CaseMark Managing Environmental Emergencies
Guides comprehensive workup and management for heat stroke, hypothermia, submersion injury, altitude illness, and envenomation using evidence-based protocols and severity classification systems.
Why This Skill Exists
Environmental emergencies are time-critical conditions where mortality correlates directly with treatment delays. Classic heat stroke carries 10-50% mortality depending on time-to-cooling—every 30 minutes of delay above core temperature 40 degrees C increases mortality by 10%. Severe hypothermia (core temp <28 degrees C) with cardiac arrest has documented full neurologic recovery when appropriate rewarming protocols are followed, making premature termination of resuscitation a critical error. Envenomation management requires species-specific antivenom timing that directly determines limb and life outcomes.
These presentations are unfamiliar to many emergency physicians who practice in temperate urban settings. Algorithmic approaches prevent the cognitive errors that arise from low-frequency, high-stakes presentations.
Checkpoint A: Pre-Draft Intake (Mandatory)
- What is the environmental exposure (heat, cold, submersion, altitude, envenomation)?
- What is the core temperature (rectal or esophageal probe—tympanic and axillary are unreliable in extremes)?
- What was the duration and context of exposure (occupational, recreational, intentional, accidental)?
- What is the patient's mental status (GCS, orientation, presence of shivering)?
- What pre-existing conditions affect thermoregulation (medications, endocrine disease, extremes of age)?
- For envenomation: what was the creature (if identified), time of bite/sting, progression of symptoms?
- For submersion: duration underwater, water temperature, was CPR initiated at scene?
- What field treatments were provided (active cooling, passive rewarming, tourniquets, antivenom)?
Documents to Request
- EMS run sheet with field vital signs and interventions
- Core temperature measurements with method and times
- Serial laboratory results (BMP, CBC, coagulation, CK, lactate, LFTs)
- ECG (Osborn/J waves for hypothermia, QTc for heat stroke)
- Toxicology consultation notes (for envenomation)
- Poison control center documentation
- Environmental conditions at scene (ambient temperature, water temperature, altitude)
- Prior medical history and medication list
Step 1: Heat Stroke Recognition and Cooling Protocol
Classification
| Type | Core Temp | Mental Status | Sweating | Key Feature |
|---|---|---|---|---|
| Heat exhaustion | <40°C (104°F) | Intact or mild confusion | Present | Can self-cool with rest and fluids |
| Classic heat stroke | ≥40°C (104°F) | Altered (confusion to coma) | Often absent | Elderly, chronic illness, medications |
| Exertional heat stroke | ≥40°C (104°F) | Altered | May be present | Young, athletic, military, laborers |
Cooling Methods (Target: reduce core temp to 39°C within 30 minutes)
- Cold water immersion (CWI): Most effective method; cooling rate 0.2°C/min. Immerse to neck in ice water bath. Gold standard for exertional heat stroke.
- Evaporative cooling: Undress patient, mist with lukewarm water, fan continuously. Cooling rate 0.05°C/min. Use when immersion is impractical.
- Ice packs to groin/axillae/neck: Adjunctive only—insufficient as sole method
- Cold IV fluids: 4°C NS at 30 mL/kg—adjunctive, helps with volume
- Peritoneal lavage/thoracic lavage: For refractory cases unresponsive to external cooling
Stop active cooling at 38.5-39°C to avoid overshoot hypothermia. Monitor continuously with rectal or esophageal probe.
Complications to Monitor
- Rhabdomyolysis (CK, urine myoglobin, maintain UOP >1 mL/kg/hr)
- DIC (PT/INR, fibrinogen, D-dimer, platelet count)
- Acute kidney injury (creatinine, BUN, electrolytes)
- Hepatic failure (AST/ALT, bilirubin—may peak at 48-72 hours)
- ARDS (serial chest X-ray, oxygenation status)
Step 2: Hypothermia Classification and Rewarming
Swiss Staging System
| Stage | Core Temp | Clinical Presentation | Cardiac Risk |
|---|---|---|---|
| HT-I (Mild) | 32-35°C | Shivering, conscious | Low |
| HT-II (Moderate) | 28-32°C | Impaired consciousness, no shivering | Atrial arrhythmias likely |
| HT-III (Severe) | 24-28°C | Unconscious, vital signs present | VF threshold reached |
| HT-IV | <24°C | No vital signs (apparent death) | Cardiac arrest |
Rewarming Protocols
| Severity | Method | Target Rate |
|---|---|---|
| Mild (HT-I) | Passive external rewarming (warm blankets, remove wet clothing, warm environment) | 0.5-2°C/hr |
| Moderate (HT-II) | Active external rewarming (forced warm air blankets like Bair Hugger, warm IV fluids 38-42°C) | 1-2°C/hr |
| Severe (HT-III/IV) | Active internal rewarming: warm humidified O2, warm peritoneal/pleural lavage, ECMO for cardiac arrest | 2-3°C/hr |
Critical rules for hypothermic cardiac arrest:
- Do NOT declare death until the patient is warm (core temp >32°C) and remains in arrest: "No one is dead until they are warm and dead"
- Limit defibrillation to 3 attempts if core temp <30°C; subsequent shocks are unlikely to convert until rewarmed
- Withhold IV medications (epinephrine, amiodarone) until core temp >30°C; space at double normal interval (every 6-10 min) between 30-35°C
- Continuous high-quality CPR or mechanical CPR device for transport
- Early ECMO/cardiopulmonary bypass is the definitive rewarming method for HT-IV with cardiac arrest
