US20030120210A1 - Method of managing patient temperature with a heat exchange catheter - Google Patents

Abstract

A central venous catheter includes coolant supply and return lumens which communicate coolant to and from first and second heat exchange membranes arranged along the distal segment of the catheter. The coolant in the heat exchange membranes removes heat from the patient. Additional lumens are provided for conventional central venous catheter uses.

Description

RELATED APPLICATION
• Priority is claimed from co-pending U.S. patent application Ser. No. 09/253,109, filed Feb. 19, 1999.[0001]
FIELD OF THE INVENTION
• The present invention relates generally to methods and apparatus for cooling patients for therapeutic purposes, and more particularly to systems for establishing central venous access while providing a means for cooling a patient.[0002]
BACKGROUND
• It has been discovered that the medical outcome for a patient suffering from severe brain trauma or from ischemia caused by stroke or heart attack is degraded if the patient's body temperature rises above normal (38° C.). It is further believed that the medical outcome for many such patients might be significantly improved if the patients were to be cooled relatively quickly for a short period, e.g., 24-72 hours. Apart from the therapeutic benefits of hypothermia, the outcomes for brain trauma or ischemia patients that develop fevers is worse than for patients that do not develop fevers. Consequently, temperature management for such patients is important, even when hypothermia is not to be used to treat the patients. Moreover, prophylactic short-term hypothermia might help patients undergoing minimally invasive heart surgery and aneurysm surgery.[0003]
• The affected organ, in any case, is the brain. Accordingly, systems and methods have been disclosed that propose cooling blood flowing to the brain through the carotid artery. An example of such systems and methods is disclosed in co-pending U.S. patent application Ser. No. 09/063,984, filed Apr. 21, 1998, owned by the present assignee and incorporated herein by reference. In the referenced application, various catheters are disclosed which can be advanced into a patient's carotid artery and through which coolant can be pumped in a closed circuit, to remove heat from the blood in the carotid artery and thereby cool the brain. The referenced devices have the advantage over other methods of cooling (e.g., wrapping patients in cold blankets) of being controllable, relatively easy to use, and of being capable of rapidly cooling and maintaining blood temperature at a desired set point.[0004]
• As recognized in co-pending U.S. patent application Ser. No. 09/133,813, filed Aug. 13, 1998, owned by the present assignee and incorporated herein by reference, the above-mentioned advantages in treating brain trauma/ischemic patients by cooling can also be realized by cooling the patient's entire body, ie., by inducing systemic hypothermia. The advantage of systemic hypothermia is that, as recognized by the present assignee, to induce systemic hypothermia a cooling catheter or other cooling device need not be advanced into the blood supply of the brain, but rather can be easily and quickly placed into the relatively large vena cava of the central venous system.[0005]
• Moreover, since many patients already are intubated with central venous catheters for other clinically approved purposes anyway, providing a central venous catheter that can also cool the blood, if only to manage temperature and thereby ameliorate fever spikes, requires no additional surgical procedures for those patients. A cooling central venous catheter is disclosed in the present assignee's co-pending U.S. patent application Ser. No. 09/253,109, filed Feb. 19, 1999 and incorporated herein by reference. The present invention is directed to such a device.[0006]
SUMMARY OF THE INVENTION
• A heat exchange catheter, preferably made of urethane, includes a catheter body defining at least a coolant supply lumen and a coolant return lumen. First and second heat exchange membranes are disposed along a distal portion of the catheter body, and the heat exchange membranes communicate with one or more of the lumens. With this structure, coolant can be supplied to the heat exchange membranes via the coolant supply lumen and received from the heat exchange membranes via the coolant return lumen to effect a closed loop heat exchanger for cooling and/or warming a patient.[0007]
• Preferably, the first and second heat exchange membranes define first and second interiors respectively communicating with first and second coolant supply ports in the coolant supply lumen. Also, first and second coolant return ports are formed in the coolant return lumen, and coolant flows from the heat exchange membranes through the return ports. At least one anchor can be engaged with the catheter body to fasten the catheter to a patient.[0008]
