Effect of Physical Exertion in Level-C Chemical and Biological Protective Equipment on Physiological Function

Abstract

Introduction:

The objective of this study was to assess the effect of 20 minutes of heavy treadmill exertion in military-style, Level-C chemical and biological personal protective equipment (PPE), including a filtering face piece respirator, on physiological variables including venous pH, venous PCO₂, SpO₂ and tympanic temperature.

Methods:

Baseline physiological variables were measured in 19 healthy subjects who undertook heavy physical exertion on a treadmill at a constant room temperature of 20°C: (1) once while wearing a short-sleeved t-shirt, shorts, and running shoes; and (2) once while wearing chemical and biological PPE. Repeat measurements of physiological variables were made after 10 and 20 minutes of exertion in both groups.

Results:

Twenty minutes of physical exertion was undertaken by healthy subjects wearing chemical and biological PPE resulted in moderate hypoxemia, significantly decreased pH (p = 0.003), elevated PCO₂ (p = 0.018) and elevated tympanic membrane temperature (p < 0.001), compared to baseline values. Despite these significant differences, none of the mean venous blood gas values deviated from the normal range during physical exertion.

Conclusions:

The degree and duration of physical exertion undertaken in chemical and biological PPE induced some significant changes in physiological variables compared to control but, with the exception of SpO₂, did not result in changes considered to represent abnormal physiology. However, it is likely that core body temperature was underestimated by tympanic measurement. Blood gas data indicating that CO₂ was retained during exertion in this type of PPE were unanticipated and require further investigation.