Heat illness, hypothermia and environmental emergencies — formative SAQs

SAQ 1 — Exertional heat stroke: recognition and rapid cooling (10 marks)

A 15-year-old cross-country runner collapses 5 kilometres into a race on a 39-degree summer afternoon. On arrival in the emergency department his rectal temperature is 41.5 degrees Celsius, he is confused and combative, his skin is hot and sweating profusely, his pulse is 140 beats per minute, and his capillary glucose is 6.2 mmol per litre. Cold-water immersion is available in the department. [1] [3]

Questions

1. Define heat stroke and justify the diagnosis in this athlete, including why the profuse sweating does not exclude it. (4 marks) [1]

2. Outline your immediate management with the cooling target, the cooling method, and the drugs you would NOT give and why. (6 marks) [3]

Model answer

Definition and diagnosis (4). Heat stroke is defined as a core temperature above forty degrees Celsius accompanied by central nervous system dysfunction — confusion, agitation, ataxia, seizure or coma — and the central nervous system state is the pivot that separates heat exhaustion (mental state intact) from heat stroke. This athlete has a core of 41.5 degrees with confusion and combativeness, which is heat stroke. The subtype is exertional heat stroke, occurring in a young athlete during intense exercise in heat, and in the exertional form sweating is often still present and profuse, so a hot, sweating skin must not be used to exclude the diagnosis; the absent-sweating (hot, dry) picture is typical of classic non-exertional heat stroke, not this athlete. The history of exertion, the rapid onset, and the preserved sweating all point to exertional heat stroke. [1] [2]

Management (6). My priority is to remove the heat load and begin cooling immediately, because the duration above forty degrees is the chief determinant of survival — I do not wait for investigations. I remove his clothing, secure the airway and give oxygen, establish intravenous access, and begin cold-water immersion, which is the gold standard for exertional heat stroke, cooling at roughly 0.15 degrees per minute. My target, from the National Athletic Trainers' Association position statement, is a core below thirty-nine degrees within thirty minutes — the cool-first, transport-second principle. I check and continue to monitor the glucose, treat the hypovolaemia with warmed intravenous crystalloid titrated to perfusion, and cool to the target before transfer. I would NOT give antipyretics (paracetamol, non-steroidal anti-inflammatory drugs) or dantrolene: the hypothalamic set point is normal in heat stroke, so antipyretics do not lower the temperature and paracetamol may compound the heat-stroke liver injury, and dantrolene has not shown benefit. Once cooled, I monitor for the multi-organ injury — rhabdomyolysis, acute kidney and liver injury, disseminated intravascular coagulation — and admit to a paediatric intensive care unit. [3] [1]