U.S. patent application number 11/204926 was filed with the patent office on 2005-12-08 for method and device for reducing secondary brain injury.
This patent application is currently assigned to MedCool, Inc.. Invention is credited to Lennox, Charles D..
Application Number | 20050273144 11/204926 |
Document ID | / |
Family ID | 34830098 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050273144 |
Kind Code |
A1 |
Lennox, Charles D. |
December 8, 2005 |
Method and device for reducing secondary brain injury
Abstract
Disclosed is an apparatus and method for reducing secondary
brain injury. The apparatus includes a brain-cooling probe and a
control console. The brain-cooling probe cools the brain to prevent
secondary injury by cooling the cerebrospinal fluid within one or
more brain ventricles. The brain-cooling probe withdraws a small
amount of cerebrospinal fluid from a ventricle into a cooling
chamber located ex-vivo in close proximity to the head. After the
cerebrospinal fluid is cooled it is then reintroduced back into the
ventricle. This process is repeated in a cyclical or continuous
manner in order to achieve and maintain a predetermined brain
ventricle temperature lower than normal body temperature. The
apparatus and method disclosed provides effective brain ventricle
cooling without the need to introduce extra-corporeal fluids into
the brain.
Inventors: |
Lennox, Charles D.; (Hudson,
NH) |
Correspondence
Address: |
NUTTER MCCLENNEN & FISH LLP
WORLD TRADE CENTER WEST
155 SEAPORT BOULEVARD
BOSTON
MA
02210-2604
US
|
Assignee: |
MedCool, Inc.
Wellesley
MA
|
Family ID: |
34830098 |
Appl. No.: |
11/204926 |
Filed: |
August 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11204926 |
Aug 16, 2005 |
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10243583 |
Sep 13, 2002 |
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6929656 |
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60322391 |
Sep 14, 2001 |
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Current U.S.
Class: |
607/105 ;
607/113 |
Current CPC
Class: |
A61F 2007/126 20130101;
A61F 7/12 20130101 |
Class at
Publication: |
607/105 ;
607/113 |
International
Class: |
A61F 007/00; A61F
007/12 |
Claims
1-20. (canceled)
21. A brain probe assembly, comprising: a probe defining a lumen
and having a distal end configured to insert within a brain
ventricle; and a cooling assembly coupled to the probe, the cooling
assembly operable to remove fluid from the brain ventricle via the
probe, adjust a temperature of the fluid, and return the fluid to
the brain ventricle via the probe.
22. The brain probe assembly of claim 21, wherein the brain probe
assembly further comprises a fixation device operable to couple the
probe to a cranium.
23. The brain probe assembly of claim 22, wherein the fixation
device comprises a fixation plug configured to insert within a
craniotomy formed in the cranium.
24. The brain probe assembly of claim 21, wherein the probe
comprises a temperature sensor.
25. The brain probe assembly of claim 21, wherein the probe
comprises a pressure sensor.
26. The brain probe assembly of claim 21, wherein the probe
comprises a drainage assembly in fluid communication with the lumen
defined by the probe.
27. The brain probe assembly of claim 21, wherein the probe
comprises an antiseptic pad disposed on a proximal end of the
probe.
28. The brain probe assembly of claim 21, wherein the brain probe
assembly further comprises a fixation device operable to couple the
cooling assembly to a cranium.
29. A brain probe system, comprising: a probe defining a lumen and
having a distal end configured to insert within a brain ventricle;
a cooling assembly coupled to the probe, the cooling assembly
operable to remove fluid from the brain ventricle via the probe,
adjust a temperature of the fluid, and return the fluid to the
brain ventricle via the probe; and a controller configured to
detect a state of the fluid of the brain ventricle and operate the
cooling assembly based upon the detected state.
30. The brain probe system of claim 29 wherein the controller is
configured to detect a temperature of the fluid and operate the
cooling assembly until the detected temperature approaches a
threshold temperature.
31. The brain probe system of claim 29 wherein the controller is
configured to detect a pressure of the fluid and operate the
cooling assembly until the detected pressure approaches a threshold
pressure.
32. The brain probe system of claim 29, wherein the system further
comprises a fixation device operable to couple the probe to a
cranium.
33. The brain probe system of claim 32, wherein the fixation device
comprises a fixation plug configured to insert within a craniotomy
formed in the cranium.
34. The brain probe system of claim 29, wherein the probe comprises
a temperature sensor.
35. The brain probe system of claim 29, wherein the probe comprises
a pressure sensor.
36. The brain probe system of claim 29, wherein the probe comprises
a drainage assembly in fluid communication with the lumen defined
by the probe.
37. The brain probe system of claim 29, wherein the probe comprises
an antiseptic pad disposed on a proximal end of the probe.
38. The brain probe system of claim 29, wherein the system further
comprises a fixation device operable to couple the cooling assembly
to a cranium.
39. A method for inducing cerebral hypothermia, comprising:
inserting a probe within a brain ventricle, the probe defining a
lumen; removing fluid from the brain ventricle via the probe;
adjusting a temperature of the fluid removed from the brain; and
returning the fluid to the brain ventricle via the probe.
40. The method of claim 39 wherein adjusting comprises adjusting a
temperature of the fluid removed from the brain ventricle based
upon a state of the fluid.
41. The method of claim 40 wherein adjusting comprises adjusting a
temperature of the fluid removed from the brain ventricle based
upon a temperature of the fluid.
42. The method of claim 40 wherein adjusting comprises adjusting a
temperature of the fluid removed from the brain ventricle based
upon a pressure of the fluid.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of application Ser. No.
10/243,583, filed Sep. 13, 2002, which claims the benefit of
Provisional Patent Application Ser. Nr.60/322,391 filed 2001 Sep.
14.
BACKGROUND
[0002] 1. Field of Invention
[0003] This invention relates to a method and device for inducing
global cerebral hypothermia for the prevention of secondary brain
injury from stroke, trauma, or surgery.
[0004] 2. Description of Prior Art
[0005] Patients suffering from stroke or head trauma, or have
undergone invasive brain surgery are at risk from secondary brain
injury. Secondary brain injury is a result of the innate healing
response of the brain to the original insult caused by several not
completely understood mechanisms. Regardless of the specific
mechanisms involved, the end result is swelling of the brain caused
by edema, which can lead to a critical or terminal rise in
intra-cranial pressure.
[0006] It has long been known that hypothermia is neuroprotective.
Hypothermia has a positive affect on all know mechanisms that lead
to secondary brain injury. Hypothermia is routinely used during
brain and other invasive surgeries to protect the brain from
surgical interruptions in blood flow. Hypothermia has also been
shown to be effective in controlling swelling of the brain in
trauma and stroke patients.
