U.S. patent application number 10/518370 was filed with the patent office on 2005-10-06 for catheter for topical cooling and topical cooling device using the same.
Invention is credited to Mori, Atsuo.
Application Number | 20050222652 10/518370 |
Document ID | / |
Family ID | 29728033 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050222652 |
Kind Code |
A1 |
Mori, Atsuo |
October 6, 2005 |
Catheter for topical cooling and topical cooling device using the
same
Abstract
Topical cooling of spinal cord, brain, esophagus, etc. can be
selectively and continuously carried out under convenient control
without causing any changes in internal pressure of spinal cord
cavity, brain pressure, etc. by inserting a catheter, which has no
hole connecting to the outside and in which a heat-cooling medium
is circulated in its inner space to thereby cool a topical site;
into the spinal cord, the epidural cavity, the subdural cavity or
the subarachnoid cavity of the brain or the esophageal cavity and
placing therein and then circulating the heat/cooling medium within
the inner space of the catheter; or using a device composed of a
heat absorption member in the form of a catheter, a heat insulation
member and a heat radiation member, inserting the heat absorption
member in the form of a catheter into the spinal cord, the epidural
cavity, the subdural cavity or the subarachnoid cavity of the brain
or the esophageal cavity and placing therein and then absorbing
heat from the heat absorption member and radiating the heat from
the heat radiation member via the heat insulation member, thereby
contributing to the treatment of spinal diseases including
prevention of paraplegia accompanying thoracic aortic aneurysm
surgery and the treatment of brain injury, esophageal injury and so
on.
Inventors: |
Mori, Atsuo; (Kumagaya,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
29728033 |
Appl. No.: |
10/518370 |
Filed: |
December 17, 2004 |
PCT Filed: |
June 16, 2003 |
PCT NO: |
PCT/JP03/07609 |
Current U.S.
Class: |
607/105 ;
607/113 |
Current CPC
Class: |
A61F 7/12 20130101; A61F
2007/126 20130101; A61B 2018/00005 20130101 |
Class at
Publication: |
607/105 ;
607/113 |
International
Class: |
A61F 007/00; A61F
007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 17, 2002 |
JP |
2002-175423 |
Claims
1. A catheter for topical cooling composed of a high thermal
conductivity that has the inner space to circulate a heat-cooling
medium therein but has no hole connecting to the outside, wherein
it is inserted into an organ or a tissue of a mammal including a
human and placed therein thereby to topical cool it selectively and
continuously.
2. The catheter for topical cooling according to claim 1 which is
inserted transdermally into the epidural cavity, the subdural
cavity, or the subarachnoid cavity of the spinal cord or the brain,
and placed therein thereby to topical cool the spinal cord or the
brain selectively and continuously.
3. The catheter for topical cooling according to claim 1 which is
inserted transnasally into the esophagus cavity, and placed therein
thereby to topical cool the esophagus selectively and
continuously.
4. The catheter for topical cooling according to claim 1 wherein a
cooling water or a cooling gas is circulated as a heat-cooling
medium.
5. The catheter for topical cooling according to claim 1 having the
shape of a U-form, a disk-form or a swirl-form.
6. A device comprising a reservoir for preserving a heat-cooling
medium, a pump for delivering said heat-cooling medium, a heat
exchanger for cooling said heat-cooling medium, and a catheter
according to claim 1, wherein these are linked and arranged in
series by a pipe-shaped tube for circulating said heat-cooling
medium.
7. A topical cooling device composed of a material having a high
thermal conductivity and comprising a heat absorption member in the
form of a catheter, a heat insulation member, and a heat radiation
member, wherein the heat absorption member in the form of a
catheter is inserted into an organ or a tissue of a mammal
including a human and placed therein to thereby cool a topical site
selectively and continuously by absorbing heat from the heat
absorption member and radiating heat from the heat radiation
member.
8. The topical cooling device according to claim 7 wherein the heat
absorption member as the catheter is transdermally inserted into
the epidural cavity, the subdural cavity, or the subarachnoid
cavity of the spinal cord or the brain, and placed therein thereby
to topical cool the spinal cord or the brain selectively and
continuously.
9. The topical cooling device according to claim 7 wherein the heat
absorption member as the catheter is transdermally inserted into
the esophagus, and placed therein thereby to topical cool the
esophagus selectively and continuously.
10. The catheter for topical cooling according to claim 2 wherein a
cooling water or a cooling gas is circulated as a heat-cooling
medium.
11. The catheter for topical cooling according to claim 3 wherein a
cooling water or a cooling gas is circulated as a heat-cooling
medium.
12. The catheter for topical cooling according to claim 2 having
the shape of a U-form, a disk-form or a swirl-form.
13. The catheter for topical cooling according to claim 3 having
the shape of a U-form, a disk-form or a swirl-form.
14. The catheter for topical cooling according to claim 4 having
the shape of a U-form, a disk-form or a swirl-form.
15. A device comprising a reservoir for preserving a heat-cooling
medium, a pump for delivering said heat-cooling medium, a heat
exchanger for cooling said heat-cooling medium, and a catheter
according to claim 2, wherein these are linked and arranged in
series by a pipe-shaped tube for circulating said heat-cooling
medium.
16. A device comprising a reservoir for preserving a heat-cooling
medium, a pump for delivering said heat-cooling medium, a heat
exchanger for cooling said heat-cooling medium, and a catheter
according to claim 3, wherein these are linked and arranged in
series by a pipe-shaped tube for circulating said heat-cooling
medium.
17. A device comprising a reservoir for preserving a heat-cooling
medium, a pump for delivering said heat-cooling medium, a heat
exchanger for cooling said heat-cooling medium, and a catheter
according to claim 4, wherein these are linked and arranged in
series by a pipe-shaped tube for circulating said heat-cooling
medium.
18. A device comprising a reservoir for preserving a heat-cooling
medium, a pump for delivering said heat-cooling medium, a heat
exchanger for cooling said heat-cooling medium, and a catheter
according to claim 5, wherein these are linked and arranged in
series by a pipe-shaped tube for circulating said heat-cooling
medium.
Description
TECHNICAL FIELD
[0001] The present invention relates to a catheter for topical
cooling and a topical cooling device using the same for topical
cooling of organs or tissues of mammals including human on a
continual basis. More specifically, the present invention relates
to a catheter that is orally or transnasally inserted into the
epidural cavity, the subdural cavity, or the subarachnoid cavity of
the spinal cord or the brain, or the esophageal cavity and placed
therein, which is a topical cooling catheter for topically cooling
the spinal cord, the brain or the esophagus selectively and
continuously by circulating a heat-cooling medium in its inner
space, and a topical cooling device that employs said catheter.
