# Patent

## Title
Self-centering patient temperature control catheter

## Abstract

A patient temperature control catheter (10) includes working fluid supply (16) and return (18) lumens through which working fluid circulates to exchange heat with a patient in whom the catheter is positioned. At least one lumen is defined by plural coils (32) axially spaced from each other. At least a first coil is a large coil that inflates with working fluid to seat against a wall of a blood vessel in which the catheter is positioned, with blood flowing through the coil so as not to block blood flow in the vessel. Alternate centering structures (116) are disclosed.

## Background
FIELD OF THE INVENTION
The present application relates generally to patient temperature control systems.
BACKGROUND OF THE INVENTION
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 or cardiac arrest is improved if the patient is cooled below normal body temperature (37° C.). Furthermore, it is also accepted that for such patients, it is important to prevent hyperthermia (fever) even if it is decided not to induce hypothermia. Moreover, in certain applications such as post-CABG surgery, it might be desirable to rewarm a hypothermic patient.
As recognized by the present application, the above-mentioned advantages in regulating temperature can be realized by cooling or heating the patient's entire body using a closed loop heat exchange catheter placed in the patient's venous system and circulating a working fluid such as saline through the catheter, heating or cooling the working fluid as appropriate in an external heat exchanger that is connected to the catheter. The following U.S. patents, all of which are incorporated herein by reference, disclose various intravascular catheters/systems/methods for such purposes: U.S. Pat. Nos. 6,881,551 and 6,585,692 (tri-lobe catheter), U.S. Pat. Nos. 6,551,349 and 6,554,797 (metal catheter with bellows), U.S. Pat. Nos. 6,749,625 and 6,796,995 (catheters with non-straight, non-helical heat exchange elements), U.S. Pat. Nos. 6,126,684, 6,299,599, 6,368,304, and 6,338,727 (catheters with multiple heat exchange balloons), U.S. Pat. Nos. 6,146,411, 6,019,783, 6,581,403, 7,287,398, and 5,837,003 (heat exchange systems for catheter), U.S. Pat. No. 7,857,781 (various heat exchange catheters).
SUMMARY OF THE INVENTION
Accordingly, a catheter includes at least one working fluid supply lumen and at least one working fluid return lumen. Working fluid circulates through the supply and return lumens to exchange heat with a patient in whom the catheter is positioned. At least one of the lumens is defined by plural coils axially spaced from each other. Furthermore, at least a first coil is a large coil that inflates with working fluid to seat against a wall of a blood vessel in which the catheter is positioned such that blood may flow through the coil so as not to block blood flow in the vessel. Thus, working fluid may flow serially through the coils to exchange heat with the patient.
In some embodiments, a second of the plural coils may be a smaller coil relative to the large coil, where the smaller coil does not contact the wall of the blood vessel when inflated with working fluid. Even further, if desired, at least one of the lumens may define plural large coils separated from each other by at least one small coil as described herein. Also if desired, at least one of the lumens may define a straight tube coaxial with the coils and in fluid communication with the coils. In non-limiting embodiments, the straight tube may extend through the coils, or may optionally be located outside the coils.
In some non-limiting embodiments, the coils may be in the working fluid supply path and the straight tube may define at least part of the working fluid return path. In other non-limiting embodiments, the coils may be in the working fluid return path and the straight tube may define at least part of the working fluid supply path.
In still another aspect, a catheter includes working fluid supply and return lumens. Working fluid circulates through the supply and return lumens to exchange heat with a patient in whom the catheter is positioned. The catheter also includes at least one expandable wire located longitudinally along the catheter and engaged with the catheter. The wire is expandable against a wall of a blood vessel in which the catheter is positioned to center heat exchange regions of the catheter in the vessel. In one example, the at least one wire includes plural wires arranged in a mesh movable between a radially expanded configuration, in which the mesh circumscribes an inner wall of a vessel in which the catheter is disposed and in which blood flowing through the vessel is not significantly impeded from flowing within the mesh past the catheter, and a radially collapsed configuration, in which the mesh lies against the catheter or is closely spaced therefrom to facilitate advancement and retraction of the catheter from the vessel.
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:



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram showing an example catheter engaged with an example heat exchange system;
FIG. 2 is a schematic diagram of a non-limiting embodiment of the intravascular temperature management catheter having coils axially spaced from each other in accordance with present principles while not positioned in a patient;
FIG. 3 is a schematic diagram of the non-limiting intravascular temperature management catheter of FIG. 2 while positioned in a patient;
FIG. 4 is a schematic diagram of a non-limiting embodiment of the intravascular temperature management catheter while not positioned in a patient having at least one wire expandable against a wall of a blood vessel in which the catheter is positioned to center heat exchange regions of the catheter in accordance with present principles;
FIG. 5 is a schematic diagram of the non-limiting embodiment of the intravascular temperature management catheter of FIG. 4 while positioned in a patient;
FIG. 6 is a schematic diagram of a second non-limiting embodiment of the intravascular temperature management catheter while not positioned in a patient having at least one wire expandable against a wall of a blood vessel in which the catheter is positioned to center heat exchange regions of the catheter in accordance with present principles;
FIG. 7 is a schematic diagram of the non-limiting embodiment of the intravascular temperature management catheter of FIG. 6 while positioned in a patient;
FIG. 8 is a flow-chart of method steps in accordance with present principles; and
FIGS. 9 and 10 are side views of yet another alternate embodiment showing a centering mesh.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially to FIG. 1, an intravascular temperature management catheter 10 is in fluid communication with a catheter temperature control system 12 that includes a processor executing logic described in one or more of the patents referenced herein to control the temperature of working fluid circulating through the catheter 10 in accordance with a treatment paradigm responsive to patient core temperature feedback signals. In accordance with present principles, the catheter 10 can be used to induce therapeutic hypothermia in a patient 14 using the catheter, in which coolant such as but not limited to saline circulates in a closed loop, such that no coolant enters the body. Such treatment may be indicated for stroke, cardiac arrest (post-resuscitation), acute myocardial infarction, spinal injury, and traumatic brain injury. The catheter 10 can also be used to warm a patient, e.g., after bypass surgery or burn treatment, and to combat hyperthermia in, e.g., patient suffering from sub-arachnoid hemorrhage or intracerebral hemorrhage.
As shown, working fluid may be circulated between the heat exchange system 12 and catheter 10 through supply and return lines 16, 18 that connect to the proximal end of the catheter 10 as shown. A patient temperature signal from a catheter-borne temperature sensor on the distal region of the catheter may be provided to the system 12 through an electrical line 20, or wirelessly if desired. Alternatively, a patient temperature signal may be provided to the system 12 from a separate esophageal probe or rectal probe or tympanic sensor or bladder probe or other temperature probe that measures the temperature of the patient 14. Note that as used herein, “proximal” and “distal” in reference to the catheter are relative to the system 12.
The catheter 10, in addition to interior supply and return lumens through which the working fluid is circulated, may also have one or more infusion lumens connectable to an IV component 22 such as a syringe or IV bag for infusing medicaments into the patient, or an instrument such as an oxygen or pressure monitor for monitoring patient parameters, etc.
The catheter 10 can be positioned typically in the vasculature of the patient 14 and more preferably in the venous system of the patient 14 such as in the inferior vena cava through a groin insertion point or the superior vena cava through a neck (jugular or subclavian) insertion point.
Next, regarding FIGS. 2-9, it is to be understood that while certain aspects and/or components of the example catheter described in reference to FIG. 1 have been omitted in FIGS. 2-9 for clarity, those aspects and/or components may still be present in the catheters described in reference to FIGS. 2-9 in non-limiting embodiments. For instance, the IV component, temperature sensor, and electrical line described in reference to FIG. 1 are not shown in FIGS. 2-9, but may still be included in the non-limiting embodiments shown in those figures.
Furthermore, it is to be understood that distal heat exchange regions of the catheters as described herein may be made of a shape memory material such as, but not limited to, nitinol in non-limiting embodiments. Also in non-limiting embodiments, the shape memory material disclosed herein may expand and contract in accordance with present principles. However, it is to be further understood that the heat exchange regions as disclosed herein may be flexible and/or pliant in non-limiting embodiments such that distal regions of the catheters of FIGS. 2-6 may be flexibly positioned into a patient to exchange heat with a patient. E.g., the catheters described herein may flexibly enter the patient at an angle relative to the surface area of the portion of the patient in which the catheter is being positioned. Nonetheless, in other non-limiting embodiments the heat exchange region 32 may be rigid if desired.