[0007] The effectiveness of hypothermia is a function of depth and
duration; the deeper the hypothermia, and/or the longer it is
applied the more neuroprotective it is. However, hypothermia has
historically been applied systemically, and the depth and duration
of hypothermia is limited by the patient's ability to tolerate the
therapy.
[0008] Systemic hypothermia has historically been accomplished by
immersion of the patient's body in a cool bath. Today there are
several commercial systemic hypothermia systems available. They
consist of blankets or pads where cooled water is circulated
through channels in the walls of the blanket or pad, and the
patient's body is maintained in intimate contact. Medivan Corp.
manufactures an example of a modern hypothermia system under the
trade name Arctic Sun Cooling System.
[0009] Systemic hypothermia has been demonstrated to be effective
in reducing secondary injury from stroke, trauma, and surgery
however, there are several drawbacks to this approach: 1) It takes
several hours to lower a patient's body to therapeutic
temperatures. This delay in achieving therapeutic temperatures
allows for the progression of irreversible secondary injury to the
brain. 2) The practical therapeutic hypothermic temperature and
duration is limited by the ability of the patient to tolerate, or
survive the therapy. 3) The side effects of systemic hypothermia
are frequent and can be life threatening, especially in frail
patients. Side effects include shivering, cardiac arrhythmia and
arrest, pneumonia, infections, and coagulation disorders. 4) The
target of hypothermia therapy is the brain; therefore inducing
hypothermia systemically places the patient at undue risk. 5)
During the "critical phase" (rewarming period) of hypothermia
treatment, there is no effective way to manage a sudden and
critical increase in intra-cranial pressure, since re-cooling the
body to reverse the increase in intra-cranial pressure takes
several hours. 6) Systemic hypothermia poses significant clinical
and logistical patient management issues.
[0010] There are several examples in the art where catheters are
constructed with a cooling means, which is placed into the carotid
artery to cool the blood entering the head. This offers an
advantage over systemic hypothermia, since it provides a means to
cool the head to lower temperatures than the rest of the body, but
it still results in systemic hypothermia. Also, since the
scientific evidence suggests that hypothermia must be maintained
for extended periods of time, there is a great risk that clots will
form on the catheters and migrate into the brain leading to
episodes of stroke.
[0011] Nowhere in the art is it suggested that cooling the
cerebrospinal fluid in a ventricle of the brain may induce global
cerebral hypothermia and therefore prevent secondary brain injury.
Nowhere in the art is it suggested that cerebral hypothermia can be
accomplished by removing a portion of the cerebrospinal fluid from
a brain ventricle, then cooling the removed cerebrospinal fluid ex
vivo, then reintroducing the cooled cerebrospinal fluid back into
the brain ventricle in a continuous or cyclical manner.
SUMMARY
[0012] Therefore, it is an object of this invention to provide a
method and apparatus for preventing secondary brain injury.
[0013] In accordance with one aspect of this invention, secondary
brain injury is prevented by placement of the distal end of a probe
in to a ventricle of the brain and then, in a continuous or
cyclical manner, using said probe to remove a portion of the
cerebrospinal fluid contained in said ventricle into a cooling
chamber located ex vivo at the proximal end of said probe, then
cooling said cerebrospinal fluid in the cooling chamber of said
probe, then reintroducing said cooled cerebrospinal fluid back into
said ventricle, thereby cooling the brain while otherwise
maintaining normal temperature in the rest of the body. In
accordance with another aspect of this invention, secondary injury
is prevented by placement of the distal end of a probe into a
ventricle of the brain, and then using said probe to cool the
cerebrospinal fluid within said ventricle to a predetermined
temperature for a predetermined time where said probe functions in
a continuous or cyclical manner to remove a portion of the
cerebrospinal fluid contained in said ventricle into a cooling
chamber located ex vivo at the proximal end of said probe, then
cooling said cerebrospinal fluid in the cooling chamber of said
probe, then reintroducing said cooled cerebrospinal fluid back into
said ventricle, thereby cooling the brain while otherwise
maintaining normal temperature in the rest of the body. In
accordance with another aspect of this invention, secondary brain
injury is prevented by placement of the distal end of a probe into
a ventricle of the brain, and then using said probe to cool the
cerebrospinal fluid contained within said ventricle to a
predetermined temperature, where then the temperature is increased
gradually over a period of time from the initial low temperature,
to normal body temperature, with the period of time being greater
than one hour and less than two months, where said probe functions
in a continuous or cyclical manner to remove a portion of said
cerebrospinal fluid contained in said ventricle into a cooling
chamber located ex vivo at the proximal end of said probe, then
cooling said cerebrospinal fluid in said cooling chamber of said
probe, then reintroducing said cooled cerebrospinal fluid back into
said ventricle, thereby cooling the brain while otherwise
maintaining normal temperature in the rest of the body. In
accordance with another aspect of this invention, secondary brain
injury is prevented by placement of the distal end of a probe into
a ventricle of the brain, and then using said probe to cool the
cerebrospinal fluid within the ventricle to a degree based on the
physiological response to said cooling, where said probe functions
in a continuous or cyclical manner to remove a portion of the
cerebrospinal fluid contained within said ventricle into a cooling
chamber located ex vivo at the proximal end of said probe, then
cooling said cerebrospinal fluid in said cooling chamber of the
probe, then reintroducing said cooled cerebrospinal fluid back into
said ventricle, thereby cooling the brain while otherwise
maintaining normal temperature in the rest of the body. In
accordance with another aspect of this invention, apparatus for
preventing secondary brain injury includes a probe, an introducer
sheath, a stereotaxic ventricle access needle, and a control
console where the introducer sheath and stereotaxic ventricle
access needle are constructed to integrally provide access to a
ventricle of the brain by standard stereotaxic neurosurgical means,
and where the distal end of said probe is placed into said
ventricle through said introducer sheath, and where said probe
functions in a continuous or cyclical manner to remove a portion of
the cerebrospinal fluid contained within said ventricle into a
cooling chamber located ex vivo at the proximal end of said probe,
then cooling said cerebrospinal fluid in said cooling chamber of
said probe, then reintroducing said cooled cerebrospinal fluid back
into said ventricle, thereby cooling the brain while otherwise
maintaining normal temperature in the rest of the body, and where
the control console provides said probe with a means to remove
cerebrospinal fluid from a ventricle of the brain, a means to cool
cerebrospinal fluid, a means to reintroduce cerebrospinal fluid
back into said ventricle, and a means to control said process of
removing, cooling, and reintroducing cerebrospinal fluid. In
accordance with another aspect of this invention, apparatus for
preventing secondary brain injury includes a probe as described
above where the distal end of the probe contains a mechanism near
the distal tip of said probe to sense the temperature of
cerebrospinal fluid contained in a ventricle of the brain. In
accordance with another aspect of this invention, apparatus for
preventing secondary brain injury includes a probe as described
above where the distal end of the probe contains a mechanism near
the distal tip of said probe to sense the pressure of cerebrospinal
fluid contained in a ventricle of the brain. In accordance with
another aspect of this invention, apparatus for preventing
secondary brain injury includes a probe as described above where
said probe provides for a means to drain excess cerebrospinal fluid
from the ventricle of the brain. In another aspect of this
invention, apparatus for preventing secondary brain injury includes
a probe as described above, and an introducer sheath as described
above, where said probe and said introducer sheath are constructed
to integrally provide for an extended period of cooling and
indwelling in a ventricle of the brain, with the period of cooling
and indwelling being greater than one hour, and as long as two
months.
