Abstract
Cooling vests alleviate heat strain. We quantified the perceptual and physiological heat strain and assessed the effects of wearing a 21°C phase change material cooling vest on these measures during work shifts of COVID-19 nurses wearing personal protective equipment (PPE). Seventeen nurses were monitored on two working days, consisting of a control (PPE only) and a cooling vest day (PPE + cooling vest). Sub-PPE air temperature, gastrointestinal temperature (T(gi)), and heart rate (HR) were measured continuously. Thermal comfort (2 [1-4] versus 1 [1-2], p(condtition) < 0.001) and thermal sensation (5 [4-7] versus 4 [2-7], p(condition) < 0.001) improved in the cooling vest versus control condition. Only 18% of nurses reported thermal discomfort and 36% a (slightly) warm thermal sensation in the cooling vest condition versus 81% and 94% in the control condition (OR (95%CI) 0.05 (0.01-0.29) and 0.04 (<0.01-0.35), respectively). Accordingly, perceptual strain index was lower in the cooling vest versus control condition (5.7 ± 1.5 versus 4.3 ± 1.7, p(condition) < 0.001, respectively). No differences were observed for the physiological heat strain index T(gi) and rating of perceived exertion across conditions. Average HR was slightly lower in the cooling vest versus the control condition (85 ± 12 versus 87 ± 11, p(condition) = 0.025). Although the physiological heat strain among nurses using PPE was limited, substantial perceptual heat strain was experienced. A 21°C phase change material cooling vest can successfully alleviate the perceptual heat strain encountered by nurses wearing PPE.