FEEDBACK CONTROLLED DISPOSABLE HEMOSTASIS DEVICE
FIELD OF THE INVENTION
This invention relates to a device for applying pressure to a tissue site, and more particularly to a device that includes an inflatable bladder which is used to apply pressure to a tissue wound site when inflated.
BACKGROUND OF THE INVENTION
Often it is necessary to quickly stop bleeding from an artery during surgery, following a diagnostic procedure such as angiopraphy that requires an arterial or venous puncture, as well as other times when the artery has been nicked or becomes patent. One method of stopping blood flow from the artery is to apply pressure directly to the artery with the use of one's finger.
Mechanical devices for effecting non-invasive compression of arteries include the use of pressure cuffs. Typically, the cuff includes a strip of non-elastic material to be wrapped around a limb. An elastic inflatable bladder is superimposed on the non-elastic material. When the bladder is inflated, the pressure exerted by all parts of the enwrapment on the limb is increased. U.S. Patent No. 3,171 ,410 discloses a pneumatic dressing which exemplifies traditional pressure cuff devices.
Other mechanical devices have been used for decades to achieve hemostasis. Many of these devices are based on a C or U- shaped clamp that uses a ratcheting effect to allow the operator to apply or release pressure to a puncture site. These clamps have proven to be efficient alternatives to manual compression for control of bleeding after the removal of transfemoral sheaths.
One C-clamp device features a rigid footplate, as disclosed in U.S. Patent No. 3,799,249 (hereafter the " '249 patent"). The apparatus of the '249 patent is used to exert non-calibrated and unevenly distributed pressure to the body surface overlying an artery. The use of C-clamps can also cause hematomas and can only be used for a limited time. U.S. Patent No. 3,625,219 discloses a transparent rubber membrane clamped to a transparent plastic plate to form an expandable pressure chamber. Clamping screws are used to maintain various members of the chamber support structure in place, and must be loosened to adjust the position of the chamber relative to the area to which pressure is to applied.
U.S. Patent Number 4,233,980 discloses a device which includes an inflatable bladder formed with two sheets of transparent, non-elastic material that provide lateral restraint. The bladder is inflated by the introduction of a fluid. Vertical expansion is accomplished by the separation of the two sheets of material due to inflation. The bladder is typically mounted on a pressure plate. The pressure plate is mounted on a positioning arm.
U.S. Patent Number 5,307,811 discloses a device which includes an inflatable bladder having a single inflatable volume, a base plate and a belt for supporting the inflatable bladder against the puncture site.
It would be desirable to provide a hemostasis device suitable for the femoral artery. It would be further desirable to provide a hemostasis device that is easy to attach and operate. It would also be desirable to have a hemostasis device which employs feedback control.
SUMMARY OF THE INVENTION
The present invention relates to a hemostasis device and method for closing wounds by the application of pressure. In general, the device includes one or more inflatable bladders which may be coupled to a portion of a patient's body in order to apply pressure to a wound site upon inflation. The one or more inflatable bladders may be shaped to conform to a wound associated with a puncture of a femoral artery. The inflatable bladder may also include one or more depressions for manually communicating pressure through the inflatable bladder to the wound.
The one or more inflatable bladders may be formed of multiple inflatable compartments where at least two of the compartments are independently inflatable to a different pressure relative to each other. For example, the multiple inflatable compartments can be inflated to apply a greater degree of pressure at a center of the wound and a lesser degree of pressure outside the center of the wound, and visa versa.
The multiple inflatable compartments may have a variety of different shapes. For example, the multiple inflatable compartments may include straight or curved parallel sections or concentric inflatable sections. The inflatable bladder may include an inner and an outer bladder section, the inner bladder section serving to apply pressure to the wound and the outer section serving to increase a rigidity of the device^ The device may also include a source of pressurized gas or liquid for inflating the inflatable bladder, as well as a mechanism for heating or cooling the pressurized liquid. The use of heated or cooled fluid enables different compartments of a multicompartment inflatable bladder to be inflated to different pressures and at different temperatures.
The device may also include one or more sensors for sensing a physical property of the patient such as the patient's pulse, temperature or blood pressure. Bleeding can also be detected using the device of the present invention. In one embodiment, the sensors are positioned adjacent to the wound site. Alternatively, the sensors may be positioned remotely from the inflatable bladder in order to sense one or more of the above physical properties at a remote location on the patient relative to the wound site.
