Environmental Emergencies: Heat, Cold, Water, Altitude, and Lightning Injuries

Introduction

Environmental emergencies result from exposure to extreme temperatures, water, altitude, or weather phenomena. These conditions can rapidly progress to life-threatening situations. Recognition of early signs and appropriate immediate management are critical for survival.

Spectrum of Heat Illness

Condition	Pathophysiology	Severity
Heat edema	Vasodilation + dependent pooling of fluid in extremities	Mild
Heat rash (miliaria)	Blocked sweat ducts causing inflamed vesicles	Mild
Heat cramps	Salt depletion from sweating causing muscle cramps	Mild-moderate
Heat syncope	Vasodilation + dehydration causing orthostatic hypotension	Moderate
Heat exhaustion	Dehydration + electrolyte depletion from heat stress	Moderate
Heat stroke	Thermoregulatory failure, core temp >104F (40C), end-organ damage	LIFE-THREATENING

Heat Exhaustion

Aspect	Details
Core temperature	Elevated but <104F (40C), typically 100-104F (37.8-40C)
Mental status	Normal or mildly altered (mild confusion, anxiety)
Skin	Cool, clammy, pale (still sweating)
Symptoms	Weakness, dizziness, nausea, headache, vomiting, thirst, cramping
Vital signs	Tachycardia, orthostatic hypotension

Management	Details
Move to cool environment	Out of sun, into air conditioning or shade
Remove excess clothing	Facilitation of heat dissipation
Cool the body	Cool water spray with fan, cold packs (neck, axillae, groin)
Oral rehydration	Cool water or sports drink if tolerating PO
IV fluids	If unable to drink, severe dehydration
Rest	In recumbent position
Observation	If no improvement in 30 minutes, suspect progression to heat stroke

Heat Stroke

Aspect	Details
Core temperature	>104F (40C), often >106F (41C)
Mental status	ALTERED: confusion, agitation, seizure, coma
Skin	Hot, DRY, red (sweating may be absent)
Classic heat stroke	Gradual, elderly/chronic illness, medication-related, unable to access cooling
Exertional heat stroke	Acute, young athletes/laborers, may still have sweaty skin
Complications	Rhabdomyolysis, AKI, DIC, ARDS, hepatic failure, cerebral edema

Management	Details
Activate EMS	Immediately
Aggressive cooling	Priority #1 (goal: core temp <102F / 38.9C within 30 min)
Cold water immersion	Best method (bucket/tub of ice water, 35-59F / 2-15C)
Evaporative cooling	Spray water + fan across body (if immersion not possible)
Ice packs	Neck, axillae, groin, behind knees
Cold IV fluids	1-2 L cold (4C) normal saline
Stop cooling at	102F (38.9C) to prevent overshoot hypothermia
ABCs	Airway, breathing, circulation support
Seizure management	Benzodiazepines
Transport	Rapid transport to definitive care

Risk Factors for Heat Illness

Risk Factor	Mechanism
Age extremes (young <4, elderly >65)	Reduced thermoregulatory capacity
Obesity	Increased heat production, reduced dissipation
Dehydration	Reduced sweating capacity
Cardiovascular disease	Impaired cardiac output for skin perfusion
Anticholinergics	Reduce sweating
Beta-blockers	Reduce cardiac response
Diuretics	Cause dehydration
Antipsychotics	Anticholinergic effect, impair hypothalamic function
Alcohol	Increases fluid loss, impairs judgment
High humidity	Reduces evaporative cooling (sweating ineffective)

Hypothermia

Stage	Core Temperature	Symptoms
Mild	32-35C (89.6-95F)	Shivering, cold diuresis, increased HR/RR, poor coordination, apathy
Moderate	28-32C (82.4-89.6F)	Shivering stops, confusion, dysarthria, bradycardia, dilated pupils
Severe	<28C (82.4F)	Unconscious, no shivering, areflexia, pulmonary edema, V-fib arrest
Profound	<24C (75.2F)	Apnea, asystole, apparent death

Hypothermia Management

Stage	Rewarming Method
Mild	Passive external rewarming: warm environment, blankets, warm PO fluids
Moderate	Active external rewarming: forced warm air (Bair Hugger), warm blankets, warm-water bottles (axillae/groin)
Severe	Active internal rewarming: warmed IV fluids (42C), heated humidified oxygen, warm peritoneal/pleural lavage, ECMO