Furthermore, it relates to a topical cooling device composed of a
material having a high thermal conductivity and comprising a heat
absorption member in the form of a catheter, a heat insulation
member, and a heat radiation member, wherein the heat absorption
member in the form of a catheter is inserted into an organ or a
tissue of a mammal including a human and placed therein to thereby
cool a topical site selectively and continuously by absorbing heat
from the heat absorption member and radiating heat from the heat
radiation member.
BACKGROUND ART
[0002] Paraplegia is a serious complication thought to occur in
5-20% of surgery cases due to defective circulation of the spinal
root arteries, the nutrient vessels of the spinal cord, at the time
of surgery for thoracoabdominal aortic aneurysm. When the thoracic
aorta is blocked at ordinary temperature, it is believed,
irreversible damages of spinal nerves develop in about one hour
(Svensson L G, Crawford E S, Hess K R, Coselli J S, Safi H J.
Experience with 1509 patients undergoing thoracoabdominal aortic
operations. J Vasc Surg 1993;17:357-70). However, during
operations, it is very difficult to specify the spinal root
arteries from a multitude of intercostal arteries, and its
reconstruction often takes a lot of time.
[0003] Clinical tests and studies have already demonstrated that
maintaining a low body temperature by central cooling with an
artificial heart and lung during operations is useful for spinal
cord protection (Kouchoukos N T, Wareing T H, Izumoto H, et al.,
Elective hypothermic cardiopulmonary bypass and circulatory arrest
for spinal protection during operations on the thoracoabdominal
aorta. J. Thorac Cardiovasc Surg 1990, 99:659-64). However,
systemic hypothermia may disadvantageously induce demerits such as
abnormal coagulation and respiratory disorders due to
extracorporeal circulation. At present, there are no methods that
can completely avoid the occurrence of paraplegia associated with
surgery for the thoracoabdominal aortic aneurysm.
[0004] As methods of topical cooling of the spinal cord, there have
been reported a method in which two catheters are separately
inserted to the subarachnoid cavity (the spinal cord cavity) (one
for injection that injects cooling water, and the other for
discharging for use in the drainage of the cooling water) and
topical cooling is accomplished under perfusion of the spinal cord
(Paul A., Spinal cord protection during thoracoabdominal aneurysm
resection. J. Thorac Cardiovasc Surg 1995, 109:1244-6). With this
method, however, when the drainage of the cooling water becomes
poor, internal pressure of the subarachnoid cavity may be
excessively enhanced which may cause serious complications such as
cerebral hernia, and thus its clinical application was difficult.
Furthermore, Cambria of Harvard Univ. has reported a method in
which a catheter was transdermally inserted in the surgery of
thoracoabdominal aortic aneurysm, through which a cooling water was
continuously injected, and during one operation about 1400 ml of
physiological saline was injected without drainage and allowed to
diffuse as it is without drainage (Cambria R P, Davidson J K,
Zannetti S et al., Clinical experience with epidural cooling for
spinal cord protection during thoracic and thoracoabdominal
aneurysm repair. J. Vasc Surg 1997, 25:234-43; Cambria R P,
Davidson J K. Regional Hypothermia for Prevention of Spinal Cord
Ischemia complications after thoracoabdominal aortic surgery:
Experience with epidural cooling. Seminars in Thoracic and
Cardiovascular Surgery, Vol. 10, No. 1 (January), 1998, pp. 61-65).
With this method, however, due to the cooling water injected,
internal pressure of the subarachnoid cavity may be excessively
enhanced leading to about twice the normal internal pressure of the
medullary cavity, and thus because of potential risk of ischemic
disorders such as cerebral hernia and reduced perfusion pressure,
the method has not been adopted in other facilities. Furthermore,
experimentally, although there has been reported a method of
injecting a bolus of cooling saline into the subdural cavity, the
method does not permit the continuous cooling of the spinal cord
for a long time. These two methods have been developed for the
cooling of the spinal cord in the operation room, it is necessary
to inject the cooling water into the epidural cavity while
monitoring internal pressure of the subarachnoid cavity and
intraspinal temperature so that internal pressure of the
subarachnoid cavity may not be excessively enhanced. Thus, since
the methods are troublesome in management, and the amount induced
into the epidural cavity is limited, it is not amenable to
continuous cooling for a long time in intensive care units or
general hospital wards.
[0005] On the other hand, traumatic brain contusion is caused by
traffic accidents or accidents, and significantly affects the
mortality and morbidity of those involved, posing a serious social
problem as well. The general hypothermic therapy for traumatic
brain contusion has a concept that nerve cells that were damaged,
specifically those cells that received medium irreversible damages,
which may be considered to be a penumbra retaining a potential of
recovery, present in the periphery of nerve cells that received
irreversible damages are protected by a nerve cells-protecting
effect retained by hypothermia so as to improve the prognosis and
QOL of the patient. Its usefulness has already been recognized and
has been put into clinical practices such as in the form of
surface-cooling the entire body with a blanket at a medium body
temperature of about 32.degree. C. (Jiang J., yu M., Zhu C., Effect
of long-term mild hypothermia therapy in patients with severe
traumatic brain injury: 1-year follow-up review of 87 cases. J.
Neurosurge. 2000, 93(4):546-9). However, there are demerits such as
decreased immune functions associated with maintaining the
hypothermia of the entire body, and the resulting infections,
arrhythmia or abnormal coagulation. In particular, it has been
pointed out, when the patient is an elderly, demerits such as
infections associated with the hypothermia of the entire body
becomes pronounced leading to the onset of complications, with a
result that the overall survival is not improved. Also in order to
overcome the demerits such as infections, arrhythmia and abnormal
coagulation, complicated management of the entire body at the
intensive care unit is required causing economic problems that more
labor and cost are required. Specifically, when the treatment is
prolonged, the brain hypothermia therapy that maintains the
hypothermia of the entire body requires an enormous personnel and
economic costs.
[0006] Also, there is a need for the development of devices for
topical cooling the esophagus as a means of preventing esophageal
injuries that may occur as a complication at the time of
radiofrequency ablation for the atrium performed as a method of
treatment of atrial fibrillation.
DISCLOSURE OF THE INVENTION
[0007] Thus, it is an object of the present invention to provide a
catheter that is applied into the epidural cavity, the subdural
cavity, or the subarachnoid cavity to cool the spinal cord
continuously, wherein the spinal cord can be cooled safely,
selectively and continuously without injecting any liquid into the
epidural cavity, the subdural cavity, or the subarachnoid cavity,
the spinal cord is free from any risk such as ischemic injuries,
paraplegia occurring after a thoracoabdominal aortic surgery can be
prevented, or the selective and continuous cooling of the spinal
cord for a long time can be attained, and management thereof is
easy, and a device using the same for cooling the spinal cord
selectively and continuously.
[0008] It is another object of the present invention to provide a
catheter for cooling the brain continuously and topically wherein
the brain alone can be selectively and continuously cooled while
maintaining at an ordinary temperature, demerits of maintaining the
hypothermia of the entire body while maintaining the
brain-protecting effect of the brain hypothermia can be overcome,
and a higher survival and an improved degree of disturbance of
consciousness can be attained, and a cooling device using the
same.