The present invention also relates to a method for applying pressure to effect the closure of a wound while sensing one or more physical properties of the patient such as temperature blood pressure, pulse an d/or bleeding. In a preferred embodiment, at least one of the one or more physical properties are sensed at a location on the patient remote from the wound. The present invention also relates to a method for applying more than one pressure to a section of tissue of a patient to effect closure of a wound. This method may be performed by attaching an inflatable bladder formed of multiple inflatable compartments to a patient, at least two of the compartments being independently inflatable to a different pressure relative to each other; and inflating at least two of the compartments to different pressures. According to the method, a greater degree of pressure can be applied at a center of the wound and a lesser degree of pressure outside the center of the wound, and visa versa. According to the method, at least two of the compartments can also be inflated with liquid having different temperatures. The present invention also relates to a method for applying pressure at more than one temperature to a section of tissue of a patient to effect closure of a wound. This method may be performed by attaching an inflatable bladder formed of multiple inflatable compartments to a patient, at least two of the compartments being independently inflatable relative to each other; and inflating the at least two compartments with liquid at different temperatures. According to this method, the temperature of the fluid adjacent the center of the wound can be different than the temperature of the fluid away from the center of the wound. The present invention also relates to a method for applying pressure to effect the closure of a wound while sensing one or more physical properties of the patient such as temperature blood pressure, pulse and/or bleeding. In a preferred embodiment, at least one of the one or more physical properties are sensed at a location on the patient remote from the wound.
The present invention also relates to a device and method for applying pressure to a section of tissue of a patient to effect closure of a wound under feedback control. In one embodiment, the device includes one or more inflatable bladders; a mechanism for coupling the one or more inflatable bladders to the section of tissue; and one or more sensors coupled to the device for monitoring at least one physical property of the patient, such as the patient's blood pressure, temperature and pulse and bleeding at the wound site. In one embodiment, the sensors used in the feedback mechanism are positioned adjacent the wound site. Alternatively, the sensors used in the feedback mechanism may be positioned remotely from the inflatable bladder in order to control the device in response to one or more of the above physical properties as sensed from a remote location on the patient relative to the wound site. In either embodiment, at least one sensed physical property is used to control an operator of the device, such as the inflation of the inflatable bladder.
Using the device with feedback control, one or more physical properties can be continuously monitored. The device may further include a source of pressurized gas or liquid coupled to the inflatable bladder for inflating the inflatable bladder. The device may also include a microprocessor which receives one or more signals from the one or more sensors and controls the source of pressurized gas or liquid in response to the one or more sensed physical properties. The device may also include an alarm system which is triggered by the microprocessor when one or more of the physical features being monitored exceeds or falls below a predetermined limit.
The present invention also relates to a device for applying pressure to a section of tissue of a patient to effect closure of a wound while detecting the positioning of the inflatable bladder relative to the wound, detecting bleeding and/or locating an artery. When detecting bleeding, a conductivity sensor may be employed on a surface of the one or more inflatable bladders. Alternatively, an optical sensor may be used to detect bleeding. The device may further include a source of pressurized gas or liquid coupled to the inflatable bladder for inflating the inflatable bladder. The device may also include a microprocessor which controls the source of pressurized gas or liquid in response to the above detected features. The device may also include a alarm system which is triggered by the microprocessor when one or more of the above detected features exceeds or falls below a predetermined limit.
The present invention also relates to a method for effecting the closure of a wound of a patient under feedback control. The method may be performed by attaching a device including an inflatable bladder to a patient such that the inflatable bladder is positioned over the wound, the device including one or more sensors for monitoring at least one physical property of the patient, such as blood pressure, temperature and pulse; inflating the inflatable bladder to apply pressure to the wound; monitoring the at least one physical property using the one or more sensors; and adjusting the pressure to which the inflatable bladder is inflated in response to the monitored physical property.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 A is a view of a side of a hemostasis device which faces the patient when in use (distal side). Figure 1 B is a view of the top of a hemostasis device which faces away from the patient when in use (proximal side).
Figure 1C illustrates an attachment mechanism coupled to the belt such that the device forms a loop. Figure 1 D illustrates the device formed into a loop encircling a patient.
Figure 2 is a sideview of a device having a plurality of inflatable bladders.
Figure 3A is a sideview of a device in which the inflatable bladder is in a fixed position relative to the belt.
Figure 3B is a sideview of a device in which the bladder is not in a fixed position relative to the belt.