OBJECTS AND ADVANTAGES
[0014] Accordingly, besides the objects and advantages of the
method and apparatus to prevent secondary brain injury described in
my patent above, several objects and advantages of the present
invention are:
[0015] (a) to provide global cerebral hypothermia to a brain at
risk of secondary injury to the degree that offers maximum clinical
benefit without inducing hypothermia in the rest of the body;
[0016] (b) to provide global cerebral hypothermia to a brain at
risk of secondary injury where the method for inducing hypothermia
takes advantage of the fact that the cerebrospinal fluid in a
ventricle of the brain can be cooled by a small caliber probe, and
brain tissue surrounding the ventricle may be cooled by heat
conduction into the ventricle to the extent that prevents secondary
injury.
[0017] (c) to provide global cerebral hypothermia to a brain at
risk of secondary injury within a minimal time after patient
presentation where therapeutic temperatures are achieved rapidly
due to the fact that only the brain is cooled;
[0018] (d) to provide global cerebral hypothermia to a brain at
risk of secondary injury where the degree of hypothermia is
adjusted according to the physiological response to hypothermia,
where the physiological response to hypothermia is a change in
intra-cranial pressure;
[0019] (e) to provide global cerebral hypothermia to a brain at
risk of secondary injury where the degree of hypothermia is
adjusted according to the physiological response to hypothermia,
where the physiological response to hypothermia is a change in
patient symptoms.
[0020] (f) to provide global cerebral hypothermia to a brain at
risk of secondary injury where the degree of hypothermia is
adjusted according to the physiological response to hypothermia,
where the physiological response to hypothermia is a change in
localized blood perfusion;
[0021] (g) to provide global cerebral hypothermia to a brain at
risk of secondary injury where the degree of hypothermia is
adjusted according to the physiological response to hypothermia,
where the physiological response to hypothermia is a change in the
size of the volume of infarcted tissue;
[0022] (h) to provide global cerebral hypothermia to a brain at
risk of secondary injury where the degree of hypothermia is
adjusted according to the physiological response to hypothermia,
where the physiological response to hypothermia is a change in
blood chemistry.
[0023] (i) to provide apparatus for inducing global cerebral
hypothermia to a brain tissue at risk of secondary injury according
to the objectives stated above;
[0024] (j) to provide a brain cooling probe system that consists of
a brain cooling probe, an introducer sheath, a stereotaxic
ventricle access needle, and a control console;
[0025] (k) to provide a brain cooling probe system that is
constructed to cool the cerebrospinal fluid contained within a
ventricle of the brain where said cooling means is ex vivo;
[0026] (l) to provide a brain cooling probe system that is
constructed to be placed into a ventricle of the brain by
stereotaxic radiological guidance using well known surgical
methods;
[0027] (m) to provide a brain cooling probe system that is
constructed to provide for long term cooling and indwelling;
[0028] (n) to provide a brain cooling probe system that is
constructed to provide for fixation to the head of the patient;
[0029] (o) to provide a brain cooling probe system that is
constructed to provide for protection against infection;
[0030] (p) to provide a brain cooling probe system that is
constructed to provide for a means to sense a response to
cooling;
[0031] (q) to provide a brain cooling probe system that is
constructed to provide for a means to control the degree of cooling
applied to the surrounding brain tissue.
DRAWING FIGURES
[0032] FIG. 1 shows a sagittal section of a human head with the
brain probe, cooling assembly and introducer sheath fixated to the
head with the distal end of the probe and the introducer sheath
placed into a ventricle of the brain.
[0033] FIG. 2A. shows a side view of the brain probe and cooling
assembly. FIG. 2B shows an end view of the brain probe and cooling
probe FIG. 3 shows the introducer sheath.
[0034] FIG. 4 shows a sectional view of the introducer sheath
placement into a ventricle of the brain with the stereotaxic
ventricle access needle.
[0035] FIG. 5 shows a sectional view of the introducer sheath in
operational position after the stereotaxic access needle has been
removed.
[0036] FIG. 6 shows in schematic form the preferred embodiment of
the integral operation of the brain probe, cooling assembly and the
control console.
[0037] FIG. 7 shows a partial sectional view of the cooling
assembly.
[0038] FIG. 8 shows a sectional view of the cooling coil prior to
formation of the coil.
[0039] FIG. 9 shows the cooling coil after formation of the
coil.
[0040] FIG. 10A shows a sectional view of the construction of the
cooling assembly. FIG. 10B and end view of the cooling
assembly.
[0041] FIG. 11A shows a sectional view of the umbilical attachment
to the cooling assembly. FIG. 11B shows the console plug assembly
of the umbilical assembly.
[0042] FIG. 11C-11F show a sectional views of the console plug
assembly. FIG. 11G shows the interaction between the console plug
assembly, and the console receptacle.
[0043] FIG. 12A shows a sectional view of the brain probe. FIG. 12B
shows a sectional view of the brain probe shaft.
[0044] FIG. 13 shows a bottom view of the brain probe depicting the
brain probe/introducer sheath docking mechanism.
[0045] FIG. 14 shows a sectional view of the introducer sheath.
[0046] FIG. 15A shows a view of the construction of the docking
ring assembly. FIG. 15B shows a sectional view of the docking ring
assembly.
[0047] FIG. 16 shows a sectional view of the introducer sheath tube
assembly.
[0048] FIG. 17A shows a front view of the control console. FIG. 17B
shows a side view of the control console.
[0049] FIG. 18 shows a view of the cooling assembly mounting
plate.
