associated with it can be reduced.
IX. Alternative EmbodimentsA. Nebulizing Catheter Incorporated in Endotracheal Tube
• The various embodiments of nebulizing catheters, disclosed above, have been described as being either adapted for use in conjunction with a separate endotracheal tube, or adapted to be used without an endotracheal tube. If used with an endotracheal tube, the embodiments of the nebulizing catheter disclosed above are preferably removable from the endotracheal tube if one is present. It is noted that many of the embodiments of the present invention disclosed herein may also be used in conjunction with a nebulization catheter that is non-removable from an endotracheal tube, i.e. in which the nebulizing catheter is incorporated into and forms part of the endotracheal tube. An endotracheal tube that provides for nebulized medication delivery is described in a patent application filed by Dr. Neil R. MacIntyre on Mar. 10, 1992 entitled “Endotracheal Tube Adapted for Aerosol Generation at Distal End Thereof”, the entire disclosure of which is incorporated herein by reference. According to a system developed by Dr. MacIntyre, there is provided an endotracheal tube that provides for nebulization of a medication at a distal end thereof. According to Dr. MacIntryre's system, an endotracheal tube includes two additional, separate lumens, in addition to its main ventilation lumen used for the patient's breathing airflow. A medication in a liquid form is conveyed through one of the additional lumens and a pressurized gas is conveyed through the other lumen. The two additional lumens have distal openings near the distal end of the endotracheal tube airflow lumen. The distal opening of the pressurized gas lumen directs the pressurized gas across the distal medication lumen opening thereby nebulizing the liquid medication so that it can be delivered to the patient's lungs. It is intended that the present invention covers embodiments of nebulization catheters that are non-removable relative to an endotracheal tube.
B. Aerosol Generation with Porous Material
• FIG. 60 shows another catheter1060 for producing an aerosol. The catheter1060 generates an aerosol, or aerosol-like plume by use of a porous material or sponge located in a lumen of the catheter. The catheter1060 has amain shaft1064 with alumen1068 through which liquid medicine is conveyed under pressure and alumen1072 through which a gas is conveyed under pressure. Aporous material1076 is located in a distal end of theshaft1064 so that bothlumens1068 and1072 convey their contents into theporous material1076. Theporous material1076 may be a porous polyethylene made by Porex. Alternatively, the porous material may be a polymer sponge or other polymer material. Located in themain shaft1064 distal of the porous1076 is anend cap1080 with an orifice1084 located therein. The orifice is small and maintains a positive back pressure in the catheter shaft and porous material area. Theend cap1080 is separated from the distal side of theporous material1076 by asmall gap1082. The liquid and gas delivered under pressure to theporous material1076 migrate through the porous across thegap1082 toward the aperture1084. The liquid and gas become intermixed under pressure and as they are expelled from the fine tip orifice the gas expands and disperses the liquid particles into fine droplets. Upon discharging through the aperture1084, the medicine forms tiny droplets, e.g. an aerosol. The aerosol is conveyed to the lungs of the patient in a manner similar to that described in the embodiments above. An advantage of using a porous material or sponge at the distal liquid orifice is that it reduces drooling of the liquid.
C. Secondary Aerosol Generation
• In some situations it may be desirable to modify the primary aerosol spray generated by a nebulization catheter. One way that this can be accomplished is by causing the primary aerosol spray to impact upon a baffle placed in its path, the velocity and direction of the spray can be altered and the size of the distribution of the aerosol can be modified creating a secondary aerosol. Impaction upon a properly located baffle can break up large aerosol particles creating a finer aerosol mist. The baffle also deflects or diffuses the airstream carrying the particles reducing their forward velocity and altering their direction. This can lessen impaction on the carina or airways and enhance the entrainment of the particles into the inspiratory flow. Embodiments of nebulizing catheters incorporating an impaction baffle to provide a secondary aerosol are shown inFIGS. 61-64.