[0009] Furthermore, it is an object of the present invention to
provide a catheter for cooling the esophagus topically and
continuously wherein it is possible to topically cool the esophagus
selectively and it is also possible to relieve complications as a
means for preventing esophagus injuries that may occur at the time
of radiofrequency ablation of the atrium performed as a treatment
of atrial fibrillation at the clinical setting, and a cooling
device using the same.
[0010] Thus, the present invention is a topical cooling catheter
that has an inner space to circulate a heat-cooling medium therein,
has no hole connecting to the outside, and is composed of a high
thermal conductivity, said catheter being inserted into organs or
tissues of mammals including humans and placing therein thereby to
topically cool them selectively and continuously. Preferably, it is
a cooling catheter that is transdermally inserted into the epidural
cavity, the subdural cavity, or the subarachnoid cavity of the
spinal cord or the brain, or the esophageal cavity and placed
therein so as to topically cool the spinal cord or the brain
selectively and continuously, or that is a topical cooling catheter
that is orally or transnasally inserted into the esophagus and
placed therein so as to topically cool the esophagus selectively
and continuously.
[0011] Also the present invention is a topical cooling device
comprising a reservoir for preserving a heat-cooling medium, a pump
for delivering said heat-cooling medium, a heat exchanger for
cooling said heat-cooling medium, and the above catheter, wherein
these are linked and arranged in series by a pipe-shaped tube for
circulating said heat-cooling medium.
[0012] Furthermore, it is a topical cooling device composed of a
material having a high thermal conductivity comprising a heat
absorption member in the form of a catheter, a heat insulation
member, and a heat radiation member, wherein the heat absorption
member in the form of a catheter is inserted into an organ or a
tissue of a mammal including a human and placed therein to thereby
cool a topical site selectively and continuously by absorbing heat
from the heat absorption member and radiating heat from the heat
radiation member. Preferably, it is a cooling catheter that is
transdermally inserted into the epidural cavity, the subdural
cavity, or the subarachnoid cavity of the spinal cord or the brain,
or the esophageal cavity and placed therein so as to topically cool
the spinal cord or the brain selectively and continuously, or that
is a topical cooling catheter in which the heat absorption member
in the form of a catheter is orally or transnasally inserted into
the esophagus and placed therein so as to topically cool the
esophagus selectively and continuously.
BRIEF EXPLANATION OF THE DRAWINGS
[0013] FIG. 1 is a drawing wherein a catheter of the present
invention in which a heat-cooling medium is circulated and a device
of the present invention were applied to the spinal cord. 1 is an
aorta, 2 is the vertebral body, 3 is the spinal cord, 4 is spinous
process of vertebra, 5 is a catheter placed, 6 is a reservoir, 7 is
a heat exchanger, and 8 is a pump.
[0014] FIG. 2 is a drawing wherein various catheters of the present
invention in which a heat-cooling medium is circulated were applied
to the spinal cord. A is a catheter inserted into the subarachnoid
cavity, B is a catheter inserted into the epidural cavity so that
the inlet and the outlet be separate from each other. and C is a
catheter inserted into the epidural cavity so that the inlet and
the outlet be separate from each other and was folded back in a
zigzag configuration.
[0015] FIG. 3 is a drawing wherein various catheters of the present
invention in which a heat-cooling medium is circulated were applied
to the spinal cord. A is a catheter of which inlet and outlet were
inserted at one site into the epidural cavity and which was folded
back in a zigzag configuration, 3 is the spinal cord, 4 is spinous
process of vertebra, B is a catheter of which inlet and outlet were
laterally folded back at one site in a zigzag configuration, and C
is two sets of catheters arranged in parallel and inserted into the
epidural cavity.
[0016] FIG. 4 represents various catheters for use in the cooling
of the brain. Arrows in the Figure may be in the opposite
direction.
[0017] FIG. 5 represents various catheters for use in the cooling
of the spinal cord and esophagus. Arrows in the Figure may be in
the opposite direction.
[0018] FIG. 6 is a drawing wherein a device of the present
invention containing a catheter in which a heat-cooling medium is
not circulated was applied to the spinal cord. 3 is the spinal
cord, 4 is spinous process of vertebra, 5 is a cooling catheter, 9
is a cauda equina, 10 is a heat absorbing member, 11 is a heat
insulation member, 12 is a heat radiation member, 13 is a cooling
device, 14 is the skin, 15 is a subcutaneous heat radiation member,
and 16 is a cooling device. Arrows in the broken line represent the
direction of heat flow.
[0019] FIG. 7 is a graph showing an effect of cooling the spinal
cord by a device of the present invention containing a catheter in
which a heat-cooling medium is circulated in its inner space.
[0020] FIG. 8 is a graph showing changes in changes in pressure of
the medullary cavity by a device of the present invention
containing a catheter in which a heat-cooling medium is circulated
in its inner space.
[0021] FIG. 9 is a graph showing an effect of cooling the brain by
a device of the present invention containing a catheter in which a
heat-cooling medium is circulated in its inner space.
[0022] FIG. 10 is a graph showing an effect of cooling the
esophagus by a device of the present invention containing a
catheter in which a heat-cooling medium is circulated in its inner
space.
BEST MODE FOR CARRYING OUT THE INVENTION
[0023] The catheter of the present invention for topical cooling
and a device using the same are intended for topical cooling
selectively and continuously by inserting a catheter that has no
hole connecting to the outside into an organ or a tissue of a
mammal including a human and placed therein, and a heat-cooling
medium such as a cooling water is circulated in the catheter to
thereby absorb heat from a topical site of the organ or the tissue.
Also, the topical cooling device of the present invention is
composed of a heat absorption member, a heat insulation member and
a heat radiation member, in which the heat absorption member in the
form of a catheter is inserted into the organ or the tissue and
placed therein and, without circulating a heat-cooling medium such
as a cooling water, heat is absorbed from the heat absorption
member in the form of a catheter and radiated from the heat
radiation member thereby to topical cool it selectively and
continuously.
[0024] Hereinbelow, the catheter of the present invention in which
a heat-cooling medium is circulated for topical cooling and a
device using the same, as well as a device in which a heat-cooling
medium is not circulated for topical cooling are explained in
detail.
[0025] First, the catheter of the present invention in which a
heat-cooling medium is circulated for topical cooling and a device
using the same is explained.
