The Collapsed Runner with a Narrowing Gap

Working diagnosis: exertional heat stroke (EHS) - hyperthermia >40 °C with CNS dysfunction (confusion, seizure) after exertional activity in a warm environment.

Differentials to exclude or co-manage:

• Hypoglycaemia - excluded here (6.8 mmol/L), but always checked first because it is rapidly reversible.
• Hyponatraemic encephalopathy - common in endurance athletes who over-drink; seizure and confusion fit. Look for a history of excessive fluid intake, weight gain, or dilute urine. Do not give hypotonic fluid; if suspected, treat as a sodium problem, not a cooling problem.
• Head injury / intracranial bleed - a fall at speed can cause both the seizure and the altered GCS.
• Stimulant toxicity (amphetamines, cocaine, MDMA) - causes hyperthermia, seizure, and combativeness; consider if the temperature seems out of proportion to the workload.
• Serotonin syndrome / NMS - less likely without a medication history but on the list.
• Cardiac event / arrhythmia - check a rhythm strip; GCS 11 with a seizure could be a post-anoxic state.

Key point: EHS is a clinical diagnosis; do not delay cooling to confirm it, but keep hyponatraemia and head injury in mind because they change fluid choice and destination.

Priority order: cool first, transport second - survival in EHS is time-dependent, and every minute above 40 °C increases mortality.

1. Airway/breathing - position for airway protection (recovery or lateral), high-flow O2 if SpO2 <94%, suction ready given seizure history.
2. Cooling (start immediately, before packaging):
   • Remove excess clothing.
   • Apply cold packs to the neck, axillae, and groin (large-vessel areas).
   • Apply the cooling vest and keep it wet.
   • Cold IV fluid: give the 1 L of 4 °C saline as a bolus - it cools and treats the hypotension (BP 98/54).
   • If available, cold-water immersion is the gold standard; otherwise evaporative cooling with fanning and misting.
   • Target: reduce core temperature to ~38.5–39 °C and stop active cooling to avoid overshoot and shivering (which generates heat).
3. Monitoring - continuous ECG (electrolyte shifts and arrhythmias are common), repeat temperature every 5 minutes, repeat glucose.
4. Fluids - the cold bolus treats hypovolaemia from sweat losses and vasodilation; reassess BP after it.
5. Seizure - if it recurs, treat with benzodiazepine per protocol, but note that cooling alone often terminates heat-related seizures.
6. Destination - the 14-minute ED is appropriate; do not wait for the second unit unless you need it for transport safety. Pre-alert the ED for EHS, GCS 11, temp 40.1, ?hyponatraemia.

Avoid: antipyretics (ineffective in EHS), and aggressive shivering suppression without monitoring.

A falling GCS is a red flag that reframes the case:

• Airway: GCS ≤8 mandates a definitive airway - intubate if you are trained and equipped, or use a supraglottic airway with careful monitoring. Reassess for hypoxia and hypoventilation.
• Re-examine the differential:
  • Hyponatraemic encephalopathy becomes more likely if there was heavy fluid intake - check for a history, and consider that rapid correction of sodium is dangerous; the ED needs the full story.
  • Intracranial pathology (bleed, oedema) - a falling GCS despite cooling suggests the brain is not recovering as expected; consider head injury from the collapse and prioritise CT-capable destination.
  • Worsening cerebral oedema from ongoing hyperthermia - if temperature is not falling, escalate cooling aggressively.
• Recheck temperature and glucose - a missed hypoglycaemia or a temperature that has climbed again would explain the deterioration.
• Transport decision: with GCS 8 and an uncertain cause, the 14-minute ED is still right, but pre-alert should now include ?raised ICP, ?hyponatraemia, airway secured.
• Documentation: record the timeline of cooling, temperatures, and GCS - the receiving team needs it to interpret the sodium and imaging.

The lesson: EHS is the working diagnosis, but a deteriorating patient means you must keep the differential alive rather than anchoring.