Real-Time Physiological Monitoring While Encapsulated in Personal Protective Equipment

Heat strain was monitored in real-time in soldiers performing chemical, biological, radiological, and nuclear (CBRN) training.  Wearable physiological status monitoring (PSM) systems (EQ-02; Hidalgo, Ltd, Swavesey, Cambridge, UK) were evaluated by nine soldiers from a Civil Support Team – Weapons of Mass Destruction (CST-WMD) team (age, 27.3±4.9 (SD) y; wt, 84.5±15.1 kg; ht, 178.1±10.1 cm).  Seven of these soldiers wore the PSM system during CBRN training and provided subjective feedback regarding the systems utility; two soldiers observed the training exercise and commented on the utility of the PSM system. During CBRN training, participants marched ~1600 m in 45 min while wearing Level A CBRN personal protective equipment (PPE).  A 0-to-10 Physiological Strain Index, i.e., a 0-to-10 index of thermal-work strain, was calculated from estimated core temperature and measured heart rate.  Individual PSI levels varied, with three individuals at a PSI > 8 (high thermal-work strain) and four individuals at a PSI < 8 (moderate strain).  Real-time PSI levels corresponded to the subjective feelings of thermal strain reported by the test volunteers.  In addition, the CST-WMD soldiers reported that real-time PSI information could be used to improve work performance and decrease the likelihood of experiencing heat illness during CBRN missions.