Now specifically in reference to FIG. 2, a schematic diagram of an intravascular temperature management catheter while not positioned in a patient having coils axially spaced from each other in accordance with present principles is shown. Thus, a catheter 24 has a working fluid supply lumen 26 and a working fluid return lumen 28 in fluid communication with a heat exchange system 30 in accordance with present principles. Working fluid such as, but not limited to, saline may circulate through the lumens 26 and 28 to exchange heat with a patient 38 in whom the catheter 24 is positioned.
As may be seen from FIG. 2, at least one of the lumens 26 and 28 are defined by plural coils 32 axially spaced from each other, wherein at least one large coil 34 can inflate with working fluid to seat against a wall of a blood vessel (the vessel is not shown in FIG. 2) in which the catheter is to be positioned. FIG. 2 also shows at least one smaller coil 36, where the size of the smaller coil(s) 36 is relative to the large coil 34. The smaller coil(s) 36 may not contact the wall of the blood vessel when positioned in the patient 38 and inflated with working fluid in the non-limiting embodiment shown.
However, it may be appreciated from the non-limiting embodiment of FIG. 2 that the catheter 24 may have plural large coils 34 separated from each other by at least one of the smaller coils 36. Thus, while in some embodiments there may only be one large coil 34 and one smaller coil 36, FIG. 2 shows plural large coils 34 and plural smaller coils 36 such that working fluid may flow serially through the coils 32. Furthermore, it is to be appreciated from FIG. 2 that the smaller coils 36 may be of varying sizes, with all the smaller coils 36 still being smaller than the large coils 34.
Still in reference to FIG. 2, the catheter 24 may also have a straight tube 40 that may be both coaxial with the coils 32 and in fluid communication with the coils 32 in non-limiting embodiments. As shown in FIG. 2, the large coils 34 and smaller coils 36 are in the working fluid supply path 26, while the straight tube 40 defines at least part of the working fluid return path 28. However, it is to be understood that, in other non-limiting embodiments, large and smaller coils may be in the working fluid return path while the straight tube may define at least part of the working fluid supply path in accordance with present principles.
Moving on to FIG. 3, a schematic diagram of the intravascular temperature management catheter 24 described in reference to FIG. 2 is shown, with the catheter 24 now positioned into a blood vessel 42 of the patient 38. Thus, the catheter 24 still has supply and return lumens 26 and 28 (and straight tube 40 defined by the lumen 28 in the non-limiting embodiment shown) which are in fluid communication with the heat exchange system 30. The catheter 24 also has large coil 34 and smaller coil 36 such that the plural coils 32 are axially spaced from each other.
It may be appreciated from FIG. 3 that the coils 32 are inflated with working fluid such that the large coils 34 are seated against the walls 44 of the blood vessel 42 in which the catheter 24 is positioned to center the smaller coils 36 in the blood vessel 42. As may be further appreciated from FIG. 3, the smaller coil(s) 36 may not contact the walls 44 of the blood vessel 42 while positioned in the blood vessel 42 and inflated with working fluid. Thus, blood may flow serially through the coils 32, as indicated by the blood-flow arrows 46, to exchange heat with the patient 38. It may also be appreciated that the coils 32 may be varying sizes such that they do not block the flow of blood through the blood vessel 42, while still providing optimum coil surface area to exchange heat with the patient 38.
Now in reference to FIG. 4, another embodiment of a catheter in accordance with present principles is shown. Specifically, FIG. 4 is a schematic diagram of an intravascular temperature management catheter while not positioned in a patient having at least one wire expandable against a wall of a blood vessel in which the catheter is positioned to center heat exchange regions of the catheter to exchange heat with a patient.
Thus, as shown in FIG. 4, a catheter 48 has a working fluid supply lumen 50 and a working fluid return lumen 52 in fluid communication with a heat exchange system 54 in accordance with present principles. Working fluid such as, but not limited to, saline may circulate through the lumens 50 and 52 to exchange heat with a patient 56 in whom the catheter 48 is to be positioned. The catheter 48 also includes at least one expandable wire(s) 58 located longitudinally along the catheter 48 and engaged therewith. It is to be understood that the wire(s) 58 are expandable against a wall of a blood vessel of the patient 56 when positioned in the patient 56 to center a heat exchange region(s) 60 of the catheter 48 in the blood vessel (not shown). Note that plural wires 58 are shown in FIG. 4, where the plural wires 58 are engaged along the same longitudinal portion of the heat exchange region 60.
