Severe accidental hypothermia and the modified arrest

(a) Initial assessment and resuscitation (6 marks).

• Gentle handling is the first principle — a cold, irritable myocardium can be thrown into ventricular fibrillation by rough movement or intubation. Move her smoothly.^[3]
• ABCDE in a warmed resus bay. Remove the wet/cold clothing (cut it off), dry and insulate her in warm blankets.
• Airway and breathing — assess the airway and the slow respiratory rate; give warmed humidified oxygen; intubate gently only if the airway is unprotected or she fails to oxygenate.
• Circulation — cardiac monitor on from the outset (the J waves, the junctional bradycardia); establish IV/IO access; feel the pulse for a full minute (a cold, slow pulse is easily missed); check capillary glucose early and correct hypoglycaemia.
• Disability — GCS 8; pupils and glucose; remember fixed dilated pupils are NOT brain death in hypothermia.
• Confirm the core with a low-reading thermometer (use a low-reading thermometer (ERC: tympanic if breathing, oesophageal if intubated)). Send blood gas (uncorrected / alpha-stat at 37 C), electrolytes (potassium is prognostic), glucose, coagulation (falsely normal — run at 37), and a troponin/CK.
• Search for and treat the precipitant — sepsis, a fracture, a stroke, myxoedema, an overdose — in parallel with the rewarming.

(b) Staged rewarming plan (4 marks).

Core 28.5 degrees = severe hypothermia (HT III). The rewarming method is active internal rewarming, escalating to extracorporeal if she arrests.^[3]

• Active external (forced-air warming over the trunk, warm blankets) as the baseline — warm the trunk first to limit afterdrop.^[3]
• Active internal adjuncts — warmed IV crystalloid at 38 to 42 degrees for every fluid; warm humidified inspired gases.
• ANZCOR: high-risk features (core below 30 C, ventricular arrhythmia, systolic blood pressure below 90 mmHg) and arrest go to an ECLS centre. ERC 2025: warm IV fluids 38–42 C.
• Extracorporeal rewarming (ECMO) is the gold standard for arrest — activate transfer to an ECMO-capable centre early.

(c) Modified advanced life support (4 marks).

• Confirm the arrest carefully — up to one minute for signs of life, and bedside ultrasound; do not start compressions on a cold but perfusing heart (compressions can precipitate VF).^[3]
• Deliver up to three shocks (biphasic 150 to 200 joules). If VF persists, defer further shocks.
• Withhold adrenaline and amiodarone until the core is above 30 degrees — below 30 degrees they are ineffective and they accumulate to toxic levels.
• Continue prolonged CPR with warmed humidified oxygen; the hypothermic myocardium tolerates ischaemia for hours, so CPR for several hours is appropriate.
• Once the core is above 30 degrees, ANZCOR: adrenaline every 6 to 10 minutes while 30 to 34 C. ERC/RCUK: a 300 mg amiodarone load if still shockable, with further doses delayed.
• Do not apply a 32 C death clock. Continue CPR to ECLS; in adults use HOPE (not a potassium-of-10 rule) for in-hospital ECLS triage.