• Referring toFIG. 61, anebulization catheter1140 has agas lumen1142 and aliquid lumen1144 located in ashaft1146 of the catheter. Thegas lumen1142 conveys a pressurized gas to adistal gas orifice1148 and theliquid lumen1144 conveys liquid to adistal liquid orifice1150. Abaffle1152 connects to abaffle extension tube1154 so that thebaffle1152 is located distally of theliquid orifice1150. Thebaffle1152 is preferably located as close to thesolution orifice1150 as possible without interfering with the generation of the primary aerosol.
• Some of the primary aerosol that is not broken into fine particles may remain on thebaffle1152 and build up over time forming a thin liquid film on the surface of thebaffle1152. If this film is left to build up, it will form droplets that either fall or are blown off the baffle. These droplets may become quite large and of little or no therapeutic value representing a waste of the solution.
• In order to recirculate this film of solution, thebaffle1152 may be used to collect and return the liquid solution to aliquid supply lumen1144 To achieve this, the baffle may have with one ormore orifices1158 or porous material on its surface of thebaffle1152 for the collection of the film of solution. Theorifices1158 drain into or through the baffle, and are in fluid communication with thesolution supply lumen1144 via a lumen located inside of theextension tube1154. The lumen inside theextension tube1154 may communicate directly with thesolution lumen1144 or extension thereof.
• In the embodiment ofFIG. 61, the negative pressure generated at thenebulization orifice1150 by the gas flow over it is used to draw the recirculated solution from thebaffle recirculation orifice1158 via the lumen in theextension1154 and out theliquid orifice1150 again. In this case, therecirculation orifices1158 or surface should be in an area of higher ambient pressure than thesolution orifice1150 to cause the recirculation of the fluid. This may be accomplished by locating thecollection orifices1158 on a distal side of thebaffle1152 opposite the solution andgas orifices1150 and1148. The flow of new solution (from the proximally located solution reservoir) pumped into thesolution lumen1144 should be less than the flow drawn from thesolution orifice1150 to ensure that least some of the solution from thebaffle1152 is recirculated to theorifice1150.
• FIG. 62 shows another embodiment of a nebulization catheter that incorporates a baffle for the purpose of generating a secondary aerosol. This embodiment is similar to the nebulization catheter inFIG. 61 with the exception that the recirculated fluid is drawn back into a recirculation lumen1160 in thecatheter shaft1146. The recirculation lumen1160 communicates with theliquid lumen1144 at a junction1162 at which location the recirculated solution is mixed with newly supplied liquid in thesolution lumen1144.
• FIG. 63 shows another alternative embodiment. This embodiment is similar to the embodiment ofFIG. 62 except that the recirculated solution is routed from thebaffle1152 to the recirculation lumen1160 and then to a separate solution orifice for re-nebulization. This dedicated solution orifice1161 is also located at the catheter tip near agas orifice1148 to produce nebulization. The aerosol generated from this separate orifice1161 is directed into thecommon baffle1158 to break it into smaller particles and a portion of the solution will again remain on the baffle and be recirculated. This approach can eliminate the difficulties of balancing the flow of new and recirculated solution to a single solution orifice.
• Referring toFIG. 64, there is another embodiment of a nebulizing catheter incorporating a baffle for the generation of a secondary aerosol. In this embodiment, anebulizing catheter1170 has a shaft1172 with aliquid lumen1174 connected to aliquid supply1176. Agas lumen1178 connects to a pressuredgas source1180. Theliquid lumen1174 communicates with adistal liquid orifice1182 and the gas lumen communicates with adistal gas orifice1184. A baffle1186 is located in front of theliquid orifice1182. Aerosol impacting on the baffle1186 produces a secondary aerosol that flows around the baffle1186. A residue film of liquid migrates around the baffle1186 and enters into baffle orifices1190 located on the distal side of the baffle1186. The baffle orifices1190 communicate with a recirculation lumen1192 that extends through the catheter shaft to a reservoir1194 located outside of the body where the recirculated solution is combined with non-recirculated solution pumped from a proximal drug reservoir. The flow of recirculated and non-recirculated solution into the system should be carefully balanced to match the amount of aerosol generated. To achieve this, flow metering and pumping strategies can be employed.