[0026] The catheter of the present invention in which a
heat-cooling medium is circulated for topical cooling is usually
inserted transdermally into the epidural cavity, the subdural
cavity, or the subarachnoid cavity of the spinal cord or the brain
by laminectomy or the puncture to the epidural cavity, the subdural
cavity or the subarachnoid cavity, or a combination of the two of
them using a puncture needle. Generally the epidural cavity, and
the subdural cavity of the spinal cord and the brain are a narrow
cavity with a thickness of about 1-2 mm and a width of about 7-9
mm, but they are surrounded by smooth fibrous connecting tissues
such as the dura mater and the yellow ligament, which is why a
catheter can be inserted therein. Also, in the case of the
subarachnoid cavity of the spinal cord and the brain, insertion can
be made into a space of the second lumber vertebra or lower. In
order to topical cool the esophagus, a catheter is inserted orally
or transnasally into the esophagus cavity.
[0027] The catheter of the present invention is a thin tubing made
of a material having an essentially high thermal conductivity, for
example a metal such as stainless, titanium, aluminum, gold,
silver, and copper, and serve as a heat-cooling medium. It must
have an inner space in which a liquid such as distilled water or a
gas such as carbon dioxide can circulate. Generally, its inner
diameter is about 05-0.8 mm and the outer diameter is 0.8-1.2 mm.
The both ends of the catheter have a connecting member capable of
connecting to a pipe-shaped tubing so as to form a circuit. The
catheter is inserted into the epidural cavity, the subdural cavity,
or the subarachnoid cavity of the spinal cord or the brain, or the
esophagus by laminectomy or the puncture of the epidural cavity at
1 or 2 sites. When insertion is made at one site, the catheter is
preferably shaped in a folded-back U form, and form the apex of the
folded-back U form, insertion is made. When insertion is made at
two sites, the inlet and the outlet are separately present in the
catheter, which may be folded back in a zigzag configuration. Also,
the two sets of catheters may be arranged in parallel and placed in
the epidural cavity, the subdural cavity, or the subarachnoid
cavity and placed therein. When the brain is cooled, a disk-shaped
or whirl-shaped catheter is preferred.
[0028] FIG. 1 shows a state in which a U-shaped catheter of the
present invention has been inserted into the epidural cavity of the
spinal cord and placed therein. FIG. 2 shows a catheter a U-shaped
catheter inserted into the subarachnoid cavity of the spinal cord
in the upper part, a catheter inserted into the epidural cavity of
the spinal cord so that the inlet and the outlet are separate in
the middle part, and a catheter inserted into the epidural cavity
of the spinal cord and folded back in a zigzag form at the lower
part. FIG. 3 shows a catheter in which the inlet and the outlet
have been inserted into the epidural cavity at one site and which
has been folded back in a zigzag form at the upper part, a catheter
in which the inlet and the outlet have been inserted into the
epidural cavity at one site and which has been folded back
laterally in a zigzag form at the middle part, and two sets of
catheters arranged in parallel and inserted into the epidural
cavity at the lower part. FIG. 4 shows various catheters Formula
(I) the cooling of the brain. FIG. 5 shows various catheters for
use in cooling the esophagus. The catheters shown in FIG. 5 may
also be used as catheters for use in cooling the spinal cord.
[0029] The catheter of the present invention has no holes
connecting to the outside. Thus, it is not a catheter for injecting
a cooling water into the epidural cavity, subdural cavity, the
subarachnoid cavity, or the esophagus cavity, but it cools the
spinal cord, the brain, and the esophagus by absorbing heat from
the surface of the catheter in contact with the dura mater or from
the surface of the catheter placed in the subarachnoid cavity or
the esophagus cavity, or across the dura mater, or directly cool
the spinal cord, the brain and the esophagus. Since the catheter is
thin, it easily reaches the same temperature as the spinal cord
etc. if it is only placed therein, whereas the catheter of the
present invention can be kept at low temperature due to the
circulation of the heat-cooling medium in the inner space, thereby
enabling to keep the spinal cord, the brain, the esophagus etc.
continuously at low temperature and protecting them. Furthermore,
since the catheter of the present invention is made of a material
having a high thermal conductivity, the effect of radiating heat
extracoporally due to the heat conductivity of the catheter per se
can be expected, and the spinal cord, the brain, the esophagus etc.
can be efficiently and continuously cooled. With a catheter made of
a material such as polyurethane and silicone having a low thermal
conductivity, efficient absorption of heat from the spinal cord,
the brain, the esophagus etc. would be difficult, in which case by
thinning the thickness of the catheter, the thermal conductivity
thereof can be enhanced and thereby can be used in the present
invention.
[0030] As a variation of the catheter of the present invention, it
may be a catheter in which a film made of a material having a high
thermal conductivity such as a gold foil, a silver foil, an
aluminum foil etc. has been attached in between the catheters such
as a folded back U-shaped catheter. Furthermore, it may be a
catheter on which an insulating film has been attached to the side
corresponding to the opposite side of the dura mater. With a
catheter to which such an insulating film has been attached, the
contact area between the catheter and the dura mater or the spinal
meanings becomes increased thereby enabling a more efficient
cooling of the spinal cord. Also, the cooling efficiency can also
be enhanced by attaching a thin semiconductor that can be cooled
such as a Peltier device in between the U-shaped catheters.
[0031] The topical cooling device of the present invention is
composed of the four units including the above catheter of the
present invention and a pipe-shaped tubing connecting them. As
shown in FIG. 1, the four units are a reservoir 6 for storing a
heat-cooling medium, a pump 8 for delivering a heat-cooling medium
such as a liquid and a gas, a heat exchanger 7 for cooling the
heat-cooling medium, and the above-mentioned catheter 5, and these
four are arranged in a series association. By circulating a
heat-cooling medium, for example a liquid such as distilled water
or a gas such as carbon dioxide, though the pipe-shaped tubing and
the four units, heat is absorbed from the spinal cord 3, the brain,
the esophagus etc. through the surface of the catheter 5 placed in
the epidural cavity, the subdural cavity, or the subarachnoid
cavity of the spinal cord or the brain, and thus a continuous
topical cooling can be realized.
[0032] Each of the units is explained below. First, in the
reservoir 6, a fixed amount of a liquid such as distilled water or
a gas such as carbon dioxide that represents a heat-cooling medium
is stored. This is to deal with changes in the flow rate associated
with the passage of time by storing a fixed amount of a medium
circulating through the circuit. Since it is a circulating type,
there is no concern that the medium leaks more than the amount
stored in the reservoir 6 in case a leak occurred in the circuit,
and thus it also plays a role of a safety unit.
[0033] Then, for the pump 8 for delivering a heat-cooling medium
such as a liquid or a gas, this is a unit that emits a liquid or a
gas representing a heat-cooling medium, and circulate it through
the circuit. Since the catheter 5 usually has a thin diameter, the
pump 8 is preferably one that can withstand high pressure such as a
syringe pump or a high-pressure roller pump. Furthermore, when the
heat-cooling medium is a gas, a high-pressure cylinder may be
substituted. The flow rate of the pump is, for example, about 20-30
ml/min when the heat-cooling medium is distilled water.
