During their shifts, nurses wear protective clothing for three hours in a row, during which the temperature can rise to uncomfortable levels. The cooling vests offer such effective cooling that they are now part of the standard work clothing for nurses in the Covid nursing departments at Radboud university medical center, in Nijmegen, Netherlands. 

Owing to the high level of contagiousness present with Covid-19, healthcare workers have to carry out their duties in protective clothing, which is not or is barely ventilated. Good protective clothing is essential for their work, but the temperature under these suits can reach up to 36^OC, leading to reduced comfort. The cooling vests, originally developed for elite athletes competing at the Tokyo Summer Olympic Games, were modified and prepared for use in Covid-related healthcare. 

Thijs Eijsvogels, exercise physiologist and principal investigator, explains: “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 care involves long-term use in which the vests are worn during the healthcare activities. The cooling power of the modified vest is lower but it works longer.” 

Although the cooling vests were already in use, a study of their effects was being carried out at the same time. The ‘Cooling for Covid-19 healthcare workers (COOLVID)’ study followed 17 nurses working in Covid care for two days: one day with and one day without a cooling vest. They wore the vest over their medical clothing but under their protective clothing. Study measurements included core temperature and heart rate, as well as subjective measurements such as comfort and heat sensation. 

Less heat stress during a shift

The results, now published in Temperature, show that the participants’ core temperature increased slightly but not enormously, even while the temperature under their protective clothing did. Therefore, the cooling vest had little effect on core temperature. 

However, the participants’ heart rates were a few beats per minute lower on the days they wore the cooling vests. The biggest difference was in the subjective perceptions of the healthcare providers. 

Co-researcher Yannick de Korte said: “Without a cooling vest, almost 90 per cent of the nurses experienced discomfort and warmth. With a cooling vest, only 20-30 per cent of the participants experienced this. They therefore perceived the conditions under which they have to do their work as more pleasant and comfortable. Virtually everyone said: ‘With a cooling vest, I can work like I normally do without protective clothing’.”

Carried out as part of the Medical Heat Stress project, COOLVID is a collaborative study between TNO, as part of its brains4corona programme, and Radboud university medical center, building on the Thermo Tokyo project. The study was financed by ZonMw. The researchers have also developed an infographic for the use of the cooling vests, which has been translated into nine languages and is supported by EU Horizon 2020.