CURRENT Essentials of Critical Care.pdf

Chapter 17 Environmental Injuries 251■■■HypothermiaEssentials of Diagnosis• Mild (32.2–35°C): shivering, confusion, slurred speech, amnesia,tachycardia, tachypnea• Moderate (28–32.2°C): decreased shivering, muscle rigidity,lethargy, hallucinations, dilated pupils, bradycardia, hypotension,ventricular arrhythmias, J wave on ECG, hypoventilation• Severe (28°C): coma, hypotension, apnea, ventricular fibrillation,asystole, pulmonary edema, pseudo-rigor mortis (appearanceof death)• Measure core temperature with rectal thermometer capable ofrecording as low as 25°C• Usually from exposure; with advanced age, alcoholismDifferential Diagnosis• Drug and alcohol intoxication• Hypothyroidism, adrenal insufficiency• Sepsis, trauma, burnsTreatment• Remove wet clothing, protect against further heat loss• Continuous cardiac monitoring; avoid excessive movement ofpatient, which can trigger arrhythmias• Intubation and mechanical ventilation• IV fluids, as most volume depleted; in moderate to severe hypothermia,warm intravenous fluids to 40–42°C• Defibrillate for pulseless ventricular rhythm; if unsuccessful, rewarm,defibrillate after every 1–2°C increase• Bradycardia, atrial fibrillation often respond to rewarming• Antiarrhythmics, vasopressors usually ineffective below 30°C• Mild hypothermia: passive external rewarming with blankets• Moderate to severe hypothermia: passive external plus activeexternal rewarming (immersion in 40°C bath, radiant heat, heatingpads, warmed forced air)• Severe hypothermia: active core rewarming with heated humidifiedoxygen, peritoneal irrigation or pleural or gastriclavage; consider extracorporeal blood rewarming■ PearlThe hypothermic patient has potential for full recovery once rewarmeddespite severely depressed cardiac function.ReferenceHanania NA et al: Accidental hypothermia. Crit Care Clin 1999;15:235.[PMID: 10331126]