Two Collapses at Kilometre Nine
During a 12-kilometre trek beginning at 09:00, the air temperature is 32 °C and relative humidity is 75 percent. At kilometre 9, Cadet A collapses. He is confused, his skin is hot and dry, his pulse is 128 beats per minute, and his core temperature is 40.1 °C. He drank 0.5 litres in the previous three hours. Cadet B stops nearby, dizzy but fully alert and sweating heavily; her pulse is 110, her core temperature is 38.3 °C, and she drank 1.5 litres.
The medic has one ice bath, two cooling towels, and a radio. Vehicle evacuation takes 25 minutes to reach the squad; the nearest hospital is a further 40 minutes away. The squad leader must decide who is treated first, whether to cool on site before moving, and what to transmit on the radio. A cadet argues that Cadet B should be treated first 'because she is smaller' and that Cadet A 'just needs water.'
1. Classify each cadet's condition and justify the classification with at least three specific findings from the scenario.
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Cadet A: exertional heat stroke. Justification:
- Core temperature 40.1 °C - at or above the 40 °C threshold.
- Altered mental status (confusion) - this is the defining feature that separates heat stroke from heat exhaustion; it signals the central nervous system is affected.
- Hot, dry skin with collapse - sweating has failed, removing the body's main heat-loss route.
- Pulse 128 - marked tachycardia consistent with severe heat stress. The low fluid intake (0.5 L in three hours) is a contributing factor, not the diagnosis.
Cadet B: heat exhaustion. Justification:
- Core temperature 38.3 °C - below the 40 °C threshold.
- Fully alert - no neurological involvement.
- Heavy sweating - thermoregulation is still working.
- Dizziness and pulse 110 indicate volume depletion and cardiovascular strain, which should improve with rest, shade, and oral fluids.
Key point: the dividing line is not how much water was drunk or how large the person is. It is core temperature plus mental status.
2. State the treatment priority and decide whether to cool before evacuating. Justify your decision physiologically.
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Priority: Cadet A, immediately. Heat stroke is a time-critical emergency; heat exhaustion is not.
Cool first, move second. Put Cadet A in the ice bath on site and start cooling before loading him. The reason is the shape of the risk curve: tissue and organ injury during heat stroke is driven by how long the body stays above roughly 40 °C, not by how quickly the patient reaches a hospital. A 25-minute evacuation plus a 40-minute drive is 65 minutes of continued heating; immersion cooling can drop core temperature several times faster than air movement or wet towels. Delay in cooling is the main preventable cause of death in exertional heat stroke.
Practical sequence:
- Ice bath for Cadet A; assign one person to monitor breathing continuously.
- Cadet B to shade, seated or lying with legs elevated, given oral fluids in small sips, towels and fanning applied, and re-checked every few minutes.
- Radio: suspected heat stroke, grid reference, core temperature, mental status, cooling already started, request advanced care at the landing or road head.
Trap to avoid: do not delay cooling to finish triage of Cadet B, and do not send the only vehicle away before Cadet A is cooling.
3. Explain why 75 percent humidity impairs cooling even though the air is only 32 °C, and evaluate the claim that Cadet A 'just needs water.'
Read the worked answer
Why humidity matters. During exercise, evaporation of sweat is the dominant heat-loss route. Evaporation depends on the difference between the water-vapour pressure at the skin and in the surrounding air. At 75 percent relative humidity that gradient is small, so sweat drips off without carrying much heat away. The result is a high skin temperature and a rising core temperature even though the air is 'only' 32 °C, and even though the cadet is sweating. This is why wet-bulb conditions, not the dry-bulb reading on a thermometer, govern heat casualty risk.
Why 'just needs water' is dangerous.
- Heat stroke is a failure of thermoregulation, not simply dehydration. Fluid alone does not restore cooling capacity fast enough; only active cooling does.
- A confused casualty cannot safely drink. Oral fluids risk aspiration, and absorption is far too slow to matter in the next 30 minutes.
- The claim delays the only intervention that changes the outcome: cold-water immersion.
- Size or sex is irrelevant to triage here; physiological severity - core temperature and mental status - determines who is treated first. Cadet B is smaller and female, yet her findings are less urgent than Cadet A's.