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ICU TopicsEnvironmental emergencies

ICU · Environmental emergencies

Accidental Hypothermia

Also known as Hypothermia · Accidental hypothermia · Osborn waves · J waves · Rewarming · ECMO hypothermia · Not dead until warm and dead

The accidental hypothermia — the core below 35 degrees C. The severity (the mild 32 to 35, the moderate 28 to 32, the severe below 28). The clinical (the shivering → the bradycardia, the decreased the LOC, the loss of shivering, the Osborn / J waves, the VF / the asystole). The rewarming (the passive, the active the external, the active the internal — the ECMO for the severe). The handle gently (the cold heart irritable). The NOT the dead until the warm and the dead. The drugs the extended intervals (the below 30).

medium23 referencesUpdated 26 July 202630 min readVerification in progress

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The one-line answer

Accidental hypothermia is a core temperature below 35 °C, graded into mild (32–35 °C, shivering intact), moderate (28–32 °C, shivering lost, Osborn J waves, atrial fibrillation) and severe (below 28 °C, VF and asystole). Match the rewarming to the grade — passive for mild, active external (Bair Hugger to the trunk) for moderate, active internal with VA-ECMO or cardiopulmonary bypass for the arrested patient. Handle the patient gently, withhold drugs below 30 °C, and remember the mantra: not dead until warm and dead.[1]

Meet the patient

A 32-year-old previously well man is found unconscious in a park on a winter morning, exposed overnight. Rectal core temperature reads 26.5 °C; the ECG shows sinus bradycardia at 28 with prominent Osborn J waves. He looks dead — fixed pupils, a barely palpable pulse — and the team reaches for the warming blanket. The moment he is rolled onto the bed he flips into ventricular fibrillation. That single beat distils the whole topic: the cold myocardium is exquisitely irritable, and a patient who appears dead may still be salvageable.[1]

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References23ShowHide
  1. [1]Waqas R, Kalsoom I, Qaiser Aziz Khan M, et al. Accidental Hypothermia in Hospitalized Adults: Risk Factors, Management Strategies, and Clinical Outcomes: A Systematic Review Cureus, 2026.PMID 41815600
  2. [2]Walpoth BH, Walpoth-Aslan BN, Mattle HP, et al. Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming N Engl J Med, 1997.PMID 9366581
  3. [3]Mallet ML Pathophysiology of accidental hypothermia QJM, 2002.PMID 12454320
  4. [4]Brown DJA, Brugger H, Boyd J, Paal P Accidental hypothermia N Engl J Med, 2012.PMID 23150960
  5. [5]Paal P, Pasquier M, Darocha T, et al. Accidental Hypothermia: 2021 Update Int J Environ Res Public Health, 2022.PMID 35010760
  6. [6]Lott C, Truhlář A, Alfonzo A, et al. European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances Resuscitation, 2021.PMID 33773826
  7. [7]Pasquier M, Hugli O, Paal P, et al. Hypothermia outcome prediction after extracorporeal life support for hypothermic cardiac arrest patients: The HOPE score Resuscitation, 2018.PMID 29481910
  8. [8]Saczkowski RS, Brown DJA, Abu-Laban RB, et al. Prediction and risk stratification of survival in accidental hypothermia requiring extracorporeal life support: An individual patient data meta-analysis Resuscitation, 2018.PMID 29580960
  9. [9]Brugger H, Bouzat P, Pasquier M, et al. Cut-off values of serum potassium and core temperature at hospital admission for extracorporeal rewarming of avalanche victims in cardiac arrest Resuscitation, 2019.PMID 31022496
  10. [10]Pasquier M, Strapazzon G, Kottmann A, et al. On-site treatment of avalanche victims: Scoping review and 2023 recommendations of the International Commission for Mountain Emergency Medicine (ICAR MedCom) Resuscitation, 2023.PMID 36709825
  11. [11]Boyd J, Brugger H, Shuster M Prognostic factors in avalanche resuscitation: a systematic review Resuscitation, 2010.PMID 20371145
  12. [12]Bjertnæs LJ, Hindberg K, Næsheim TO, et al. Rewarming From Hypothermic Cardiac Arrest Applying Extracorporeal Life Support: A Systematic Review and Meta-Analysis Front Med (Lausanne), 2021.PMID 34055829
  13. [13]Podsiadło P, Darocha T, Svendsen OS, et al. Outcomes of patients suffering unwitnessed hypothermic cardiac arrest rewarmed with extracorporeal life support: A systematic review Artif Organs, 2021.PMID 32920881
  14. [14]Pasquier M, Darocha T, Husby P Survival of a cardiac arrested victim with hypothermia despite severely elevated serum potassium (9.0 mmol/L) Cryobiology, 2017.PMID 28754211
  15. [15]Mazur P, Kosiński S, Podsiadło P, et al. Extracorporeal membrane oxygenation for accidental deep hypothermia - current challenges and future perspectives Ann Cardiothorac Surg, 2019.PMID 30854323
  16. [16]Gilbert M, Busund R, Skagseth A, et al. Resuscitation from accidental hypothermia of 13.7 degrees C with circulatory arrest Lancet, 2000.PMID 10665559
  17. [17]Omar HR The Osborn wave: what have we learned? Herz, 2016.PMID 26272271
  18. [18]Antzelevitch C, Yan GX J wave syndromes Heart Rhythm, 2010.PMID 20153265
  19. [19]Elshimy G, Chippa V, Anastasopoulou C, Correa R Myxedema Coma StatPearls, 2026.PMID 31424777
  20. [20]Boué Y, Payen JF, Brun J, et al. Survival after avalanche-induced cardiac arrest Resuscitation, 2014.PMID 24971508
  21. [21]Wollenek G, Honarwar N, Golej J, Marx M Cold water submersion and cardiac arrest in treatment of severe hypothermia with cardiopulmonary bypass Resuscitation, 2002.PMID 11886730
  22. [22]Romlin BS, Winberg H, Janson M, et al. Excellent Outcome With Extracorporeal Membrane Oxygenation After Accidental Profound Hypothermia (13.8°C) and Drowning. Crit Care Med, 2015.PMID 26317568
  23. [23]Recover of peripheral nerve function after prolong hypothermic cardiac arrest in a porcine model with extra corporeal life support. J Therm Biol, 2017.PMID 28166944
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