What is the Difference Between Exertional Heat Stroke (EHS) and Classical Heat Stroke (CHS)?

Employers within industries that expose employees to high heat have updated guidance to better prepare and protect their workforce from potentially life-threatening conditions. Experts from the Department of Defense, American College of Occupational and Environmental Medicine, and American College of Sports Medicine have highlighted an emphasis on clear, concise, and evidence-based public health messaging on the distinction between symptoms shown during Classical Heat Stroke (CHS) and Exertional Heat Stroke (EHS).

According to the International Labor Organization (ILO), excessive heat exposure at work results in nearly 19,000 fatalities annually and over 2 million disability-adjusted life years (DALYs). Employers who understand the differences between CHS and EHS will be better equipped to significantly mitigate risks, implement effective safety measures, and provide proper prehospital care. New guidance indicates that sweating or the lack of sweating should not be a defining symptom when diagnosing exertional heat stroke. Also, differentiating between fainting (heat exhaustion) and loss of consciousness (heat stroke) can be challenging for untrained individuals, further complicating the need for emergency response.

Exertional heat stroke (EHS) can occur in otherwise healthy individuals (athletes, military, and workers in high-risk environments e.g. agriculture, construction) and is often triggered by prolonged physical exertion, particularly in hot and humid conditions, and develops rapidly as the body overheats and is unable to cool down. EHS is often influenced by motivational factors that influences an individuals’ behavior responses, such as meeting a work deadline or training. Symptoms shown by an individual suffering from EHS include moist, sweaty skin, and a change in mental status – such as confusion, agitation, headache, or loss of consciousness.

To an individual suffering from EHS, rapid cooling is the most effective management strategy, and, with immediate action can be lifesaving. It had previously been believed that cooling in ice water could cause intense vasoconstriction (‘shock’) and delay core cooling, but current understanding has disproven this theory, with most evidence coming from studies on males.

Classical Heat Stroke (CHS) typically affects the ill, the elderly, and those with comorbidities during heat waves. CHS is a condition caused by the body overheating, and usually occurs due to exposure to high temperatures or physical activity in high temperatures for too long. The skin of individuals suffering from CHS is usually hot and dry but can sometimes have moist, sweaty skin.

How Can Adopting the H.A.S.T.E. Mnemonic Help Employers Keep Their Workforce Safe from Heat-Related Exposures?

To enhance awareness, recognition, and response to heat-related emergencies, the Department of Defense, American College of Occupational and Environmental Medicine, and American College of Sports Medicine have created the H.A.S.T.E. acronym to offer a straightforward and effective tool to enhance awareness, recognition, and response to heat-related emergencies and help differentiate between CHS and EHS. By implementing these recommendations, employers can improve outcomes to employees who may be suffering from heat-related illness.