Hypothermia — SAQ

Stem

A 75-year-old man with known alcohol misuse is found collapsed in a park in mid-winter. On arrival in the emergency department he is unconscious (GCS 8), cold to touch, and is not shivering. Rectal temperature (low-reading thermometer) is 28 degrees C. Pulse 32 per minute, blood pressure 78/45, respiratory rate 6 per minute, SpO2 88 per cent on room air. The cardiac monitor shows sinus bradycardia with a prominent positive deflection at the J point in the lateral leads. Capillary glucose is 2.1 mmol/L.^[5]

Questions

a) What is the diagnosis, the Swiss stage, and the name of the ECG sign? (2 marks)

Diagnosis: severe accidental hypothermia (ANZCOR severe = core below 28 C) with co-existing hypoglycaemia (and probable alcohol as co-factor).^[5]

Swiss stage: HT III — unconscious with vital signs present. HT III is below 28 C, not a 28-to-24 band. There is no HT V in ERC/Paal 2021. Absence of shivering does not by itself define the stage (revised Swiss removed shivering as a stage-defining sign).^[5]

ECG sign: the positive deflection at the J point is the Osborn (J) wave, the exam hallmark of hypothermia. Fetched ERC/Paal texts do not give a 32 C J-wave cut-off.^[5]

b) Outline the immediate resuscitation, including FOUR universal first actions and the rewarming strategy. (4 marks)

Universal first actions:

1. Remove from the cold; cut off wet clothes while minimising movement; dry; insulate.
2. Handle GENTLY — rescue collapse / VF risk.
3. Airway and breathing: warmed oxygen; gentle intubation for coma/bradypnoea. Check signs of life for up to one minute before starting CPR if pulselessness is uncertain.^[3]
4. Circulation and glucose: IV access; only warmed crystalloid (38 to 42 C); correct hypoglycaemia; thiamine if malnourished.^[5]

Rewarming: HT III / ANZCOR severe — active internal adjuncts (warmed IV fluid, humidified gases, lavage as a bridge) and transfer toward an ECLS centre because he is high-risk (elderly, core 28 C, hypotension). ECLS/ECMO if he arrests. Paal: elderly/comorbid arrest-risk threshold is below 32 C.^[5]

c) Explain why you do not use a 32 C 'warm and dead' clock, and how ALS is modified. (2 marks)

Apparent death may still be salvageable if cooling preceded anoxia, but in-hospital ECLS triage uses HOPE (age, sex, mechanism, core temperature, potassium, CPR duration) — not a rule that death cannot be declared until 32 C. HOPE below 0.10 had NPV 97% in external validation.^[8]

Modified ALS: if VF persists after three shocks, delay further shocks until core above 30 C. Withhold adrenaline below 30 C; give it every 6 to 10 minutes at 30 to 34 C. ECMO preferred over CPB for ECLS rewarming.^[3][8]

d) He is not an avalanche victim. Why is serum potassium 13 mmol/L not, on its own, a reason to stop? Name the avalanche pair that IS a futility marker. (2 marks)^[8]

HOPE is superior to dichotomous potassium triage for ECLS. A very high potassium is a HOPE covariate and a poor sign, but K above 12 mmol/L is an ANZCOR avalanche marker, not a universal indoor cease rule.^[8]

ANZCOR avalanche pair: burial over 35 minutes and cardiac arrest with an obstructed airway on extrication, or initial potassium above 12 mmol per litre.^[8]

References3ShowHide

1. [3]Lott C, Truhlář A, Alfonzo A, et al. European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances Resuscitation, 2021.PMID 33773826
2. [5]Paal P, Pasquier M, Darocha T, Lechner R, Kosinski S, Wallner B, Zafren K, Brugger H. Accidental Hypothermia: 2021 Update Int J Environ Res Public Health, 2022.PMID 35010760
3. [8]Pasquier M, Rousson V, Darocha T, et al. Hypothermia outcome prediction after extracorporeal life support for hypothermic cardiac arrest patients: An external validation of the HOPE score Resuscitation, 2019.PMID 30940473