Efficacy Of Impervious Shroud-Assisted Cooling (ISAC) Method Following A Road Race In The Heat

Exertional heat stroke (EHS) has been 100% survivable with proper diagnosis and treatment. While whole-body cold-water immersion (CWI) in a tub is the gold-standard treatment for EHS, it is not feasible in some situations, threatening the prognosis of EHS patients. The efficacy of the impervious shroud-assisted cooling (iSAC) method (i.e., whole-body CWI in a body bag) in lieu of a traditional cooling tub is not fully understood in a field-setting. PURPOSE: To compare cooling-rates of the iSAC method to passive cooling (PC) in hyperthermic individuals following a road race in a hot environment. METHODS: Sixteen healthy active adults (50% women) age (mean ± standard deviation (SD)): 46 ± 12 years-old completed an 11 km road race in the heat. Following the race, participants self-inserted a rectal thermistor for continuous monitoring and were immediately separated into two groups: iSAC or PC. For the iSAC group, participants entered the iSAC and ice water (~1-5 °C) was continuously circulated; cooling ceased upon rectal temperature (Trec) reaching 38.5 °C. Depending on Trec of participants upon entry to the bag, cooling duration ranged from ~5-15 minutes. For PC, participants were asked to remain seated in the shade for ~10-15 minutes. Trec cooling rates (°C per minute) were calculated and independent-samples t-tests were utilized to compare cooling rates and Trec between groups. RESULTS: iSAC cooling rate was significantly higher compared to PC (iSAC: 0.19 ± 0.06 °C per minute; PC: 0.08 ± 0.06 °C per minute, p = 0.002). The mean difference in Trec between PC and iSAC before initiating the interventions was -0.43 °C (p = 0.056), and 0.25 °C (p = 0.25) following the intervention. CONCLUSION: In hyperthermic individuals following a road race in the heat, the iSAC method effectively produced a cooling rate faster than the acceptable threshold (i.e., 0.15 °C per minute). With additional research, the iSAC method may be recommended as an acceptable method of treatment for EHS in emergency and remote settings where CWI in a tub is not feasible. Given its portability and inexpensive cost, the iSAC could be recommended as standard medical equipment in athletic, combat, EMS, and occupational worksites to initiate treatment until a CWI site can be reached and increase survivability from EHS in remote settings.