D. Nebulization Catheter with Pressurized Propellant-Drug Canister
• In the embodiments described above, medicine is delivered in liquid form to the distal liquid orifice. In another embodiment, illustrated in the diagram ofFIG. 65, the medicine may be mixed with a propellant and maintained under pressure and delivered under pressure to the distal tip of a nebulizing catheter1198. A pressured medicine-liquid propellant mixture could be supplied from apressurized canister1200 such as those used as a component of a metered or non-metered dose inhaler. By using a propellant, an aerosol could be generated from thedistal end1202 of the catheter even without the addition of the pressurized nebulizing gas. However, the delivery ofpressurized gas1204 from the distal end of the nebulization catheter would be used to assist in breaking up any larger medicine particles and also assist dispersing the aerosolized drug solution delivered through the catheter as well as help shape the aerosol plume. For example, the delivery of the pressurized, nebulizing gas may assist in shielding the aerosol generated by the medicine-liquid propellant mixture and help avoid losses due to impaction.
E. Nebulizing Function Incorporated in Suction Catheter
• As mentioned above, the nebulizing catheter can be incorporated into another device, such as an endotracheal tube, either removably or non-removably. Another such device into which a nebulizing catheter can be adapted is a suction or aspiration catheter. A suction catheter is sometimes used in conjunction with patients who are intubated. A suction catheter has an O.D. and a length such that it can be inserted through the ventilation lumen of an endotracheal tube. The suction catheter is used to aspirate fluids and mucin secretions that collect in the respiratory tract of in the endotracheal tube of a patient who is intubated. A conventional suction catheter is inserted down the ventilation lumen of the endotracheal tube and out the distal end. A mucolytic agent may be instilled as a liquid via a lumen of the suction catheter to help in the withdrawal of mucin from the trachea or bronchi. The suction catheter may then be withdrawn from the endotracheal tube and either disposed or retained in a sterile sheath connected to a proximal end of the endotracheal tube so that it can be reinserted into the endotracheal tube again.
• A nebulizing catheter can be incorporated into a suction catheter so that a single device can perform both the functions of aspiration and nebulization for aerosol delivery. In an alternative embodiment of the present invention, the nebulizing catheter, such as described above, could be incorporated into a suction catheter so that a single catheter can provide both functions. This could be accomplished by provided any of the embodiments of the nebulization catheter described above with a separate lumen for the purpose of providing a suction to withdraw fluid from a patient's respiratory tract. Combining the functions of a suction catheter and nebulization catheter into a single device has the advantages of avoiding the expense of separate products as well as avoiding the inconvenience of inserting and withdrawing separate devices.
• Embodiments of a suction catheter combined with a nebulization catheter are shown catheter isFIGS. 66-73.FIGS. 66-70 show a suction catheter assembly1220. The suction catheter assembly1220 includes asuction catheter shaft1222 slidably located inside of aflexible sheath1224. A suction lumen1225 extends through thesuction catheter shaft1222. Aproximal manifold1226 includes aport1228 for connecting a vacuum source to the suction catheter lumen1225. A valve1230 operates to open and close theport1228. A distal sleeve1232 provides for connecting to an endotracheal tube such that thesuction catheter shaft1222 can be inserted into the endotracheal tube by pushing theproximal manifold1226 toward the distal sleeve1232. The distal sleeve1232 may include a manifold for connection to aflush port1233. Aseal1235 located in the sleeve1232 closely bears on the suction catheter shaft to remove mucous or other unwanted materials that can be removed via theflush port1233. The shaft of the suction catheter may be provided with a low friction, e.g. hydrophilic, coating to reduce adhesion of mucous.