Figure 3C illustrates an attachment mechanism which may be used in the device illustrated in Figure 3B. Figure 4 is a sideview of a device having a surface which has a high coefficient of friction which assists in securing the positioning of the bladder relative to the patient's skin.
Figure 5A is a sideview of a doughnut shaped bladder.
Figure 5B is a sideview of a bladder shaped to conform to a wound associated with a typical surgical femoral artery puncture.
Figure 5C is a sideview of a bladder shaped to conform to a leg or an arm.
Figure 5D is a sideview of a u-shaped bladder.
Figure 6A is a sideview of an inflatable bladder formed of concentric inflatable subcompartments.
Figure 6B is a sideview of an inflatable bladder formed of straight and parallel compartments.
Figure 7 illustrates an inflatable bladder with an inner inflatable compartment for applying pressure to the wound site and an outer inflatable compartment which enhances the rigidity of the device. Figure 8A is a sideview of an inflatable bladder with depressions for manually applying pressure to a wound site.
Figure 8B is an alternate embodiment of an inflatable bladder with depressions for manually applying pressure to a wound site. Figure 9 provides a top down view of a device with a single inflatable compartment.
Figure 10 provides a top down view of a device with multiple inflatable compartments.
Figure 11 provides a top down view of a device which is inflated by fluid of a desired temperature.
Figure 12 provides a top down view of a device which has multiple inflatable compartments which can be inflated by fluids of different desired temperatures.
Figure 13 is a sideview of an inflatable bladder with a matrix of position sensors.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention relates to a hemostasis device and method for closing wounds by the application of pressure. In general, the device includes one or more inflatable bladders which may be coupled to a portion of a patient's body in order to apply pressure to a wound site upon inflation. The device may be used in a variety of applications. For example, the device may be used to close puncture wounds in blood vessels, such as the femoral artery created by the introduction of a catheter into the body. The device may also be used as a tourniquet for applying pressure to lacerations.
The device may include a belt or other mechanism for coupling the inflatable bladder to the patient. When a belt is employed, the belt should be minimally stretchable and flexible enough to encircle various patient bodyparts. The belt may be permanently attached to the device or may be attachable to the device. Coupling of the device to the patient is preferably performed by encircling the device around a portion of the patient's body. In this regard, the device may include a variety of attachment mechanisms for causing the device to encircle a portion of the patient's body.
The device preferably includes a quick release mechanism attached to the inflatable bladder and/or the belt which allows the device to be rapidly decoupled from the patient. This enables medical personnel to rapidly remove the device and access the wound being treated.
The device should be designed to remain immobilized on the patient. In this regard, the belt and/or inflatable bladder are preferably designed to have a surface that is in contact with the patient with a high coefficient of friction. This may be accomplished by modifying the surface of the belt and/or inflatable bladder, either mechanically or chemically to be slip resistant.
An adhesive may also be applied to the device and/or the patient. S.C. Temin, in the Encyclopedia of Polymer Science and Engineering, vol. 13 (New York: John Wiley & Sons, 1988), at pp. 345 to 368 and the
Handbook of Pressure-sensitive Adhesive Technology, ed. Donates Satas (New York: Van Nostrand Reinhold Co., Inc., 1982), both provide a comprehensive overview of medical and other adhesives which may be used in conjunction with the device of the present invention and are incorporated herein by reference.
In one embodiment, a flexible polymeric film material is used as a backing material for the inflatable bladder and/or the belt. Flexible polymeric film materials are known as described in European Patent Applications Nos. 0107915 and 0147119 and PCT/GB91/00496, all of which are incorporated herein by reference. These references disclose materials with particular moisture vapor transmission rates. Film materials which have moisture vapor transmission rates generally compatible with human skin are most preferred.
WO91/14462, published October 3, 1991 refers to medical devices comprised of a substrate with a particular moisture vapor transmission rate with an adhesive thereon which is tacky at skin temperature but less tacky or not sticky at room temperature. A similar medical adhesive device is disclosed in WO91/14461. The disclosure of both of these PCT publications is incorporated herein by reference to the extent they disclose such devices including particular backing layers, adhesives and methods of use and manufacture.
