The guideline also reviews evidence for different techniques for treating heat illness, mostly focused around which ones can most rapidly and safely drop the core temperature. Field treatment teams should focus first on the basic resuscitation principles of stabilizing the airway, breathing, and circulation, then focus on measuring, then lowering the patient’s temperature. When concerned about core temperature, measure it like you mean it: rectally if at all possible.
Passive cooling techniques limit heat exposure and promote natural heat loss—getting the patient into a cooler environment and isolated from hot surfaces like pavement. These are important steps for everyone’s safety but have relatively little evidence to prove their efficacy.
Active cooling techniques remove heat from the body by direct interventions. These are best done after removing all equipment and loosening clothing. Cold water immersion is the fastest method to drop the core temperature. A slurry of water and ice can also be wrapped against the patient in a tarp if an immersion bath is not practical. If using immersion in a body of water, protecting the airway against aspiration is of paramount importance. If cold-water immersion is not available, then evaporative cooling with misting and fanning is the next best thing, about half as effective as immersion, when it is done with a good breeze and maximized skin exposure. If using chemical cold packs, put them on the face, palms, and soles instead of the neck, groin, or armpits. Antipyretic drugs such as aspirin or acetaminophen do not help—save them for the headache your team will have after transferring the patient to a hospital.
If practicing in a hospital setting, consider establishing protocols to use conductive cooling with cold-water immersion. This approach is the most effective, but may be impractical in the elderly critically ill patient. Your team may love it though, for treating multiple patients arriving from a high-risk event such as a hot-weather road marathon. Just imagine it—a dozen icy tarp tacos with coolers of ice in the ambulance bay sounds much nicer than twelve crazed, combative athletes in the main ED who need to be sedated, intubated, then have cooling lines placed—everyone on the team, from the chief medical officer to your inventory staff, hates the second plan. Let’s all give peace, and ice, a chance.
Lipman GS, Gaudio FG, Eifling KP, Ellis MA, Otten EM, Grissom, CK. Wilderness Medical Society clinical practice guidelines for the prevention and treatment of heat illness: 2019 update. Wilderness Environ Med. 30(4S):S33–46.