• Uncontrolled lowering of core body temperature below 35 °C by exposure to cold
• EtOH facilitates induction of hypothermia by producing sedation (inhibiting shivering) and cutaneous dilation
• Heart is most sensitive organ to cooling and is subject to ventricular fibrillation or asystole when temperature drops to 21-24 °C
• Elderly patients living alone in inadequately heated homes
• Alcoholics exposed to the cold during a binge
• People engaged in winter sports
• People lost in cold weather
• Predisposing diseases include:
• Mentally depressed (somnolent, stuporous, or comatose)
• Pale or cyanotic
• Shivering absent below 32 °C
• Slow and shallow respirations
• Usually normotensive and bradycardic
• At temperatures < 32 °C, patients may appear to be dead
• Frostbitten or frozen extremities
• Severe hypoglycemia is common
• Elevated serum amylase in 50%
• Elevations of aspartate aminotransferase (AST), lactic dehydrogenase (LDH), and creatine kinase (CK) enzymes
• ECG shows PR lengthening, pathognomonic J wave at junction of the QRS and ST segment
• When severely hypothermic, patients should not be declared dead until measures for rewarming and resuscitation have failed
• Mild hypothermia (32-35 °C) can be treated by passive rewarming with continuous monitoring of rectal or esophageal temperatures
• Active rewarming is indicated for temperatures below 32 °C, cardiovascular instability, or failure of passive rewarming
• Methods for rewarming include:
-Immersion in warm water
-Inhalation of heated air
-Pleural and peritoneal lavage
-Extracorporeal blood warming
• Immersion in warm water (40-42 °C) will raise body temperature 1-2 °C per hour
• Pleural irrigation via 2 right thoracostomy tubes (anterior, posterior) with warm saline (40-42 °C)
• Peritoneal lavage involves giving warm (40-45 °C) crystalloid solutions at 6 L/h which will raise temperature 2-4 °C per hour
• Partial cardiopulmonary bypass (CPB) is the most efficient technique and is indicated for ventricular fibrillation, severe hypothermia, or frozen extremities
• Partial CPB with flows of 6-7 L/min can raise core temperature 1-2 °C every 3-5 minutes
• Endotracheal intubation and mechanical ventilation are often necessary
• Bretylium tosylate 10 mg/kg is best drug for ventricular fibrillation
• Antibiotics are often indicated for pneumonitis
• Hypoglycemia should be treated with IV D50
• Increased capillary permeability may lead to generalized and pulmonary edema upon rewarming
• Coagulopathies (including disseminated intravascular coagulation) are seen occasionally
• Pancreatitis and acute renal failure (ARF) common in < 32 °C
• Failure to respond to treatment should suggest adrenal insufficiency...
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