Cooling Vests May Ease Clinicians' PPE Heat Strain

By Linda Carroll

January 13, 2021

(Reuters Health) - Nurses who wear cooling vests under their PPE feel less burdened by heat during their shifts, a new study finds.

An analysis of data from seventeen nurses who wore a cooling vest under their PPE on one day and PPE only on another found that the vests led to a slight improvement in body temperature but a much bigger improvement in the sensation of being too hot, according to the report published in Temperature.

"Nurses wearing a cooling vest during a COVID-19 shift experience a substantial reduction of heat stress during their work," said study coauthor, Thijs Eijsvogels, an assistant professor of exercise physiology in the department of physiology at the Radboud University Medical Center.

"This is an important finding, because PPE is known to induce heat stress, which increases fatigue and sensory displeasure, and is known to impair effective decision making," Eijsvogels said in an email. "Hence, the use of cooling vests may extend work tolerance time and improve of recovery of nurses involved in COVID-19 care."

An earlier unpublished survey showed that heat was getting to healthcare workers, Eijsvogels said.

"Among 386 healthcare workers involved in COVID-19 care, we found a high prevalence of thermal discomfort (77%), excessive sweating (64%), thirst/dehydration (81%), headache (57%) and fatigue (59%)," he said. "These findings highlight the need to find and implement effective solutions to reduce heat stress among nurses involved in COVID-19 care."

To explore the possibility that a cooling vest might help nurses wearing full PPE while caring for COVID-19 patients, Eijsvogels and his colleagues recruited 17 volunteers who would wear a cooling vest under PPE one day and PPE alone on another as a control. The volunteers also were asked to swallow an ingestible electronic temperature capsule system to give a continuous reading of core body temperature under each scenario.

Core temperatures measured by the capsules were slightly lower when participants wore the cooling vests: 37.5 degrees C (98.96 F) at the end of the day versus 37.2 degrees C (99.5 F) in the control condition. But thermal comfort and thermal sensation were improved by the vests. Only 18% of nurses reported thermal discomfort and 35% reported a slightly warm thermal sensation at the end of the day as compared to 81% and 94%, respectively, in the control group. The average heart rate was slightly lower when cooling vests were worn.

"Beyond their effectivity, cooling vests are very easy to implement in routine clinical care," Eijsvogels said. "Due to their low weight, easy fit, and long-lasting cooling power, nurses can benefit from up to three hours of pleasant working conditions. Also, the vests are easy to disinfect and re-activate in a refrigerator."

The cooling vest might be worth trying, said Jennifer S. White an assistant professor with the department of occupational therapy at the University of Pittsburgh School of Health and Rehabilitation Sciences.

White hasn't been working with COVID-19 patients but did have 14 years of experience that included wearing PPE during epidemics including SARS.

"I can definitely speak to the discomfort and heat involved in wearing PPE," she said. "If there was something that could have cooled me down when I was working with patients, I definitely would have been interested."

While cooling vests might improve working conditions, it would be better if healthcare workers could be switched out more often, said Jade Flinn, a biocontainment nurse educator at the Johns Hopkins Hospital. "In situations where you can't switch out, like the back of an ambulance on a long transport, this might be helpful," she added.

In hospitals overwhelmed by the surge of COVID-19 patients it also may not be possible to switch out healthcare workers as often, Flinn said. "I would consider wearing a cooling vest especially if I were in a full Tyvek suit," she added. "I am very sensitive to heat exhaustion and I would want to wear one. Even if it would not bring my core temperature down, at least it would be comforting."

SOURCE: Temperature, online December 26, 2020.