WO2003059218A1

WO2003059218A1 - Method and system for therapeutic hypothermia

Info

Publication number: WO2003059218A1
Application number: PCT/US2002/000490
Authority: WO
Inventors: Scott Evans; William Worthen
Original assignee: Alsius Corporation
Priority date: 2002-01-09
Filing date: 2002-01-09
Publication date: 2003-07-24
Also published as: AU2002243488A1

Abstract

A method for treating a patient includes inducing mild to moderate hypothermia in the patient using one or more closed loop heat exchange catheters positioned in the patient's central venous system while simultaneously warming the patient with an external heat source such as a warming blanket or a heater to reduce patient discomfort and shivering.

Description

METHOD AND SYSTEM FOR THERAPEUTIC HYPOTHERMIA

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application serial no. 09/266,452, entitled "Method and Apparatus for Establishing and Maintaining Therapeutic Hypothermia," filed 3/11/99 which is a continuation-in-part of U.S. application serial no. 09/253,109, entitled "Central Venous Line Catheter Having Temperature Control System," filed 2/19/99.

FIELD OF THE INVENTION

The present invention relates to methods and systems for treating a patient with therapeutic hypothermia.

BACKGROUND

The above-referenced patent applications recognize that many brain-related maladies, including traumatic brain injury, stroke, high intracranial pressure (ICP), and cardiac arrest (which causes total brain ischemia) can be treated using therapeutic hypothermia. As recognized in these patent applications, inducing mild to moderate hypothermia (e.g., lowering the patient's temperature to around 35°C - 32°C) is preferred in treating maladies such as brain-related maladies.

One potential drawback of therapeutic hypothermia is patient discomfort. Should the discomfort become excessive, uncontrolled shivering might result, which in turn might require pharmacologically paralyzing the patient until the hypothermia treatment is complete. Inducing paralysis in turn requires intubating and ventilating the patient, which are significant medical procedures which would be preferable to avoid for a number of reasons. The present invention has recognized the above considerations and has provided the solutions disclosed herein.

SUMMARY OF THE INVENTION

A method for treating a patient includes lowering the patient's temperature using at least one catheter placed in the vasculature of the patient. Simultaneously, the patient is externally warmed by an external heat source, preferably a warming blanket or a heater.

In another aspect, a system for treating a patient includes at least one catheter having a heat exchange region on a distal portion thereof, and an external heat source configured to externally warm the patient.

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

Figure 1 is a schematic view of the therapeutic hypothermic system using a cooling catheter and at least one external heat source, such as a warming blanket and/or a heater. Figure 2 is a flow chart of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to Figure 1, a therapeutic system, generally designated 10, is shown for treating a patient 12 using therapeutic hypothermia. As shown, the system 10 includes a cooling system 14 that can be a water-bath system such as the system disclosed in the present assignee's co-pending U.S. patent application serial no. 09/220,897 filed December 28, 1998 and incorporated herein by reference, or a cooling system including at least one thermal electric cooler (TEC) 16, as disclosed in the present assignee's U.S. patent application serial no. 09/260,950, filed March 2, 1999, issued as U.S. Patent No. 6,019,783 and incorporated herein by reference. In any case, the cooling system 14 can be considered a source of coolant, preferably sterile saline, for the catheters of the present invention.

As set forth in these applications, the cooling system 14 can include a heat exchanger, a pump, and, if desired, a controller. Preferably, the pump is a peristaltic pump, but other types of positive displacement pumps, such as, but not limited to, piston pumps and gear pumps, or even centrifugal pumps, can be used. A peristaltic pump is preferred in the present implementation because it can pump coolant without directly contacting the coolant, but instead simply by squeezing a tube through which the coolant flows. In this way, the pump is reusable, and only the present catheters and portions of the system 10 coming in direct contact with the coolant need be made disposable to render an advantageously disposable and sterile coolant delivery system. The controller controls the rate at which coolant is pumped by the pump and, if desired, the rate at which heat is added or subtracted from the coolant. The controller can be implemented by a software or firmware executing processor or by discrete logic circuits or other electronic circuitry device to establish a desired patient temperature by appropriately controlling the pump and/or heat exchanger in response to a temperature signal derived from a sensor in the patient 12.

As shown in Figure 1 , a cooling catheter 18 can communicate with the cooling system 14 via coolant supply and return lines 20, 22. The coolant lines 20, 22 can be IV lines or tubes or other suitable fluid conduits, such as metal (steel) tubes. When the coolant lines 20, 22 are plastic tubes, they can be connected to the catheter 18 and the cooling system 14 by suitable connecting structure, such as Luer fittings, interference fits, solvent bonding, heat staking, ultrasonic welding, and the like.

The cooling catheter 18 includes a heat exchange region 24. The heat exchange region 24 can be established by one or more hollow fibers, as disclosed in the present assignee's U.S. patent application serial no. 09/133,813, filed August 13, 1998 and incorporated herein by reference. Alternatively, the heat exchange region 24 can include one or more cooling membranes such as balloons as disclosed in the present assignee's U.S. patent application serial nos. 09/253,109 (filed February 19, 1999) and 09/305,613 (filed May 5, 1999) and both incorporated herein by reference. In a preferred embodiment, multiple cooling membranes, such as balloons, are axially staggered along the shaft 19 of the catheter 18.

In any case, as set forth in the referenced applications, coolant is circulated in a closed fluid communication loop between the heat exchange region 24 and cooling system 14 to remove heat from the patient 12. As set forth in greater detail below, the catheter 18 is advanced (sometimes through an introducer sheath) into the vena cava of the patient 12 through a groin entry point 26 to establish hypothermia in the patient 12. Preferably, the catheter 18 is advanced either through the saphenous vein or femoral vein.

