Exertional Heat Illness Considerations in the Military

Warfighters, as tactical athletes, confront a wide variety of environmental and physiologic challenges. Unfortunately, despite efforts to mitigate exertional heat illness (EHI), rates have continued to rise. The rate of exertional heat stroke (EHS) cases in the US military in 2017 was 58% higher than in 2013, with highest rates in the Marine Corps and Army. The warfighter is exposed to many specific risk factors, including gear and equipment (often 60–100 lbs.), dietary supplements, powerful motivating factors, sleep deprivation, dehydration, lack of acclimatization due to mission requirements, solo training in remote areas, and leadership factors. Military leaders are expected to proactively implement primary, secondary, and tertiary preventive measures. Primary prevention strategies include hydration, acclimatization, monitoring environmental conditions, and work-rest ratios. Secondary prevention entails reducing risk of progression to EHI after exposure to a heat load. Examples include arm immersion cooling systems, wearable cooling gear, and mist fans. When a warfighter is diagnosed with EHS, immediate and aggressive cooling measures are employed. Cold water immersion or ice slurry dousing have been shown to be extremely effective with zero mortality when initiated within 15–20 minutes. Return to duty is individualized based upon identified risk factors and after treatment for any medical sequelae. EHS patients may return to duty when they have re-established heat tolerance and completed a period of rest followed by progressive heat/exercise exposure. Heat tolerance testing is considered in exceptional cases where the return to duty process has been either difficult or prolonged or a medical evaluation board with potential separation from service is being considered.