In yet another embodiment, a pressure-sensitive adhesive (hereafter "PSA") is used in combination with the inflatable bladder and/or the belt. PSA adhesives are characterized as being normally tack and exhibit instant tack when applied to a substrate. A variety of polymers have been used to manufacture PSA, for example acrylic and methacrylic ester homo- or copolymers, butyl rubber-based systems, silicones, urethanes, vinyl esters and amides, olefin copolymer materials, natural or synthetic rubbers, and the like. The device may include a single inflatable bladder or multiple inflatable bladders. When multiple inflatable bladders are employed, the separation between the multiple inflatable bladders is preferably variable so that the device may be adapted to apply pressure to more than one wound site at the same time. The bladder may be constructed from any material which is impermeable to the substance used to inflate the bladder, which is flexible and which substantially retains its shape under pressure. The bladder is preferably constructed from a hypo-allergenic material such as PVC.
The shape and size of the inflatable bladder may be manipulated to perform a variety of different functions. For example, the lateral shape of the inflatable bladder may be circular, rectangular, u-shaped, or donut shaped (i.e., with a hole in the middle). The radial vertical contour of the inflatable bladder may also be modified to perform a variety of different functions. For example, the inflatable bladder may have a rounded radial vertical contour, an elliptical radial vertical contour, a cone-shaped radial contour or a flat radial vertical contour. By varying the degree of curvature of the inflatable bladder in the vertical direction, different amounts of pressure can be applied to different areas of tissue covered by the device. For example, a highly curved radial vertical contour provides a larger pressure gradient than a flatter radial vertical contour which provides substantially uniform pressure gradient.
The inflatable bladder may be formed of one or more inflatable compartments. By employing multiple inflatable compartments where each inflatable compartment is inflatable to a different pressure, multiple pressure zones can be created. For example, it may be desirable to apply more pressure in the center of the wound and less pressure outside the center. Alternatively, it may be desirable to apply less pressure in the center of the wound and more pressure outside the center.
When multiple inflatable compartments are employed, the multiple compartments may consist of straight or curved parallel sections. Alternatively, the multiple inflatable compartments may consist of concentric inflatable sections. By using concentric inflatable sections, the pressure applied to a wound can be varied radially.
The inflatable bladder may also consist of inner and outer bladders sections. In this embodiment, the inner bladder section performs the function of the inflatable bladders used in the devices of the present invention. Meanwhile, the outer section forms a rigid structure when inflated which assists in the application of pressure to the wound.
The inflatable bladder may also include one or more depressions which allow a medical practitioner to manually communicate pressure through the inflatable bladder to the wound without having to remove the device from the patient. These depressions may also be used to locate a wound site underneath the device, to apply pressure to the wound prior to inflation of the device or to apply pressure to the would after inflation of the device. In one embodiment, the inflatable bladder is shaped to conform to a particular wound site. For example, the inflatable bladder may be shaped to conform to a wound associated with a puncture of a femoral artery. The inflatable bladder may also be shaped to conform to a section of the patient's body in order to assist retention of the device in a particular position on the patient.
The inflatable bladder may be inflated by a variety of mechanisms. For example, the device may include or be coupleable to a source of pressurized gas which is used to inflate the inflatable bladder. Alternatively, the device may include or be coupleable to a mechanism for manually inflating the inflatable bladder. The device may also include or be coupleable to a source of pressurized liquid for inflating the inflatable bladder. When using liquid to inflate the inflatable bladder, it is possible to heat or cool the wound site using heated or cooled liquid. By using a multicompartment inflatable bladder as described above, it is also possible to heat and/or cool different regions of tissue underneath the multicompartment inflatable bladder to different degrees.
The device may also include one or more sensors. These sensors may be used to monitor the blood pressure, temperature and/or pulse of a patient, the pressure and/or temperature within the inflatable bladder and the presence of blood at the wound site, as detected by conductivity. These sensors may also be used to provide continuous monitoring of the temperature, pressure, pulse of the patient. In one embodiment of the device, one or more sensors are positioned in the device adjacent the wound. Alternatively or in addition, one or more sensors may be attached to the device for positioning on a patient at a remote location relative to the wound. The ability to detect bodily functions such as temperature, pulse or pressure at a remote location relative to the wound site is an important feature of the present invention since it may be used to insure that the device is not unduly preventing the circulation of blood to the patient's extremities.
