Patent Publication Number: US-RE39651-E

Title: Apparatus for rapid cooling of the brain and method of performing same

Description:
This application claims the benefit of U.S. Provisional Application No. 60/030,030 filed Nov. 4, 1996. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to apparatus and method for cooling the brain, and in particular to apparatus and method for inducing hypothermia throughout the tissues of the brain. 
     2. Description Relative to the Prior Art 
     It is well known in the medical art that depriving the brain of oxygen for even a short period of time results in irreversible damage to the brain tissue. Such deprivation occurs during stroke, respiratory arrest, cardiac arrest, trauma and other severe bodily disturbances that slow or otherwise hinder the flow of oxygenated blood to the brain. However, it is also known that lowering the temperature of the brain (hypothermia) slows its metabolic activity, and reduces the chance of tissue damage when the oxygen supply is diminished. 
     At present, operative neurosurgery and cardiac surgery is done in many cases using hypothermia for the specific purposes of maintaining cerebral and cardiac function. In an operating room, this requires use of a cooling module in conjunction with heart/lung bypass techniques by which the patient&#39;s blood, and resultantly the patient&#39;s brain tissue, is cooled. This widespread ability to rapidly lower brain temperature by as little as four or five degrees can make an enormous difference in preservation of function. However, out in the field, when medical emergencies occur, brain cooling must quickly and expeditiously take place without access to the sophisticated equipment available in the hospital operating room. A portable brain cooling apparatus usable in the field is described in U.S. Pat. No. 5,261,399, issued in the names of Klatz et al. For use on an injured or disabled patient, the patent discloses a helmet and back plate containing cavities in which a coolant flows to cool the brain by means of heat conduction through the skull and upper spinal column. 
     SUMMARY OF THE INVENTION 
     Rather than cooling the brain by the relatively slow heat conduction through the low heat conductivity of the bony skull and hair covering the head, the present invention teaches the use of a light weight, easily applied neck encircling collar in firm contact with the soft tissue of the neck, and particularly in good thermal contact with the carotid arteries traversing the neck. A coolant flowing through channels embedded in the collar rapidly cools the blood flowing through the carotid arteries which branch into blood vessels throughout the brain providing vascular access and attendant rapid internal cooling throughout the brain including its deepest recesses. Placing the collar on the patient&#39;s neck is easily and quickly accomplished simultaneously with other emergency medical techniques, such as CPR, which maintain the patient&#39;s heart and lung activity. 
     The collar of the invention contains no metallic parts; the collar, including the coolant channel, may be non-metallized fabric or plastic. This allows X-ray, Cat scan, or MRI procedures to be used while the collar is in place without impairing the effectiveness of the procedure. 
     In a second embodiment for rapid internal cooling of the brain, a conventional endotracheal tube, inserted into the trachea, is provided with an toroidal bladder surrounding the tube. The toroidal bladder is positioned at the back of the oral cavity, and a coolant flowing through the toroid cools blood vessels in the oral cavity which also traverse the brain, providing cooling of the brain tissue. 
     The endotracheal tube and the bladder are made from materials including non- metallic fabric or plastic materials, such that these components are compatible with X - ray, MRI or CAT scan procedures.   
     The coolant flowing through the channels of the collar or the toroidal bladder may be any of the well known liquid or gaseous refrigerants, for example, gaseous CO 2 , freon, or ice water, pumped through the channels of the collar or toroidal bladder in a manner known in the refrigeration art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with respect to the drawings, of which: 
         FIG. 1  is a drawing of the collar of the invention, 
         FIG. 2  is a drawing of the collar of  FIG. 1  in place around a patient&#39;s neck, 
         FIG. 3  is a drawing of a second embodiment of the invention, and 
         FIG. 4  is a drawing of the second embodiment of the invention in use with a patient. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     Referring to  FIG. 1 , a substantially circular collar  10 , containing a gap  11 , has a channel  12  running about the circumference of the collar  10 . The ends  14 , 16  of the channel  10  are sealed, leaving the gap  11  in the collar  10 . Inlet tube  18  and outlet tube  20 , located proximate to the ends  14 , 16 , serve as entrance and exit for a coolant flowing through the collar  10  in channel  12 . The collar&#39;s height “X” is sufficient to cover a large portion of the carotid artery in the neck of a patient having the collar  10  in place. A fastener  22 , such as a Velcro strip, is used to firmly secure the collar  10  about the neck of the patient. The collar  10  is fabricated from either a fabric or plastic having a good thermal transfer coefficient, and capable of sustaining coolant fluid flow through the channel  12  without leakage. 
     Referring to  FIG. 2 , the collar  10  is shown in position on the neck  24  of a patient. The collar  10  is in contact with the carotid artery  26  substantially over the full distance where the carotid artery  26  traverses the neck  24 . The collar  10  is firmly secured in position against the skin of the neck  24 , and is in solid contact over the carotid artery  26 . Coolant flows from the refrigerant supply  28  via the inlet tube  18  through the channel  12  of the collar  10  and back down to the refrigerant supply  28  via the outlet tube  20 , cooling the carotid artery  26  as well as other vascular vessels in the neck  24 , and attendantly the brain  30 . 
     In  FIG. 3 , an endotracheal tube  32  known in the art, has a toroidal shaped bladder  34  positioned to surround the endotracheal tube  32  proximate the end which is inserted into a patient&#39;s trachea. When the tube  32  is in use, (FIG.  4 ), the bladder  34  is in intimate contact with the back of the patient&#39;s oral cavity  35 . The bladder  34  has inlet and outlet tubes  36 , 38  which carry coolant that flows through the bladder  34 , cooling the back of the oral cavity  35 , and attendantly the blood vessels located in the oral cavity  35 . These blood vessels are both adjacent to the brain and connect to the brain, and hence cooling these blood vessels also provides cooling of the brain tissue. The bladder  34  may either be rubber or a flexible plastic which will conform to the shape of the oral cavity  35 , and will make firm contact with the tissues and vessels of the oral cavity  35 . This second embodiment of the invention may be used in conjunction with the first embodiment described above, in which case the same refrigerant supply  28  is connected to both the inlet tubes  18 ,  36  and outlet tubes  20 ,  38 . Or, when used alone, a refrigerant supply equivalent to the refrigerant supply  28  of  FIG. 2  is connected to the tubes  36 , 38 . 
     The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. For example, the first embodiment of the invention may be incorporated into a neck support collar used for supporting an injured patient&#39;s head.