In another embodiment, the catheter 18 is configured for use as a central venous catheter and can be advanced (sometimes through an introducer sheath) into the central venous system of the patient through a neck entry point 29 or chest entry point 30. The catheter 18 can be embodied by the catheter disclosed in assignee's co-pending patent application serial nos. 09/253,109 and 09/305,613. Accordingly, the catheter 18 can communicate with the cooling system 14 via coolant supply and return lines 20, 22. Also, the catheter 18 can communicate with one or more central venous components 34, such as IV infusion devices, drug delivery syringes for infusing epinephrine, blood withdrawal devices, and so on. The component 34 can also be established by a device such as a syringe for infusing a diuretic such as Mannitol into the patient, or for administering sedatives or paralytics to the patient. Also, the component 34 can be used to administer barbiturates to the patient.

As disclosed in the referenced applications, one embodiment of catheter 18 includes a heat exchange region 24 that can be established by one or more membranes such as balloons, but in a different embodiment, the membranes could be established by hollow fibers as disclosed in U.S. application ser. No. 09/133,813.

In another embodiment, the catheter 18 can be advanced into the superior vena cava through the jugular vein or subclavian vein to cool the patient 12 by means of coolant circulating in a closed loop between the cooling system 14 and the balloon. As mentioned above, the catheter 18 in this embodiment can also be used to undertake conventional central venous catheter functions.

Referring back to Figure 1 , in addition to the cooling components discussed above, the system 10 can include a defibrillator 38 for defibrillating a cardiac arrest patient, as well as other components including but not limited to a cerebral spinal fluid (CSF) drainage system 43 for draining excess CSF from the patient. Also, a ventilation system 42 can be connected to the patient 12 to hyperventilate the patient.

Still further, the system 10 can include an external heat source. In one preferred embodiment, the external heat source is a warming blanket 45. The blanket 45 is any suitable blanket that can be applied to the skin of the patient to externally warm the patient. As non-limiting examples, the blanket 45 can be a conventional cotton or wool blanket, or it can be a specialized heating blanket. Also, conventional electric blankets may be used for external warming.

In another embodiment, the system 10 can include a heater 46 to externally apply heat to the patient. The warming blanket 45 can be used exclusively to the heater 46; the heater 46 can be used exclusively to the warming blanket 45; or both the warming blanket 45 and the heater 46 can be used together simultaneously.

Figure 2 shows the details of a preferred method for treating the patient 12 using therapeutic hypothermia. As indicated at block 46, hypothermia is induced by advancing the catheter 18 into the vena cava, and then circulating coolant through the catheter 18. The catheter 18 may be advanced into the vena cava through either a groin, neck or chest entry point. Simultaneously, the patient is externally warmed by applying a warming blanket 45 and/or by using a heater 46.

In another embodiment, a first catheter can be advanced into the vena cava through a groin entry point. Once target temperature of 35°C to 32°C (or even lower) has been reached, the first catheter can be removed and a second catheter can be advanced into the vena cava through a neck or chest entry point to maintain the target temperature. In a preferred embodiment, both the first and second catheters include heat exchange elements that include balloons. In another embodiment, the first catheter includes heat exchange elements that include hollow fibers while the second catheter includes heat exchange elements that include at least one balloon. It is to be understood that while one preferred sequence of steps for inducing hypothermia in a patient is discussed here, other sequences can be used. For example, the first catheter can be used exclusively to the second catheter, the second catheter can be used exclusively to the first catheter, or both catheters can be used together while simultaneously also warming the patient with an external heat source.

In any case, in addition to establishing hypothermia using the catheters of the present invention, at block 48 in Figure 2 the preferred method also contemplates externally warming the patient with at least one external heat source. By using an external heat source (either a warming blanket 45 and/or a heater 46) simultaneously with the maintenance of hypothermia using at least one cooling catheter at block 46, shivering is prevented, reduced or totally alleviated, reducing patient discomfort and avoiding other significant medical procedures necessitated by shivering.

The above method acts are set forth in the presently preferred order, it being understood that the method acts could be performed in other orders as determined to be appropriate.

While the particular METHOD AND SYSTEM FOR THERAPEUTIC HYPOTHERMIA 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 embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase "means for".

Claims

WHAT IS CLAIMED IS:

1. A method for treating a patient, comprising the acts of: lowering the patient's temperature using at least one catheter placed in the vasculature of the patient; and simultaneously with the lowering act, externally warming the patient.

2. The method of Claim 1 , wherein the act of externally warming is undertaken using at least one blanket.

3. The method of Claim 1 , wherein the act of externally warming is undertaken using at least one heater.

4. The method of Claim 2, wherein the act of externally warming further comprising using at least one heater.

5. The method of Claim 1 , comprising lowering the temperature using a first catheter and maintaining the temperature at a moderate hypothermic level using a second catheter.

6. The method of Claim 5, wherein the act of externally warming is undertaken using at least one blanket.

7. The method of Claim 5, wherein the act of externally warming is undertaken using at least one heater.

8. The method of Claim 6, wherein the act of externally warming further comprising using at least one heater.

9. A system for treating a patient, comprising: at least one catheter having a heat exchange region on a distal portion thereof; and at least one heat source configured to warm the patient externally.

10. The system of Claim 9, comprising at least two cooling catheters.

11. The system of Claim 9, comprising a cooling system for heat exchange with coolant flowing through the cooling catheter.

12. The system of Claim 9, wherein the heat source is a blanket.

13. The system of Claim 9, wherein the heat source is a heater.