Makindo Medical Notes

ℹ️ About

• 🌡️ Heat stroke = life-threatening emergency defined by core temperature >40°C with cerebral dysfunction (delirium, seizures, coma).
• ⚡ Mortality is high if not rapidly recognised and cooled.

🔥 Types of Heat Stroke

• 🌞 Non-exertional (classic): – Highest risk in elderly, very young, chronically unwell, or socially vulnerable (e.g. no access to air conditioning). – Triggered by prolonged exposure to hot, humid conditions. – Risk factors: obesity, immobility, Parkinson’s drugs, diuretics, anticholinergics.
• 🏃 Exertional heat stroke: – Affects young, fit people in hot, humid environments (athletes, military, outdoor labourers). – Exacerbated by clothing/equipment limiting cooling. – Symptoms: altered mental status, ataxia, coma, nuchal rigidity, posturing. – Profuse sweating is typical, though sweating may cease in later stages. – Drugs: cocaine, amphetamines, LSD, alcohol withdrawal can contribute.

🩺 Clinical Features

• 🌡️ Core body temperature >40°C
• 🧠 CNS dysfunction: anxiety, confusion, delirium, bizarre behaviour, hallucinations, seizures, coma
• 💦 Sweating may be present (exertional) or absent (classic/late presentation)
• ❤️ Hypotension, tachycardia, shock in severe cases

🔎 Investigations

• 🧪 FBC: raised WCC (exclude infection)
• 🧪 U&E: AKI, hypokalaemia, hypophosphataemia
• 💪 CK: ↑ in exertional heat stroke (rhabdomyolysis)
• 🩸 LFTs: ↑ AST = poor prognostic indicator
• 🫁 VBG/ABG: respiratory alkalosis ± lactic acidosis (exertional)

⚠️ Complications

• 🧠 Encephalopathy, cerebral oedema
• 💪 Rhabdomyolysis → renal failure
• 🫁 Acute respiratory distress syndrome (ARDS)
• ❤️ Myocardial injury, circulatory collapse
• 🩸 Disseminated intravascular coagulation (DIC)
• 🧪 Hepatic & pancreatic injury
• 🩻 Intestinal ischaemia & infarction

🔍 Differentials

• 💉 Malignant hyperthermia (post-anaesthesia)
• 🧠 Neuroleptic malignant syndrome (antipsychotics)
• 💊 Drug-induced hyperthermia (stimulants, serotonergic drugs)
• 🦠 Infection: meningitis, encephalitis, sepsis
• 🦴 Endocrine: thyroid storm, phaeochromocytoma
• 🧠 CNS lesions: hypothalamic bleed, hydrocephalus

🛡️ Prevention

• 💧 Stay hydrated; avoid alcohol excess
• 🚫 Limit strenuous activity in hot/humid weather
• 🧢 Rest in cool, shaded, or air-conditioned areas
• 👕 Wear lightweight, loose clothing
• ⏳ Gradually acclimatise to heat exposure
• 👀 Monitor for early symptoms of heat illness and intervene promptly

💊 Management

• 🫁 ABCs, IV access, monitor core body temperature (rectal probe)
• 💧 IV fluids for dehydration and shock
• ❄️ Rapid cooling = main treatment goal – Immersion in ice water baths (fastest, but poorly tolerated long-term) – Tepid water spray (≈40°C) + fans for evaporative cooling – Ice packs to axillae, groin, neck
• 🎯 Target core temperature: <39°C (safe threshold)
• 💊 Dantrolene is not indicated (used in malignant hyperthermia, not heat stroke)
• 🩸 Monitor/treat rhabdomyolysis (fluids, urine alkalinisation if severe)
• ⚠️ ICU support may be required for multiorgan failure

📌 Exam Pearl: The key difference is that exertional heat stroke often has profuse sweating and occurs in young fit individuals, whereas classic heat stroke often occurs in elderly/comorbid patients with impaired heat dissipation.