[0034] The cooling heat exchanger 7 is a unit that renders the
temperature of the heat-cooling medium low while it passes through
the unit. For example, there can be mentioned a cooling device that
cools the outside of the spiral metal circuit with crushed ice. In
addition to them, any unit that can cool can be used, for example,
a semiconductor such as a Peltier device, a cooling gas etc.
[0035] By circulating a heat-cooling medium through the device
composed of the four units, i.e. the reservoir 6, the pump 8, the
cooling heat exchanger 7 and the catheter 5, it becomes possible to
topically cool the spinal cord, the brain, the esophagus etc.
continuously for a long time without injecting any cooling water
into the epidural cavity, the subdural cavity, the subarachnoid
cavity, the esophagus cavity or the like, thus without increasing
the internal pressure of the subarachnoid cavity.
[0036] Nextly, the device of the present invention that cools the
spinal cord, the brain, the esophagus etc. without circulating a
heat-cooling medium is explained below.
[0037] The device of the present invention that cools the spinal
cord, the brain, the esophagus etc. without circulating a
heat-cooling medium is made of a material having a high thermal
conductivity, and is composed of a heat absorption member in the
form of a catheter, a heat insulation member, and a heat radiation
member, wherein the heat absorption member in the form of a
catheter is inserted into the epidural cavity, the subdural cavity,
the subarachnoid cavity, the esophagus cavity or the like and
placed therein to thereby cool a topical site selectively and
continuously by absorbing heat from the heat absorption member and
radiating heat from the heat radiation member.
[0038] An example of a case wherein such a device was applied to
the spinal cord is shown in FIG. 6. As to the shape of the catheter
of such a device, it may be the same as the above catheter for
circulating the heat-cooling medium, and preferably the overall
shape is, for example, a pipe, a bar, a plate, a disk, or a swirl.
In the case of a pipe, it is usually preferred that the outer
diameter is about 0.5-2.0 mm, in the case of a plate, it is usually
preferred that the thickness is preferably about 0.1-2.0 mm and the
width is about 2-8 mm, and the length is about 3-30 cm. In the case
of a disk, it is usually preferred that the diameter is about 4-10
cm and the thickness is about 1-2 mm. As is also shown in FIG. 6,
the cooling device of the present invention is composed of a heat
absorption member 10 in the form of a catheter 5, a heat insulation
member 11, and a heat radiation member 12. The heat absorption
member 10 in the form of a catheter is a part that is inserted into
the epidural cavity, the subdural cavity, the subarachnoid cavity
of the spinal cord or the brain, the esophagus cavity or the like,
and placed therein so as to absorb heat from the spinal cord, the
brain, the esophagus etc. from across the dura mater, or by a
direct contact with the spinal cord, the brain, the esophagus etc.
The shape of the heat absorption member in the form of a catheter
is usually a pipe, a bar, a plate, a disk, or a swirl. The heat
absorption member is composed of a material having a high thermal
conductivity, and as such a material there can be preferably
mentioned gold, silver, copper, an aluminum alloy, titanium and the
like. When the heat absorption member is a plate, it is preferred
that the surface of the side opposite to the side in contact with
the spinal cord, the brain, the esophagus etc. has been insulated
so that heat is not lost from the tissues other than the spinal
cord, the brain, the esophagus etc. It is because there occurs no
wasteful heat exchange with the surrounding tissues other than the
spinal cord etc. As materials for insulation, specifically there
can be mentioned silicone, polyurethane, rubber, and the like.
[0039] The heat insulation member 11 is a middle part of a cooling
device that is not in contact with the spinal cord, the brain, the
esophagus etc., and it is preferred that the central part thereof
is made of gold, silver, copper, an aluminum alloy, titanium and
the like. The shape is similar to that of the heat absorption
member, and the length depends on the distance between the heat
absorption member and the heat radiation member. In order to avoid
wasteful heat exchange between the heat insulation member and the
adjacent tissues, the outside thereof is preferably insulated so as
to cover the central part. As materials for insulation,
specifically there can be mentioned silicone, polyurethane, rubber,
and the like. The heat insulation member is a part that transports
heat from the heat absorption member to the heat radiation member
depending on the temperature difference between the heat absorption
member and the heat radiation member.
[0040] The heat radiation member 12 is a part in which heat
transmitted from the heat absorption member of the catheter is
forcefully radiated, and thus a larger surface area is preferred.
For example, as shown in FIG. 6, the heat radiation member 12 is a
plate, and one side of this plate is preferably a radiation surface
that is not insulated. The heat radiation surface of such a plate
heat radiation member may be cooled by a cooling unit 13 that
performs cooling with ice or a cooling gas, or may be cooled by
connecting it to a heat exchanger, or may be forcefully air-cooled
by intensely blowing the air.
[0041] Alternatively, the surface may be forcefully cooled with a
cooling unit having a cooling surface such as a Peltier device. The
heat radiation member may be placed extracorporally or
subcutaneously. The size and shape of the heat radiation member
are, but not limited to, preferably, for example, a square of
5.times.5 cm to 10.times.10 cm. When it is placed subcutaneously,
it is implanted so that the heat radiation surface is directly
under the dermis, and by sandwiching the dermis with an
extracorporal cooling unit such as ice, a cooling gas, a Peltier
device etc., heat is radiated from the subcutaneous cooling surface
to an extracorporal cooling unit such as ice, a cooling gas, a
Peltier device etc. In this case, since the catheter does not
extracorporally protrudes through the skin, it has an advantage
that a risk of infection etc. may be reduced. When it is placed
subcutaneously, the surface opposite to the dermis is preferably
insulated so that wasteful heat exchange does not occur with the
surrounding tissue. As materials for insulation, specifically there
can be preferably mentioned silicone, polyurethane, rubber, and the
like.
[0042] As mentioned above, in the device of the present invention,
heat absorbed at the heat absorption member from the spinal cord,
the brain, the esophagus etc. passes through the heat insulation
member to the subcutaneous heat radiation member, from which the
heat is continuously absorbed by a cooling unit or a heat
exchanger, or the surrounding air, with a result that the spinal
cord, the brain, the esophagus etc. can be continuously and
selectively cooled. Furthermore, since there is no cooling water
injected to the epidural cavity, the subdural cavity, the
subarachnoid cavity, the esophagus cavity or the like, there is no
fear of increasing the internal pressure of the subarachnoid
cavity.
[0043] The catheter of such a device, as with a catheter in which a
heat-cooling medium is circulated in the inner space for topical
cooling, may be inserted transdermally into the epidural cavity,
the subdural cavity, or the subarachnoid cavity by laminectomy or
the puncture to the epidural cavity, the subdural cavity or the
subarachnoid cavity, or a combination of the two of them using a
puncture needle, or orally or transnasally into the esophagus
cavity, and placed therein to cool the spinal cord, the brain, the
esophagus etc.