Step 3: Submersion Injury (Drowning)
- Begin CPR immediately for pulseless patients—do not attempt to drain water from lungs
- Assume cervical spine injury if diving, surfing, or unknown mechanism
- Fresh vs. salt water: The clinical distinction is irrelevant for acute management—both cause surfactant washout, alveolar collapse, and ARDS
- Intubate early for significant aspiration—high PEEP ventilation strategy (similar to ARDS protocol)
- Core temperature: all drowning patients may be hypothermic—check and rewarm
- Prognostic factors: submersion time >25 minutes, CPR >25 minutes, initial pH <6.8, and initial GCS 3 are associated with poor neurologic outcome but should not be used to terminate resuscitation in the field
Step 4: Envenomation Assessment and Antivenom Protocol
Crotalid (Pit Viper) Envenomation — North American
| Severity | Local Findings | Systemic | Lab Abnormalities | Antivenom |
|---|---|---|---|---|
| Minimal | Pain, swelling <2 joint spaces | None | None | Observe 8-12 hrs; may not need antivenom |
| Moderate | Swelling 2-3 joint spaces, ecchymosis | Mild nausea, perioral paresthesias | Mild thrombocytopenia, elevated PT | CroFab 4-6 vials IV |
| Severe | Rapidly progressive swelling, hemorrhagic blebs | Hypotension, coagulopathy, altered mental status | Platelets <50K, INR >3, fibrinogen <100 | CroFab 6-12+ vials; repeat PRN |
Antivenom administration: CroFab (crotalidae polyvalent immune Fab) — initial dose reconstituted in 250 mL NS, infuse over 60 minutes. Monitor for anaphylaxis (skin test is NOT predictive and is NOT recommended). Repeat dosing every 6-8 hours as maintenance (2 vials x 3 doses) to prevent recurrent coagulopathy.
Coral Snake Envenomation
- Fixed front fangs, minimal local findings, delayed neurotoxicity (2-13 hours)
- Antivenom (if available) should be given prophylactically for confirmed coral snake bites, even before symptom onset
- Monitor for bulbar symptoms: ptosis, diplopia, dysphagia, respiratory failure
- Ventilatory support may be required for days to weeks
Step 5: Altitude Illness
| Condition | Altitude | Symptoms | Treatment |
|---|---|---|---|
| AMS (acute mountain sickness) | >2500 m | Headache, nausea, fatigue, insomnia | Descent or rest at altitude; acetazolamide 250 mg BID |
| HACE (high altitude cerebral edema) | >3000 m | Ataxia, altered mental status, papilledema | Immediate descent; dexamethasone 8 mg then 4 mg q6h; supplemental O2 |
| HAPE (high altitude pulmonary edema) | >3000 m | Dyspnea at rest, cough, pink frothy sputum, cyanosis | Descent; nifedipine 30 mg ER; supplemental O2; portable hyperbaric chamber if descent impossible |
Checkpoint B: Post-Draft Alignment (Mandatory)
- Is the core temperature measurement method documented (rectal/esophageal vs. unreliable tympanic/axillary)?
- For heat stroke: was time-to-target-temperature tracked and documented?
- For hypothermia: was the rewarming method appropriate for severity stage?
- For envenomation: was antivenom timing, dosing, and monitoring documented?
- Are serial labs and imaging ordered to track expected complications?
Quality Audit
| # | Criterion | Pass/Fail |
|---|---|---|
| 1 | Core temperature obtained via reliable method (rectal or esophageal) | |
| 2 | Environmental exposure type and duration documented | |
| 3 | Cooling/rewarming method appropriate for severity | |
| 4 | Target temperature and time-to-target recorded | |
| 5 | Serial vital signs including continuous core temperature monitoring | |
| 6 | Relevant labs ordered (CK, coags, LFTs, renal function) | |
| 7 | ECG obtained and interpreted for temperature-specific findings | |
| 8 | Envenomation severity graded with serial limb measurements | |
| 9 | Antivenom dose, timing, and adverse reactions documented | |
| 10 | Poison control consulted and documented for envenomation | |
| 11 | Hypothermic arrest: rewarming before death declaration | |
| 12 | Submersion: cervical spine precautions maintained if indicated | |
| 13 | Disposition appropriate for severity with ICU criteria applied |
Guidelines
- Core temperature defines severity—tympanic thermometers are unreliable below 34°C and above 40°C; insist on rectal or esophageal probe for environmental emergencies
- Cold water immersion is the gold standard for exertional heat stroke—do not delay cooling for transport, diagnostics, or IV access; cool first, then do everything else
- Shivering cessation in hypothermia indicates core temp below approximately 30°C—this is a clinical warning sign, not a reassuring finding
- Do not use tourniquets for snake bites—arterial tourniquets increase tissue ischemia without proven benefit; pressure immobilization is only for neurotoxic species (coral snakes, non-US elapids)
- Activated charcoal and wound incision/suction are contraindicated in snake envenomation—they do not remove venom and increase wound complication risk
- Drowning is the preferred term—the terms "near-drowning," "dry drowning," and "secondary drowning" are deprecated per WHO and Utstein-style guidelines
- Prophylactic antibiotics are NOT indicated for submersion injury—treat pneumonia only if it develops clinically
- ECMO for refractory hypothermic cardiac arrest should be considered for any patient with core temp <28°C and no contraindications to resuscitation—coordinate early transfer to ECMO-capable center