• In addition to the coolant supply and return lumens, the catheter can define a drug delivery lumen and a guide wire lumen. A connector manifold can be engaged with the catheter body to interconnect the lumens with respective connector lines. More specifically, the connector manifold defines plural channels, and each channel establishes a respective pathway for fluid communication between a respective connector line and a respective lumen. As set forth in detail below, the anchor is on the connector manifold.[0009]
• To provide for infusing medicament into a patient while simultaneously cooling the patient, at least one drug delivery port is formed in the catheter body. Preferably, the drug delivery port is formed at a location that is between two adjacent heat exchange membranes to establish a pathway for fluid communication from the drug delivery lumen to a location outside the catheter body. If desired, additional drug delivery ports can be formed along the length of the catheter.[0010]
• In another aspect, a method for making a heat exchange catheter includes disposing a multi-lumen catheter body in a connector manifold mold, and disposing plural connector tubes in the connector manifold mold. Also, the method includes interconnecting a respective lumen with a respective connector tube using a mandrel, and then directing a plastic material into the connector manifold mold. The mandrels are then removed, such that a respective channel is defined between each respective lumen and its connector line.[0011]
• In another aspect, a method is disclosed for treating a patient. The method includes advancing a heat exchange catheter device into the patient, and then circulating coolant through the catheter device while preventing infusion of the coolant directly into the patient's bloodstream. Per the present invention, the catheter device includes a heat exchange region that is established by: one or more heat exchange membranes, or one or more hollow fibers, or one or more chamber-defining enclosures.[0012]
• In still another aspect, a catheter configured as a Swan-Ganz catheter or central venous catheter has at least one balloon-like membrane distally located on the catheter for heating or cooling blood in a patient. More particularly, the membrane defines an interior communicating with a coolant supply lumen of the catheter and with a coolant return lumen of the catheter, to circulate coolant through the interior of the membrane.[0013]
• The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which:[0014]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of the present cooling catheter, schematically showing a medicament source and coolant source in an exploded relationship with the catheter;[0015]
• FIG. 2 is a cross-sectional view as seen along the line[0016]2-2 in FIG. 1;
• FIG. 3 is a cross-sectional view as seen along the line[0017]3-3 in FIG. 1; and
• FIG. 4 is a top view of the interior of the connector manifold, as seen along the line[0018]4-4 in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• Referring initially to FIG. 1, a therapeutic catheter system, generally designated[0019]10, is shown for establishing and maintaining hypothermia in a patient, or for attenuating a fever spike in a patient and then maintaining normal body temperature in the patient. Commencing the description of thesystem10 at the proximal end, as shown thesystem10 includes acooling source12 that can be a water-bath system or a TEC-based system such as either of the systems disclosed in co-pending U.S. patent application Ser. No. 09/220,897, filed Dec. 24, 1998 and incorporated herein by reference, or U.S. patent application Ser. No. 09/260,950, filed Mar. 2, 1999, also incorporated herein by reference. In any case, the coolant source provides coolant such as saline through acoolant supply line14, and coolant is returned to thesource12 via acoolant return line16. A catheter, generally designated18, includes asource tube20 terminating in a fitting such as a female luer fitting22. Also, thecatheter18 has areturn tube24 terminating in a fitting such a male luer fitting26. Thefittings22,26 can be selectively engaged with complementary fittings28,30 of thelines14,16 to establish a closed circuit coolant path between thecatheter18 andcoolant source12.
• Additionally, the[0020]catheter18 includes a guide wire andprimary infusion tube32 that terminates in a fitting such as afemale luer34. Aguide wire36 can be advanced through thetube32 in accordance with central venous catheter placement principles, or medicament or other fluid can be infused through the guide wire andprimary infusion tube32. Moreover, asecondary infusion tube38 with female luer fitting40 can be selectively engaged with amedicament source42 for infusing fluid from thesource42 through thesecondary tube38.
• As discussed further below, the[0021]tubes20,24,32,38 are held in a distally-tapered connector manifold44. As also set forth further below, theconnector manifold44 establishes respective pathways for fluid communication between thetubes20,24,32,38 and respective lumens in acatheter body46.