The above sensors may be used in a variety of different applications. For example, the device may include a mechanism for locating an artery, for example, by detecting an acoustic Doppler effect. In this embodiment, the sensors are used to detect the artery and facilitate the positioning of the device relative to the artery. The device may also include sensors which detect the positioning of the inflatable bladder relative to the wound site and can be used to provide a warning signal when the position of the device shifts relative to the wound site. The above sensors may also be used in combination with a microprocessor to act as a feedback mechanism for the device. For example, the sensors may serve as inputs to a microprocessor which modulates the pressure and/or temperature of the inflatable bladder in response to the blood pressure, temperature and/or pulse of the patient or the presence of blood at the wound site which may be detected by conductivity or optically.
The device may also include an alarm system which operates in combination with the sensors and the microprocessor to indicate to a medical practitioner when the pulse, blood pressure or temperature of the patient exceed or fall below preselected limits, when conductivity rises above a certain level indicating that bleeding is probably occurring, or when the device has moved relative to the wound site.
Figure 1A through 1D illustrate one embodiment of a device according to the present invention. Figure 1 A provides a view of the underside (distal side 13) of the device which faces the patient when in use. Figure 1 B is a view of the top (proximal side 12) of the device which faces away from the patient when in use. As illustrated in Figures 1A-1B, the device 10 includes a housing 11 which is coupled to an inflatable bladder 14. The housing 11 is further coupled to a belt 18 and an attachment mechanism 20. As illustrated in Figures 1C and 1 D, the device 10 may be formed into a loop which encircles a portion of the patient by coupling the belt 18 to an attachment mechanism 20.
The device 10 is positioned on the patient 22 such that the inflatable bladder 14 is coupled to a section of tissue 23 which includes a wound site 24. The belt 18 is cinched through the attachment mechanism 20 until the device 10 is tight enough that the device 10 remains in place on the patient 22. The bladder 14 is then inflated to apply pressure to the wound site 24 and aid the wound closure process. In another embodiment of the device, illustrated in Figure 2, the device 10 includes a plurality of inflatable bladders 14. The belt 18 is coupled to a plurality of housings 11 which are each coupled to an inflatable bladder 14. This embodiment is advantageous when several wound sites 24 are present. Figures 1 and 3A illustrate embodiments where the housing 11 is in a fixed position relative to the belt 18. In Figure 3A, the housing 11 is fixed to a first belt section 26 and a second belt section 28. The first belt section 26 is coupled to a first attachment mechanism 30 and the second belt section 28 is coupled to a second attachment mechanism 32. The first attachment mechanism 30 and the second attachment mechanism 32 may be coupled together such that the device 10 forms a loop. In applying the device, the bladder 14 is preferably positioned over the wound site 24 before coupling the attachment mechanisms together.
Figure 3B illustrates an embodiment of the device where the position of the housing 11 is not fixed relative to the belt 18. As illustrated, the belt 18 is slidably positioned through a plurality of belt connectors 34. Because the housing 11 is not fixed on the belt 18, the position of the bladder 14 can be changed after the device 10 is formed into a loop encircling the patient 22. The device may also include a locking mechanism 36 for immobilizing the inflatable bladder relative to the belt.
The attachment mechanism 20 can be any mechanism which allows the device 10 to form a loop encircling a portion of a patient. The attachment mechanism is preferably designed in combination with the belt to allow the device to form loops having a plurality of circumferences. For instance, the attachment mechanism 20 illustrated in Figure 1 is a single buckle through which the belt 18 can be cinched.
The attachment mechanism 20 can also be a quick release attachment mechanism 20 which allows the device 10 to be quickly removed from the patient 22 in the case of an emergency. For instance, the attachment mechanism 20 illustrated in Figure 2A is formed of
VELCRO which can be attached at a variety of circumferences. Figure 2B illustrates an attachment mechanism 20 which is similar to a seatbelt. The first mechanism 30 has a plurality of tabs 37 and the second mechanism 32 has a plurality openings 38 which are complementary to the tabs 37. The second mechanism is a buckle which allows the belt 18 to be cinched so the circumference of the loop encircling the patient 22 can be adjusted. When the first mechanism 30 is inserted into the second mechanism 32 the tabs 37 extend through the openings 38 as illustrated in Figure 3C. The device 10 can be quickly and easily removed from the patient 22 by pushing the tabs 37 through the openings 38 and pulling the first mechanism 30 from the second mechanism 32.
Figure 4 illustrates an embodiment which minimizes movement of the bladder 14 relative to the wound site 24. A bladder distal end 39 has a treated surface 40 which increases the coefficient of friction between the inflatable bladder 14 and the patient's skin. The treated surface 40 does not cover the portion of the inflatable bladder 14 which contacts the wound site 24 to avoid further irritation of the wound site 24. The treated surface 40 can be one of the adhesives discussed above or a rough material on the surface of the inflatable bladder 14.
