# Clinical Cases: Environmental Emergencies

## 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

| Condition | Temperature | Mental Status | Treatment |
|-----------|-------------|---------------|-----------|
| Heat cramps | Normal | Normal | Oral rehydration, rest |
| Heat exhaustion | <40C (104F) | Intact | Cooling, IV fluids |
| **Heat stroke** | >40C (104F) | **Altered** | **Aggressive cooling, resuscitation** |

**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
![Cold Water Immersion for Heat Stroke](case_01_image.jpg)

**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

---

## Case 2: Severe Hypothermia - The Found Down Patient

### Patient Demographics
- **Age:** 58 years
- **Sex:** Male
- **Occupation:** Unemployed

### Chief Complaint
"Found unresponsive in the park."

### History of Present Illness
A 58-year-old homeless male is found unresponsive on a park bench by police during a cold snap (ambient temperature -8C/18F). He was last seen by shelter workers 18 hours ago. On EMS arrival, patient is unresponsive with very slow respirations and barely palpable pulse. EMS initiated gentle handling and passive rewarming en route.

### Initial Assessment

**ESI Level:** 1 - Critical hypothermia

**First Impression:**
- Appearance: Unresponsive, appears lifeless
- Work of breathing: Very slow, shallow
- Circulation: Cyanotic, cold to touch

**Vital Signs (obtained carefully):**
- Heart rate: 32 bpm (difficult to palpate)
- Blood pressure: 78/palp
- Respiratory rate: 6 breaths/min
- SpO2: Unable to read (vasoconstriction)
- **Core Temperature (esophageal): 26.4C (79.5F)** - SEVERE HYPOTHERMIA
- GCS: 3

### Hypothermia Classification

| Severity | Temperature | Clinical Features |
|----------|-------------|-------------------|
| Mild | 32-35C (90-95F) | Shivering, tachycardia, confusion |
| Moderate | 28-32C (82-90F) | Shivering stops, bradycardia, altered LOC |
| **Severe** | <28C (<82F) | **Coma, arrhythmias, undetectable vitals** |

**This patient: SEVERE hypothermia (26.4C)**

### Primary Survey - Modified for Hypothermia

**Airway:**
- Patent
- Endotracheal intubation performed (warmed, humidified oxygen)

**Breathing:**
- Very slow (6/min) - assisted ventilation
- Lungs clear
- Bag-valve-mask with warmed, humidified oxygen

**Circulation:**
- Severe bradycardia (32 bpm)
- Hypotensive
- Difficult IV access (vasoconstriction)
- **Check pulse for 60 seconds** (may be very slow/weak)
- ECG obtained

**Disability:**
- GCS 3 (comatose)
- Pupils fixed, dilated (BUT may recover with rewarming)

**Exposure:**
- Remove wet clothing
- Dry thoroughly
- Cover with warming blankets
- Handle GENTLY (avoid rough movement - arrhythmia risk)

### ECG Findings

**Classic ECG Changes in Hypothermia:**
- Bradycardia (HR 32)
- **Osborn (J) waves** present (positive deflection at J point)
- Prolonged intervals (PR, QRS, QT)
- Atrial fibrillation at presentation (common)

### Rewarming Strategy

**Severity determines approach:**

| Method | Indication |
|--------|------------|
| Passive external | Mild hypothermia |
| Active external | Mild-moderate hypothermia |
| Active internal | **Severe hypothermia, cardiac instability** |

**This patient - ACTIVE INTERNAL REWARMING indicated:**
1. Warm IV fluids (38-42C)
2. Warm humidified oxygen
3. Body cavity lavage (bladder, gastric, thoracic)
4. **ECMO/cardiopulmonary bypass** - if available and cardiac arrest

**Initial Rewarming Initiated:**
- Warm IV crystalloid via rapid infuser
- Bair Hugger warming blanket
- Bladder lavage with warm saline
- Heated, humidified ventilation

### Management Considerations

**CPR in Hypothermia:**
- If no pulse after 60 seconds of checking, start CPR
- Continue CPR until rewarmed to >30-32C or spontaneous circulation
- "Not dead until warm and dead"
- Defibrillation: May attempt once, but usually ineffective until temp >30C
- ACLS medications: Withhold until temp >30C (reduced metabolism)

**This patient:**
- Had detectable pulse (32 bpm) - no CPR indicated
- Focus on rewarming and supportive care

### Secondary Survey

**SAMPLE History (limited):**
- Symptoms: Found unresponsive
- Allergies: Unknown
- Medications: Unknown
- PMH: Per shelter records - alcohol use disorder, no other known medical history
- Last Meal: Unknown
- Events: Cold exposure overnight

