Gait instability and estimated core temperature predict exertional heat stroke

ObjectiveExertional heat stroke (EHS), characterised by a high core body temperature (Tcr) and central nervous system (CNS) dysfunction, is a concern for athletes, workers and military personnel who must train and perform in hot environments. The objective of this study was to determine whether algorithms that estimate Tcr from heart rate and gait instability from a trunk-worn sensor system can forward predict EHS onset.MethodsHeart rate and three-axis accelerometry data were collected from chest-worn sensors from 1806 US military personnel participating in timed 4/5-mile runs, and loaded marches of 7 and 12 miles; in total, 3422 high EHS-risk training datasets were available for analysis. Six soldiers were diagnosed with heat stroke and all had rectal temperatures of >41°C when first measured and were exhibiting CNS dysfunction. Estimated core temperature (ECTemp) was computed from sequential measures of heart rate. Gait instability was computed from three-axis accelerometry using features of pattern dispersion and autocorrelation.ResultsThe six soldiers who experienced heat stroke were among the hottest compared with the other soldiers in the respective training events with ECTemps ranging from 39.2°C to 40.8°C. Combining ECTemp and gait instability measures successfully identified all six EHS casualties at least 3.5 min in advance of collapse while falsely identifying 6.1% (209 total false positives) examples where exertional heat illness symptoms were neither observed nor reported. No false-negative cases were noted.ConclusionThe combination of two algorithms that estimate Tcr and ataxic gate appears promising for real-time alerting of impending EHS.

Proper Recognition and Management of Exertional Heat Stroke in a High School Cross Country Runner: A Validation Clinical Case Report

A 14-year-old female high school cross country runner (height = 154 cm, mass = 48.1 kg) with no history of exertional heat stroke (EHS) collapsed at the end of a race. An athletic trainer (AT) assessed the patient, who presented with difficulty breathing then other signs of EHS (i.e. confusion, agitation). The patient was taken to the medical area, draped with a towel, and a rectal temperature (Tre) of 106.9°F(41.6°C) was obtained. The emergency action plan was activated and emergency medical services (EMS) were called. The patient was submerged in a cold-water immersion tub until EMS arrived (~15 minutes; Tre = 100.1°F; cooling rate: 0.41°F·min−1[0.25°C·min−1]). At the hospital, the patient received intravenous fluids, and urine and blood tests were normal. The patient was not admitted and returned to running without sequelae. Following best practices, AT's in secondary schools can prevent death from EHS by properly recognizing EHS and providing rapid cooling before transport.

Prehospital management of exertional heat stroke at sports competitions for Paralympic athletes

ObjectivesTo adapt key components of exertional heat stroke (EHS) prehospital management proposed by the Intenational Olympic Committee Adverse Weather Impact Expert Working Group for the Olympic Games Tokyo 2020 so that it is applicable for the Paralympic athletes.MethodsAn expert working group representing members with research, clinical and lived sports experience from a Para sports perspective reviewed and revised the IOC consensus document of current best practice regarding the prehospital management of EHS.ResultsSimilar to Olympic competitions, Paralympic competitions are also scheduled under high environmental heat stress; thus, policies and procedures for EHS prehospital management should also be established and followed. For Olympic athletes, the basic principles of EHS prehospital care are: early recognition, early diagnosis, rapid, on-site cooling and advanced clinical care. Although these principles also apply for Paralympic athletes, slight differences related to athlete physiology (eg, autonomic dysfunction) and mechanisms for hands-on management (eg, transferring the collapsed athlete or techniques for whole-body cooling) may require adaptation for care of the Paralympic athlete.ConclusionsPrehospital management of EHS in the Paralympic setting employs the same procedures as for Olympic athletes with some important alterations.

Exertional heat stroke with reversible severe cerebral edema

Severe cerebral edema associated with exertional heat stroke is a major cause of death or disability. However, few studies on severe cerebral edema resulting from heat stroke have reported neuroradiological findings. Moreover, all the patients in these previous reports either died or remained severely disabled. Here, we report a case of exertional heat stroke with severe cerebral edema that probably developed or worsened due to delayed body temperature normalization. In contrast to previous reports, the patient showed complete clinical and neuroradiological recovery. This rare case suggests that severe cerebral edema could be reversed through meticulous supportive management. Moreover, it confirms the importance of rapid and effective cooling in heat stroke treatment.