DESCRIPTION
FIG. 1-6 Preferred Operational Embodiments
[0050] FIG. 1 depicts, in simplified form, a section of the head 20
with a brain probe 1 and introducer sheath 2 in operational
position and cooling assembly 3 mounted on the head 20 with
self-tapping bone screws 17. The distal end 7 of probe 1, and the
distal end of introducer sheath 2 is located in a lateral ventricle
of the brain 6. Probe tube 13 connects probe 1 to cooling assembly
3 and provides fluid communication from the probe 1 to cooling
assembly 3. The distal end 7 of probe 1 contains a thermocouple 18
(FIG. 2B), which measures the temperature of the cerebrospinal
fluid 19 contained in ventricle 6. The shaft 21 of probe 1 passes
through the introducer sheath 2 introducer sheath tube 8 and
connects the distal end 7 of probe 1 to the sheath docking collar
24 of probe 1 (See FIG. 8). Probe shaft 21 provides fluid
communication from the ventricle 6 to probe tube 13 which therefore
provides fluid communication from ventricle 6 to cooling assembly
3. The probe and introducer sheath 1&2 is fixated to the head
20 by outward expansion of the fixation plug 22 of introducer
sheath 2 against the surgically created craniotomy hole 23 in the
skull 10. The fixating plug as 22 seals the craniotomy hole 23 and
prevents infection, providing for long term indwelling (greater
than 1 hour and as long as two months) of the probe and introducer
sheath 1&2 in the brain 5. Antiseptic pad 145 provides further
protection against infection. Fluid tube 15, stop cock 9, and luer
fitting 25 provides fluid communication from the ventricle 6 via
probe shaft 21 of probe 1, and cooling assembly 3 and provides for
drainage of excess cerebrospinal fluid from the ventricle. A
commercially available physiological pressure sensor 4 may be
mounted to luer fitting 25 to monitor cerebrospinal fluid pressure.
Electrical cable 12 connects the pressure sensor 4 to the pressure
meter (not shown). The cooling assembly 3 is connected to control
console 76 by umbilical 14. During operation a portion of
cerebrospinal fluid 19 (1 cc to 20 cc) is drawn from ventricle 6
into cooling assembly 3 through probe 1 and probe tube 13. The
cerebrospinal fluid drawn into cooling assembly 3 is then cooled to
between 0 Deg. C. and 25 Deg. C. The cooled cerebrospinal fluid 19
is then reintroduced into the ventricle 6 via probe tube 13 and
probe 1. This cycle is repeated as necessary until the temperature
within the ventricle 6 is between 10 Deg. C. and 36 Deg. C. as
measured by thermocouple 18.
[0051] FIG. 2A depicts a side view of brain probe 1 and cooling
assembly 3. FIG. 2B depicts an end view of brain probe 1 and
cooling assembly 3. Probe tube 13 connects probe 1 to cooling
assembly 3 and provides fluid communication from distal tip 7 of
probe 1 to cooling assembly 3. Fluid tube 13 also contains
thermocouple wires that connect thermocouple 18 mounted on distal
tip 7 of probe 1 to control console 76 via umbilical 14. Fluid tube
15, stop cock 9 and luer fitting 25 provides for drainage of excess
cerebrospinal fluid 19. Probe 1 consists of probe shaft 21, sheath
expansion plug 29, sheath docking collar 24, and thermocouple 18.
Fluid port 26 at distal end 7 of probe shaft 21 provides fluid
communication from ventricle 6 (FIG. 1) into shaft 21. Thermocouple
18 at distal end 7 of probe shaft 21 senses temperature of
cerebrospinal fluid 19 in ventricle 6 (FIG. 1). Signals from
thermocouple 18 are sent to control console 76 and are used to
control brain cooling. Probe shaft 21 connects distal end 7 of
probe 1 to proximal end 31 of probe 1 and provides fluid
communication from distal end 7 to proximal end 31. Probe shaft 21
contains a fluid communication lumen 32, and thermocouple lead
lumen 33 (FIG. 12 A & B). Sheath expansion plug 29 and sheath
docking collar 24 work integrally with introducer sheath 2 to
fixate the probe 1 and introducer sheath 2 to the head 20 and to
seal the craniotomy hole 23 to prevent infection. Cooling assembly
3 is mounted to head 20 (FIG. 1) with (4) mounting tabs 27, and
self-tapping screws 17 (FIG. 1). Rubber feet 28 provides for
hermetic sealing of screw 17 to prevent infection. Umbilical 14
connects cooling assembly 3 to control console 76 and contains gas
lines 35 & 36 for cooling, pneumatic line 37 for actuating
cerebrospinal fluid removal and replacement, and thermocouple leads
34 & 77 (FIG. 6). Umbilical retaining flange 161 secures
umbilical 14 to cooling assembly 3.
[0052] FIG. 3 depicts the introducer sheath 2. The introducer
sheath 2 is placed into a ventricle of the brain 6 through
craniotomy hole 23 (FIG. 1) with stereotaxic access needle 39 (FIG.
4) and probe 1 is then placed into the ventricle of the brain 6
through the introducer sheath 2. The introducer sheath 2 provides
for access to a ventricle by standard stereotaxic surgical methods,
and allows for removal and replacement of probe 1 during the course
of the treatment. Introducer sheath 2 consists of sheath tube 8,
housing 40, antiseptic pad 145, and probe docking pins 42. Fixation
plug 22, and probe sealing boss 41 are formed integrally with the
introducer housing 40. The fixation plug 22 works integrally with
probe 1 to fixate the assembly to the head, and seal the craniotomy
hole 23. The probe sealing boss 41 mates with the bottom surface of
docking collar 24 of probe 1 and seals the assembly to prevent
contamination and infection.
[0053] FIG. 4 depicts introducer sheath 2 placement into ventricle
6 with the stereotaxic access needle 39. The diameter of the
stereotaxic access needle 39 is tapered at the distal tip to the
diameter of the probe shaft 21 as shown. Proximal to the taper, the
diameter of the stereotaxic needle 39 is sized to slidably fit the
inside diameter of the introducer tube 8. Needle stop 43 pushes the
introducer sheath into ventricle 6 when the stereotaxic access
needle 39 is advanced. The proximal end 44 of the stereotaxic
access needle 39 is configured to function with various commercial
stereotaxic needle guidance systems (not shown). FIG. 5 depicts the
introducer sheath 2 in ventricle 6 after the stereotaxic access
needle 39 (FIG. 5) is removed.
[0054] FIG. 6 depicts in schematic form the integral operation of
probe 1, cooling assembly 3 and control consol 76. The functional
components of probe 1 are probe shaft 21, fluid port 26, and
thermocouple 18. The functional components of the cooling assembly
are cooling cylinder 72, piston 48, cooling coil assembly 47, and
thermocouple 45. The control console 76 contains control circuitry
53, motor shaft position transducer 54, motor 55, crank 56,
connecting rod 57, pneumatic cylinder 58, piston 59, AC power
source 60, Transformer 61, low-pressure solenoid valve 63,
high-pressure solenoid valve 64, low-pressure line 65, low-pressure
pneumatic line 68, umbilical connector 69, high pressure gas
connector/valve 71, low-pressure gas connector/valve 73, and user
control panel 74. The basic operation (after probe 1 and introducer
sheath 2 is placed in operational position as previously described,
and the system has been purge of air as described in detail below)
is as follows:
[0055] 1) Cerebrospinal fluid 19 (FIG. 1) is drawn into cooling
cylinder 72 of cooling assembly 3 through fluid port 26 and probe
shaft 21 by movement of piston 48 from position (1) (shown in
dashed lines) to position (2) (shown in solid lines). (Cooling
cylinder 72 of cooling assembly 3 is connected to pneumatic
cylinder 58 of control console 76 by pneumatic gas line 37.