[0044] The present invention will now be explained in further
details with reference to Examples, but it should be noted that the
present invention is not limited to these examples in any way.
EXAMPLE 1
[0045] Cooling of the Spinal Cord using the Catheter of the Present
Invention and a Device Using the Same and their Effects
[0046] The device of the present invention was applied to a porcine
survival model in order to examine the effect of protecting the
spinal cord. Thus, while blocking the descending aorta of a porcine
survival model with a blocking clamp for 30 minutes, the device of
the present invention was used in which the catheter was placed in
the epidural cavity and distilled water was circulated through the
catheter, the spinal cord was topical cooled, and the effect of
protecting the spinal cord on the porcine survival model was
evaluated by a neurological score. In the experiment, changes in
the spinal cord somatosensory evoked potential (sSSEP) with time
was monitored, and the effect of protecting the spinal cord was
evaluated. sSSEP is an electrophysiological test of the spinal
nerve termed as the spinal cord-induced potential, and specifically
it is a test in which a stimulus by the stimulatory sSSEP electrode
that was transmitted to the center (the direction of the cerebra)
via the sensory nerves of the spinal cord is picked up by a
detecting sSSEP electrode to investigate the function of the
sensory nerves of the spinal cord.
[0047] 1. Experimental Method
[0048] As the experimental animal, pigs weighing about 30 kg were
used. After intramuscular injection of ketamine 15 mg/kg, a venous
line was secured in the marginal ear vein. After tracheostomy was
performed and a tracheal tube was inserted, controlled respiration
was started using a respirator. For the maintenance of anesthesia,
the depth of anesthesia was controlled with nitrous oxide and
halothane. An arterial line was secured at the right axillary
artery and electrocardiogram (ECG) was continuously monitored.
Using a temperature sensor, the temperature of the spinal cord, the
epipharynx and the rectum was monitored.
[0049] Pigs were placed in a lateral position to shave the back. At
the height of the third lumber vertebra and the seventh thoracic
vertebra, laminectomy was performed, and the catheter for topical
cooling of the device of the present invention shown in FIG. 1 was
transdermally inserted into the epidural cavity by epidural cavity
puncture using a puncture needle. After confirming that the
waveform of sSSEP can be reproducibly detected, the posture was
changed to the dorsal position. After abdominal section at the
center line, a hole was made in the aortic hiatus and thoracic
descending aorta was taped.
[0050] Distilled water was circulated through the catheter for
topical cooling of the present invention for 60 minutes, and after
the spinal cord was cooled and heparin 5 ml was intravenously
injected, the thoracic descending aorta was blocked at the distal
position of the left subclavian artery with a blood vessel
clamp.
[0051] While measuring sSSEP, the thoracic descending aorta was
blocked at the distal position of the left subclavian artery for 30
minutes, and the spinal cord was made ischemic to determine
changes. After removal of blocking, the thorax was closed.
[0052] After removing the catheter for cooling and the sSSEP
electrodes, the wound was closed, and after awakening from
anesthesia, the tracheal tube was removed, and the neurological
status of the lower limb to 48 hours post-operation was evaluated
according to the Tarlov score.
[0053] A similar experiment was performed without circulating
distilled water through the catheter for topical cooling of the
device of the present invention and with the spinal cord at an
ischemic sate, sSSEP and the neurological status were
evaluated.
[0054] Then, the pigs were anesthetized by a bolus intravenous
injection of pentobarbital and a KCl solution.
[0055] 2. Experimental Result
[0056] 1) Changes in and Effect of sSEP by the Device of the
Present Invention Under the Aortic Blocking
[0057] First, placing the sSSEP electrode for epidural cavity
placing for stimulation and detection from the laminectomy site,
highly reporducible and stable sSSEP was detected in all
animals.
[0058] In the experiment group in which the topical cooling of the
spinal cord was performed by the device of the present invention,
there were no changes in wave height even 30 minutes after blocking
of sSSEP in four of seven cases. In three cases, decreases in wave
height of sSSEP started at 20-25 minutes after blocking of the
thoracic descending aorta, but no disappearances in wave height
occurred even 30 minutes after blocking. The amplitude of sSSEP
after removal of blocking of the thoracic descending aorta
exhibited a recovery of 89.+-.7% as compared to before blocking.
During the 20 minutes when the aorta was pre-cooled with PCEC
without blocking the aorta, no significant changes in amplitude
were noted in sSSEP.
[0059] In the control group in which distilled water was not
circulated through the catheter for topical cooling of the present
invention placed in the epidural cavity, decreases in wave height
and changes into such as a biphase occurred at about 10 minutes
after the blocking of the thoracic descending aorta in all seven
cases, and about 15-20 later sSSEP disappeared. In the control
group, the amplitude of sSSEP after removing the blocking of the
thoracic descending aorta remained recovery of 55.+-.6% as compared
to that before blocking.
[0060] 2) Evaluation of Neurological Status of the Spinal Cord
After Ischemic Stress
[0061] For neurological findings of pigs, the experimental animal,
after operation, the motor function of the lower limb were
evaluated using the Tarlov's score. The result is shown in Table
1.
1 TABLE 1 The experiment group by the device of the The control
group present invention (n = 7) (n = 7) 12 24 48 12 24 48 hours
hours hours hours hours hours later later later later later later
Tarlov 5 5 7 7 0 0 0 Tarlov 4 2 0 0 0 0 0 Tarlov 3 0 0 0 0 0 0
Tarlov 2 0 0 0 0 1 1 Tarlov 1 0 0 0 3 2 2 Tarlov 0 0 0 0 4 4 4
[0062] Tarlov's score is a method for evaluating the motor function
of the lower limb that was established in order to evaluate stages
in grades with 5 representing a complete recovery and 0
representing a complete paraplegia. As can be clearly seen from the
result in Table 1, in the experiment group in which the topical
cooling of the spinal cord was performed by the device of the
present invention, five cases of seven exhibited a complete
recovery (Tarlov score 5) and two cases exhibited a recovery of 4
in Tarlov score. In the control group in which distilled water was
not circulated through the catheter, four cases of seven exhibited
a complete paraplegia (Tarlov score 0) and two cases exhibited an
incomplete paraplegia (Tarlov score 1). Statistically, the
experiment group with the invention device has given a
significantly better neurological scores than the control group
(p<0.05). Thus, the protective effect against ischemic injuries
of the spinal cord by the device of the present invention was
demonstrated.
[0063] 3) Effect of Cooling the Spinal Cord by the Device of the
Present Invention
[0064] Changes in the temperature of the spinal cord, the
epipharynx and the rectum with time when the spinal cord was cooled
by the device of the present invention are shown in FIG. 7. As can
be seen from the graph in FIG. 7, by cooling with the device of the
present invention, only the temperature of the spinal cord
decreased by about 5.degree. C. about 10 minutes later. In
contrast, the temperature of the rectum and the epipharynx did not
change. Then, after removing the blocking of the aorta, the
temperature of the spinal cord increased by about 2.degree. C., and
after cessation of cooling, the temperature of the spinal cord
became the same as those of the rectum and the epipharynx in about
5 minutes. From these results, it was demonstrated that the spinal
cord is selectively cooled.
