Clinical Analysis: 45M - Sudden Onset Altered Sensorium with Heat Exposure

Primary Diagnosis: Classic (Non-Exertional) Heat Stroke

• Heat exposure history + altered sensorium/coma - these are the two cardinal features
• Age 45M, chronic alcoholic (predisposed due to dehydration, impaired thermoregulation, poor nutritional reserve)
• Intubated, unconscious - indicates severe CNS involvement (the cerebellum and cortex are highly sensitive to thermal injury; coma, decerebrate posturing, and seizures are all recognized presentations)
• BP 170/80 - hypertension can occur in heat stroke, especially early; catecholamine surge from thermal stress

Why the Troponin is Elevated (3790 - 10,000)

1. Direct thermal myocardial injury - heat denaturation of cardiomyocyte proteins at core temps >40-42°C
2. Rhabdomyolysis - skeletal muscle necrosis releases troponin (cTnI > cTnT for cardiac specificity, but both can rise)
3. Critical illness / hypoperfusion - demand ischemia from tachycardia + systemic hypoperfusion
4. Catecholamine surge - Takotsubo-type stress cardiomyopathy pattern possible

Complications to Anticipate (Tintinalli's Table 210-4)

Alcohol Factor (Important)

• Dehydration and electrolyte depletion (especially Mg, K, PO4) - worsens heat stroke severity
• Wernicke's encephalopathy must be considered in the differential; give thiamine IV before or with glucose
• Hepatic vulnerability - alcohol-related liver disease + thermal hepatic injury = higher risk of severe hepatic failure
• Coagulopathy risk - baseline coagulopathy from liver disease + DIC from heat stroke
• Alcohol withdrawal is in the differential for altered sensorium; however, the heat exposure history makes heat stroke the primary diagnosis; monitor for withdrawal seizures concurrently
• Rhabdomyolysis risk is increased (alcoholic myopathy as baseline)

Immediate Management Priorities

• Every minute of delay increases mortality
• Target core temp: ≤39°C (avoid overshoot hypothermia)
• Preferred: Evaporative cooling (cool water spray + fan) - practical, effective, compatible with monitoring
• Adjuncts: Ice packs to neck, axillae, groin
• Stop cooling at 39°C (rectal/esophageal probe monitoring)

• Two large-bore IV lines, isotonic fluids (avoid hypotonic - risk of rapid sodium drop)
• BP 170/80 is likely a catecholamine-surge response; will likely correct with cooling
• If persistent hypotension develops: dopamine or dobutamine preferred (norepinephrine may impair cooling by causing peripheral vasoconstriction)

• ECG (stat - rule out STEMI, arrhythmia)
• CBC, CMP, LFTs, coagulation (PT/aPTT/fibrinogen), CPK (rhabdomyolysis)
• Serum myoglobin, urinalysis (myoglobinuria - dark urine)
• ABG (pCO2 often <20 due to hyperventilation; check pH, lactic acid)
• Blood glucose (hypoglycemia common - treat promptly)
• Serial troponins at 0, 3, 6 hours
• Blood cultures, LP if infection cannot be excluded
• CT head (to rule out intracranial bleed, especially given hypertension)

• Aggressive IV fluids to maintain urine output >1-2 mL/kg/hr (protects against myoglobin-induced AKI)
• Urine alkalinization (sodium bicarbonate to maintain urine pH >6.5) if myoglobinuria confirmed
• Avoid NSAIDs, nephrotoxics

• FFP, cryoprecipitate, platelets as indicated by coag profile

Differential Diagnosis to Actively Exclude

Prognosis Notes

• Duration of hyperthermia and peak temperature are the strongest predictors of neurologic outcome
• Sustained temp >42°C = risk of permanent brain injury
• Troponin elevation and cardiac complications are associated with significantly worse outcomes in heat stroke
• Chronic alcoholism worsens prognosis due to multi-organ vulnerability

• Tintinalli's Emergency Medicine, pp. 1389-1391
• Fuster & Hurst's The Heart, 15th Ed, Table 19-3
• Plum & Posner's Diagnosis and Treatment of Stupor and Coma, p. 406

Lab Interpretation: Full Multi-Organ Damage Profile

Summary Table

1. Sodium 162 mEq/L - Severe Hypernatremia

• Massive insensible water loss from hyperthermia + sweating
• Chronic alcoholic = poor water intake at baseline
• Intubated = no oral intake
• This is hypertonic dehydration - pure water deficit

Water deficit = 0.6 × LBW × (Na/140 - 1) = 0.6 × 70 kg × (162/140 - 1) = 42 × 0.157 = ~6.6 litres of free water deficit