Pneumatic piston 59 is actuated from position (1) (shown in dashed
lines) to position (2) (shown in solid lines) by crank 56,
connecting rod 57, and motor 55. Pneumatic coupling between cooling
cylinder 72 and pneumatic cylinder 58 causes piston 48 to move from
position (1) to position (2) when pneumatic piston 59 is actuated
from position (1) to position (2).)
[0056] 2.) High-pressure solenoid valve 64 is opened allowing high
pressure gas to enter cooling coil assembly 47. Cerebrospinal fluid
19 contained in cooling cylinder 72 is then cooled by cooling coil
assembly 47 by thermal conduction of heat through the walls of
cooling cylinder 72 into cooling coil assembly 47. (Detailed
description of cooling mechanism is described in description of
FIG. 8 below).
[0057] 3.) When the cerebrospinal fluid 19 in cooling cylinder 72
is cooled to predetermined temperature (5 Deg. C. to 30 Deg. C.) as
sensed by thermocouple 45 of cooling assembly 3, high-pressure
solenoid valve 64 is closed thereby stopping the cooling process,
and pneumatic piston 59 is actuated from position (2) to position
(1) causing piston 48 to move from position (2) to position (1)
which reintroduces the cooled cerebrospinal fluid into ventricle
6.
[0058] 4.) After a predetermined time to allow for thermal
diffusion (5 to 60 seconds) the temperature of the cerebrospinal
fluid 19 in ventricle 6 is measured by thermocouple 18. If after
this period of time the temperature of the cerebrospinal fluid 19
in ventricle 6 is above a predetermined temperature (20 Deg. C. to
35 Deg. C.) the cycle (steps 1-3 above) is repeated. If the
temperature of the cerebrospinal fluid 19 in ventricle 6 remains at
or below the predetermined temperature after the time allowed for
thermal diffusion, ventricle temperature is continuously monitored
by thermocouple 18. The cycle (steps 1-3 above) is repeated once
the temperature of the cerebrospinal fluid 19 in ventricle 6 rises
above the predetermined value as described above. Cooling coil
assembly 47 removes heat from cooling cylinder 72 by a cooling
process commonly known as Joule-Thompson effect where gas
(nitrogen, argon, or a mixture of nitrogen and argon) is expanded
from a high-pressure to low-pressure within the cooling coil
assembly 47 (FIG. 8). Cooling gas is supplied to cooling coil
assembly 47 from the control console 76 at a pressure between 200
pounds per square inch absolute (PSIA) and 1600 PSIA by
high-pressure tube 35 contained in umbilical 14 (FIGS. 1 & 2).
Expanded low-pressure gas (5 to 100 PSIA) is returned to the
control console 76 by low-pressure tube 36 contained in umbilical
14. Prior to use, the probe 1 and cooling assembly 3 is connected
to the control consol 76 by umbilical 14 and umbilical connector 69
(shown in schematic form). After connecting umbilical 14 to control
console 76 the system is purged of air, and cooling piston 48 is
moved into position 1 as follows:
[0059] 1.) Pneumatic piston 59 is moved into position (1) by motor
55, crank 56, and connecting rod 57. Position transducer 54
provides control circuitry 53 with a signal indicative of pneumatic
piston 59 position.
[0060] 2.) High-pressure solenoid valve 64 is then opened allowing
cooling gas to flow into cooling coil assembly 47 at high pressure,
and cooling gas to flow from cooling coil assembly 47 at low
pressure back to the control console thereby displacing air from
cooling coil 47, and gas lines 35, 36, 65, and 66.
[0061] 3.) After a predetermined period of time (20 to 60 seconds)
to allow for complete purging of air, low-pressure solenoid valve
63 is opened forcing cooling piston 48 into position (1).
Low-pressure solenoid valve 63 is then closed, leaving both
pneumatic piston 59, and cooling piston 48 in position (1).
[0062] 4.) Probe 1 is then placed into brain ventricle 6 as
previously described and cerebrospinal fluid 19 is drawn from
ventricle 6 by syringe (not shown) through fluid tube 15 and luer
fitting 25 (FIG. 2A) to remove air from probe shaft 21.
[0063] Control console 76 is connected to a source of high-pressure
cooling gas by high-pressure valve/connector 71. Low-pressure gas
is vented to the room trough low-pressure valve/connector 73.
Electrical power is supplied to the control console by power source
60, which is normally an AC wall outlet. Transformer 61 transforms
voltage from local standard AC voltage (120 or 240 volts) to system
operating voltage (5 to 21 V). Control circuit 53 contains
rectifier circuitry to transform source voltage from AC to DC. User
control panel 74 contains user controls and operational display of
system function. The user control panel provides for a means to set
the desired temperature of the cerebrospinal fluid 19 in ventricle
6, a means to display the temperature of cerebrospinal fluid 19 in
ventricle 6, a means to set the duration for cooling the
cerebrospinal fluid 19 in ventricle 6, a means to set the rate of
cooling and rewarming of cerebrospinal fluid 19 in ventricle 6, a
means to initiate the air purge cycle as described above, and a
means to turn the cooling cycle on and off. It obvious to those
skilled in the art of electronic design how to design the
electronic circuits, user controls, and how to specify the
appropriate components to provide system functionality as described
above. Those familiar with the art of mechanical design know how to
design the pneumatic cylinder 58, to design the pneumatic piston 59
actuation mechanisms, to specify the appropriate motor 55 and
position transducer 54, to specify the appropriate valves 71, 73,
64, & 63, to specify the appropriate gas lines 65, 66, and 68,
and how to physically integrate all system components into a
console configuration to provide system functionality as described
above.
