Hypothermia following cold-water immersion treatment for exertional heat illness

Cold-water immersion (CWI) is the gold standard therapy for exertional heat illness (EHS), and it is critical to perform CWI expeditiously when the core temperature exceeds 40°C; however, the treatment comes with risks, most notably hypothermia. Following a major marathon, three runners presented to our emergency department (ED) with symptomatic mild hypothermia requiring re-warming. Prior to developing hypothermia, all three were treated at the racecourse with CWI for EHS. During CWI, there are monitoring methods to determine appropriate cessation: continuous temperature measurement, regular temperature checks, using an equation to predict immersion time, and symptom observation. There is no consensus on the best system, but a monitoring method should be used to prevent over-cooling. This case series illustrates the importance of proper CWI execution in order to avoid harm.