• The suction catheter assembly1220 includes twoadditional lumens1234 and1236. Theselumens1234 and1236 are located in a wall of thesuction catheter shaft1222. Theselumens1234 and1236 communicate withdistal orifices1238 and1240 located at a distal end of thesuction catheter shaft1222. Theselumens1234 and1236 are used to deliver a liquid medicine and a pressurized gas for nebulizing the liquid medicine, as described above. Also located at a distal end of thesuction catheter shaft1222 aresuction openings1242.
• The suction catheter assembly1220 can be used in a conventional manner to remove mucin from the trachea and from the bronchi. The suction catheter assembly1220 can also be used to deliver medicines to the lungs as an aerosol by means of thenebulizing lumens1234 and1236. The nebulizing lumens can also be used to deliver mucolytic agents as an aerosol. Because the fine aerosol delivered by the nebulizing lumens can be carried by a patient's inspiratory airflow into the bronchi, the mucolytic agent can be delivered further into bronchi compared to a suction catheter that merely instills or generates a coarse spray of a mucolytic agent. In addition, the flow velocity produced by the gas pressurization lumen may be used to assist in breaking up mucous at the end of the suction catheter.
• When using the suction catheter assembly1220, it can be positioned so that a distal end of thesuction catheter shaft1222 is close to the distal end of theendotracheal tube1250 as shown inFIG. 68 or alternatively thesuction catheter shaft1222 can be positioned so that it extends past the distal end of theendotracheal tube1250 as shown inFIG. 70. As shown inFIG. 70, the suction catheter shaft1220 may be formed with a distal curvature so that the distal end can be brought into proximity with the tracheal wall.
• Rather than incorporate the nebulizing lumens into the wall of the suction catheter, it may be preferably in many situations to use a conventional suction catheter with a stand-alone nebulizing catheter. The stand-alone nebulizing catheter may be similar to any of the embodiments described above. A suction catheter and a nebulizing catheter can readily be used together with the alternative versions of the manifolds shown inFIGS. 71-73.
• Referring toFIG. 71, anendotracheal tube1252 has a proximal end with asingle port1254. Asuction catheter1256 has adistal manifold1258. Thedistal manifold1256 could be formed as part of thesuction catheter1256 or could be provided as a separate component. Thesuction catheter manifold1258 connects to thesingle port1254 of theendotracheal tube1252. The manifold1258 has afirst port1260 for connecting to a ventilator and asecond port1264 for connecting to a proximal end of anebulizing catheter1266. As shown inFIG. 71, thenebulizing catheter1266 includes asterile sheath1268 which is similar to the sheath included on the suction catheter1262. In the embodiment ofFIG. 71, thesuction catheter1256 and thenebulizing catheter1266 are positioned alternately inside the ventilation lumen of theendotracheal tube1252. The suction catheter or the nebulizing catheter can be withdrawn temporarily and maintained in its sterile sheath while the other is being used.
• Referring toFIG. 72 there is another arrangement for connecting a suction catheter and nebulizing catheter to an endotracheal tube. In this embodiment, amanifold1270 connects to the proximal end of theendotracheal tube1252. The manifold1270 hasport1274 for receiving thenebulizing catheter1266 and asecond port1276. Adistal manifold1278 of asuction catheter1280 connects to thesecond port1276. Thesuction catheter manifold1278 has aport1282 for connecting to the ventilator. This arrangement can be used similarly to the arrangement ofFIG. 71.
• FIG. 73 shows still another arrangement for connecting a suction catheter and a nebulizing catheter to an endotracheal tube. In this embodiment, theendotracheal tube1252 is provided with a proximal end that includes dual ports. Afirst port1284 receives thenebulizing catheter1266. Thesecond port1286 may be connected to either directly to a ventilator or may be connected to a distal end of a suction catheter (not shown) in a conventional manner.
• In another alternative embodiment (not shown), the nebulizing catheter could be positioned down the suction lumen of the suction catheter.