The rough material can be a second material which is laminated to the surface of the bladder 14 or can integral with the inflatable bladder 14. The inflatable bladder 14 can have a variety of shapes designed to perform different functions. Figure 5A illustrates a doughnut shaped inflatable bladder 14. This shape may be used to apply pressure around a wound site 24.
The inflatable bladder 14 can also be shaped to conform to a particular region 23 of a patient's body. For instance, the inflatable bladder 14 in Figure 5B is shaped to conform to a tissue section located near the intersection of the thigh and hip. This location is associated with puncturing the femoral artery for insertion of a catheter during many surgeries. The inflatable bladder 14 illustrated in Figure 5C is shaped to conform to a tissue section located on an arm or a leg. The inflatable bladder 14 illustrated in Figure 5D has a u-shape. The vertical contour of the inflatable bladder 14 can also be designed to perform different functions. For instance, the inflatable bladder 14 illustrated in Figure 1C has a curved vertical contour while the bladder 14 of Figure 4 has a flat vertical contour. Other vertical contours are also contemplated. For example, the vertical contour may be rounded, elliptical, or cone-shaped. By varying the degree of curvature at the bladder distal end 39, different amounts of pressure can be applied to an area of tissue. For example, a small radius of curvature provides a larger pressure gradient than smaller radius of curvature which provides a substantially uniform pressure gradient. In another embodiment, the inflatable bladder 14 is formed of multiple inflatable compartments 42. Figure 6A illustrates an inflatable bladder with multiple concentric inflatable compartments 42. Each inflatable compartment 42 is independently inflatable to a different pressure. As a result, when the inflatable bladder 14 is placed adjacent to the wound site 24 and inflated, the pressure applied at a center of the wound site 24 can be greater or less than the pressure applied outside the center of the wound site 24 by varying the pressures within the inflatable compartments. A variety of other configurations for the inflatable compartments 42 are also contemplated. For instance, Figure 6B illustrates an inflatable bladder 14 constructed of a plurality of straight parallel inflatable compartments 42. Figure 5D illustrates a u- shaped inflatable bladder 14 constructed from a plurality of curved parallel compartments 42.
Figure 7 illustrates another embodiment of the inflatable bladder which includes an inner inflatable compartment 44 and an outer inflatable compartment 46. In this embodiment, the inner inflatable compartment 44 is inflated to apply pressure to the wound site 24. Meanwhile, the outer inflatable compartment 46 is inflated to increase the rigidity of the device 10. The device may also be designed to allow the wound site 24 to be manually manipulated while the device is attached to the patient. For example, Figure 8A illustrates an inflatable bladder 14 with a plurality of depressions 46. Fingers can be inserted into the depressions 46 to manually communicate pressure through the bladder 14 to the wound site 24. The depressions 46 can also be used to make minor adjustments to the position of the bladder distal end 39 without readjusting the position of the housing 11. Figure 8B illustrates an alternate embodiment of the inflatable bladder in which the depressions 46 extend from the top of the device to adjacent the underside of the device.
Inflation of the device may be performed manually or with the assistance of a compressed gas or pressurized liquid source. For example, Figure 4 illustrates an inflatable bladder 14 coupled to a release valve 50, a pressure gauge 52 and an inflation bulb 54. The inflation bulb is compressed and released until pressure gauge 52 indicates that the pressure within the bladder 14 has reached the desired pressure. The pressure within the bladder 14 can then be reduced by using the valve 50 to release the pressure.
Figure 9 illustrates an embodiment where the inflatable bladder is inflated by a source of compressed gas or pressurized liquid under feedback control. The bladder 14 is coupled to a reservoir 56, an inlet valve 57 and an outlet valve 58. The inlet valve 57 and outlet valve 58 are controlled by a microprocessor 60 which is powered by an energy source 62, such as a 9 Volt battery. The microprocessor 60 monitors the signal from a pressure sensor 61 positioned within the bladder 14.
