Heat Related Disorders: Signs, Treatments and Prevention
15 Aug. 2015 – Heat related disorders occur when thermoregulatory mechanisms fail to compensate for elevations in core temperature caused by environmental or metabolic heat load.
See related article: How the heat can influence the Body
Heat related disorders might encompass a wide spectrum of symptoms of varying severity, ranging from heat cramps and dehydration to heat exhaustion and life-threatening heat stroke.
Heat cramps, the least serious type of heat related disorders, are caused by loss of sodium and potassium associated with heavy sweating in unacclimatised individuals.
- Signs/symptoms: painful skeletal muscle spasms, primarily of the muscles most heavily used during exercise (e.g. calves, abdomen).
- Treatment: move individual to a cooler location and administer fluid/electrolyte solutions or a saline solution, generally taken orally.
- Prevention: adequate fluid/electrolyte replacement, added salt to food; eat a balanced, high K+ diet.
Dehydration commonly accompanies exercise in warm, humid conditions, when fluid replacement is inadequate. It complicates heat exhaustion and heat stroke.
- Signs/symptoms: fatigue, lethargy, irritability, loss of coordination, faintness, altered consciousness.
- Treatment: cool fluids; dilute electrolyte solutions.
- Prevention: pre-hydrate; adequate fluid replacement during activities.
Heat exhaustion is a serious heat illness caused by increased exercise heat load plus dehydration. The pathophysiology of heat exhaustion is the inability of the cardiovascular system to adequately supply blood to organs, especially to the brain.
- Signs/Symptoms: “core” (rectal) temperature elevated, usually not above 39.5oC (103oF); “goose flesh”, headache, lethargy, fatigue, dizziness, fainting, hypotension, rapid pulse, altered consciousness, nausea, vomiting, incoordination.
- Move to a cool, shaded area.
- Remove excess clothing.
- Elevate feet to avoid shock
- Begin immediate cooling with cold or iced cloths, sponges, etc. to torso, axillae, groin, other exposed areas.
- Begin hydrations with cool fluids, orally if possible, otherwise start IV fluids (Dextrose/0.5N saline).
- Monitor vital signs, rectal temperature if possible.
- Transfer to hospital, when unconscious or incomplete response to therapy.
- Avoid competition under adverse conditions, or adjust pace to existing conditions.
- Utilise acclimatisation measures prior to competition.
- Pre-hydrate; emphasise hydration during the competition.
- Wear appropriate clothing, which will “breathe” and allow sweat to evaporate.
Heat stroke, a life-threatening heat-related disorder and a medical emergency, is difficult to distinguish from heat exhaustion because sweating may continue. Heat stroke represents thermoregulatory failure, with reduction in skin blood flow in order to maintain the central circulation. Core temperature is more elevated, usually 40oC or higher.
- Signs/symptoms: core temperature exceeding 40oC, cessation of sweating, rapid pulse, rapid respiration, hypotension, CNS symptoms predominate: unsteady gait, confusion, combative behaviour, reduced consciousness, convulsion, and coma. These signs and symptoms represent a medical emergency.
- Move to a cool, shaded area. Lay down with feet elevated.
- Loosen or remove clothing.
- Begin cooling at once. In the field, it may be necessary to assume that temperature is elevated, as taking a rectal temperature may not be feasible. Oral or axillary temperature is quite unreliable. Apply cool water, and fan to increase evaporation. Apply ice packs over major vessels in neck, axillae, groin. Cool to a rectal temperature of 39oC (102oF).
- Start IV fluids (Normal saline)
- Evacuate to a medical facility as early as possible. Manage as a medical emergency, with monitoring of cardiac, neurologic, and renal function, and electrolyte balance.
Documents Source: IAAF