Environmental Disorders
Core approach
Environmental emergencies require recognition of abnormal physiology caused by heat, cold, altitude, pressure, immersion, electricity, and envenomation. Core topics include heat exhaustion versus heat stroke, hypothermia, frostbite, drowning, decompression illness, high-altitude illness, electrical and lightning injury, and snake or marine envenomation. Heat stroke is a emergency with altered mental status and core temperature elevation; cooling should begin immediately. Severe hypothermia requires gentle handling, rewarming, and prolonged resuscitation because the arrest rhythm may respond only after rewarming.
Traps
Do not confuse heat exhaustion with heat stroke; mental status change is the key distinction. In drowning, do not routinely perform abdominal thrusts to remove water; start rescue breathing and CPR. A normal temperature does not exclude heat stroke if cooling has begun. Osborne waves suggest hypothermia but are not required. Electrical injury can cause cardiac arrhythmia, rhabdomyolysis, and compartment syndrome despite minor skin burns. Altitude illness can mimic pneumonia, migraine, or gastroenteritis.
Worked example
A collapsed marathon runner is confused, hot, and hypotensive. Remove clothing, begin rapid evaporative cooling, check glucose, and give fluids cautiously. Do not wait for a specific temperature before cooling. Rule of thumb: altered mental status plus heat exposure equals heat stroke and requires immediate cooling.
Key concepts
Frostbite is treated with rapid warm-water immersion, not rubbing. Drowning resuscitation prioritizes ventilation and oxygenation. Decompression illness may require hyperbaric oxygen; transport planning matters.