The reservoir 56 contains the source of compressed gas or pressurized liquid. Examples of compressed gas which may be used include air, carbon dioxide, nitrogen, oxygen, and inert gases such as neon and argon. The microprocessor 60 increases the pressure within the bladder
14 by opening the inlet valve 57 and allowing the pressure within the reservoir 56 to drive the substance into the bladder 14. The microprocessor 60 reduces the pressure within the bladder 14 by closing the inlet valve 57 and opening the outlet valve 58 to release the substance from the bladder 14. When the substance is a fluid, the fluid is retained in a catch reservoir 64 which is vented to avoid an accumulation of pressure. When the substance is a gas, the gas can be released directly to the atmosphere or to an unvented catch reservoir 64. The device may operate under feedback control using the microprocessor. For example, the microprocessor 60 can continuously monitor one or more signals from temperature, pressure, pulse and/or conductivity sensors and use those signals to determine when to increase or decrease the pressure being applied to the wound by increasing or decreasing the pressure in the inflatable bladder.
In one embodiment, the pressure within the inflatable bladder 14 is adjusted by the microprocessor in response to at least one sensed physical feature. For example, as illustrated in Figure 1A and 1D, the device 10 can include one or more sensors 76 which can be positioned adjacent to the inflatable bladder 14 (Figure 1A) and/or remote from the inflatable bladder 14 (Figure 1D). The sensor 76 is coupled to a microprocessor which is used to control the pressure being applied to the wound by controlling the pressure within the inflatable bladder in response to signals from the one or more sensors 76. The one or more sensors 76 can be selected from a variety of sensors including, but not limited to temperature sensors, pulse sensors, blood pressure sensors, and conductivity sensors. Figure 1 D illustrates the sensor 76 coupled to the patient 22 by attaching an adhesive patch 78 to the patient 22 over the sensor 76. The sensor 76 can also be coupled to the patient 22 by placing the sensor 76 on a band which can be fastened around the patient 22 (not illustrated). The microprocessor 60 continuously monitors the sensor 76 and adjusts the pressure in the bladder 14 in response to the signal.
In one embodiment, the sensor is used to sense whether the device is cutting off blood flow to an extremity where the sensor is situated. The sensor may sense temperature, pulse, or blood pressure. For example, it is well known that when blood circulation is reduced in an extremity, the temperature in the extremity begins to drop. As a result, a sensor can be attached to an extremity and used to indicate whether the temperature (or blood pressure or pulse) at the extremity has dropped below a pre-determined limit. In response, the microprocessor will cause the pressure in the inflatable bladder to be reduced in order to increase the amount of blood flowing to the extremity. The microprocessor may also be used in the device to control the automatic inflation of the inflatable bladder. As illustrated in Figure 10, a housing 11 is provided which can be used to independently inflate the compartments 42 of the inflatable bladder 14 illustrated in Figure 6A. The reservoir 56 is coupled to a plurality of inlet valves 57 and outlet valves 58. Each inlet valve 57 and outlet valve 58 corresponds to a particular inflatable compartment 42. The microprocessor 60 monitors the signal from a pressure sensor 61 positioned in each compartment 42. The microprocessor 60 increases the pressure within a particular compartment 42 by opening the corresponding inlet valve 57 to allow the pressure within the reservoir 56 to drive the substance into the compartment 42. The microprocessor 60 reduces the pressure within the same compartment 42 by opening the corresponding outlet valve 58 to release the substance from the compartment 42. During operation of the device 10, the microprocessor 60 monitors the signals from one or more sensors, illustrated in Figure 10 as a pressure sensor 61. The microprocessor 60 maintains the pressure within a compartment at a desired pressure by adjusting the pressure in response to the signal from the sensor being monitored.
The device 10 may also be used as a patient monitor and alert system. In this embodiment, the microprocessor 60 is coupled to a plurality of LEDs 78 or an alarm speaker 79 located on the proximal side 12 of the housing 11 as illustrated in Figure 1 B. The microprocessor 60 monitors the sensor 76 and alerts the user when an alert situation is sensed by, for example, a visual signal on the LEDs 78 or an audible signal over an alarm speaker 79. Examples of alert situations include the blood pressure or pulse rate falling below a pre-determined limit or bleeding being detected by a conductivity or optical sensor for detecting blood.
In another embodiment of the device, the inflatable bladder 14 is inflated using a fluid. By using a fluid, it is possible to heat or cool the wound site. Heated or cool fluid can be delivered into the inflatable bladder from a source outside the device. Alternatively, as illustrated in Figure 11, the device may include a heating element 80 (or cooling element) positioned within the bladder 14. The temperature of the fluid in the bladder 14 can be raised (or lowered) by the heating element 80
(cooling element). The microprocessor 60 maintains the temperature of the fluid at a desired temperature by adjusting the temperature of the fluid in the bladder 14 in response to the signal from the sensor 76.