**Physical Examination:**
- General: Cold, cyanotic, appears lifeless
- Skin: No frostbite visible, no trauma
- Abdomen: Distended (diminished motility)
- Neuro: Comatose, areflexic

### Diagnostic Testing

**Labs:**
- ABG: pH 7.08, pCO2 32, HCO3 10 (severe metabolic acidosis)
- K: 5.2 (increases with hypothermia)
- Glucose: 42 (hypoglycemia common) - D50 given
- Lactate: 9.2 mmol/L
- Ethanol level: 0.18% (intoxication, contributed to exposure)
- Ammonia: Mildly elevated
- CBC: Hematocrit 52% (hemoconcentration)
- Coagulation: PT 22, prolonged (coagulopathy)

**Toxicology:** Consider carbon monoxide if enclosed space

### Clinical Course

**Rewarming Progress:**
- Hour 1: Temp 27.8C, HR 38
- Hour 2: Temp 29.4C, HR 48, BP 92/60
- Hour 4: Temp 32.0C, HR 68, BP 108/72, spontaneous movements
- Hour 8: Temp 35.2C, extubated, following commands

**Complications During Rewarming:**
- "Afterdrop" phenomenon: Core temp initially dropped slightly as cold peripheral blood returned to core
- Hypotension: Required fluid resuscitation
- Arrhythmias: Brief runs of VT during rewarming (treated expectantly)

### Disposition
- ICU admission for continued monitoring
- Full neurological recovery by day 2
- Social work consultation
- Shelter placement arranged
- Alcohol cessation resources provided
- Discharged day 4

### Teaching Points

1. **"Not dead until warm and dead":** Neurological recovery possible even after prolonged hypothermia with apparent death
2. **Check pulse for 60 seconds:** Pulses may be very slow and weak
3. **Gentle handling:** Rough movement can trigger ventricular fibrillation in cold heart
4. **J waves (Osborn waves):** Pathognomonic ECG finding of hypothermia
5. **Defibrillation timing:** Usually ineffective until temperature >30C; one attempt reasonable
6. **Core temperature measurement:** Rectal, esophageal, or bladder; peripheral unreliable
7. **Rewarming method matches severity:** Severe hypothermia needs active internal rewarming
8. **Look for underlying cause:** Sepsis, hypoglycemia, intoxication, trauma often coexist

### Clinical Image
![ECG showing Osborn J Waves](case_02_image.jpg)

**Image Description:** 12-lead ECG demonstrating classic features of hypothermia including bradycardia and Osborn (J) waves - the characteristic positive deflection at the J point seen best in leads II, V5, and V6 (arrows).

**Attribution:** Image from Wikimedia Commons, Osborn wave ECG. Licensed under CC BY-SA 3.0. Source: https://commons.wikimedia.org/wiki/File:Osborn_waves.jpg

---

## Case 3: Snakebite Envenomation - The Pit Viper Bite

### Patient Demographics
- **Age:** 42 years
- **Sex:** Male
- **Occupation:** Landscaper

### Chief Complaint
"I got bit by a rattlesnake on my hand!"

### History of Present Illness
A 42-year-old male landscaper presents 45 minutes after being bitten on the right hand by a snake while clearing brush. He reports seeing a rattlesnake (heard the rattle) that struck his right hand when he reached under a bush. He killed the snake with a shovel (brought the specimen). He is now experiencing severe pain and swelling in his hand progressing up his forearm.

### Initial Assessment

**ESI Level:** 2 - Envenomation with progressive symptoms

**First Impression:**
- Appearance: Anxious, holding right arm
- Work of breathing: Normal
- Circulation: Appears well-perfused

**Vital Signs:**
- Heart rate: 112 bpm
- Blood pressure: 148/88 mmHg
- Respiratory rate: 18 breaths/min
- SpO2: 98% on room air
- Temperature: 37.2C

### Primary Survey

**Airway:** Patent
**Breathing:** Normal
**Circulation:** Tachycardic (anxiety/pain), normotensive
**Disability:** Alert, GCS 15
**Exposure:** Right hand with visible bite marks, progressive swelling

### Snake Identification

**Snake Brought to ED (confirmed):**
- **Western Diamondback Rattlesnake (Crotalus atrox)**
- Pit viper (triangular head, heat-sensing pits, vertical pupils, rattle)

**Pit Viper Envenomation Syndrome:**
- Local: Pain, swelling, ecchymosis, necrosis
- Hematologic: Coagulopathy, thrombocytopenia
- Systemic: Hypotension, altered mental status (severe cases)