• A[0022]suture anchor48 advantageously is formed on theconnector manifold44 for suturing thecatheter18 to a patient in accordance with central venous catheter operating principles. In one intended environment, thesuture anchor48 includes opposed ears50 formed with respective suture holes52. Other equivalent anchor structure can be used to hold thecatheter18 onto the patient, however, including surgical tape. When the catheter is a so-called Swan-Ganz catheter, i.e., a catheter of the type disclosed in U.S. Pat. No. 3,995,623, incorporated herein by reference, theanchor48 typically would not be provided.
• In cross-reference to FIGS. 1 and 2, the[0023]catheter body46 includes at least two lumens, and in the preferred embodiment thecatheter body46 includes at least four lumens. More specifically, thecatheter body46 defines a generally wedge- or triangular-shaped (in the transverse cross-section shown)coolant supply lumen54, a generally wedge-shapedcoolant return lumen56, a roundguide wire lumen58, and a wedge-shapedsecondary infusion lumen60. As mentioned above, however, the catheter can be a Swan-Ganz catheter, in which case additional lumens can be provided for Swan-Ganz catheter applications, including a lumen for inflating an anchoring balloon for holding the distal tip of the catheter in an appropriate blood vessel for various heart-related measurements and another lumen for holding a wire or wires that are attached to one or more distally-located sensors, such as temperature sensors, pressure sensors, gas sensors, and electrical sensors.
• In any case, the[0024]connector manifold44 establishes a pathway for fluid communication between thecoolant supply tube20 and thecoolant supply lumen54. Likewise, theconnector manifold44 establishes a pathway for fluid communication between thecoolant return tube24 and thecoolant return lumen56. Further, theconnector manifold44 establishes a pathway for fluid communication between the guide wire andprimary infusion tube32, and theguide wire lumen58, which terminates at an opendistal hole62 defined by a distally tapered and chamfereddistal tip63 of thecatheter body46. Also, theconnector manifold44 establishes a pathway for fluid communication between thesecondary infusion tube38 and thesecondary infusion lumen60, which terminates at aninfusion port64 in a distal segment of thecatheter body46. Additional ports can be provided for eachlumen58,60 along the length of the catheter.
• Referring now to FIGS. 1 and 3, at least proximal and distal thin-walled[0025]heat exchange membranes66,68 are arranged along the last fifteen or so centimeters of thecatheter body46 and are bonded to the outer surface of thecatheter body46, with theinfusion port64 being located between theheat exchange membranes66,68. Thus, each heat exchange membrane is about six centimeters to seven and one-half centimeters in length, with the heat exchange membranes being longitudinally spaced from each other along thecatheter body46 in the preferred embodiment shown. Essentially, theheat exchange membranes66,68 extend along most or all of that portion of thecatheter46 that is intubated within the patient. The heat exchange membranes can be established by a medical balloon material.
• The[0026]heat exchange membranes66,68 can be inflated with coolant from thecoolant source12 as supplied from thecoolant supply lumen54, and coolant from theheat exchange membranes66,68 is returned via thecoolant return lumen56 to thecoolant source12. In their inflated configurations, the heat exchange membranes define a diameter of about ten French, and preferably no more than twelve French. Thus, theheat exchange membranes66,68 are relatively long and comparatively thin, to advantageously avoid excessively blocking blood flow through the vena cava while nevertheless effecting patient cooling.
• As shown in FIG. 3, a[0027]wall70 separates the coolant supply and returnlumens54,56. Taking the proximalheat exchange membrane66 as an example, a supply port72 is formed in thecatheter body46 through which coolant from thesupply lumen54 can flow into the interior74 of theheat exchange membrane66, as indicated by the arrows76. Moreover, areturn port78 is formed in thecatheter body46, and coolant can flow out of theheat exchange membrane66 through thereturn port78 and into thereturn lumen56, as indicated by thearrows80. As can be appreciated in reference to FIG. 3, for eachheat exchange membrane66,68, the respective coolant supply port is distal to the respective coolant return port, to optimize fluid flow and heat transfer, although if desired the direction of fluid flow can be in the opposite direction. Both the coolant supply andcoolant return lumens54,56 terminate proximal to thedistal tip63. For example, thecoolant return lumen56 can terminate just distal of the coolant return port for the distalheat exchange membrane68, and the coolant supply lumen can terminate just distal of the coolant supply port of the distalheat exchange membrane68.