Key Principles in Severe Hypothermia

Principle	Detail
Handle gently	Rough movement can precipitate V-fib
No CPR if pulse present	Check for 30-60 seconds (bradycardia may be extreme)
CPR if no pulse	Continue during rewarming
You’re not dead until you’re warm and dead	Successful resuscitation after prolonged hypothermia with good neurologic outcome
Defibrillation	May be ineffective below 30C; limit to 3 shocks, then rewarm
Medications	Ineffective below 30C; withhold until above 30C
Transport	Continue rewarming en route

Frostbite

Degree	Depth	Appearance	Sensation
First degree	Epidermis	Erythema, edema, white plaque	Numb, then burning
Second degree	Dermis	Blisters (clear fluid), erythema, edema	Numb, then pain
Third degree	Subcutaneous	Hemorrhagic blisters, necrosis	Numb
Fourth degree	Muscle, bone, tendon	Black, mummified eschar	No sensation

Frostbite Management

Phase	Action
Pre-thaw	Remove wet/constrictive clothing; protect from further cold
Thawing	Rapid rewarming in water bath 37-39C (98.6-102.2F) for 15-30 min
Do NOT	Rub or massage (causes further tissue damage)
Do NOT	Use dry heat (uneven heating, burn risk)
Post-thaw	Blister management: debride clear blisters, leave hemorrhagic intact
Medications	Ibuprofen (anti-prostaglandin), tetanus prophylaxis, wound care
Surgical	Amputation delayed (demarcation may take weeks-months)
Adjunctive	TPA for severe cases (within 24 hours), iloprost, sympathetic blockade

Trench Foot (Immersion Foot)

Aspect	Details
Cause	Prolonged wet + cold (above freezing) conditions
Onset	12+ hours of wet feet
Symptoms	Tingling, numbness, pain, swelling, redness, blisters
Treatment	Clean, dry, elevate, warm gradually
Prevention	Keep feet dry, change socks regularly

Drowning

Drowning Classification

Term	Definition
Drowning	Process resulting in primary respiratory impairment from submersion/immersion in liquid
Fatal drowning	Death from drowning
Non-fatal drowning	Survival (with or without morbidity)
Rescued	No respiratory impairment (not drowning)
Dry drowning	Laryngospasm without aspiration (rare, <10-15%)
Wet drowning	Aspiration of fluid into lungs

Pathophysiology of Drowning

Stage	Event
1	Panic, breath-holding
2	Involuntary gasping under water
3	Aspiration of water into larynx -> laryngospasm
4	Hypoxia, loss of consciousness
5	Laryngospasm relaxes -> aspiration of water into lungs
6	Cardiac arrest from hypoxia

Drowning Management

Step	Action
1	Rescue from water (protect rescuer’s safety)
2	Assess responsiveness, breathing
3	Call 911
4	If not breathing: give 2 rescue breaths (even in water)
5	Begin CPR (30:2) if no pulse
6	If spinal injury suspected: immobilize C-spine
7	Remove wet clothing, cover with blanket
8	Transport to hospital (even if recovered)
9	Hospital: respiratory support, treat aspiration pneumonia, manage ARDS, therapeutic hypothermia

Special Considerations

Aspect	Detail
Water type	Fresh water: washes surfactant -> atelectasis; Salt water: draws fluid into alveoli -> pulmonary edema
Chlorine	May cause chemical pneumonitis
Cold water	May provide protective hypothermia (improves neurologic outcome)
Secondary drowning	Pulmonary edema develops hours after initial rescue
Prevention	Supervision, fence pools, swimming lessons, life jackets

Altitude Illness

Altitude Classification

Altitude	Category	Physiological Effects
1,500-2,500m (5,000-8,000 ft)	High	Mild hyperventilation, increased urine output
2,500-3,500m (8,000-11,500 ft)	Very high	AMS possible, sleep disruption
3,500-5,500m (11,500-18,000 ft)	Extremely high	AMS, HACE, HAPE risk
>5,500m (>18,000 ft)	Death zone	Severe deterioration, no long-term survival

Acute Mountain Sickness (AMS)

Symptom	Onset	Management
Headache (required for diagnosis)	6-12 hours after arrival	Acetaminophen/ibuprofen
Nausea/vomiting	6-12 hours	Antiemetics
Fatigue/weakness	6-12 hours	Rest, descend
Dizziness/lightheadedness	6-12 hours	Descend if severe
Sleep disturbance	6-12 hours	Acetazolamide