[0065] 4) Changes in Internal Pressure of the Subarachnoid Cavity
of the Spinal Cord by the Device of the Present Invention
[0066] Changes with time in internal pressure of the subarachnoid
cavity of the spinal cord, pulses, the systolic pressure and the
diastolic pressure during the period of cooling the spinal cord by
the device of the present invention are shown in FIG. 8. As can be
seen from the graph in FIG. 8, since no cooling water is injected
into the epidural cavity in the device of the present invention, no
changes in internal pressure of the subarachnoid cavity of the
spinal cord occurred after cooling. Furthermore, by the blocking of
the thoracic descending aorta, the systolic pressure and the
diastolic pressure increased and pulses decreased slightly. After
removing the blocking of the aorta, the systolic pressure and the
diastolic pressure returned to the original values.
[0067] 3. Discussion
[0068] The above-mentioned experiment clarified the following two
points.
[0069] Firstly, since paraplegia by the blocking of the thoracic
descending aorta for 30 minutes could be avoided by the effect of
cooling the spinal cord by the device of the present invention, it
was demonstrated that the device of the present invention has a
spinal cord protecting effect in the survival model. As shown in
Table 1, six cases of seven in the control group were paraplegia or
incomplete paraplegia, whereas in the experiment group in which
topical cooling was performed by the device of the present
invention, all cases after awakening from anesthesia were able to
stand up on its own. This indicates that the cooling of the spinal
cord by the device of the present invention is promising as a means
for avoid paraplegia that is accompanied with surgery for
thoracoabdominal aortic aneurysm in clinical settings. Thus, it can
be expected that the spinal cord alone is selectively cooled while
maintaining the other organs at ordinary temperature, and during
the blocking of the aorta, time to anastomose more intercostal
arteries to artificial blood vessels and to reconstruct them can be
secured.
[0070] It was demonstrated that the effect of sSSEP can be further
increased under the condition of the aorta being blocked, and the
spinal cord can be cooled to 30.5.degree. C., 7.degree. C. lower
than the body temperature. This result can be explained as follows.
Thus, it is believed that when the cooling of the spinal cord was
performed by the device of the present invention under a normal
condition, the temperature of the spinal cord tissue is moved to
the direction of being increased by the blood and of being
decreased by the cooling catheter. At the condition in which the
aorta is blocked, it is speculated that blood flow to the spinal
cord tissue decreased, and the force of increasing the tissue
temperature weakened with a result that the cooling effect by the
cooling catheter was higher during blocking. By rendering the
spinal cord at a low temperature, the metabolism of the nerve cells
should be further inhibited and a more potent protective effect
should be expected. Clinically, it can be expected that while
maintaining the other organs at ordinary temperature, and during
the blocking of the aorta, time to anastomose more intercostal
arteries to artificial blood vessels and to reconstruct them can be
secured.
[0071] Secondly, with the blocking of the aorta, the control group
has exhibited a decrease and disappearance of the wave height of
sSSEP and an incomplete recovery after removal, whereas in the
group in which the spinal cord was cooled by the device of the
present invention, sSSEP due to the epidural cavity electrode
stimulation--the epidural cavity electrode derivation did not
disappear, and recovered almost completely 30 minutes after
removing the blocking. What is interesting is that sSSEP does not
change greatly by the cooling of the spinal cord alone by the
device of the present invention before blocking the aorta. This may
be considered advantageous since in the clinical setting it also
means that sSSEP can be used during cooling to judge whether the
reconstruction of the spinal cord root arteries is sufficient or
not.
[0072] Also, the result is very interesting that sSSEP does not
change for about 20 minutes even if the aorta is blocked during
cooling. This result would be explained as follows. Thus, by
blocking the aorta, the supply of oxygen and energy to the spinal
cord decreased, while the metabolism of the spinal cord was
inhibited by topical cooling and the demand for oxygen and energy
of the spinal cord tissue was also inhibited, which means a well
balanced state meaning no insufficient metabolism. Thus, under an
environment of moderate hypothermia, it is believed, sSSEP can be
used as an index showing a balance sheet of metabolism rather than
an index showing the blood flow of the spinal cord tissue.
[0073] The above-mentioned experiment demonstrated the most
important problem that the cooling of the spinal cord by the device
of the present invention can actually protect the spinal cord from
disorders derived from ischemia. By rendering sSSEP the epidural
cavity electrode stimulation--the epidural cavity electrode
detection, it became a highly sensitive index having a reliability
and a reproducibility. Also, it was also shown, using a survival
model, to have a neurologically protective effect as well.
EXAMPLE 2
[0074] Cooling of the Brain Using the Catheter of the Present
Invention and a Device Using the Same and their Effects
[0075] An experiment was carried out in which during the operation
of cerebral decompression, a catheter in a swirl form having no
hole connecting to the epidural cavity was placed in the epidural
cavity of the brain, and a cooling water was circulated through
this catheter to absorb heat from the surface of the brain to
topically cool the brain selectively and continuously.
[0076] 1. Experimental Method
[0077] As the experimental animal, pigs weighing about 35-40 kg
were used. After intramuscular injection of ketamine 15 mg/kg, a
venous line was secured in the marginal ear vein. After a tracheal
tube was inserted, controlled respiration was started using a
respirator. For the maintenance of anesthesia, the depth of
anesthesia was controlled with nitrous oxide and isoflurane. An
arterial line was secured at the right axillary artery and
electrocardiogram (ECG) was continuously monitored. Using a
temperature sensor, the temperature of the rectum and the
epipharynx was monitored.
[0078] Pigs were placed in a lateral position to shave the head,
and then the scalp and the subcutaneous tissue were dissected to
expose the cranial bone. The cranial bone in the forehead was cut
to a circle with a diameter of about 4 cm to expose the dura mater
of the parietal lobe from the frontal lobe. To the exposed dura
mater was contacted the cooling surface in a disk form made by
rendering the catheter in a swirl form. Into the subdural cavity, a
brain pressure sensor and a temperature sensor for determining the
internal pressure of the subarachnoid cavity were placed to
determine the brain temperature.
[0079] For 10 minutes a cooling water was circulated through the
catheter for topical cooling, and the brain was topical cooled
while determining the brain temperature. The circulation of the
cooling water was stopped to confirm when the brain temperature
becomes enhanced. After removing the catheter for cooling, the
wound was closed, and the animals were euthanatized by a bolus
intravenous injection of pentobarbital and a KCl solution.
