Hypothermia: documentation that holds up
Hypothermia rewards patience and punishes rough handling. The defensible chart documents a true core temperature, that the patient was handled gently to protect an irritable myocardium, the rewarming strategy chosen for the severity, and — in arrest — why resuscitation continued: not dead until warm and dead.
01What's at stake
Good neurologic recovery has been reported from a core temperature as low as 13.7°C and after hours of CPR — so the failures are giving up too early, and precipitating arrest in a salvageable patient through movement or an overlooked complication. Hypothermia also masks: a "normal" heart rate is relative tachycardia, and hyperkalemia hides because its ECG changes are blunted.
02Staging & can't-miss points
- Severity by core temp: mild 32–35°C, moderate 28–32°C, severe <28°C (Swiss staging by clinical signs when no thermometer).
- Measure a true core temperature — esophageal (lower third) is best in the intubated; rectal/bladder lag and mislead during rewarming. A standard thermometer only reads to ~34°C; use a low-reading probe. → core temp + method
- Irritable myocardium — handle gently; jostling or limb manipulation can trigger VF.
- Afterdrop — warm the trunk before the extremities.
- Occult cause — failure to rewarm suggests infection (treat empirically); also hypoglycemia, tox, trauma, endocrine.
03Workup
- Glucose, electrolytes, potassium (renal failure/rhabdo), CK, coagulation, ABG (do not temperature-correct), alcohol/tox; broaden (TSH, cortisol, sepsis) if failure to rewarm.
- ECG: Osborn (J) waves; expect bradycardia, AF with slow ventricular response, then VF/asystole with cooling.
- Interpret "normal" vitals as relative — bradycardia is expected; normal HR → seek hypovolemia/hypoglycemia/tox.
Skip the typing
Work the case in the Hypothermia Workup — it records the core temperature and method, the ECG, the rewarming approach, and glucose, and assembles an MDM that documents gentle handling and the resuscitation rationale.
04Rewarming & arrest
- Passive external (mild): dry, insulate, warm environment.
- Active external (moderate/severe, stable): forced-air warming, warming devices — trunk before extremities.
- Active core: warm IV fluids 40–42°C (avoid LR; avoid microwaved dextrose), heated humidified O₂, peritoneal/thoracic lavage; ECLS (ECMO/CPB) for arrest, instability, severe hyperkalemia, or failure of other methods — the fastest and best for arrest.
- Cardiac arrest: confirm with ultrasound/monitor (palpate a full minute); a single max-power shock, limited drugs until ~30°C; continue until rewarmed. Potassium is prognostic; consider terminating if pulseless at 32°C.
05What to document
06Where charts fail
- Recording an oral/tympanic temp instead of a true core temperature with a low-reading probe.
- Moving/transporting a moderate-severe patient before rewarming to 30–32°C.
- Starting CPR on a perfusing (just bradycardic) rhythm — confirm first.
- Calling a poor prognosis off fixed pupils, or terminating a hypothermic arrest too early.
- Missing hyperkalemia (blunted ECG) or the occult infection behind a failure to rewarm.
07Sources
- Rischall ML, Rowland-Fisher A. Evidence-based management of accidental hypothermia in the emergency department. Emergency Medicine Practice (EB Medicine). 2016;18(1).
- Danzl DF, Pozos RS. Accidental hypothermia. N Engl J Med. 1994;331(26):1756-1760.
- Zafren K, Giesbrecht GG, Danzl DF, et al. Wilderness Medical Society practice guidelines for accidental hypothermia. Wilderness Environ Med. 2014;25(4):425-445.
- Dunne B, Christou E, Duff O, et al. Extracorporeal-assisted rewarming in accidental deep hypothermic cardiac arrest: a systematic review. Heart Lung Circ. 2014;23(11):1029-1035.
© 2026 Kim Trinh, MD. All rights reserved. Educational only — synthesized from EB Medicine and primary literature. Synthetic examples. Not medical advice — apply local protocol and judgment.