WO2001017471A1

WO2001017471A1 - Method and system for treating high intracranial pressure using hypothermia

Info

Publication number: WO2001017471A1
Application number: PCT/US2000/024404
Authority: WO
Inventors: Xia Luo; Scott M. Evans; William J. Worthen
Original assignee: Alsius Corporation
Priority date: 1999-09-03
Filing date: 2000-09-05
Publication date: 2001-03-15
Also published as: AU7351200A

Abstract

A method for treating high ICP includes inducing mild or moderate hypothermia in the patient using one or more closed loop heat exchange catheters positioned in the patient's central venous system when the patient's ICP is above a predetermined threshold. Additional steps for lowering ICP can also be undertaken, e.g., infusing sedatives, paralytics, diuretics, or barbiturates into the patient and/or draining excess CSF fluid and/or hyperventilating the patient.

Description

METHOD AND SYSTEM FOR TREATING HIGH INTRACRANIAL PRESSURE

USING HYPOTHERMIA

RELATED APPLICATIONS

Priority is claimed from co-pending U.S. patent application serial no. 09/266,452,

filed March 11, 1999.

FIELD OF THE INVENTION

The present invention relates to methods and systems for lowering intracranial

pressure (ICP).

BACKGROUND

High intracranial pressure (ICP) is a major complication of severe head injury and

many other pathologies, including brain tumors, acute hydrocephalus, craniosynostosis and

benign cranial hypertension. It is believed that as a result of cellular injury and the brain's

inflammatory process, the brain can swell, increasing ICP. Since ICP is the difference

between mean arterial blood pressure and cerebral perfusion pressure (CPP), high ICP

generally means low CPP, which can lead to a risk of ischemia (lack of oxygen to the brain).

In any case, it is widely believed that an elevated ICP is closely correlated to poor medical outcomes.

It has been discovered that the medical outcome for a patient suffering from high ICP

can be improved by lowering ICP using hypothermia, i.e., by lowering ICP below about 20

mm Hg by cooling the patient below normal body temperature (38°C). As understood by the

present invention, the medical outcome for many such patients might be significantly

improved if the patients were to be mildly or moderately cooled to 32°C-37°C relatively

quickly for a short period, e.g., 12-72 hours.

Currently, to the extent that hypothermia is used to lower ICP, cooling blankets, ice

lavages, or other external means are used. As understood herein, however, such cooling

methods are difficult to control, are typically somewhat slow to cool the patient, and being

applied to the skin can cause a natural shivering reaction which increases ICP considerably

and which consequently should be avoided for patients suffering from high ICP.

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. pat. app. serial no. 09/063,984, filed April 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.

As recognized in co-pending U.S. pat. app. serial no. 09/133,813, filed August 13,

1998, owned by the present assignee and incorporated herein by reference, the above-

mentioned advantages in treating high ICP by internal cooling can also be realized by cooling

the patient's entire body, i.e., by systemic, internally-induced 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. 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 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 applications serial nos. 09/253,109, filed February 19, 1999 and

09/305,613, filed May 5, 1999, both of which are incorporated herein by reference.

SUMMARY OF THE INVENTION

A method for treating high ICP in a patient includes determining that the patient has a

high ICP, and in response lowering the patient's temperature using at least one catheter

placed in the venous system of the patient.

In a preferred embodiment, the method can also include elevating the patient's head,

and/or hyperventilating the patient, and/or draining cerebral spinal fluid from the patient as necessary to lower ICP. Moreover, if necessary the method can include administering one or

more of: a sedative, a paralytic, a diuretic, and a barbiturate, to the patient to lower ICP.

In another aspect, a system for treating elevated pressure in a patient's head includes

at least one catheter having a heat exchange region on a distal portion thereof, and at least

one pressure probe advanceable into the patient to provide a signal representative of ICP.

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 cooling system using the first cooling catheter;

Figure 2 is a schematic view of the cooling system using the second cooling catheter;

and

Figure 3 is a flow chart of the present invention for treating high ICP in a patient.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to Figure 1, a therapeutic system, generally designated 10, is shown

for treating high ICP in a patient 12. 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 co-pending U.S. patent application

serial no. 09/260,950, filed March 2, 1999 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-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 first 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 first 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 above-

referenced U.S. patent application serial no. 09/133,813. Alternatively, the heat exchange

region 24 can include one or more cooling membranes such as balloons as disclosed in the above-referenced U.S. patent application serial nos. 09/253,109 and 09/305,613. For

example, the heat exchange region 24 of the first catheter 18 can be established by four

axially staggered balloons, each ten millimeters in diameter when inflated with coolant.

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 first catheter 18 is

advanced (preferably 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 addition to or in lieu of the first catheter 18, a second cooling catheter 28 (Figure 2)

which is configured for use as a central venous catheter can be advanced into the central

venous system of the patient through a neck entry point 29. The second catheter 28 can be

embodied by the catheter disclosed in the above-referenced patent application serial nos.

09/253,109 and 09/305,613. Accordingly, the second catheter 28 can communicate with the cooling system 14 via coolant supply and return lines 30, 32. Also, the second catheter 28

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, the second catheter 28 includes a heat

exchange region 36 that can be established by one or more membranes such as balloons,

although it could be established by hollow fibers in the manner of the catheter 18, but on a

smaller scale. The catheter 28 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 36. As mentioned above, the

second catheter 28 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 cerebral spinal fluid (CSF) drainage system, represented by a box

38, that is coupled to the patient via a line 40 that communicates with the patient's spine or

brain cavity for draining excess CSF from the patient. Also, a ventilation system 42 can be

connected to the patient 12 via a tube 44 to hyperventilate the patient.

