Accidental Hypothermia

Stage: mild 32–35°C, moderate 28–32°C (shivering stops), severe <28°C. The cold myocardium is irritable — handle gently, keep horizontal. J (Osborn) waves are classic; bradycardia is physiological — rewarm, don't pace. Arrest: <30°C limit to 3…

Hypothermia Rewarming & Modified ALS

The pathway

1 · Measure properly

Low-reading thermometer — standard ones stop at 34°C
Oesophageal/rectal more accurate than tympanic
Shivering stops <32°C — no more self-rewarming

2 · Handle gently

Keep horizontal — prevents rescue collapse
Minimal movement; rough handling precipitates VF
Cut off wet clothing, insulate incl. head

3 · ECG

J (Osborn) waves, bradycardia, long PR/QRS/QT, AF
Bradycardia is physiological — rewarm, don't pace
Drugs largely ineffective when cold

4 · Rewarm 1–2°C/hr

Forced-air blanket to the TRUNK (reduces afterdrop)
Warmed IV fluids 38–42°C, warmed humidified O₂
Never rub limbs or immerse — afterdrop and hypotension

5 · Severe/unstable

ECMO / cardiopulmonary bypass is gold standard
Discuss with critical care early

6 · Modified ALS

<30°C: max 3 shocks, NO drugs
30–35°C: double drug intervals
>35°C: standard
Prolonged CPR justified while rewarming

7 · Find the cause

Glucose always
Sepsis, hypothyroidism/myxoedema, alcohol/drugs, adrenal insufficiency
Why were they on the floor? Fall, stroke, MI — plus safeguarding/social review

Drugs

Drug	Dose	Route	Notes
Warmed crystalloid	38–42°C	IV	Active internal rewarming. Cold fluids worsen hypothermia.
Glucose 10%	As required	IV	Check glucose in every hypothermic patient — hypoglycaemia is common.
Levothyroxine / hydrocortisone	Specialist decision	IV	If myxoedema coma or adrenal insufficiency suspected.
NOTE: cardiac drugs	—	—	Largely ineffective <30°C and accumulate — withhold until rewarmed.

When to escalate

Core temperature <30°C — critical care, consider ECMO,Cardiac arrest in hypothermia — prolonged CPR + extracorporeal rewarming,Haemodynamic instability during rewarming (afterdrop),K⁺ >12 mmol/L — marker of pre-cooling hypoxia and futility, senior decision

Reference: Resuscitation Council UK — Special Circumstances / Swiss staging system

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