• FIG. 74 shows another embodiment of a suction catheter also incorporating a nebulization of an aerosol. InFIG. 74, a suction catheter1400 is extends from the ventilation lumen of anendotracheal tube1250. The suction catheter1400 includesdistal suction orifices1402 located close to the distal end of the suction catheter shaft. Located along the suction catheter shaft proximally of thesuction orifices1402 are one or more pairs of liquid andgas orifices1404. The liquid and gas orifice pairs1404 are located with respect to each other to produce an aerosol of the liquid being delivered to the liquid orifice as in the previous embodiments. Thenebulization orifices1404 are oriented radially from the suction catheter shaft to direct the aerosol delivered from thenebulization orifices1404 toward the airway passage wall. In one embodiment, the aerosol being delivered is a mucolytic agent. The suction provided by the suction orifices draws the mucolytic agent delivered from the nebulization orifices as well as mucous treated by the mucolytic agent in a distal direction into thesuction orifices1402.
• Another embodiment of the suction catheter with aerosol delivery is shown inFIG. 75. Asuction catheter1410 is located in a ventilation lumen of theendotracheal tube1250. As in the previous embodiment, thesuction catheter1410 has adistal suction orifice1412 for removing mucous from the airway passage. In addition, thesuction catheter1410 also includes distal gas and liquid orifices1414 located in proximity to each other to produce a aerosol. The liquid and gas orifices are located in adistal extension1416 of the suction catheter shaft so that they are distal of thesuction orifice1412. The liquid and gas nebulization orifices1414 are oriented in a proximal direction toward thesuction orifice1412. Thedistal extension1416 is formed to bring the nebulization orifices1414 close to the wall of airway passage so that the aerosol delivered from the nebulization orifices1414 washes the airway passage wall. As in the previous embodiment, the aerosol delivered may be a mucolytic agent to facilitate suctioning of the mucous out of the airway passage. The pressurized gas flow may be used to contribute to the dislodgement of mucous from the airway passage walls.
F. Nebulization with Vibration
• A vibrating orifice, a screen with multiple orifices or perforations, or a vibrating wire located at the distal tip of the nebulizing catheter may also be employed to assist in the generation of fine aerosol particles. The vibration may be generated by electromechanical, hydraulic, pneumatic, or piezoelectric means. The vibrations may be generated at the tip of the catheter, in the shaft, or extracorporeally.
• One embodiment of a nebulizing catheter incorporating a vibrating tip is shown inFIG. 76. Anebulizing catheter1300 includes ashaft1302 through which extend alumen1304 for the delivery of a liquid medicine and alumen1306 for the delivery of a pressurized gas. Theliquid lumen1304 communicates with adistal liquid orifice1308 and thegas lumen1306 communicates with adistal gas orifice1310 located at a distal end of the nebulizing catheter shaft. At the tip theorifices1308 and1310 may be drilled or formed in apiezoelectric material1314 or may be drilled or formed in an orifice insert, plate, tube or screen mechanically attached to the tip such that the vibrations of the material are transferred to orifices. Although both the gas and liquid orifices may be vibrated, alternatively only the liquid orifice may be vibrated. In still a further embodiment, the entire shaft of the catheter may be vibrated so that the vibrations are transferred to the tip. The vibrations may be amplified by mechanical means to increase the amplitude of the orifice oscillation. Twoelectrical lead wires1316 and1318 may be used to conduct bipolar or unipolar pulses from an extracorporeal generator and control circuit to thepiezoelectric material1314. The amplitude and frequency of the orifice vibrations may be adjusted to optimize aerosol production based on the gas and solution flow rates, the orifice configuration, and the desired size of the aerosol particles. The generation device would be provided with a current leakage sensor to terminate its operation in the event it detects current leakage in the system. The vibrations can be pulsed to coincide with inspiration and also to control heat generated by vibration at the tip. One or more gas supply lumens and orifices at the catheter tip can be used to assist in the dispersion and transport of the particles produced at the vibrating orifice.
• In a further alternative embodiment, the orifice may be vibrated by means of a vibrating wire connected to the orifice that is caused to vibrate from a generator connected to the proximal end. In still a further embodiment, a vibrating wire, similar to the wire tip shown inFIGS. 16-19, may extend distally past a non-vibrating orifice to cause aerosolization of a liquid delivered from the orifice that impinges onto the vibrating wire. In a still further embodiment, the tip may be vibrated remotely, e.g. from a source outside the body, by means of a magnetic field.