As understood herein, the wire(s) 58 may be made of a shape memory substance such as, but not limited to, nitinol. It is to be further understood that the heat exchange region(s) 60 may be substantially coaxial with the wire(s) 58 when the wire(s) 58 is expanded against the wall of the blood vessel, which may be further appreciated in FIG. 5 as described below. However, in other non-limiting embodiments, the wire(s) 58 need not be substantially coaxial with the heat exchange region(s) 60 as long as a portion of the wire(s) 58 may expand against the wall of the patient's blood vessel.
Thus, FIG. 5 shows a schematic diagram of the intravascular temperature management catheter 48 described in reference to FIG. 4, with the catheter 48 now positioned into a blood vessel 62 of the patient 56. The catheter 48 still has the lumens 50 and 52 which are in fluid communication with the heat exchange system 54. The catheter 48 also has the wire(s) 58 which may be located generally longitudinally along the catheter 48 and engaged therewith.
It may be appreciated from FIG. 5 that a portion of the wire(s) 58 expands against the wall(s) 64 of the patient's blood vessel 62 to center the heat exchange region 60 in the blood vessel 62. Thus, blood may contact the heat exchange region(s) 60 as is passes the region(s) 60, as indicated by the blood-flow arrows 66, to exchange heat with the heat exchange region(s) 60.
Now in reference to FIG. 6, an alternate, non-limiting embodiment of a catheter in similar to the one described in reference to FIGS. 4 and 5 is shown. FIG. 6 also shows an intravascular temperature management catheter having at least one wire expandable against a wall of a blood vessel in which the catheter is positioned to center heat exchange regions of the catheter. However, the catheter shown in FIG. 6 includes plural wires that alternate longitudinally along the heat exchange region, where only one wire is engaged with only one longitudinal portion of the heat exchange region.
Thus, as shown in FIG. 6, a catheter 68 has a working fluid supply lumen 70 and a working fluid return lumen 72 in fluid communication with a heat exchange system 74 in accordance with present principles. Working fluid such as, but not limited to, saline may circulate through the lumens 70 and 72 to exchange heat with a patient 76 in whom the catheter 68 is to be positioned. The catheter 68 also includes expandable wires 78 located longitudinally along the catheter 68 and engaged with the catheter 68. It is to be understood that the wires 78 are expandable against a wall of a blood vessel of the patient 76 when positioned in the patient 76 to center a heat exchange region(s) 80 of the catheter 68 in the blood vessel (not shown).
As understood herein, the wires 78 may be made of a shape memory substance in accordance with present principles. It is to be further understood that the heat exchange region(s) 80 may be substantially coaxial with the wires 78 when the wires 78 are expanded against the wall of the blood vessel, which may be further appreciated in reference to FIG. 7 as described below. However, it is to be understood that in other non-limiting embodiments, the wires 78 need not be substantially coaxial with the heat exchange region(s) 80 as long as a portion of the wires 78 may expand against a wall of the patient's blood vessel.
In contrast to the embodiment described in reference to FIGS. 4 and 5, it may now be appreciated from FIG. 6 that the wires 78 alternate longitudinally along the heat exchange region 80 such that only one wire is included on only one longitudinal portion of the heat exchange region 80. The longitudinally alternating wires 78 can also been seen in reference to FIG. 7, where FIG. 7 is a schematic diagram of the catheter 68 while positioned in the blood vessel of the patient 76.
Accordingly, the catheter 68 as shown in FIG. 7 still has the lumens 70 and 72 which are in fluid communication with the heat exchange system 74. The catheter 68 also has the wires 78 located generally longitudinally along the catheter 68 and engaged therewith, with only a one wire 78 engaged along a particular longitudinal portion of the heat exchange region 80.
Similar to FIG. 5, it may be appreciated from FIG. 7 that a portion of the wires 78 may expand against the walls 84 of the patient's blood vessel 82. Thus, blood may contact the heat exchange region(s) 80 as is passes the region(s) 80, as indicated by the blood-flow arrows 86, to exchange heat with the patient 76. However, in contrast to the embodiment of FIG. 5, the non-limiting embodiment shown in FIG. 7 has wires 78 alternating longitudinally along the heat exchange region 80 such that only one wire is engaged with only one portion of the heat exchange region 80 while still centering the heat exchange region 80 in the blood vessel 82.
Moving on to FIG. 8, method steps in accordance with present principles are shown as a flow-chart. Beginning at block 88, a catheter having at least one self-centering lumen as disclosed herein is positioned in a patient so that the patient may be warmed or cooled. Then, at block 90, a heat exchange system fluidly connected to the catheter is activated to circulate working fluid through the lumens such that the lumens inflate to seat at least one large coil defined by one of the lumens against the wall of the blood vessel in which the catheter is positioned. At least one smaller coil also defined by at least one of the lumens is centered in the blood vessel. Blood may thus flow through the coil in accordance with present principles such that heat is transferred between the lumens and the blood.