Description FIGS. 7-18
Preferred Construction Embodiments
[0064] FIG. 7 depicts in a partial sectional view the cooling
cylinder sub-assembly 62 of cooling assembly 3. Cooling cylinder
sub-assembly 62 consists of cooling cylinder 72, piston 48,
cylinder cap 66, pneumatic stem 67, cooling coil assembly 47,
thermocouple 45, thermocouple leads 77, fluid manifold 78, O-ring
79, O-ring 80, and silver solder 81. Cylinder 72, and cylinder cap
66 are machined from a copper allow to maximize thermal heat
transfer to cooling coil assembly 47. After machining, cylinder 72
and cylinder cap 66 are plated with gold to provide for
biocompatibility. Cylinder 72 has an inner diameter between 0.4
inches and 1.0 inches. Cylinder 72 has a wall thickness between
0.02 inches and 0.1 inches. The length of cylinder 72 is between
1.5 and 4 inches. The displacement of piston 48 in cylinder 72 is
between 1 cc and 5 cc. Piston 48 is machined or molded from a
medical grade polymer such as nylon, but may also be machined from
a metal alloy. The outer diameter of piston 48 is between 0.001 and
0.015 inches smaller than the inner diameter of cylinder 72. O-Ring
80 pneumatically isolates one side of piston 48 from the opposite
side, and resides in an appropriately sized gland formed in piston
48 as shown. The length of piston 48 is between 0.5 and 1.5 its
outer diameter. The construction of cooling coil assembly 47 is
described in detail in FIGS. (8 & 9). O-ring 79 resides in a
gland formed in cylinder cap 66 during the machining process and
provides for a pneumatic seal between the cylinder 72 and the
cylinder cap 66. Fluid manifold 78 is formed from type 304
stainless steel tubing and provides for fluid connection between
fluid tube 13 and fluid tube 15 (FIG. 1) and cylinder 72. The inner
diameter of fluid manifold 78 is between 0.06 and 0.08 inches in
diameter, and the walls of fluid manifold 78 are between 0.002 and
0.005 inches thick. Pneumatic stem is made from type 304 stainless
steel and has an inner diameter of 0.08 to 0.12 inches in diameter
and has a wall thickness of 0.002 to 0.005 inches thick. The
cooling cylinder sub-assembly is assembled as follows: 1.) Fluid
manifold 78 is inserted into end hole 85 in cylinder 72 and
soldered into place with silver solder 81. 2.) Cooling coil
assembly 47 is soldered to cylinder 72 with silver solder 81 as
shown. 3.) Thermocouple 45 is inserted into cylinder end hole 83
and glued in place with silicon rubber adhesive 86. 4.) O-ring 80
is mounted to piston 48. Piston 48 is then inserted into cylinder
72. 5.) O-ring 79 is mounted on cylinder cap 66. Cylinder cap is
then inserted into cylinder as shown and crimped into place with
dimple crimps 82 as shown.
[0065] FIG. 8 depicts a sectional view of the construction of
cooling coil assembly 47 prior to the coiling operation. Cooling
coil assembly 47 consists of manifold 50, low-pressure tube 88,
high-pressure tube 89, end cap 90, silver solder 91, high-pressure
stub 52, and low-pressure stub 51. Manifold 50, and end cap 90 are
machined from type 304 stainless steel as shown. Low-pressure tube
88, high-pressure tube 89, high-pressure stub 52, and low-pressure
stub 51 are made from type 304 stainless steel tubing. Low-pressure
tube 88 has an inner diameter of 0.09 to 0.12 inches, and has a
wall thickness between 0.02 and 0.05 inches. High pressure tube 89
has a inner diameter of 0.03 and 0.06 inches and has a wall
thickness of 0.002 and 0.005. High-pressure stub 52 and
low-pressure stub 51 have an inner diameter of 0.06 and 0.10
inches, and has a wall thickness of 0.002 to 0.005. High-pressure
tube 89 has a least one hole drilled through the wall to form gas
expansion orifice 96. Gas expansion orifice 96 is between 0.002 and
0.008 inches in diameter. Cooling coil assembly 47 is assembled as
follows: 1.) High-pressure tube 89, and low pressure tube 88 are
soldered to end cap 90 as shown with silver solder 91. 2.)
High-pressure stub 52 and low pressure stub 51 are soldered to
manifold 50 as shown with silver solder 91. 3.) Manifold 87 is then
soldered to high-pressure tube 89 and low-pressure tube 88 as shown
with silver solder 91. The length (from manifold 50 to end cap 90)
of the cooling coil assembly 47 prior to coiling is between 3 and 8
inches. Gas at high pressure enters high-pressure tube 89 and forms
high-pressure zone 95 through manifold 50 and high-pressure stub 52
and is expanded to a low pressure in low-pressure zone 94. Gas from
low-pressure zone 94 is exhausted through manifold 50 and
low-pressure stub 51, and ultimately to the room as previously
described. During gas expansion from high pressure to low pressure
heat is lost according to the Joule-Thompson principle causing the
temperature of the expanded gas to be lowered, thereby cooling the
walls of low-pressure tube 88 causing absorbs ion of heat from
cooling cylinder 72 as previously described.
[0066] FIG. 9 depicts the cooling coil assembly 47 after coiling
operation. The coiling accomplished by wrapping the assembly around
a mandrel. The inner diameter of the coil in relaxed state is 0.010
to 0.030 inches smaller than the outside diameter of cooling
cylinder 72 to ensure intimate contact between cooling coil
assembly 47 and cooling cylinder 72.
[0067] FIG. 10A depicts a sectional view of the construction of the
cooling assembly 3. FIG. 10B shows an end view of cooling assembly
3 prior to attachment of umbilical assembly 14. Cooling assembly 3
consists of cooling cylinder sub-assembly 62, probe 1 (see FIGS.