• A liquid supply to the catheter tip can also be rapidly pulsed to cause small droplets to be ejected at the solution orifice. This may cause a finer aerosol to be developed than by feeding a continuous stream of solution to the orifice. The pulsation can be accomplished by rapidly expanding and contracting all or part of the solution reservoir (including the lumen). The expansion and contraction of the reservoir can be caused by electromechanical, hydraulic, pneumatic, or piezoelectric actuators forming the reservoir, within the reservoir or moving flexible portions of the reservoir. Such an embodiment is shown inFIG. 76. A nebulizing catheter1500 includes ashaft1502 having agas lumen1502 connected to a source ofpressurized gas1504 and aliquid medicine lumen1506 connected to a source ofliquid medicine1508. Included in theliquid medicine source1508 is a means for imparting compression waves or pulsation into the liquid. The waves are indicated in the liquid at1509. The wave imparting means may be atransducer1510 or other similar device. Thevibration inducing device1510 may be driven by afrequency generator1513 at a frequency greater than 100 hertz. The vibrations induced in the liquid may be focussed or directed toward thedistal liquid orifice1514.
• In the case where the vibrations are generated at a location proximal of the tip, the nebulizing catheter shaft may incorporate a mechanical means in the shaft or near the orifices capable of transmitting or amplifying the pulsations. In the embodiment ofFIG. 77, awire1516 may extend from the pulsation generating means1510 into theliquid lumen1506 to help convey thevibrations1509 to thedistal orifice1514. The pulsations imparted to the liquid may be used to generate an aerosol from thedistal liquid orifice1514 or alternatively may be used in conjunction with the pressurized gas delivered through thegas lumen1502 for enhanced aerosolization. The amplitude and frequency of the orifice vibrations may be adjusted to optimize aerosol production based on the gas and solution flow rates, the orifice configuration, and the desired size of the aerosol particles.
• The volume dispersed from theliquid orifice1514 by each pulse should be less than approximately 10 microliters and the pulsation should occur at a frequency greater than 100 Hertz, although smaller volumes and faster frequencies may be used to produce a finer aerosol. It is preferable that the reservoir and lumens be constructed or a material of minimal compliance to ensure minimal attenuation of the pulsation. The gas supply orifice at the catheter tip can be used to assist in the dispersion and transport of the particles produced at the solution orifice. These micro pulsations can be incorporated into a series with pauses between them to coincide with the patient's inspiratory phase.
G. Other Method for Aerosol Generation
• The above embodiments describe a nebulization catheter in which an aerosol is generated by directing a pressurized gas through a catheter near an orifice from which the liquid to be nebulized exits. It is considered to be within the scope of the invention described herein to use other means or agents to generate an aerosol for delivery of a medication to the respiratory tract. For example, the above embodiments may be used in conjunction with devices that utilize other means to generate an aerosol of a liquid medication. A liquid delivered by a single liquid lumen may be nebulized by applying ultrasonic energy to the liquid, electrospray, steam, or a micropump similar to those used in ink jet type printers. These alternative approaches to nebulization may be substituted for the use of a pressurized gas for some of the embodiments described above, or may be combined with pressurized gas or with each other to produce an aerosol of the liquid medication.
• The nebulization catheter embodiments described herein could also be used in other types of nebulizers that are used externally of a patient's respiratory system, such as small volume nebulizers (SVN), humidification nebulizers, or nebulizers used for ocular or nasal drug administration. When used in such other types of nebulizers, the embodiments of the nebulization catheter disclosed herein provide for a fine aerosol without the potential disadvantages of impacting the liquid on a baffle or recirculating the liquid medicine on a continuous basis which are common in such nebulizers.
• It is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is understood that the following claims including all equivalents are intended to define the scope of the invention.

