Does Gender Affect Rectal Temperature Cooling Rates? A Critically Appraised Topic

Exertional heat stroke (EHS) is a medical emergency characterized by body core temperatures >40.5°C and central nervous system dysfunction. An EHS diagnosis should be immediately followed by cold-water immersion (CWI). Ideally, EHS victims cool at a rate >0.15°C/min until their temperature reaches 38.9°C. While generally accepted, these EHS treatment recommendations often stem from research that examined only males. Since gender differences exist in anthropomorphics (eg, body surface area, lean body mass) and anthropomorphics impact CWI cooling rates, it is possible that CWI cooling rates may differ between genders. Do CWI rectal temperature (T_rec) cooling rates differ between hyperthermic males and females? The average T_rec cooling rate across all examined studies for males and females was 0.18 (0.05) and 0.24 (0.03)°C/min, respectively. Hyperthermic females cooled ∼33% faster than males. Hyperthermic females cooled faster than males, most likely because of higher body surface area to mass ratios and less lean body mass. Regardless of gender, CWI is highly effective at lowering T_rec. Clinicians must be able to treat all EHS victims, regardless of gender, with CWI, given its high survival rate when implemented appropriately. Moderate evidence (2 level 3 studies) suggests that females cool faster than males when treated with CWI following severe hyperthermia. Despite gender differences, cooling rates exceeded cooling rate recommendations for EHS victims (ie, 0.15°C/min).