Hypothermia: recognition, rewarming and cold arrest

Manage now— do this, in order

• Handle minimally and keep horizontal: cardiac output and cerebral blood flow are already low and fall further if the patient is sat up, stood or suspended in a harness — below 30°C, movement alone can precipitate ventricular fibrillation.
• Stop ongoing heat loss before adding heat: remove wet clothing, dry the patient, cover them including the head, insulate from cold surfaces, warm the environment — this costs nothing and is often worth more than anything that follows. Rewarm the trunk, not the limbs (heat to the extremities causes vasodilatation and afterdrop), and never use an electric blanket — vasoconstricted skin burns easily and the patient cannot feel it.
• Oxygen for everyone — the leftward oxyhaemoglobin shift impairs tissue delivery even with acceptable-looking saturations, and oximetry is unreliable in the vasoconstricted patient; where available give it heated and humidified to 40–45°C, which eliminates respiratory heat loss and adds 1–2°C per hour. If protective reflexes are absent: gentle endotracheal intubation, with adequate preoxygenation — that is what prevents intubation-associated ventricular arrhythmia.Doctor / NurseNot available at your setup — Endotracheal intubation kit.
• Glucose within the first minute for documented hypoglycaemia: adult 50 mL of 25% glucose IV (or 100 mL of 10%); child 2 mL/kg of 10% glucose IV — never 25% or 50% in a neonate; recheck at 15 minutes.Doctor / Nurse
• Fluid, warmed to 38–42°C: dehydration is the rule in chronic hypothermia — 0.9% sodium chloride is preferable to lactated Ringer's/Hartmann's because the cold liver metabolises lactate inefficiently; adult 500–1000 mL, child 20 mL/kg, reassessing between boluses. Add a gastric tube (cold-induced ileus) and a urinary catheter (cold diuresis, ancillary temperature site).Doctor / Nurse
• Choose the rewarming strategy: passive external (drying, covering including the head, insulating, warm environment; 0.5–2°C/h) suits acute mild primary hypothermia in the previously healthy — it fails in the malnourished, elderly and alcohol-dependent, who lack glycogen. Active rewarming is necessary for core below 32°C, cardiovascular instability, extremes of age, CNS dysfunction, hormone insufficiency or suspected secondary hypothermia: forced-air blankets to the trunk (0.1–3.4°C/h); core methods — heated humidified oxygen (1–2°C/h), bladder lavage 300 mL warm saline instilled, drained, repeated (1–2°C/h), closed thoracic lavage (2–3°C/h, the most efficient without extracorporeal support). Aim for roughly 1°C per hour in the perfusing patient — speed matters only in arrest.Doctor / Nurse
• Drug rule: below 30°C withhold adjunctive medications (adrenaline, amiodarone and the rest); between 30°C and 35°C double the interval between doses or use a lower dose. Do not treat the arrhythmias — slow atrial fibrillation and bradycardia are monitored, not treated; atropine is ineffective; the definitive antiarrhythmic is heat.Doctor / Nurse
• Hypothermic arrest: confirm over a full 60 seconds; high-quality continuous compressions (intermittent CPR may still be effective below 28°C where continuous is impossible); defibrillate VF/pulseless VT with up to three shocks at maximal energy below 30°C (paediatric 4 J/kg), then delay further shocks until the core exceeds 30°C; rewarm aggressively and in combination; continue resuscitation until the core is at least 32°C before considering termination — 'you are not dead until you are warm and dead' is literal guidance.Doctor / NurseNot available at your setup — Defibrillator.
• Blood pressure: target a mean arterial pressure of at least 60 mmHg early; most hypothermic hypotension responds to warmed crystalloid and rewarming — where it does not, low-dose dopamine 2–5 micrograms/kg/min IV is the specifically recommended agent (same weight-based dose in children); perfusion may also improve with low-dose IV glyceryl trinitrate.Doctor / NurseNot available at your setup — Infusion pump.