Claims (20)

1-88. (canceled)

89. A method for delivering a medicine to a patient, comprising:

positioning a nebulization catheter in the patient; and

operating the nebulization catheter to produce an aerosol of the medicine at a distal end of the nebulization catheter in synchronism with the patient's inhalation while the nebulization catheter is positioned in the patient.

90. The method ofclaim 89, wherein operating the nebulization catheter comprises applying an electric signal to the distal end of the nebulization catheter to produce the aerosol from the distal end.

91. The method ofclaim 89, wherein operating the nebulization catheter further comprises:

delivering a liquid medicine to a first orifice located at the distal end of the nebulization catheter; and

delivering a pressurized gas to a second orifice located at the distal end of the nebulization catheter in proximity to the first orifice.

92. The method ofclaim 91, further comprising:

imparting pulsation to the liquid medicine being delivered.

93. A method for delivering a medicine to a patient, comprising:

sensing a physiological condition of the patient; and

operating a nebulization catheter to produce an aerosol of the medicine at a distal end of the nebulization catheter as a function of the sensed physiological condition.

94. The method ofclaim 93, wherein sensing the physiological condition of the patient comprises sensing inhalation of the patient.

95. The method ofclaim 93, wherein sensing the physiological condition comprises detecting one of a pressure, flow or physiological parameter in the patient with a sensor.

96. The method ofclaim 95, wherein the sensor comprises a plurality of sensors.

97. The method ofclaim 95, wherein the sensor is positioned on the nebulization catheter.

98. A nebulization catheter system comprising:

a nebulization catheter having a catheter shaft comprising:

a liquid lumen centrally located in said catheter shaft and adapted for conveying a medicine in liquid form;

a gas lumen peripherally located adjacent said liquid lumen and adapted for conveying a gas;

a distal liquid orifice communicating with said liquid lumen; and

a distal gas orifice communicating with said gas lumen, said distal gas orifice being aligned with respect to said distal liquid orifice so as to nebulize a liquid medicine discharged from the liquid orifice; and

a sensor configured to detect information regarding a patient's respiration for use in controlling a flow of the medicine or gas to the nebulization catheter.

99. The system ofclaim 98, wherein the sensor is positioned on the nebulization catheter.

100. The system ofclaim 98, wherein the sensor is configured to detect a pressure, a flow or a physiological parameter of a patient.

101. The system ofclaim 98, wherein the physiological parameter comprises a muscle contraction.

102. The system ofclaim 98, further comprising a controller in communication with the sensor, the controller configured to control a fluid flow of medicine to the nebulization catheter or a gas pressurization of gas supplied to the nebulization catheter in response to detected information regarding the patient's respiration.

103. The system ofclaim 98, wherein the controller is configured to operate in a first mode to provide medicine to the nebulizing catheter except when an exhalation is detected at the sensor.

104. The system ofclaim 102, wherein the controller is selectably adjustable to operate in the first mode or a second mode, where the controller is operable to provide a controlled volume of medicine to the nebulizing catheter during each of a plurality of predetermined nebulization pulses in the second mode.

105. The system ofclaim 98, wherein the sensor comprises a plurality of sensors.

106. The system ofclaim 98, wherein the sensor comprises one of a piezoelectric, optical or Hall effect sensor.

107. The system ofclaim 98 wherein the sensor is configured to control the flow of medicine or gas in synchronism with the patient's inhalation.

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