PHTLS Environmental Trauma (Hypothermia, Heat Emergencies, and Drowning) — Questions and Answers
Question 1: A backcountry skier is found unresponsive with a core temperature of 28°C (82.4°F) and is in ventricular fibrillation. According to current resuscitation guidelines taught in PHTLS, what is the correct immediate action?
- Attempt defibrillation up to 3 times, then defer further shocks until rewarming above 30°C (Correct answer)
- Do not defibrillate — hypothermic VF cannot be converted and defibrillation is contraindicated
- Administer amiodarone IV before any defibrillation attempt
- Begin CPR and transport without defibrillation until the patient reaches hospital
Correct answer: Attempt defibrillation up to 3 times, then defer further shocks until rewarming above 30°C
Current guidelines support up to 3 defibrillation attempts in severely hypothermic patients in VF. If VF persists below 30°C, further shocks are deferred until rewarming has raised the core temperature, as the cold myocardium is resistant to cardioversion. The principle is 'not dead until warm and dead.' CPR should continue throughout transport.
Question 2: Which two clinical findings best allow a PHTLS provider to distinguish severe hypothermia from mild hypothermia in the field without a thermometer?
- Skin color and capillary refill time
- Cessation of shivering and declining level of consciousness (Correct answer)
- Heart rate below 60 and systolic BP below 90
- Absence of peripheral pulses and fixed pupils
Correct answer: Cessation of shivering and declining level of consciousness
Shivering is the body's active thermogenic mechanism and ceases at approximately 30–32°C as the hypothermia progresses beyond the body's ability to compensate. The simultaneous decline in level of consciousness at this temperature range marks the transition to severe hypothermia. These two clinical signs are more field-accessible than any vital sign measurement.
Question 3: A construction worker is found with hot, dry skin, confusion, and a core temperature of 41°C (105.8°F). What is the HIGHEST treatment priority?
- Establish IV access and administer a fluid bolus
- Apply supplemental oxygen and transport without active cooling
- Begin rapid active cooling immediately (Correct answer)
- Assess and stabilize the airway before any cooling measures
Correct answer: Begin rapid active cooling immediately
This presentation is classic heat stroke — hyperthermia with CNS dysfunction (confusion) and anhidrosis. Rapid active cooling is the definitive field treatment and is time-critical; neurological injury accumulates with each minute at elevated core temperature. Cooling with ice packs to the neck, axillae, and groin (or cold water immersion if available) must begin immediately and continue during transport.
Question 4: A near-drowning victim is pulled from cold water, is apneic, and has no palpable pulse. Which action takes HIGHEST priority according to PHTLS principles?
- Rewarm the patient before initiating CPR to optimize cardiac response
- Begin CPR immediately — do not delay resuscitation for rewarming (Correct answer)
- Assess for spinal injury before moving the patient from the water
- Suction the airway for 90 seconds to clear aspirated water before ventilating
Correct answer: Begin CPR immediately — do not delay resuscitation for rewarming
CPR must begin immediately in submersion victims in cardiac arrest regardless of water temperature. Cold water submersion may be neuroprotective, reinforcing — not reducing — the urgency of resuscitation. Spinal immobilization concerns do not supersede CPR in a pulseless patient. Suctioning beyond clearing visible obstruction delays ventilation unnecessarily.
Question 5: Passive rewarming alone (removing wet clothing, dry insulating blankets, shelter from wind) is the appropriate field rewarming strategy for which hypothermia category?
- Core temperature below 28°C — the patient needs passive rewarming only
- Core temperature 28–32°C — moderate hypothermia
- Core temperature above 32°C — mild hypothermia where the patient is still shivering (Correct answer)
- Passive rewarming is never appropriate in the field
Correct answer: Core temperature above 32°C — mild hypothermia where the patient is still shivering
Passive rewarming is appropriate when the patient is in mild hypothermia (core >32°C) and is still shivering — meaning they retain the capacity to generate their own heat. Severe hypothermia (core <30°C) requires active external rewarming and expedited transport to a facility capable of active internal rewarming (warm IV fluids, cardiopulmonary bypass).
Question 6: Which feature MOST reliably distinguishes heat exhaustion from heat stroke in a field setting?
- Heat exhaustion causes anhidrosis (dry skin); heat stroke causes diaphoresis
- Heat exhaustion is associated with normal or near-normal mentation; heat stroke involves CNS dysfunction (Correct answer)
- Heat stroke presents with a higher heart rate than heat exhaustion
- Heat exhaustion affects only younger patients; heat stroke affects only the elderly
Correct answer: Heat exhaustion is associated with normal or near-normal mentation; heat stroke involves CNS dysfunction
The defining feature that separates heat stroke from heat exhaustion is CNS involvement. Heat exhaustion patients have intact or near-intact mentation and are typically still diaphoretic. Heat stroke patients have altered mental status (confusion, agitation, coma) and often anhidrosis. This distinction drives the urgency of active cooling, which is critical in heat stroke and less urgent in heat exhaustion.
PHTLS Environmental Trauma (Hypothermia, Heat Emergencies, and Drowning)
A backcountry skier is found unresponsive with a core temperature of 28°C (82.4°F) and is in ventricular fibrillation.
According to current resuscitation guidelines taught in PHTLS, what is the correct immediate action?