Emergency Medicine · Year 3 · from Emergency Medicine

Case 1: Exertional Heat Stroke - The Marathon Runner

Patient Demographics

• Age: 34 years
• Sex: Male
• Occupation: Software engineer

Chief Complaint

"He collapsed at the finish line and isn't making sense."

History of Present Illness

A 34-year-old male collapses after completing a marathon on a hot, humid day (ambient temperature 32C/90F, humidity 85%). Race medical staff report he crossed the finish line but immediately became confused and collapsed. He is not responsive to commands and appears to be seizing intermittently. Bystanders report he was running well throughout the race but slowing significantly in the last few miles.

Initial Assessment

ESI Level: 1 - Immediate life-threatening emergency

First Impression:

• Appearance: Unresponsive, appears seizing, flushed
• Work of breathing: Tachypneic, irregular
• Circulation: Hot, flushed skin

Vital Signs:

• Heart rate: 148 bpm
• Blood pressure: 88/54 mmHg
• Respiratory rate: 28 breaths/min
• SpO2: 92% on room air
• Core Temperature (rectal): 42.1C (107.8F) - CRITICAL
• GCS: 6 (E1V2M3)

Heat-Related Illness Spectrum

This patient has HEAT STROKE - elevated core temperature with altered mental status

Primary Survey

Airway:

• Partially obstructed (secretions, intermittent seizing)
• Jaw thrust performed
• Suctioning
• Airway adjunct placed

Breathing:

• Tachypneic, irregular
• Supplemental oxygen applied
• Bag-valve-mask available

Circulation:

• Tachycardic, hypotensive
• Hot, flushed skin (DRY - classic heat stroke)
• Weak peripheral pulses
• IV access obtained

Disability:

• GCS 6
• Intermittent tonic-clonic activity
• Pupils 4mm, reactive

Exposure:

• Remove all clothing
• Hot to touch
• INITIATE COOLING IMMEDIATELY

Immediate Cooling Interventions

Gold Standard: Cold Water Immersion

• Patient placed in ice water bath (2-3C water)
• Head supported above water
• Continuous agitation of water
• Goal: Lower temperature to 39C (102.2F) then remove

Alternative Methods (if immersion unavailable):

• Ice packs to neck, axillae, groin
• Evaporative cooling (mist and fan)
• Cold IV fluids
• Cold water lavage (gastric, bladder, peritoneal) - reserved for refractory cases

Avoid:

• Antipyretics (ineffective - hyperthermia not from pyrogens)
• Alcohol rubs (vasoconstriction, absorption)

Management

Cooling Results:

• Temperature at 15 minutes: 40.2C
• Temperature at 30 minutes: 38.8C (goal reached, removed from ice bath)

Seizure Management:

• Midazolam 5mg IV for intermittent seizure activity
• Resolved after cooling initiated

Resuscitation:

• 2L crystalloid for hypotension
• Post-cooling BP: 102/68

Intubation:

• Intubated for airway protection (GCS 6, ongoing altered mental status)

Secondary Survey

SAMPLE History (from race companion):

• Symptoms: Collapsed, confused, possible seizure
• Allergies: None known
• Medications: None
• PMH: Healthy, regular runner
• Last Meal: Energy gel 1 hour before finish
• Events: Hot/humid conditions, slowing in final miles

Risk Factors:

• Environmental: High temperature and humidity
• Exercise: Marathon (high exertional heat production)
• Hydration: Uncertain during race
• Acclimatization: Lives in cooler climate, traveled for race

Diagnostic Testing

Labs:

• CBC: WBC 18.2, Hgb 16.8 (hemoconcentration), Plt 98,000 (low)
• BMP: Na 148, K 5.8, Cl 108, HCO3 14, BUN 42, Cr 2.4
• Glucose: 62 (give D50)
• Liver: AST 2,450, ALT 1,890 (markedly elevated)
• CPK: 45,000 IU/L (severe rhabdomyolysis)
• Lactate: 8.4 mmol/L
• Coagulation: PT 18, INR 1.8, PTT 48, Fibrinogen 140 (DIC developing)
• ABG: pH 7.18, pCO2 28, HCO3 12 (metabolic acidosis)

ECG: Sinus tachycardia, peaked T waves (hyperkalemia)

Complications Identified

1. Rhabdomyolysis - CPK 45,000, AKI
2. Acute kidney injury - Cr 2.4
3. Hepatic injury - Transaminases >2000
4. Coagulopathy/DIC - Low platelets, elevated PT/PTT, low fibrinogen
5. Hyperkalemia - K 5.8 with ECG changes
6. Metabolic acidosis - pH 7.18

Ongoing Management

Rhabdomyolysis/AKI:

• Aggressive IV fluids (target UOP 200-300 mL/hour)
• Calcium gluconate 2g IV for hyperkalemia with ECG changes
• Monitor for compartment syndrome

DIC:

• FFP and platelets if active bleeding
• Monitor coagulation parameters

Hepatic Injury:

• Serial LFTs
• Avoid hepatotoxic medications
• Most cases resolve with cooling

Supportive Care:

• ICU admission
• Continuous temperature monitoring
• Avoid overcooling (risk of shivering, which generates heat)

Clinical Course

At 24 hours:

• Extubated, GCS 15
• Temperature normalized
• Cr 3.1 (peaking), CPK 78,000 (peaking)
• LFTs trending down
• Coagulopathy improving

At 72 hours:

• Cr improving (2.2)
• CPK trending down
• Neurologically intact
• Ambulating

Disposition

• ICU admission for 48 hours
• Step-down unit for 24 hours
• Discharged day 5
• Full neurological recovery
• Follow-up for renal function
• Counseling on future exercise in heat

Teaching Points

1. Core temperature is mandatory: Rectal or esophageal; oral/axillary unreliable
2. Cool first, then transport: Cooling should not be delayed; mortality correlates with duration of hyperthermia
3. Cold water immersion is gold standard: Most effective cooling method; target 39C
4. Multi-organ failure common: Liver, kidney, coagulation, muscle all affected
5. Antipyretics don't work: Hyperthermia is not fever; no role for acetaminophen/ibuprofen
6. Exertional vs. classic heat stroke: Exertional in young exercisers; classic in elderly/chronically ill
7. Prevention: Acclimatization, hydration, avoid exercise in extreme conditions

Clinical Image

Image Description: Photograph demonstrating cold water immersion technique for treatment of exertional heat stroke. The patient is submerged in an ice water bath with head supported above water level while medical personnel monitor vital signs and core temperature.

Attribution: Image from Wikimedia Commons, Heat stroke treatment. Public domain (US Government work). Source: https://commons.wikimedia.org/wiki/File:Defense.gov_photo_essay_080718-F-1644L-052.jpg

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