### Local Examination - Severity Assessment

**Right Upper Extremity:**
- Two puncture wounds on dorsum of right hand
- Intense pain at bite site
- Edema: Hand + wrist + mid-forearm (progressing)
- Ecchymosis developing around puncture sites
- Bullae: None yet
- Necrosis: None
- Sensation: Intact
- Motor: Can make fist but painful
- Pulses: Present (radial 2+)

**Mark the Leading Edge:**
- Circumference measured and marked with time
- Forearm: 28cm at presentation
- Plan: Reassess every 30-60 minutes

### Severity Classification

| Grade | Local Effects | Systemic Effects | Labs |
|-------|--------------|------------------|------|
| None (dry bite) | Fang marks only | None | Normal |
| Mild | Swelling at bite | None | Normal |
| **Moderate** | **Swelling beyond bite** | **Mild systemic symptoms** | **Abnormal** |
| Severe | Entire limb swelling | Shock, bleeding | Markedly abnormal |

**This patient: MODERATE envenomation** (progressive swelling, mild tachycardia)

### Secondary Survey

**SAMPLE History:**
- Symptoms: Pain, swelling, anxiety
- Allergies: None (no prior antivenom exposure)
- Medications: Lisinopril
- PMH: Hypertension
- Last Meal: Lunch 2 hours ago
- Events: Bite 45 minutes ago, progression of symptoms

**What NOT to Do (prehospital myths):**
- No tourniquet (ischemia)
- No ice (increases necrosis)
- No incision/suction (ineffective, causes harm)
- No electrical shock (ineffective)

### Diagnostic Testing

**Labs:**
- CBC: WBC 14.2, Hgb 13.8, **Platelets 128,000 (low)**
- BMP: Normal
- Coagulation: **PT 18.2, INR 1.5, PTT 42** (abnormal)
- **Fibrinogen: 180** (low-normal)
- D-dimer: Elevated

**Baseline Labs Abnormal = Envenomation confirmed, antivenom indicated**

### Management

**Antivenom Indication:**
- Progressive local swelling (beyond bite site)
- Abnormal coagulation studies
- Moderate severity

**CroFab (Crotalidae Polyvalent Immune Fab):**
- Mixed according to package insert
- Initial dose: 4-6 vials IV
- Infuse slowly initially (allergic reaction risk)
- Monitor for improvement

**Antivenom Administration:**
- Premedicaton: Not routinely needed, but have epinephrine available
- Started at slow rate, advanced as tolerated
- 6 vials CroFab given over 1 hour

### Response to Antivenom

**At 1 hour post-antivenom:**
- Pain improving
- Swelling progression slowed
- Repeat labs: Platelets 142, INR 1.3, Fibrinogen 210

**At 4 hours:**
- Swelling stabilized at mid-forearm
- No new ecchymosis
- Labs normalizing

**Maintenance Dosing:**
- 2 vials CroFab at 6, 12, and 18 hours after initial control

### Additional Management

**Supportive Care:**
- IV fluids
- Pain management (opioids, avoid NSAIDs)
- Tetanus prophylaxis
- Limb elevation
- Wound care

**Monitoring:**
- Serial exams every 4-6 hours
- Mark swelling margins
- Repeat labs at 6 hours, then daily
- Watch for compartment syndrome

**Compartment Syndrome Consideration:**
- Rare with snakebite (antivenom usually sufficient)
- Fasciotomy rarely needed
- Measure compartment pressures if concern

### Disposition
- Admitted to ICU/monitored bed
- Completed antivenom protocol
- Swelling peaked at 36 hours, then improved
- Labs normalized
- Discharged day 3
- Return for repeat labs in 1 week (recurrent coagulopathy risk)

### Teaching Points

1. **Identify the snake if safe:** Helps guide management (not all bites envenomated)
2. **Dry bites occur:** ~25% of pit viper bites have no envenomation
3. **Mark the swelling:** Serial measurements track progression and response to treatment
4. **Antivenom indications:** Progressive local swelling, coagulopathy, systemic symptoms
5. **CroFab vs. Anavip:** Both available; Anavip may have lower recurrence rate
6. **Recurrent coagulopathy:** Can occur days after antivenom; follow-up labs essential
7. **Fasciotomy rarely needed:** Antivenom usually controls swelling; measure compartment pressures before surgery
8. **Don't delay treatment for labs:** Start antivenom based on clinical progression

### Clinical Image
![Pit Viper Bite with Progressive Swelling](case_03_image.jpg)

**Image Description:** Photograph of upper extremity with pit viper envenomation demonstrating puncture wounds at bite site with progressive edema, ecchymosis, and bullae formation extending from the hand to the forearm.

**Attribution:** Image from Wikimedia Commons, Rattlesnake bite. Public domain. Source: https://commons.wikimedia.org/wiki/File:Crotalus_bite.jpg