Cooling vests alleviate perceptual heat strain perceived by COVID-19 nurses

Cooling vests can 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 real-life work shifts of COVID-19 nurses wearing personal protective equipment (PPE). 17 nurses were monitored on two working days, consisting of a control (PPE only) and a cooling vest day (PPE + cooling vest). Thermal comfort, thermal sensation, and rating of perceived exertion were scored after each work bout. Sub-PPE air temperature, gastrointestinal temperature (Tgi), and heart rate (HR) were measured continuously. Thermal comfort (2 [1-4] versus 1 [1-2], pcondtition<0.001) and thermal sensation (5 [4-7] versus 4 [2-7], pcondition<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, the perceptual strain index was lower in the cooling vest versus control condition (5.7±1.5 versus 4.3±1.7, pcondition<0.001, respectively). No differences were observed for the physiological heat strain index (pcondition=0.40), average Tgi (pcondition=0.90), peak Tgi (pcondition=0.79), and rating of perceived exertion (pcondition=0.86) across conditions. Average HR was slightly lower in the cooling vest versus the control condition (85±12 versus 87±11, pcondition=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 vests can successfully alleviate the perceptual heat strain encountered by nurses wearing PPE.