Cooling vests relieve COVID-19 nurses of heat strain from PPE

Wearing cooling vests during shifts in COVID-19 wards can help nurses feel less heat strain, the COOLVID* study shows.

“Wearing the complete PPE** ensemble is a major physical challenge, as PPE insulation is very uncomfortable and makes you feel very hot,” according to statements from nurses. During their shifts, nurses wore PPE for long hours in a stretch, during which the temperature may rise to as high as 36^oC.

Originally developed for athletes competing at the Tokyo Olympic Games, the cooling vests were modified for use in COVID-related care. The vests contain a 21°C phase change material that can help relieve the perceptual heat strain experienced by nurses wearing PPE.

“The elite-athlete cooling vests were not immediately suitable for this use because they were designed to cool aggressively before or after physical exertion. COVID-19 care involves long-term use in which the vests are worn during the health care activities. The cooling power of the modified vest is lower, but it works longer,” explained study principal investigator Dr Thijs Eijsvogels of Radboud university medical center (umc), Nijmegen, The Netherlands.

The cooling vests were effective in helping nurses feel less hot such that it is now part of the standard work suit for nurses involved in COVID-19 care at Radboudumc.

In the COOLVID study, 17 nurses involved in COVID-19 care were followed for 2 days: one day with a cooling vest donned under their PPE and another day without the cooling vest. [Temperature 2021;doi:10.1080/23328940.2020.1868386]   

Majority of the nurses reported feeling more thermal comfort and thermal sensation (p-condition <0.001 for both) on the day when they had the cooling vests on than the day without. This was despite there being no significant changes in their body core temperature. 

Also, fewer nurses reported thermal discomfort (18 percent vs 81 percent; odds ratio [OR], 0.05) and warm thermal sensation (36 percent vs 94 percent; OR, 0.04) when they had the cooling vest on vs without. 

Accordingly, the nurses perceived less heat strain when they were wearing the cooling vests (perceptual strain index, 5.7 vs 4.3, p-condition<0.001), even though their physiological temperature did not change.

“Without a cooling vest, almost 90 percent of the nurses experienced discomfort and warmth. With a cooling vest, only 20-30 percent of the participants experienced this. They therefore perceived the conditions under which they have to do their work as more pleasant and comfortable,” noted co-author Yannick de Korte, also from Radboudumc.

“Since sensory displeasure impairs effective decision-making, even in the absence of elevated core temperature, improving comfort might be helpful to nurses. During an already intensive and stressful crisis like the current COVID-19 pandemic, comfortable working conditions are of utmost importance,” explained Eijsvogels and co-authors.

In addition, the average heart rate of nurses was lower during the time with cooling vest vs without (85 vs 87; p-condition=0.025).

“[The] medical cooling vests can be used beyond the ongoing COVID-19 pandemic, as infectious disease outbreaks occur more frequently (ie, SARS/MERS/Ebola), and occupational heat strain could be attenuated under these conditions as well,” the researchers added.

*COOLVID: The Cooling for COVID-19 healthcare workers
**PPE: Personal protective equipment