HYPOTHERMIA n Dr. Josep Vidal Alaball

“No previously healthy person should die of hypothermia after he has been rescued and treatment has been started” Cameron C.Bangs, M.D. The Mountaineers 1986

DEFINITION DEFINITION n Body temperature < 35ºC with low reading rectal thermometer CAUSES n Exposure to adverse environments: wet and windy conditions n Immersion in cold water Risk increases by drug/alcohol ingestion, illness or injury. Elderly & very young: more susceptible.

ACTIONS TO ALL DE PATIENTS n A B C n Remove wet clothing n Patient dried and covered with blankets or insulating equipment n Maintain horizontal position n Avoid rough movement and excess activity n Monitor core temperature and cardiac rhythm.

ASSESS RESPONSIVENESS, BREATHING AND PULSE Pulse/Breathing absent: Start CPR Pulse/Breathing present: Rewarming

34ºC - 36ºC (mild hypothermia) 34ºC - 36ºC (mild hypothermia) n Passive rewarming n Active external rewarming 30ºC - 34ºC (moderate hypothermia) 30ºC - 34ºC (moderate hypothermia) n Passive rewarming n Active external rewarming of truncal areas only < 30ºC (severe hypothermia) < 30ºC (severe hypothermia) n Active internal rewarming WHAT IS CORE TEMPERATURE ?

REWARMING n PASSIVE REWARMING –Blankets, insulating equipment n ACTIVE EXTERNAL REWARMING –Heated blankets –Warm bath (up to 40ºC) n ACTIVE INTERNAL REWARMING –Warm, humidified oxygen –Warm i.v. fluids –Gastric, peritoneal or pleural lavage with warm fluids (at 40ºC) –Blood rewarming by haemodialysis or cardiopulmonary bypass.

DECISION TO RESUSCITATE n Beware of pronouncing death in patients with hypothermia! n Death should not be confirmed until patient has warmed to a temperature > 33ºC, or attempts to raise core temperature have failed. n Cold itself may produce a very slow, small volume and irregular pulse with unrecordable BP. n Hypothermia confers a degree of protection to vital organs. Associated arrhythmias are potentially reversible. n Resuscitation has to be prolonged.

RESUSCITATION n Open, clear and maintain airway. n If no respiration ventilate with high concentration of warm, humid oxygen. n Pulse can be very slow. Palpate a major artery for a minimum 1 min. n Consider hypothermia as a cause of bradycardia in any casualty.

RESUSCITATION n Rates for ventilation and chest compression as for normothermic patient, but hypothermia may cause stiffness of the chest wall. n Cannulate a central or large proximal vein. n Infuse warm N-Saline.

ARRHYTHMIAS n As body temperature falls: –Sinus bradycardia –Atrial fibrillation –Ventricular fibrillation –Asystole n Standard treatment protocols should be followed.

ARRHYTHMIAS n If core T.< 30º VF may not respond to cardioversion. Rapid core rewarming is necessary with CPR being continued until defib. becomes effective. n Lignocaine no significant effect on VF in hypothermic patients. n Mechanical disturbance ( tracheal intubation, excessively vigorous chest compressions ) can precipitate VF until core T. is raised. n Other arrhythmias tend to revert spontaneously as core T. rises, and usually do no require immediate treatment.

INVESTIGATIONS n ABG’s n Electrolyte & glucose n CXRay* n Check for underlying illness or trauma n TFT n Urine output * Stomach should be decompressed with a nasogartric tube to reduce respiratory complications.

PROGNOSIS n Neurological recovery still possible after prolonged cardiac arrest, as hypothermia reduces cerebral oxygen requirements. n Prognosis usually determined by severity of underlying illness.

THE END