Environmental and Metabolic Emergencies
Core concepts
Cover heat illness (heat exhaustion versus heat stroke, cooling methods, and the risk of rhabdomyolysis), hypothermia with the concept of "not dead until warm and dead" and gentle handling to avoid arrhythmia, and frostbite. Understand drowning management (no routine cervical spine immobilisation, early ventilation), electrical injury, and altitude illness. Metabolic emergencies include diabetic ketoacidosis and hyperosmolar hyperglycaemic state (fluids first, insulin later, potassium replacement), thyroid storm, adrenal crisis, and hypoglycaemia. Learn the anion gap and osmolal gap calculations.
Traps
In DKA, giving insulin before fluids can precipitate cardiovascular collapse; and potassium must be checked before insulin - never give insulin if potassium is low. In heat stroke, antipyretics are useless. In hypothermia, do not pronounce death until rewarmed unless there is a lethal injury. Hypoglycaemia is the great mimic - always check glucose.
Rule of thumb
In DKA: fluid, then potassium assessment, then insulin. In any collapsed or confused patient, check glucose and temperature immediately.
Worked example
A 22-year-old type 1 diabetic with glucose 30 mmol/L, pH 7.05, ketones 6 mmol/L, and potassium 3.2: give fluids and replace potassium before starting an insulin infusion.