ICU · Environmental

Acute severe hypothermia: rewarming, Osborn waves, and 'warm and dead'

Also known as Hypothermia · Accidental hypothermia · Environmental hypothermia · Osborn waves · Rewarming · Warm and dead

Hypothermia = core temperature <35°C from excessive heat loss (environmental) or impaired thermogenesis (endocrine, sepsis, drugs). SEVERITY: MILD (32-35°C — tachycardia, tachypnoea, shivering, confusion). MODERATE (28-32°C — bradycardia, decreased reflexes, somnolence, shivering stops, Osborn J waves on ECG, AF). SEVERE (<28°C — coma, fixed pupils, hypotension, ventricular arrhythmias [VF], asystole, pulseless — appears dead but may be recoverable). KEY PRINCIPLES: (1) HANDLE GENTLY — cold myocardium is extremely irritable — rough handling/movement → VF (irreversible). (2) REWARM: mild → passive (blankets, warm environment); moderate → active external (forced warm air [Bair Hugger], warmed IV fluids); severe → active internal (warmed fluids + body cavity lavage + ECMO/cardiopulmonary bypass). (3) 'NO ONE IS DEAD UNTIL WARM AND DEAD' — prolonged resuscitation is warranted; survivors rewarmed from 13.7°C. (4) DON'T RUB/MASSAGE (triggers VF). (5) GUIDELINES do not recommend vasopressor or antiarrhythmic drugs in VF if <30°C — treat with CPR and extracorporeal rewarming.