• In any case, it may now be appreciated that coolant is circulated through the[0028]catheter device18 in a closed loop. That is, infusion of the coolant directly into the patient's bloodstream is prevented. As detailed above, the catheter device includes a heat exchange region established by one or more heat exchange membranes. Alternatively, the heat exchange region can be established by or one or more hollow fibers, or one or more chamber-defining enclosures, such as metal or plastic bellows-type enclosures.
• In the preferred embodiment, the components of the[0029]catheter18 are made of urethane, and more preferably are made of an aromatic, polyether-based polyurethane, although other suitable materials can be used. In a specific embodiment, thetubes20,24,32,38 are made of Tecothane TT-1095A made by Thermedics, Inc. of Woburn, Mass. Also, theheat exchange membranes66,68 are made of Pellethane 2363-65D, made by Dow Chemical Corp. In contrast, thecatheter body46 is made of Tecothane TT-2055D-B20 with Barium Sulfate radiopacifying agent incorporated into the polymer matrix for optimum visualizing during fluoroscopic maneuvering to a desired location. Thecatheter18 can be coated with an anti-microbial agent and an anti-clotting agent if desired.
• Now referring to FIG. 4, the details of the[0030]connector manifold44 can be seen. As shown, thepreferred connector manifold44 is flat and wedge-shaped, with thedistal end82 of theconnector manifold44 being narrower than theproximal end84. Within theconnector manifold44, plural channels86 are established. As can be appreciated in reference to FIG. 4, each channel86 establishes a respective pathway for fluid communication between arespective connector line20,24,32,38 and arespective lumen54,56,58,60. Owing to the wedge shape of theconnector manifold44, thetubes20,24,32,38 are closely juxtaposed to each other near thedistal end82 of theconnector manifold44.
• In making the[0031]connector manifold44, thetubes20,24,32,38 are positioned on what will become the interior of the connector manifold, and thecatheter body46 likewise is positioned on the connector manifold, closely spaced from the distal ends of the tubes. A respective mandrel is then advanced into each tube and the lumen of thecatheter body46 that is to communicate with the tube. Next, plastic is directed over and around the tubes, mandrels, andcatheter body46 by insert molding. The mandrels are removed after the plastic hardens, establishing the channels86.
• As envisioned by the present invention, the structure set forth above can be used in many medical applications to cool a patient and/or to maintain temperature in a normothermic or hypothermic patient, for purposes of improving the medical outcomes of patients on whom, e.g., aneurysm surgery is to be performed, preferably while the patient's temperature is below normal body temperature. The structure can then be used to rewarm the patient in a controlled manner by circulating warm coolant through the structure, or by otherwise regulating natural body rewarming by circulating coolant that is maintained at an appropriate cool (relative to normal body temperature) or warm (relative to normal body temperature) temperature through the structure.[0032]
• As another example, head trauma can be treated by and after lowering and maintaining the patient's temperature below normal body temperature. Or, cardiac arrest can be treated while the patient's temperature is below normal body temperature. Yet again, minimally invasive heart surgery can be performed on the patient while the patient's temperature is below normal body temperature. And, cardiac arrest in the patient can be treated by and while the patient's temperature is below normal body temperature. Also, the present invention understands that for certain patients, e.g., stroke victims, it is important to maintain the temperature of a patient at or below normal body temperature, when the patient runs or attempts to run a fever. For severe ischemic stroke victims, the malady can be treated by maintaining the patient's body temperature at a hypothermic level.[0033]
• If desired, a[0034]temperature sensor100 such as a thermistor or other suitable device can be attached to thecatheter18 as shown. Thesensor100 can be mounted on thecatheter18 by solvent bonding at a point that is proximal to themembranes66,68. Or, thesensor100 can be disposed in a lumen of thecatheter18, or attached to a wire that is disposed in a lumen of thecatheter18, with the sensor hanging outside thecatheter18. Alternatively, a separate temperature probe can be used, such as the esophageal probe disclosed in co-pending U.S. patent application Ser. No. 09/282,971, filed Mar. 31, 1999 and incorporated herein by reference. As yet another alternative, a rectal probe or tympanic temperature sensor can be used. In any case, the sensor is electrically connected to thecoolant source12 for control of the temperature of the coolant as described in the above-referenced '897 and '940 applications. While the particular CENTRAL VENOUS CATHETER WITH HEAT EXCHANGE MEMBRANE as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and is thus representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more”. All structural and functional equivalents to the elements of the above-described preferred