As understood by the present invention, one way to measure ICP is to advance a pressure probe 45, shown schematically in Figure 2, into the head of the patient 12. The pressure probe 45 can include a pressure sensor 45a on the distal end of the probe 45, with

the sensor 45a being connected to a pressure indicator 45b that indicates ICP. Alternatively,

the pressure probe 45 can be advanced into the neck of the patient to position the sensor 45a

in the jugular vein of the patient. In either embodiment, the pressure sensor 45a generates a

pressure signal that represents a measure of ICP.

Figure 3 shows the details of a preferred method for treating high ICP in the patient

12. As indicated at block 46, hypothermia is induced by advancing the first catheter 18

through the groin into the vena cava, and then circulating coolant through the first catheter

18. Once target temperature of 32°C-37°C has been reached, the first catheter 18 can be

removed and the second catheter 28 advanced into the vena cava through a neck entry point

to maintain target temperature. It is to be understood that while this is one preferred

sequence of the order of steps for inducing hypothermia in a high ICP patient, other

sequences can be used. For example, the first catheter 18 can be used exclusively to the

second catheter 28, the second catheter 28 can be used exclusively to the first catheter 18, or

both catheters 18, 28 can be used together simultaneously.

Moreover, as indicated at block 47 in Figure 3, if desired hypothermia can be induced

after first receiving the pressure signal from the sensor 45 a. If desired, either one or both of

the catheters 18, 28 can be prepositioned in the patient, with cold coolant flow through the

heat exchange regions of the catheters being established only after high pressure is sensed.

The cold coolant flow can be established manually by a person after observing a high

pressure reading on the indicator 45b, or it can started automatically. In such a system, the signal from the pressure sensor 45 a (or a signal from a circuit component that is activated by

a predetermined high pressure signal from the sensor 45a) can be input to the above-

mentioned controller of the cooling system 14 to activate the above-mentioned system pump

or to cause the above-mentioned cooling components to lower the temperature of the coolant

flowing through the catheters 18, 28, or both.

In any case, in addition to establishing hypothermia using the catheters of the present

invention, the preferred method also contemplates elevating the head of the patient at block

48 by, e.g., thirty degrees or so. If ICP remains above a predetermined threshold pressure,

e.g., 20mm Hg as indicated by the pressure indicator 45b, the patient can be sedated and/or

paralyzed at block 50 by infusing a sedative or paralytic into the patient using, e.g., the

component 34 and second catheter 28 shown in Figure 2.

If ICP still remains above the threshold pressure, at block 52 cerebral spinal fluid

(CSF) can be drained from the patient using the CSF system 38 shown in Figure 1. If ICP

still remains high, a diuretic such as Mannitol can be administered at block 54 through, e.g.,

the second catheter 28 using a syringe as the component 34. Should ICP still remain high,

the ventilation system 42 shown in Figure 1 can be used to hyperventilate the patient at block

56. In the event that hyperventilation fails to lower ICP sufficiently, at block 58 barbiturates

can be administered using, e.g., the component 34 and second catheter 28 shown in Figure 2.

If necessary, at block 60 appropriate surgery can be performed to alleviate the high ICP.

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 -in¬

appropriate. In any case, it is to be appreciated that as represented by the arrows 62,

hypothermia can be induced during some or all of the above method acts, or in lieu thereof.

While the particular METHOD AND APPARATUS TREATING HIGH INTRACRANIAL PRESSURE USING 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 high ICP in a patient, comprising the acts of:

determining that the patient has a high ICP; and

in response to the determining step, lowering the patient's temperature using

at least one catheter placed in the venous system of the patient.

The method of Claim 1, further comprising the act of elevating the patient's

head.

3. The method of Claim 1, further comprising the act of hyperventilating the

patient.

4. The method of Claim 1 , further comprising the act of administering a diuretic

to the patient.

5. The method of Claim 1, further comprising the act of administering

barbiturates to the patient.

6. The method of Claim 1, further comprising the act of sedating and or

paralyzing the patient.

7. The method of Claim 1 , further comprising the act of draining cerebral spinal

fluid from the patient.

8. A system for treating elevated pressure in a patient's head, comprising:

at least one catheter having a heat exchange region on a distal portion thereof; and

at least one pressure probe advanceable into the patient to provide indication of

pressure in the patient's head.

9. The system of Claim 8, further comprising a drug delivery component and at

least one diuretic drug in the drug delivery component.

10. The system of Claim 8, further comprising a drug delivery component and at

least one sedative in the drug delivery component.

11. The system of Claim 8, further comprising a drug delivery component and at

least one paralytic drug in the drug delivery component.

12. The system of Claim 8 , further comprising a drug delivery component and at

least one barbiturate in the drug delivery component infusable into the patient.

13. The system of Claim 8, comprising at least two cooling catheters.

14. The system of Claim 8, comprising a cooling system for heat exchange with

coolant flowing through the cooling catheter.

15. The system of Claim 8, comprising a ventilator for hyperventilating the

patient.

16. The system of Claim 8, further comprising a CSF drainage system

connectable to the patient to drain CSF fluid therefrom.