In a variation of the above embodiment, the device may include multiple inflatable compartments 42 which form the inflatable bladder
14. By designing the device so that each inflatable compartment is individually inflatable, it is possible to inflate each compartment with fluid of a different temperature, thereby making it possible to heat or cool different regions of tissue to different temperatures. Figure 12 illustrates a variation of this embodiment where the device includes a plurality of heating elements 80 and temperatures sensors 76. In this embodiment, the temperature of the fluid in a particular compartment 42 can be raised when the microprocessor 60 directs current through the heating element 80 in the particular compartment 42. Meanwhile, the temperature of the fluid in the compartment 42 can be reduced by opening the outlet valve 58 to release warmed fluid. The microprocessor 60 can be used to maintain the temperature of the fluid within a compartment 42 at a desired temperature by adjusting the temperature of that compartment 42 in response to the signal from the corresponding sensor 76. The device of the present invention may also include a mechanism for positioning the inflatable bladder relative to the wound site 24 and for monitoring the position of the inflatable bladder once the device has been positioned. As illustrated in Figure 13, the inflatable bladder distal end 39 includes a matrix of position sensors 82 capable of sensing the puncture wound which define a plurality of quadrants 84.
The position sensors 82 are coupled to the microprocessor 60 which is further coupled to position lights 86, also illustrated in Figure 1 D. The microprocessor 60 monitors the signals from the position sensors 82 to determine the quadrant 84 overlying the wound site 24 and lights a position light 86 to indicate which direction the bladder distal end 39 should be moved to position the wound site 24 within the center quadrant 84. For instance if the wound site 24 is beneath a quadrant to the left of the center quadrant, the microprocessor 60 will light the position light 84 pointing to the left. The bladder distal end 39 can then be moved to the left until the position light 84 turns off.
The position sensors 82 can be any sensor which can be used to detect the location of the wound site 24. For instance, in one embodiment, the position sensor 82 is a conductivity sensor. A typical conductivity sensor has two electrical leads separated by a gap. A potential is applied across the gap so that a conductive material positioned in the gap allows a current to flow across the gap. An increased amount of conductive material in the gap will yield a higher current and result in a larger signal. Since blood is known to be conductive, a conductivity sensor is able to detect the presence of blood. Further, the largest amount of blood at a wound site 24 will tend to concentrate near the skin puncture. As a result, the microprocessor 60 can locate the skin puncture by isolating the conductivity sensors with the largest signal. As a result, the bladder distal end 39 is positioned relative to the skin puncture. In another embodiment the position sensor 82 is an acoustic blood pulsometer. A pulsometer is sensitive to sound waves caused by the pulse. In most wound sites 24, the most detectable pulse sounds originate from a puncture in a vessel which underlies the skin puncture. The microprocessor 60 effectively isolates the vessel puncture by isolating the sensor 82 with the strongest signal. As a result, the bladder distal end 39 is positioned relative to the vessel puncture and pressure is applied directly to the vessel puncture. This embodiment is advantageous when the vessel puncture is not directly beneath ihe skin puncture and it is desired to apply pressure to the vessel puncture. The position sensor system described above may be used in combination with an alarm system which alerts the user when the device 10 moves relative to the wound site 24. In this embodiment, the microprocessor 60 continuously monitors the position sensors 82. If the microprocessor 60 determines that the position sensors 82 emitting the strongest signals have changed, the microprocessor 60 alerts the user that the bladder distal end 39 has moved by lighting one of the LEDs 78 on the proximal side 12 of the housing 11 or by proving an audible alarm over the speaker 79.
In yet another embodiment, the device includes a mechanism for alerting the user when closure has been completed. According to this embodiment, sensors are employed which can determine when the wound is closed, e.g., a conductivity sensor or a pulse sensor. When the sensors send a signal to the microprocessor indicating that closure has been completed, the microprocessor can send a control signal to either deflate the inflatable bladder and/or release the device from the patient. The device may also provide a visual or audible alarm to the user indicating that closure has been completed.
While the present invention is disclosed by reference to the preferred embodiments and examples detailed above, it is to be understood that these examples are intended in an illustrative rather than limiting sense, as it is contemplated that modifications will readily occur to those skilled in the art, which modifications will be within the spirit of the invention and the scope of the appended claims.