Claims (25)

What is claimed is:

1. A heat exchange catheter, comprising:

a catheter body defining at least a coolant supply lumen and a coolant return lumen;

at least first and second heat exchange membranes disposed along a distal portion of the catheter body and communicating with one or more of the lumens, such that coolant can be supplied to the heat exchange membranes via the coolant supply lumen and received from the heat exchange membranes via the coolant return lumen to effect a closed loop heat exchanger for cooling and/or warming a patient.

2. The catheter ofclaim 1, wherein the first and second heat exchange membranes define first and second interiors respectively communicating with at least first and second coolant supply ports in the coolant supply lumen and at least first and second coolant return ports in the coolant return lumen.

3. The catheter ofclaim 2, wherein the catheter is made of a urethane.

4. The catheter ofclaim 1, further comprising at least one anchor engaged with the catheter body.

5. The catheter ofclaim 1 wherein the catheter defines at least a drug delivery lumen.

6. The catheter ofclaim 5, wherein the catheter defines at least a guide wire lumen.

7. The catheter ofclaim 6, further comprising a connector manifold engaged with the catheter body and interconnecting the lumens with respective connector lines.

8. The catheter ofclaim 7, wherein the anchor is on the connector manifold.

9. The catheter ofclaim 8, wherein the connector manifold defines plural channels, each channel establishing a respective pathway for fluid communication between a respective connector line and a respective lumen.

10. The catheter ofclaim 9, wherein at least one drug delivery port is formed in the catheter body at a location that is between two adjacent heat exchange membranes to establish a pathway for fluid communication from the drug delivery lumen to a location outside the catheter body.

11. A method for making a heat exchange catheter device, comprising the acts of:

disposing a multi-lumen catheter body in a connector manifold mold;

disposing plural connector tubes in the connector manifold mold;

interconnecting a respective lumen with a respective connector tube using a mandrel;

directing a plastic material into the connector manifold mold; and

removing the mandrels such that a respective channel is defined between each respective lumen and its connector tube.

12. The method ofclaim 11, further comprising the act of engaging at least one heat exchange membrane with a distal segment of the catheter body.

13. The method ofclaim 12, wherein the catheter body is made of urethane.

14. A method for treating a patient, comprising the acts of:

advancing a heat exchange catheter device into the patient; and

circulating coolant through the catheter device while preventing infusion of the coolant directly into the patient's bloodstream, the catheter device including a heat exchange region established by: one or more heat exchange membranes, or one or more hollow fibers, or one or more chamber-defining enclosures.

16. The method of claim15, further comprising the act of performing aneurysm surgery while the patient's temperature is below normal body temperature.

17. The method of claim15, further comprising the act of treating head trauma in the patient while the patient's temperature is below normal body temperature.

18. The method of claim15, further comprising the act of treating cardiac arrest in the patient while the patient's temperature is below normal body temperature.

19. The method of claim15, further comprising the act of performing minimally invasive heart surgery on the patient while the patient's temperature is below normal body temperature.

20. The method of claim15, further comprising the act of treating cardiac malady in the patient while the patient's temperature-is below normal body temperature.

21. The method of claim15, further comprising the act of maintaining the temperature of a patient at or below normal body temperature, when the patient runs or attempts to run a fever.

22. The method of claim15, further comprising the act of treating ischemic stroke in the patient while the patient's temperature is below normal body temperature.

23. The catheter ofclaim 1, further comprising a temperature sensor attached to the catheter body.

24. The catheter ofclaim 3, wherein the urethane is an aromatic urethane.

25. A catheter configured as a Swan-Ganz catheter or central venous catheter having at least one membrane distally located on the catheter for heating or cooling blood in a patient.

26. The catheter ofclaim 25, wherein the membrane defines an interior communicating with a coolant supply lumen of the catheter and with a coolant return lumen of the catheter, to circulate coolant through the interior for heating or cooling a patient.

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