Skin Temperature Feedback Increases Thermoregulatory Efficiency and Decreases Required Microclimate Cooling Power.

摘要

Personal protective equipment (PPE) markedly increases heat strain, reduces work performance, and increases the incidence of heat casualties. Microclimate cooling (MCC) technologies have been successfully used to alleviate this heat strain in mounted soldiers, but cooling limitations, power and weight restrictions do not currently make this technology applicable to dismounted soldiers. This composite of studies investigated the potential for intermittent-regional cooling and skin temperature feedback approaches to better enable MCC systems for the dismounted soldier. PURPOSE: The purposes of this study were to (1) determine, using a variety of intermittent cooling paradigms, the optimal skin temperature for maximizing thermoregulatory efficiency, and (2) examine the potential power savings associated with using biofeedback to maintain optimal skin temperature. METHODS: Two studies were conducted using the same facilities and test equipment. In study one, 5 male soldiers exercised moderately (approximately 500W) in a warm environment (30 deg C, 30%rh) while wearing PPE (clo: 2.1; im/clo: .32) over a water-perfused (21 deg C) liquid MCC garment covering the head, chest, back, and legs (72% of body surface area, BSA). All four body regions were independently controlled. A matrix of six randomized trials was conducted in which conventional MCC (constant perfusion, CP), no MCC (NC), or 4 trials of intermittent and regional (IR1-4) MCC was provided. IR1-4 was time-activated and on:off cooling ratios and the % BSA cooled were systematically varied. In study two, 8 male soldiers were subjected to the same conditions as study one, but only three trials were performed to include CP, IR2 (2 min on: 2 min off, 72% BSA), and skin temperature feedback (STF, 72% BSA) using a skin temperature range of 33-35 deg C. Heart rate (HR), body core (Tc) and skin temperatures (Tsk) were measured at regular intervals in both studies.