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.

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&#39;s ability to tolerate the therapy.  
         [0008]     Systemic hypothermia has historically been accomplished by immersion of the patient&#39;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&#39;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&#39;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: 
        (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;     (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.     (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;     (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;     (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.     (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;     (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;     (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.     (i) to provide apparatus for inducing global cerebral hypothermia to a brain tissue at risk of secondary injury according to the objectives stated above;     (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;     (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;     (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;     (m) to provide a brain cooling probe system that is constructed to provide for long term cooling and indwelling;     (n) to provide a brain cooling probe system that is constructed to provide for fixation to the head of the patient;     (o) to provide a brain cooling probe system that is constructed to provide for protection against infection;     (p) to provide a brain cooling probe system that is constructed to provide for a means to sense a response to cooling;     (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 &amp; 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 &amp; 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  &amp; 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  &amp;  36  for cooling, pneumatic line  37  for actuating cerebrospinal fluid removal and replacement, and thermocouple leads  34  &amp;  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: 
        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 ).)     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).     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 .     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 &amp; 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:     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.     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 .     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 ).     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 , &amp;  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  &amp;  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 &amp; 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  11 E 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  &amp;  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&#39;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. 17   a  and  17 B 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: 
        (a) The therapeutic agent (hypothermia) for preventing secondary injury according to this invention is applied directly to the brain.     (b) The therapeutic agent (hypothermia) for preventing secondary injury according to this invention is limited to the brain.     (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.     (d) Lower hypothermic temperatures can be achieved in the brain than with methods described in the art.     (e) Hypothermic temperatures can be maintained longer in the brain than with methods described in the art.     (f) Hypothermic temperatures can be achieved in the brain by means of a single small caliber-cooling probe.     (g) The degree of hypothermia in the brain can be adjusted according to the physiological response to hypothermia.     (h) Ventricle cooling may be accomplished without introducing extra-corporeal fluids.