Skip to content

Environmental Emergencies

Category: Medical Sources: raw/protocols/nm-sop-guidelines-treatment-2022.pdf; UCLA EMT Ultimate Study Guide (2026) Last updated: 2026-05-06

Overview

Environmental emergencies result from exposure to temperature extremes (heat and cold), water submersion (drowning), and other environmental hazards. New Mexico's geography — high desert elevations, extreme summer temperatures, and cold winters — makes heat stroke, hypothermia, and frostbite relevant. Drowning can occur in irrigation canals, rivers, and recreational water despite the arid climate.

This article covers hyperthermia/heat illness, hypothermia/cold exposure (including frostbite), and drowning.

Hyperthermia / Heat Illness

Spectrum (mild to severe): 1. Heat cramps: muscle cramping from salt/fluid loss; alert, normal or mildly elevated temp 2. Heat exhaustion: heavy diaphoresis, weakness, nausea, headache, elevated temp but <104°F; altered LOC may begin 3. Heat stroke: core temp >104°F + altered LOC — thermoregulatory failure; THIS IS THE LIFE THREAT

Heat stroke = medical emergency. Skin may be wet (classic exertional heat stroke) or dry (classic heat stroke in elderly/chronically ill).

Key Points: - Altered LOC is the key differentiator between heat exhaustion and heat stroke - Rapid cooling is the definitive treatment — do not wait for hospital - Cooling goal: core temp <102.2°F (39°C) with improved mental status - Most effective cooling: continuous misting with tepid water while fanning - Elderly, chronically ill, and pediatric patients are highest risk - Check BGL in heat illness with AMS

NM Protocol — Hyperthermia (2022): - Move to cool area; shield from sun/heat source - Remove clothing (practical amount) - If alert and oriented: small sips cool liquids - If AMS: glucometry; consider drug use and other causes - If temp >104°F (40°C) OR AMS present — begin active cooling: - Misting with tepid water while fanning (most effective prehospital method) - Truncal ice packs (less effective than evaporation) - Ice bath immersion (most rapid but rarely available prehospital) - Continue cooling until temp <102.2°F (39°C) AND improved mental status - Transport as soon as possible; consider ALS - IV/IO NS bolus 250–500 mL increments for heat stroke to support LOC, HR, and perfusion — reassess between boluses

Hypothermia / Cold Exposure

Classification by core temp: - Mild (35–32°C / 95–89.8°F): Normal/mildly impaired mental status, shivering intact, vital signs not severely depressed - Moderate (32–28°C / 89.7–82.5°F): Uncontrollable shivering initially, then shivering stops below 30°C; progressive bradycardia and hypotension; slurred speech - Severe (<28°C / <82.4°F): Shivering absent (muscle rigidity), stupor to unresponsiveness, barely detectable vital signs

Key Points: - Level of consciousness is the most reliable field indicator of hypothermia severity - Pulse check for hypothermic patients: up to 60 seconds (pulse may be very slow and weak) - "Not dead until warm and dead" — do NOT terminate resuscitation on scene until patient is rewarmed - Handle gently — extreme cold heart is prone to VF; rough movement or unnecessary manipulation of extremities can trigger VF - In severe hypothermia: if organized EKG rhythm but no palpable pulses — do NOT start CPR (may trigger VF); continue to monitor; if rhythm deteriorates to asystole, then begin CPR - Defibrillation: attempt once for VF; if unsuccessful and core temp <30°C (86°F), do not repeat until patient is warmed to >30°C - Do NOT rewarm frostbite if refreezing is possible — additive injury occurs if area is refrozen

NM Protocol — Hypothermia (2022):

Mild hypothermia: - Remove from environment; dry skin; remove wet clothes; insulate from ground; shelter from wind; wrap in dry clothing or hypothermia blankets; vapor barrier - Oxygen only if needed; if used, should be warmed (104–108°F / 40–42°C) and humidified if possible - Beverages/foods with glucose if awake and can manage airway independently - IV/IO access with warmed NS (42°C); bolus preferred over continuous drip - Monitor; if temp or LOC decreases → treat as severe

Moderate/Severe hypothermia: - ABCs — pulse check up to 60 seconds - Airway management as needed; do NOT hyperventilate (hypocarbia lowers VF threshold in cold) - Prevent further heat loss; field rewarming (heat packs/blankets to anterior chest/thorax) - Handle gently; horizontal position; limit extremity motion; cut clothing rather than removing - Cardiac monitor/AED - IV/IO warmed NS; repeat as necessary - If pulseless and apneic: CPR before defibrillation; ventilate with warm humidified O2 - VF: defibrillate once; if unsuccessful and temp <30°C, hold further defibrillation until temp >30°C - Asystole: CPR is mainstay; no medications until core temp >30°C per Alaska/WMS guidelines - Organized rhythm with no pulses: do NOT start CPR; monitor; if deteriorates to asystole, then CPR - Rapid transport to hospital capable of aggressive rewarming (extracorporeal circulation if available for cardiac arrest)

Frostbite: - If refreezing preventable: use circulating warm water 98.6–102°F (37–39°C) for rewarming; cover with loose sterile dressing after rewarming - If refreezing not preventable: do NOT rewarm until definitive treatment — avoid further additive injury - Do not rub or cause physical trauma to frostbitten tissue

Drowning

Key Points: - Drowning can cause respiratory and/or cardiac arrest — use ABC approach (unlike CAB for standard cardiac arrest; airway/ventilation priority) - C-spine consideration if MOI includes diving, unknown jump, trauma, or history unclear - Do not stop CPR in cold-water drowning — hypothermia may be protective - All drowning patients require hospital evaluation — pulmonary edema and cardiac dysrhythmias can have delayed onset