• Sodium must NOT fall faster than 10-12 mEq/L per 24 hours (0.5 mEq/L/hour maximum)
• Target: reduce Na by ~10 mEq in first 24 hours (aim for ~152 by tomorrow)
• Full correction over 3-5 days

• Since he's intubated with volume depletion AND AKI:
  • Start with 0.45% NaCl (half-normal saline) or 0.9% NaCl if hemodynamically unstable first to restore perfusion
  • Once hemodynamically stable, switch to D5W or 0.45% NaCl to replace free water deficit
  • If he gets a NG tube, enteral free water is ideal and safer
• Avoid pure D5W alone in large boluses (rapid correction risk + high glucose load)
• Recheck Na every 4-6 hours and adjust rate accordingly

2. Creatinine 3.4 / Urea 55 - Acute Kidney Injury (AKI Stage 2-3)

1. Volume depletion - massive insensible losses + alcohol-related dehydration
2. Direct thermal tubular injury - heat directly damages tubular cells
3. Myoglobinuria from rhabdomyolysis - check urine for dark color, dipstick blood without RBCs
4. Reduced renal perfusion - from hyperthermia-induced circulatory dysfunction

• Aggressive IV fluids to maintain urine output >1-2 mL/kg/hr
• If myoglobinuria confirmed: target UO >200-300 mL/hr; consider urine alkalinization (sodium bicarbonate) to prevent myoglobin cast formation
• Avoid nephrotoxins: NSAIDs, aminoglycosides, contrast
• Monitor K+ very closely - as AKI worsens, K will RISE (currently low, but creatinine at 3.4 means K can shift rapidly, especially after fluid/correction)
• Dialysis criteria: if K rises >6.5, severe acidosis, oliguria/anuria, uremic symptoms

• CPK (if >5000, definitive rhabdomyolysis; if >10,000, high AKI risk)
• Urine myoglobin / urine dipstick
• Urine sodium and FeNa to confirm intrinsic vs pre-renal

3. SGPT 333.9 U/L - Acute Hepatocellular Injury

1. Direct thermal liver injury (centrilobular necrosis - classic in heat stroke)
2. Chronic alcoholic liver disease at baseline = reduced hepatic reserve
3. ALT typically peaks at 24-72 hours post-heat stroke then can rise much further

• Repeat LFTs at 24h, 48h, 72h - if ALT trends to >1000, severe hepatic injury
• Check PT/INR - this is the real test of synthetic function; normal INR = liver still working
• Check AST (not mentioned) - in alcoholic liver disease, AST:ALT ratio >2:1 is characteristic
• Bilirubin currently normal but may rise over 48-72h
• Hypoglycemia risk - damaged liver cannot maintain gluconeogenesis; check glucose every 1-2 hours, keep dextrose infusion running
• Avoid hepatotoxic drugs (paracetamol absolutely contraindicated)

4. Potassium 2.5 mEq/L - Significant Hypokalemia

• Massive sweating (K loss in sweat)
• Chronic alcoholism (nutritional K depletion + GI losses)
• Metabolic alkalosis tendency drives K intracellularly
• Hyperventilation alkalosis (pCO2 usually <20 in heat stroke)

• K of 2.5 + likely hypomagnesemia + elevated troponin = HIGH RISK FOR VENTRICULAR ARRHYTHMIA
• QT prolongation + hypokalemia + heat-damaged myocardium = potential VT/VF

• KCl via central line preferred - max rate 20 mEq/hr via central line
• Peripheral line: max 40 mEq in 500 mL saline over 4-6 hours
• Total deficit: for K of 2.5, roughly 200-400 mEq total body deficit
• Do NOT give in glucose solutions (insulin drives K further intracellularly)
• Co-replace Magnesium (20-60 mEq/24h MgSO4) - hypokalemia is refractory without correcting Mg
• Continuous cardiac monitoring mandatory throughout replacement
• Recheck K every 2-4 hours; as AKI evolves, K will rise - adjust replacement accordingly

Overall Organ System Scorecard

CNS          → Coma/severe (heat stroke)
Cardiac      → Myocardial injury (Trop 3790-10000), arrhythmia risk (K 2.5)
Renal        → AKI Stage 2-3 (Cr 3.4), likely rhabdomyolysis
Hepatic      → Acute injury (ALT 333, rising), alcoholic baseline
Electrolytes → Severe hypernatremia (Na 162), hypokalemia (K 2.5)
Hematologic  → Check DIC (PT, fibrinogen, platelets)

Immediate Priority Action List

• NKF Primer on Kidney Diseases, 8e
• Tintinalli's Emergency Medicine, pp. 1390-1392
• Fuster & Hurst's The Heart, 15th Ed