Heat illness is prevalent around this time of year. And compared to hypothermia, hyperthermia has a lower threshold for danger. From heat cramps to heat stroke, clinicians need to know how to identify and treat each stage appropriately. But what contributes to severe heat illness? How do we treat each stage of illness? And how much time do we have before it becomes fatal? From Texan turned Aussie, we are joined by Dr. Justin Hensley, Flight Physician, to discuss.
Myth: “Load and go”, so these patients can can be rapidly cooled at the receiving facility.
Truth: Transport should be delayed to initiate rapid cooling within the 1st 60 minutes of exposure.
Myth: Ice packs should be placed in the groin and axilla for cooling.
Truth: Ice packs should be placed on the palms of the hands, soles of the feet, and cheeks for cooling.
Myth: Exertional hyperthermia should be treated with Dantrolene and antipyretics.
Truth: Exertional hyperthermia is not malignant hyperthermia or sepsis and should be treated with active cooling.
Myth: Water has to be ice cold to initiate cooling.
Truth: Water only has to be below core body temperature to initiate cooling.
Myth: ECMO can cool faster than an ice bath.
Hyperthermia: A rise in body temperature above the hypothalamic set point when heat-dissipating mechanisms are impaired (by clothing or insulation, drugs, or disease) or overwhelmed by external (environmental) or internal (metabolic) heat production.
Heat edema: Dependent extremity swelling due to interstitial fluid pooling.
Heat cramps: Exercise-associated painful involuntary muscle contractions during or immediately after exercise.
Heat syncope: Transient loss of consciousness with spontaneous return to normal mentation.
Heat exhaustion: Mild to moderate heat illness due to exposure to high environmental heat or strenuous physical exercise; signs and symptoms include intense thirst, weakness, discomfort, anxiety, dizziness, syncope; core temperature may be normal or slightly elevated >37°C (98.6°F) but <40°C (104°F).
Heat stroke: Severe heat illness characterized by a core temperature >40°C (104°F) and central nervous system abnormalities such as altered mental status (encephalopathy), seizure, or coma resulting from passive exposure to environmental heat (classic heat stroke) or strenuous exercise (exertional heat stroke).
Dr. Justin Hensley is an emergency physician who went to medical school at East Tennessee State University and did his residency at East Carolina University. After residency, he moved to Texas where he worked as an EMS medical director, as well as the medical director for the Padre Island National Seashore and the Texas State Aquarium. He was also the medical director of Region 11 of the Texas Emergency Medical Task Force. He is a Fellow of the Academy of Wilderness Medicine and has worked overseas in rural and remote medicine in Fiji, India, and Mozambique. Recently, he moved to Australia to become a retrieval physician with Sydney HEMS, fulfilling a lifelong goal.
Cooling Effectiveness of a Modified Cold-Water Immersion Method After Exercise-Induced Hyperthermia
Tarp-assisted cooling as a method of whole body cooling in hyperthermic individuals
Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2019 Update