FIG. 9 shows a catheter 100 with working fluid supply and return ports 102, 104 arranged on a catheter hub 106 on a proximal segment of the catheter. Additional through-ports 108 may be provided, including a guide wire port and one or more infusion ports. The ports 102, 104, 108 have associated lumens within a catheter body 110 that extend through the body 110. In the case of the lumens associated with the through-ports 108, the associated lumens terminate at exit ports on a distal segment 112 of the catheter to infuse medicament into or withdraw fluid from the bloodstream of a patient. The distal segment 112 may include one or more heat exchange elements 114 for exchanging heat between the blood and working fluid entering the supply port 102, circulating through the supply lumen and heat exchange elements, and exiting the return port 104. Without limitation, the heat exchange elements 114 may be inflatable balloons, alternating metallic bellows and fluted sections, etc.
As shown in FIG. 9, a tubular mesh 116 made of braided wires, e.g., steel wires, polymer strands, nitinol, or the like) surround the distal segment 112 and heat exchange elements 114 thereon. The mesh 116 can be moved between a radially expanded configuration shown in FIG. 9, in which the mesh 116 circumscribes the inner wall of a vessel 118 in which the distal segment 112 is disposed and in which blood flowing through the vessel is not significantly impeded from flowing within the mesh 116 past the heat exchange elements 114, and a radially collapsed configuration (FIG. 10), in which the mesh 116 lies against the heat exchange elements 114 or is closely spaced therefrom to facilitate advancement and retraction of the catheter 100 from the patient.
To this end, a distal end portion 120 of the mesh 116 is fixedly secured to the distal end of the catheter 100 as shown. This securing may be effected by, without limitation, solvent bonding, rf sealing, ultrasonic welding, etc. If desired, a marker band 122 may be disposed along the distal portion of the catheter to visualize positioning of the catheter using, e.g., fluoroscopy.
On the other hand, a proximal end portion 124 of the mesh 116 is fixedly secured to an axially movable sheath 126 that may surround the body of the catheter 100, terminating proximally at an operator 128. The operator 128 may be moved proximally by a person to pull the proximal portion 124 of the mesh 116 away from the distal portion 120, moving the mesh 116 toward the radially collapsed configuration of FIG. 10. Yet again, the operator 128 may be moved distally by a person to push the proximal portion 124 of the mesh 116 toward the distal portion 120, moving the mesh 116 toward the radially expanded configuration shown in FIG. 9. In this configuration, the braided wires that establish the mesh 116 open against the vessel wall with blood flowing through at the same time centering the catheter system inside the vessel. If desired, a marker band 130 may be disposed along the proximal portion 124 of the mesh to visualize positioning of the catheter using, e.g., fluoroscopy.
While the particular SELF-CENTERING PATIENT TEMPERATURE CONTROL CATHETER is herein shown and described in detail, it is to be understood that the subject matter which is encompassed by the present invention is limited only by the claims.

## Claims

1. A catheter, comprising:
working fluid supply and return lumens through which working fluid can circulate to exchange heat with a patient, at least one of the lumens being defined by plural coils axially spaced from each other, at least two successive coils being axially spaced from each other by an axially straight tube segment of at least one of the lumens extending axially between the at least two successive coils, at least a first coil being a large coil that is configured to inflate with working fluid to seat against a wall of a blood vessel in which the catheter is positionable with blood flowing through the coil so as not to block blood flow in the vessel, wherein at least a second coil is a small coil that is configured to be spaced from the wall of the blood vessel and not contact the wall of the wall of the blood vessel when the second coil is inflated with working fluid and the catheter comprises plural large coils separated from each other by at least one small coil.

2. The catheter of claim 1, wherein the coils are configured to establish serial working fluid flow through the coils when working fluid is directed into the catheter.

3. The catheter of claim 1, wherein at least one of the lumens comprises a straight tube coaxial with the coils and in fluid communication therewith.

4. The catheter of claim 3, wherein the coils are in the working fluid supply lumen and the straight tube defines at least part of the working fluid return lumen.

5. The catheter of claim 4, wherein the coils are in the working fluid return lumen and the straight tube defines at least part of the working fluid supply lumen.