12A & 12B for construction details) cooling assembly housing
97, cooling assembly mounting plate 27 (See FIG. 18 for
construction detail), mounting pads 28, fluid tube crimp ring 98,
stop cock assembly 99 which consists of fluid tube 15, stop cock
19, and luer fitting 25, and crimp ring 100. Cooling assembly 3 is
formed as follows: 1.) Fluid tube 13 of probe 1 is mounted to fluid
manifold 78 of cooling cylinder sub-assembly 62 as shown, and is
held in place with crimp ring 100. 2.) Cooling cylinder
sub-assembly, probe 1, mounting plate 27 are mounted into injection
mold and cooling assembly housing 97 is formed by standard
injection molding process. Housing 97 may be made any suitable
thermoplastic such as nylon or high density polyethylene. Stop cock
assembly 99 which consists of fluid tube 15, stop cock 19, and luer
fitting 25 is attached to manifold 78 and held in place with crimp
ring 98. Stopcock assembly 99 is readily available from many OEM
medical device suppliers. Mounting pads 28 are common rubber
grommets and are inserted into mounting holes 102 in mounting plate
27. Holes 101 are then drilled and tapped.
[0068] FIG. 11A depicts the attachment of the umbilical assembly 14
to the cooling assembly 3. FIG. 11B depicts the umbilical plug
assembly 120. FIG. 11C, 11D, and 11E depicts radial sections of
umbilical plug assembly 120. FIG. 11F depicts a transverse section
of umbilical plug assembly 120. FIG. 11G depicts the removable
connection mechanism of umbilical assembly 14 to control console
76. Umbilical assembly 14 consists of umbilical flange 161,
umbilical sheath 92, umbilical plug assembly 120, thermocouple
connectors 107 and 108, high-pressure tube 35, low-pressure tube
36, pneumatic tube 37, thermocouple lead 34, thermocouple lead 77,
thermocouple lead sheath 126 and 127, sheath retainer 121, tube
crimp rings 105, silicone rubber compound 104, screw 103, and epoxy
adhesive 106. The umbilical assembly 14 is between 3 and 8 feet
long. The umbilical sheath 92 is vinyl tubing with an inner
diameter of 0.25 to 0.375 inches and has a wall thickness of 0.010
to 0.025 inches. Umbilical flange 161 is injection molded from a
suitable thermoplastic such as nylon. One end of umbilical sheath
92 is attached to umbilical flange 161 with epoxy adhesive 106 as
shown. High pressure tube 35 is 0.125 to 0.31 inches in outer
diameter and has a wall thickness of 0.025 to 0.040 inches in
diameter and is made from nylon. Low-pressure tube 36, and
pneumatic tube 37 are 0.125 to 0.31 inches in outer diameter with a
wall thickness of 0.010 to 0.015 inches and are made of nylon.
Parker Hannifin Corp. manufactures a full line suitable tubing
under the brand name Parflex that is suitable for use for tubes 35,
36 and 37. Thermocouple leads 34 and 77 are selected for
compatibility with thermocouples 45 and 18. Omega Corp.
manufactures thermocouples, and thermocouple leads suitable for the
application. Tubes 35, 36, and 37, and thermocouple leads 34 and 77
inserted into umbilical sheath 92 such that tubes 35, 36 and 37,
and thermocouple leads 34 and 77 protrude past both ends of
umbilical sheath 92 and umbilical flange 161 2 to 3 inches.
High-pressure tube 35 is attached to high-pressure stub 52 of
cooling assembly 3 and crimped into place with stainless steel
crimp ring 105. Low-pressure tube 35 is attached to low-pressure
stub 51 of cooling assembly 3 and crimped into place with stainless
steel crimp ring 105. Pneumatic tube 37 is attached to pneumatic
stub 67 of cooling assembly and crimped into place with stainless
steel crimp ring 105. Thermocouple leads 34 and 77 are spot welded
to thermocouple leads from thermocouple 18 and 45 respectively, and
silicone rubber 104 is used to electrically insulate the weld
joints. Umbilical flange 161 is then bolted to cooling assembly 3
with screws 103. Plug assembly 120 is attached to the opposite end
the umbilical assembly 14 and provides removable connection of the
cooling assembly 3 to the control console 76. FIG. 11B-11F depicts
the plug assembly 120. Plug assembly 120 consists of: plug tube
129, end cap 125, plug handle 119, sheath retainer 121, crimp ring
128, bulkhead 130, bulkhead 131, bulkhead 132, pneumatic tube 134,
low-pressure tube 133, high-pressure tube 135, crimp ring 105,
thermocouple lead sheath 126 & 127, thermocouple connectors 107
and 108, vinyl adhesive 137, epoxy adhesive 138, silver solder 136.
Bulkhead 130 and end cap 125 form pneumatic gas chamber 139,
bulkhead 130 and bulkhead 131 form high pressure gas chamber 140,
bulkhead 131 and bulkhead 132 form low-pressure gas chamber 141.
Pneumatic tube 134 connects pneumatic tube 37 to pneumatic gas
chamber 139. High-pressure tube 135 connects high-pressure tube 35
to high-pressure gas chamber 140. Low-pressure tube 133 connects
low-pressure tube 36 to low-pressure chamber 141. Pneumatic port
124, high-pressure port 123, and low-pressure port 122 provide gas
communication with console receptacle 110 (FIG. 11G). Bulkheads
130, 131, 132, end cap 125, and plug handle are machined from type
304 stainless steel. Pneumatic tube 134, low-pressure tube 133, and
high-pressure tube 135 are stainless steel with 0.125 to 0.187 inch
outer diameter with 0.010 to 0.020 wall thickness. Plug tube 129 is
soldered to plug handle 119 with silver solder 136. End cap 125 is
soldered to plug tube 129 with silver solder 136. Bulkhead 130, is
soldered to pneumatic tube 134 with silver solder 136. Bulkhead 131
is silver soldered to pneumatic tube 134 and high-pressure tube
135. Bulkhead 132 is soldered to pneumatic tube 134, high-pressure
tube 135, and low-pressure tube 133. The soldered assembly
described above is inserted into plug tube 129 as shown and is
swaged by a rotary swager to form a seal between bulkheads 130,
131, and 132 and plug tube 129. Thermocouple leads 34 and 77 exit
umbilical sheath 92 approximately 6 inches from umbilical plug
assembly 120 and are reinforced with vinyl sheaths 126 and 127 whch
are retained by vinyl adhesive 137 as shown. Pneumatic tube 37 is
attached to pneumatic tube 134 with crimp ring 105. High-pressure
tube 35 is attached to high-pressure tube 135 with crimp ring 105.
Low-pressure tube 36 is attached to low-pressure tube 133 with
crimp ring 105. Vinyl sheath retainer 121 is glued to umbilical
sheath 92 with epoxy 138, and fixated to plug handle 119 with
stainless steel crimp ring 128. FIG. 11G depicts the construction
of the control console 76 plug receptacle assembly 110 in
functional relationship with umbilical plug assembly 120. Plug
receptacle assembly 110 consists of manifold 142, pneumatic stem
115, high-pressure stem 117, low-pressure stem 118 and O rings 114,
113, 112, and 111. Stems 115, 117 and 118 are stainless steel tubes
0.125 to 0.187 inch outer diameter with 0.010 to 0.015 wall
thickness. Stems 115, 117, and 118 are silver soldered to manifold
142 with silver solder 116 as shown. O-rings 114 and 113 provide
gas communication to console 76 pneumatic line 68 as shown. O-rings
113 and 112 provide gas communication to console 76 high-pressure
line 65 as shown. O-rings 112 and 111 provide gas communication to
console 76 low-pressure line 66 as shown. Plug receptacle assembly
110 is mounted to control console 76 control panel 74 with hardware
as shown. Thermocouple leads 34 and 77 are connected to the control
console by standard thermocouple plugs 107 and 108 vie standard
thermocouple receptacles (not shown).
[0069] FIG. 12A depicts a sectional view of probe 1. FIG. 12B
depicts a sectional view of probe shaft 21. Probe 1 consists of
shaft 21, probe tube 13, sheath docking collar 24, sheath expansion
plug 29, thermocouple 18, and thermocouple lead 34. Probe shaft 21
is extruded from high density polyethylene and has two lumens.
