Objective: To examine whether non-heat acclimatized (NHA) emergency responders endure greater physiological and perceptual strain than heat acclimatized (HA) counterparts in tropical field settings.
Methods: Eight HA and eight NHA men urban search and rescue personnel had physiological and perceptual responses compared during the initial 4 hours shift of a simulated disaster in tropical conditions (ambient temperature 34.0 °C, 48% relative humidity, wet bulb globe temperature [WBGT] 31.4 °C).
Results: From the 90th minute through to end of shift, HA (38.5 °C) sustained a significantly higher gastrointestinal temperature than NHA (38.1 °C) (mean difference 0.4 ± 0.2 °C, 95% confidence interval [CI] 0.2 to 0.7 °C, P = 0.005) despite comparable heart rate (P = 0.30), respiratory rate (P = 0.88), and axilla skin temperature (P = 0.47). Overall, perception of body temperature was similar between cohorts (P = 0.87).
Conclusions: The apparent tolerance of greater physiological strain by HA responders occurred in the absence of perceptual differences.
National Critical Care and Trauma Response Centre, Level 8 Royal Darwin Hospital (Dr Brearley), Tiwi, NT, Australia; World Health Organisation (Dr Norton), Geneva, Switzerland; Queensland Fire and Emergency Services (Mr Rush, Mr Smith), Cannon Hill, Queensland; Northern Territory Fire and Rescue Service (Mr Hutton), Darwin, Northern Territory; Menzies School of Health Research (Ms Ward), Tiwi, Northern Territory; Princess Alexandra Hospital (Dr Fuentes), Woolloongabba, Queensland, Australia.
Address correspondence to: Matt B. Brearley, PhD, National Critical Care and Trauma Response Centre, Level 8 Royal Darwin Hospital, Rocklands Drive, Tiwi 0810, Australia (email@example.com).
This project was funded by a Trauma and Disaster Management (TRADIM) research grant.
The authors were funded by their respective employers and have no conflict of interest to declare.