AMS Score (Lake Louise)	Criteria
0	No symptoms
1-2	Mild: headache + one other symptom, normal activities
3-4	Moderate: headache + other symptoms, reduced activity
5+	Severe: incapacitating, cannot ascend

High Altitude Cerebral Edema (HACE)

Feature	Details
Definition	Life-threatening progression of AMS with neurologic involvement
Symptoms	Severe headache, ataxia (gait instability), confusion, hallucinations, seizures, coma
Signs	Papilledema, focal neurologic deficits, altered mental status
Treatment	IMMEDIATE DESCENT (500-1000m minimum)
Adjunctive	Dexamethasone 8 mg PO/IM/IV then 4 mg q6h; supplemental O2; portable hyperbaric chamber (Gamow bag)
Prevention	Slow ascent, acetazolamide prophylaxis

High Altitude Pulmonary Edema (HAPE)

Feature	Details
Definition	Non-cardiogenic pulmonary edema from exaggerated hypoxic pulmonary vasoconstriction
Risk factors	Rapid ascent, cold, prior HAPE, male sex, respiratory infection
Symptoms	Dyspnea at rest, cough (dry -> pink frothy sputum), reduced exercise tolerance
Signs	Tachycardia, tachypnea, cyanosis, rales/crackles, O2 sat <70%
Treatment	IMMEDIATE DESCENT; supplemental O2 (target SpO2 >90%); nifedipine 30 mg ER q12h; portable hyperbaric chamber
Prevention	Slow ascent, acetazolamide, nifedipine for susceptible individuals

Altitude Illness Prevention

Strategy	Recommendation
Ascent rate	Above 2,500m: ascend no more than 300-500m (1,000-1,600 ft) per day
Rest day	Every 3rd day at same altitude
“Climb high, sleep low”	Ascend during day, descend to sleep
Acetazolamide (Diamox)	125-250 mg PO BID, starting 1 day before ascent, continuing 2 days at highest
Dexamethasone	4 mg PO q6h for prevention (second-line if acetazolamide intolerant/contraindicated)
Hydration	Adequate fluid intake
Avoid	Alcohol, sedatives, tobacco, heavy exertion first 48 hours

Lightning Injuries

Mechanisms of Lightning Injury

Mechanism	Description	Frequency of Injury
Direct strike	Lightning directly hits victim	3-5%
Side flash (splash)	Current jumps from primary strike to nearby victim	15-25%
Contact voltage	Current travels through object victim is touching	5-10%
Step voltage (ground current)	Current spreads through ground, enters victim through feet	40-50%
Blunt trauma	Explosive force from thunder shockwave	Common associated injury

Lightning Injury Classification

Severity	Characteristics
Mild	Confusion, amnesia, temporary hearing loss, superficial burns
Moderate	Loss of consciousness, seizure, transient paralysis (keraunoparalysis), tinnitus, minor burns
Severe	Cardiac arrest, coma, intracranial hemorrhage, fractures, deep burns, death

Keraunoparalysis

Feature	Details
Definition	Transient paralysis from lightning strike
Mechanism	Sympathetic nervous system over-activation causing vasospasm
Duration	Minutes to hours
Characteristics	Blue, mottled, pulseless extremities (usually lower); resolves spontaneously
Differentiate from spinal injury	Keraunoparalysis resolves; spinal injury does not

Lightning Strike Management

Step	Action
1	Ensure scene safety (lightning continues to strike)
2	Triage: reverse triage (treat the “dead” first; respiratory/cardiac arrest can survive)
3	ABCs: many victims have primary respiratory arrest -> secondary cardiac arrest
4	CPR: if no pulse, start immediately
5	Defibrillation: V-fib/VT as per ACLS
6	Immobilize spine (blunt trauma + fall)
7	Burns: treat as thermal burns
8	Ophthalmologic exam (cataracts can develop)
9	Neurologic assessment (memory, cognition, neuropathy)
10	Observation: cardiac monitoring for 24 hours if abnormal ECG

Lightning Safety

Rule	Detail
30-30 rule	When time between lightning and thunder <30 seconds, seek shelter; wait 30 minutes after last thunder
Safe shelter	Substantial building with plumbing/wiring; hard-topped metal vehicle
Unsafe shelter	Open structures (picnic shelters, dugouts), vehicles without hard tops
Position if trapped	Crouch low, minimize ground contact, remove metal objects
Avoid	Open fields, high ground, isolated trees, water, metal fences, umbrellas
Group dispersion	Spread out at least 15-20 feet apart to reduce multiple casualties