NM Protocol — Drowning (2022): - ABC approach (not CAB): aggressive airway management and oxygenation/ventilation priority - History: circumstances, MOI, time submerged, water temperature, fresh/salt/polluted water, pre-existing conditions - C-spine precautions if indicated by history/MOI; manage c-spine during extrication from water - Begin artificial respirations in water if needed, with c-spine precautions - Advanced airway per respiratory arrest guidelines; 100% O2 - Suction as needed - If cardiac arrest: follow Medical Cardiac Arrest Guidelines - Do NOT stop CPR if cold water drowning - If hypothermia: refer to Hypothermia Guidelines - IV/IO large bore isotonic solution en route, flow rate to maintain adequate vital signs

NREMT Relevance

  • Heat stroke = AMS + elevated core temp — differentiate from heat exhaustion (no AMS)
  • Misting + fanning = most effective prehospital cooling
  • Hypothermia = LOC is best severity indicator; pulse check up to 60 seconds
  • "Not dead until warm and dead" — full resuscitation until rewarmed
  • Frostbite: do NOT rub; do NOT rewarm if refreezing possible
  • Drowning: ABC approach (not CAB); c-spine consideration
  • Cold-water drowning: do NOT stop CPR

NREMT Differentiators

Heat Illness Progression

Stage Core Temp AMS? Skin Treatment
Heat Cramps Normal or mild ↑ No Moist Rest, fluids, move to cool area
Heat Exhaustion <104°F (40°C) Possible (early) Pale, moist, diaphoretic Cool environment, fluids, position flat + legs elevated
Heat Stroke >104°F (40°C) YES — required for diagnosis Hot (wet OR dry) Active cooling NOW + transport

KEY DIFFERENTIATOR — Heat Stroke: AMS is the threshold. Heat exhaustion patients are alert; heat stroke patients are not. If AMS is present with hyperthermia → heat stroke → medical emergency → active cooling immediately.

NREMT TRAP — Dry vs. Wet Skin: Classic heat stroke (elderly, non-exertional) = dry skin. Exertional heat stroke (young athlete) = wet skin. Both are heat stroke if AMS + high core temp. Do NOT assume wet skin rules out heat stroke.

Cold Exposure Progression

Stage Core Temp LOC Shivering Key Finding
Frostnip Normal Alert Normal Numbness, pallor — superficial, reversible
Mild Hypothermia 32–35°C (89.6–95°F) Alert / Confused Present Slurred speech, clumsy
Moderate Hypothermia 28–32°C (82.4–89.6°F) Drowsy / Stupor Absent (stopped below 30°C) Muscle rigidity begins
Severe Hypothermia <28°C (<82.4°F) Unresponsive Absent (rigid) Barely detectable pulse; VF risk
Frostbite Local tissue Alert (initially) Normal Waxy skin; hard; blisters form

KEY DIFFERENTIATOR — Shivering Stops: When shivering stops in a cold patient, it means the body has lost the ability to self-warm — this is a dangerous sign, not improvement.

Diving Emergencies — DCS vs. Air Embolism

Feature Decompression Sickness (DCS / "The Bends") Arterial Gas Embolism (AGE)
Cause Nitrogen bubbles forming in tissues during ascent Gas bubble entering pulmonary circulation (breath-hold on ascent)
Onset Hours after surfacing Immediate — within minutes of surfacing
Symptoms Joint/muscle pain ("the bends"), rash, numbness Stroke-like: sudden LOC, paralysis, seizure
Position Lateral recovery (NOT Trendelenburg) Lateral recovery (NOT Trendelenburg)
Treatment Hyperbaric oxygen chamber Hyperbaric oxygen chamber
O2 High-flow O2 immediately High-flow O2 immediately

KEY DIFFERENTIATOR — DCS vs. Air Embolism: Timing is the differentiator. Immediate after surfacing = air embolism. Hours after = DCS. Both go to hyperbaric chamber. Both get high-flow O2 immediately.

NREMT RULE — Position: Do NOT place diving emergency patients in Trendelenburg. Use lateral position. Air bubbles rise — Trendelenburg pushes them into the brain.

Lightning Strike

Lightning can cause cardiac and respiratory arrest simultaneously. Unlike other cardiac arrests, respiratory arrest often outlasts the cardiac arrest — victims may survive with aggressive CPR.

Feature Detail
Priority Treat the apparently dead first (reverse triage — lightning victims are not "charged")
Cardiac VF or asystole; AED/CPR immediately
Respiratory Respiratory arrest may persist after cardiac return — prolonged BVM
Trauma Assume spinal injury — explosive force
Burns Entry/exit burn sites; internal burns may be severe despite minor skin appearance
Reverse triage In mass lightning event, treat non-breathing/pulseless FIRST (unlike standard MCI)

KEY DIFFERENTIATOR — Lightning Reverse Triage: Standard MCI = save the salvageable, skip the dead. Lightning = treat the apparently dead FIRST. They have the best chance with immediate CPR. Lightning victims are NOT electrically charged after strike.

Heat/Cold Summary — Key Numbers

Parameter Value
Heat stroke threshold (temp) >104°F (40°C) + AMS
Cooling goal <102.2°F (39°C) with improved mental status
Best prehospital cooling Misting with tepid water + fanning
Hypothermia pulse check Up to 60 seconds
Defibrillation in hypothermia Once; do not repeat until core temp >30°C (86°F)
Frostbite — rewarm? Only if refreezing is NOT possible
Frostbite — what NOT to do Do not rub; do not break blisters

Sources

  • raw/protocols/nm-sop-guidelines-treatment-2022.pdf — Drowning (p. 25); Hyperthermia (p. 26–27); Hypothermia (p. 28–31)