Lumen 32 is the cerebrospinal fluid 19 channel. Lumen 33 contains
thermocouple leads 34 and thermocouple 18 at distal end 7. Probe
shaft 21 is 1.0 to 1.5 mm in diameter. Lumen 32 is 0.7 to 1.0 mm in
diameter. Lumen 33 is 0.2 to 0.3 mm in diameter. The length of
probe shaft is 3 to 10 cm. Distal end 7 is closed by melting
process commonly referred to as tip forming by those skilled in the
art catheter making. A stainless steel mandrel occupies lumen 32
during the tip forming process which maintains the shape of lumen
32 as shown. Thermocouple 18 is secured during tip forming by
melting and collapsing lumen 33. A milling process forms fluid port
26. Sheath docking collar 24 is injection molded of a nylon
compound. Sheath expansion plug 29 is stainless steel tubing who's
inside diameter is equal to the outside diameter of probe shaft 21
and has a wall thickness of 0.015 to 0.030 inches. Sheath expansion
plug 29 is integrated with sheath docking collar 24 by insert
molding technique during molding process. Fluid tube 13 is a
continuation of probe shaft 21. Probe shaft 21 and fluid tube 13
are fastened to sheath docking collar 24 and sheath expansion plug
29 with adhesive 143.
[0070] FIG. 13 shows a bottom view of probe 1 depicting the
sheath/housing docking mechanism. Introducer sheath docking pins 42
(FIG. 3) enter pinhole 93 in docking collar 24. The probe 1 is then
rotated 45 degrees in the direction shown to lock probe 1 to
introducer sheath 2.
[0071] FIG. 14 depicts a sectional view of the introducer sheath 2.
The introducer sheath consists of the sheath/probe docking ring
assembly 147 (See FIG. 15 for construction details), introducer
sheath tube assembly 144 (See FIG. 16 for construction details)
Antiseptic pad 145, and introducer sheath housing 40. The
introducer sheath assembly, except the antiseptic pad is formed by
placing the sheath/probe docking ring assembly 147, and introducer
sheath tube assembly 144 into a fixturing mold and casting the
introducer sheath housing 40 to form the integrated assembly. The
introducer sheath housing 40 is cast from a two-part medical grade
silicon rubber with a hardness of between 40 and 60 durometer.
Dow-Corning Corporation manufactures a full line of medical grade
silicon rubber suitable for this application. The antiseptic pad
145 is made from open cell foam, and is saturated with antiseptic
fluid either at the factory, or in the field prior to use.
Antiseptic foam pad 145 is between 10 and 20 durometer in hardness.
A suitable antiseptic fluid is an iodine solution marketed under
the registered trade name Betadine. The foam pad 145 may be glued
to the bottom face of the introducer housing 40 with a suitable
adhesive.
[0072] FIG. 15A shows a sectional view of the sheath/probe docking
ring assembly 147. The sheath/probe docking ring assembly 147
consists of type 304 stainless steel docking ring 148 and two type
304 stainless steel docking pins 42. The docking ring 148 has a
hole in the center which mates with the sheath tube assembly 144 as
shown in FIG. 14. The docking ring has (6) holes 149 which provides
anchorage within the introducer sheath housing 40 when the
introducer sheath housing 40 is molded around the sheath/probe
docking assembly 147. The docking pins 42 are welded to the docking
ring 148.
[0073] FIG. 16 shows a sectional view of the introducer sheath tube
assembly 144. The introducer sheath tube assembly 144 consists of
the sheath tube 8, and the sheath ferrule 150. The sheath tube 8
and the sheath ferrule 150 are made of high density polyethylene or
other suitable thermoplastic. The sheath tube is extruded into
tubular form by standard means, and then blow molded into final
shape. The wall thickness of the sheath tube 8 is between 0.001 and
0.002 inches. The inside diameter of the sheath tube 8 at the
distal end is 0.020 to 0.025 inches greater than the diameter of
the probe shaft 21 it is designed to mate with. The inside diameter
of the sheath tube at the proximal end is 0.001 to 0.004 inches
smaller than the sheath expansion plug 29 of probe 1 that it is
designed to mate with. The sheath ferrule 150 is injection molded
and is bonded to sheath tube 8 by standard ultrasonic welding
techniques.
[0074] FIGS. 17a and 17B depicts the system control console 76. The
control console 76, contains a source for cooling gas (argon or
nitrogen) in multiple, replaceable tanks 151. The gas tanks 151 are
connected to the console 76 using common medical grade pressure
regulators 152. The control console 76 has a control panel 74,
which provides for cerebrospinal fluid 19 temperature display means
158, and a means to display relative cooling power (0% to 100% of
maximum heat removal capacity) 159. The control panel has a means
to adjust the cerebrospinal fluid 19 temperature setting 160. The
control console may be constructed to provide for operation of
multiple probes 1 simultaneously by means of multiple display and
control channels 157. The control console 76 has means to removably
connect the probe umbilical 14 to the control console, where the
connection means is by gas plug 120 on the end of the probe
umbilical cable 14, and gas plug receptacle 110 mounted on the
front of the control panel 74. The control console also provides an
electrical connection means for the probe tip thermocouple leads 34
and 77 by the thermocouple receptacle 154 and 155 on the control
panel 74.
[0075] FIG. 18 depicts the construction of mounting plate 27.
Mounting plate 27 is made from stainless steel sheet and is 0.005
to 0.010 inches thick.
ALTERNATE EMBODIMENTS
[0076] A fluid pump may be used, instead of a syringe mechanism as
described in the preferred embodiment, in conjunction with a probe
that contains 2 fluid channels, or multiple probes, to continuously
remove, replace and cool cerebrospinal fluid. The cerebrospinal
fluid cooling mechanism may placed in the control console, or
further away from the head than as described in the preferred
embodiment. The method of cooling may be other than Joule-Thompson
effect.
ADVANTAGES
[0077] From the description above there are a number of advantages
my method and apparatus for treating secondary brain injury
provide:
[0078] (a) The therapeutic agent (hypothermia) for preventing
secondary injury according to this invention is applied directly to
the brain.
[0079] (b) The therapeutic agent (hypothermia) for preventing
secondary injury according to this invention is limited to the
brain.
[0080] (c) Lower hypothermic temperatures can be practically
achieved in the brain than can be achieved by the methods currently
described in the art since only the brain is exposed to
hypothermia.
[0081] (d) Lower hypothermic temperatures can be achieved in the
brain than with methods described in the art.
[0082] (e) Hypothermic temperatures can be maintained longer in the
brain than with methods described in the art.
[0083] (f) Hypothermic temperatures can be achieved in the brain by
means of a single small caliber-cooling probe.
[0084] (g) The degree of hypothermia in the brain can be adjusted
according to the physiological response to hypothermia.
[0085] (h) Ventricle cooling may be accomplished without
introducing extra-corporeal fluids.
* * * * *