Acute Physiological Responses While Wearing Various Configurations of the MCU-2/PGroundcrew Chemical Defense Mask

摘要

Resistance to breathing is a major factor that determines individual tolerance tophysical work while wearing a protective mask. This study evaluated some of the acute effects associated with the use of the MCU-2/P mask. Three MCU-2/P mask configurations (MC) were tested: mask + 1 filter (MCU-IF), mask + 2 filters in parallel (MCU-2F), and mask + 1 filter + air blower (MCU-lAB). The air blower provided 65 L min-1 (2.3 cfm) of ambient air through the filter. Five subjects pedaled a cycle ergometer at 2 workloads (60 120 watts). Each MC was tested consecutively for 5 min under each workload, for a total of 30 min per experiment. Each subject repeated the experiment three times while randomizing the mask/workload test order. Variables measured included heart rate, respiratory rate, tidal volume, minute volume, inspiratory and expiratory mask cavity pressures, perceived inspiratory expiratory effort, and overall breathing discomfort. The lowest inspiratory resistance was observed with the MCU1AB, followed by MCU-2F and MCU-IF. Subjects experienced less breathing effort and discomfort with the MCU-IAB, followed by a more modest reduction with the MCU-2F. Heart rates, respiratory rates, tidal volumes, and minute volumes showed no correlation with the three levels of inspiratory resistance, but were related to workload. The best approach to reduce the respiratory burden imposed by the MCU-2/P mask is to provide powered ventilation through the filter. Unfortunately, this approach creates logistical problems. A more practical approach may simply be to attach a second filter canister to the mask. Breathing resistance, M17 Mask, MCU-2/P Mask, Physical exercise, Breathing discomfort, Manikin testing, Human testing.