[0080] 2. Experimental Result
[0081] The result on the effect of cooling the brain by the device
of the present invention is shown in FIG. 9. As can be seen from
FIG. 9, in about 5 minutes after starting cooling the temperature
dropped from 39.7.degree. C. to 31.2.degree. C., indicating the
reduction in temperature of about 8.5.degree. C. in the brain
temperature than the rectum temperature. During this time, the
temperature of the rectum did not change despite the reduction in
the temperature of the brain. During the cooling by the device of
the present invention, the temperature of the brain was kept at
about 8.5.degree. C. lower than that of the rectum. After stopping
cooling by the device of the present invention, the temperature
returned to the temperature of the brain in about three
minutes.
[0082] 3. Discussion
[0083] From the above experiment, it can be expected that by the
effect of cooling by the device of the present invention, the
damaged brain tissue alone can be selectively cooled while keeping
other organs at ordinary temperature. It was demonstrated that the
brain tissue around the catheter can be cooled to 30.degree. C. or
lower which is about 7.degree. C. lower than the body
temperature.
EXAMPLE 3
[0084] Cooling of the Esophagus Using the Catheter of the Present
Invention and a Device Using the Same and their Effects
[0085] An experiment was carried out in which a U-shaped catheter
having no hole connecting to the esophagus cavity was orally placed
in the esophagus, and a cooling water was circulated through this
catheter to absorb heat from the surface of the esophagus to
topically cool the esophagus selectively and continuously.
[0086] 1. Experimental Method
[0087] As the experimental animal, pigs weighing about 35-40 kg
were used. After intramuscular injection of ketamine 15 mg/kg, a
venous line was secured in the marginal ear vein. After a tracheal
tube was inserted, controlled respiration was started using a
respirator. For the maintenance of anesthesia, the depth of
anesthesia was controlled with nitrous oxide and isoflurane. An
arterial line was secured at the right axillary artery and blood
pressure was monitored. By monitoring an electrocardiogram
continuously, the temperature of the rectum and the epipharynx was
monitored.
[0088] Pigs were placed in a lateral position, and then intercostal
chest opening was performed by postero-lateral thoracotomy to
expose the esophagus. A U-shaped catheter having no hole connecting
to the esophagus cavity was orally placed in the esophagus, and a
cooling water was circulated through this catheter to absorb heat
from the surface of the esophagus to topically cool the esophagus
selectively and continuously. A needle-shaped temperature sensor
was punctured through the right thoracic cavity to determine the
temperature of the esophagus.
[0089] Twenty minutes later, a cooling water was circulated through
the catheter for topical cooling, and the esophagus was topical
cooled while determining the esophagus temperature. The circulation
of the cooling water was stopped to confirm whether the esophagus
temperature becomes enhanced. After removing the catheter for
cooling, the wound was closed, and the animals were euthanatized by
a bolus intravenous injection of pentobarbital and a KCl
solution.
[0090] 2. Experimental Result
[0091] The result on the effect of cooling the esophagus by the
device of the present invention is shown in FIG. 10. As can be seen
from FIG. 10, in about 20 minutes after starting cooling the
temperature dropped from 39.7.degree. C. to 28.1.degree. C.,
indicating the reduction in temperature of about 11.6.degree. C. in
the esophagus temperature than the rectum temperature. During this
time, the temperature of the rectum did not change despite the
reduction in the temperature of the esophagus. During the cooling
by the device of the present invention, the temperature of the
esophagus was kept at about 11.degree. C. lower than that of the
rectum. After stopping cooling by the device of the present
invention, the temperature returned to the temperature of the
esophagus in about eight minutes.
INDUSTRIAL APPLICABILITY
[0092] As has been explained in detail above, the catheter and the
device of the present invention have the following advantages, and
thus are industrially highly applicable.
[0093] First of all, what is different from other methods of
cooling the epidural cavity is that since no liquid is injected
into the epidural cavity, the subdural cavity, or the subarachnoid
cavity, cooling can be continued for a long time without increasing
the internal pressure of the medullary cavity or the brain
pressure, and thus the spinal cord or the injured cerebrum can be
selectively topical cooled.
[0094] Second is a point that it is a device that can cool the
spinal cord or the injured cerebrum continuously and selectively,
without causing changes in the systemic body temperature even
outside of the operation room without any time constraint. Since no
liquid is injected into he epidural cavity, the subdural cavity, or
the subarachnoid cavity, the internal pressure of the subarachnoid
cavity or the brain pressure will not increase even if cooling is
continued, and it became possible to continue cooling for any days
or any weeks theoretically by merely circulating a heat-cooling
medium within the circuit.
[0095] Thirdly, it is possible to control the temperature of the
spinal cord or the temperature of the brain at the injured site.
That the general hypothermia therapy is useful for the injuries to
the brain has already been known, at which time, it is thought,
"rewarming" from the hypothermia to the normothermia is important
in preventing brain injuries. The catheter of the present invention
that circulates a heat-cooling medium within the inner space and a
device using the same can change the degree of cooling with a heat
exchanger, and another advantage is that by changing the flow rate
of the heat-cooling medium to be circulated, the degree of cooling
the spinal cord or the brain can be changed, and rewarming can be
made slowly in stead of quickly. Furthermore, in the case of a
catheter in which the heat-cooling medium is not circulated, the
degree of cooling the spinal cord, the brain, the esophagus etc.
can be changed by controlling the cooling unit or the heat
exchanger that are in contact with the heat radiation member of the
catheter or by controlling the temperature of the surrounding
air.
[0096] Fourthly, it can be easily accessed and can be easily
controlled. In the case of emergency, the catheter for cooling can
be inserted into the epidural cavity, the subdural cavity, or the
subarachnoid cavity by puncture with a puncture needle, or by
laminectomy, and then it only needs to be connected to the
circulating cooling unit, or to a cooling unit, a heat exchanger
etc. to cool which automatically and continuously controlling the
temperature of the spinal cord, the esophagus etc.
[0097] The protection of the spinal cord by the catheter and the
device of the present invention can contribute to the treatment of
spinal cord disorders containing the prevention of paraplegia in
the surgery of thoracoabdominal aortic aneurysm in the clinical
settings. Furthermore, they are expected to be effective for
injuries of the spinal cord due to traumas to the spinal cord,
disorders due to spinal cord compression or stenosis, disorders
from tumors, degenerative diseases of the spinal cord (specifically
amyotrophic lateral sclerosis (ALS) etc.). Furthermore, the
catheter and the device of the present invention are useful for
topical cooling the brain selectively without changing the general
body temperature, and in the clinical settings they are expected to
improve the vital prognosis of patients with brain injuries due to
traumas, and alleviate the disorders such as consciousness
disorders, paralysis or epilepsy. They are also useful for topical
cooling the esophagus selectively without changing the general body
temperature, and it is expected that they can alleviate
complications as a means for preventing the esophagus injuries that
may occur during radiofrequency ablation of the atrium performed as
a treatment of atrial fibrillation in the clinical settings.
* * * * *