Newsletters

POSTED: October 14th, 2022
POSTED IN: EM Pulse - The Official Newsletter of MOCEP, September/October 2022,

Kelly Sinclair, MD, FAAP, FACEP
Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Associate Professor of Pediatrics, University of Kansas School of Medicine

During summer months, heat related illness in children is a significant medical concern. In 2021 there were 23 deaths from heat stroke in children left in a hot car. While heat stroke is the extreme of heat related illnesses, there are many other medical conditions seen in hot and humid environments. The body temperature in children when outside in the heat may rise three to five times faster when compared to an adult. Living in the Midwest, humidity plays a significant factor and increases the risk of heat related illness.

Heat related illness is caused by the outdoor temperature, the inability of a person to dissipate heat or both. Children rely primarily on evaporation to disperse heat and cool down when it is hot outside. Once the relative humidity is over 75%, evaporation is much less effective as sweat on the skin no longer functions to cool a child off. Children have a larger surface area to mass ratio allowing more absorption of heat from the environment. Along with their higher metabolic rate and lower blood volumes when compared to adults, children are at increased risk in these hot and humid summer months.

Heat related illness comes in many forms. Miliaria rubra, or prickly heat, is most common in infants and young children. Obstruction of sweat ducts in the skin leads to this raised, erythematous rash that is often times itchy. Loose clothing and limiting skin emollients or lotions may prevent heat rash. Treatment is not necessary as it resolves spontaneously but often times symptomatic care for the puritis makes children more comfortable.

Heat edema, although more common in the elderly, is seen in children. This presents as swelling in the lower extremities due to vasodilation and venostasis. Moving to a cooler environment and elevating the legs will help resolve the edema.

Heat cramps may be associated with an increase in body temperature (>38 C but <40 C). Cramping is typically in large muscle groups – legs, arms and less frequently abdomen. This is seen after moderate to intense exercise in a hot environment and felt to be due to sodium depletion from sweating. Drinking sodium containing products such as sports drinks and stretching in addition to moving to a cooler environment helps treat the cramping.

Heat syncope is seen with a normal core temperature along with dizziness and orthostatic hypotension. This is seen more often in the poorly acclimatized, elderly or chronically ill. Staying out of the heat, drinking lots of fluids and lying supine will make patients feel better and improve symptoms within about 30 minutes.

Heat exhaustion is due to water and/or salt depletion. Body temperature is elevated, but <40 C. Tachycardia, nausea, vomiting, syncope, dizziness and confusion accompany mild to moderate dehydration. Confusion is mild and resolves quickly when the patient is in a cool environment and given liquids to rehydrate. Heat exhaustion may progress to heat stroke and patients should be observed. If vital signs and confusion does not self-resolve, patients should be seen in an emergency department.

When temperatures and humidity are high outside, it is best to take precautions to ensure safety. Activities should be restricted based on heat index and age. Staying in the shade or in an air conditioned environment are helpful. Drinking salt containing fluids, water and sports drinks prevent dehydration. Loose, wicking and light colored clothing is helpful. Acclimatizing to hot and humid environments is also important and may take as long as 14 days in younger children. Patients with heat related symptoms that are unresolved in 30 minutes or worsening should seek emergency care.

References:

Council on Sports Medicine and Fitness and Council on School Health, Bergeron MF, Devore C, et al. Policy Statement- Climatic heat stress and exercising children and adolescents. Pediatrics 2011; 128:e741.

Xu Z et al. Impact of ambient temperature on children’s health: a systematic review. Environ Res 2012; 117-120.

Lipman GS et al. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2019 Update. Wilderness Environ Med 2019; 3-:S33.

Jardine DS. Heat illness in children. Pediatr Rev 2007; 28:249.