Effect of cold and warm water ingestion on physiological and performance parameters during simulated hot burn surgeries

This study assessed the effects of hydration and hydration/cooling on various psycho-physiological and cognitive responses in staff during a simulated burns surgery. Twelve participants completed three 2.5-h trials in the heat (33.6°C, 36.4% RH) whilst walking on a treadmill at a rating of perceived exertion of 12 on the Borg scale. Trials consisted of: i) ingestion of 37°C water (HYD); ii) ingestion of 5°C water (COLD); and iii) a no cooling/hydration control (CON). Water ingestion (0.9% of body-mass) was based on fluid loss calculated during a previous 2.5-h burn surgery. Results demonstrated that while treadmill distance was similar between trials (<i>p</i> > 0.05), cold water ingestion resulted in improved manual dexterity (<i>p</i> = 0.03), better thermal comfort (<i>p</i> < 0.01) and lower core and skin temperatures (<i>p</i> < 0.01), compared to CON. Skin temperature was also lower in COLD vs HYD (<i>p</i> < 0.01). Moderate to large effect sizes (ES, <i>g</i> = 0.38-0.77) were observed in favor of COLD versus CON and/or HYD for manual dexterity, counting span, grammatical reasoning and several perceived workload subsets at various time points, however associated 95% confidence intervals were wide and crossed zero, suggesting statistical uncertainty. Similarly, moderate to large ES (<i>g</i> = 0.45-0.77) favored HYD over CON for counting span (120 min) and various perceived workload outcomes, though again confidence intervals suggest that these effects were not statistically conclusive. No differences were observed between trials for sweat loss, thermal sensation, or heart-rate (<i>p</i> > 0.05). Overall, cold water ingestion resulted in benefit to numerous variables assessed here. Small boluses of cold water ingestion are recommended during hot burn surgeries.