INTRODUCTION: Exertional heatstroke (EHS) is a life-threatening condition that requires quick recognition and cooling for survival. Experts recommend using cooling modalities that reduce rectal temperature (T_REC) faster than 0.16°C/min though rates above 0.08°C/min are considered “acceptable.” Hyperthermic individuals treated in body bags filled with ice water (∼3°C) have excellent cooling rates (0.28 ± 0.09°C/min). However, clinicians may not have access to large amounts of ice or ice water when treating EHS victims. The purpose of this study was to determine if using a body bag filled with water near the upper limits of expert recommendations for EHS treatment would produce acceptable (>0.08°C/min) or “ideal (>0.16°C/min)” T_REC cooling rates or different nadir values.

METHODS: A total of 12 individuals (9 men, 3 women; age: 21 ± 2 yr; mass: 74.6 ± 10.2 kg; height: 179.5 ± 9.6 cm) exercised in the heat until T_REC was 39.5°C. They lay supine while 211.4 ± 19.5 L of 10°C (Ten) or 15°C (Fifteen) water was poured into a body bag. Subjects cooled until T_REC was 38°C. They exited the body bag and rested in the heat for 10 min.

RESULTS: Subjects exercised in similar conditions and for similar durations (Ten = 46.3 ± 8.6 min, Fifteen = 46.2 ± 7.8 min). T_REC cooling rates were faster in Ten than Fifteen (Ten = 0.18 ± 0.07°C/min, Fifteen = 0.14 ± 0.09°C/min). T_REC nadir was slightly higher in Fifteen (37.3 ± 0.2°C) than Ten (37.1 ± 0.3°C).

DISCUSSION: Body bag cooling rates met expert definitions of acceptable (Fifteen) and ideal (Ten) for EHS treatment. This information is valuable for clinicians who do not have access to or the resources for ice water cooling to treat EHS.

Miller KC, Amaria NY. Body bag cooling with two different water temperatures for the treatment of hyperthermia. Aerosp Med Hum Perform. 2024; 95(4):194–199.