Physiological Impact of Surgical Mask and N95 Mask on Obese Operating Room

Physiological Impact of Surgical Mask and N95 Mask on Obese Operating Room Staff：A Randomized-Controlled Cross-Over Trial

During the SARS CoV-2 pandemic, in order to reduce the risk of infection among healthcare workers, healthcare workers are usually required to wear N95 masks for extended periods of time in high-risk environments. The long-term use of masks by medical staff has been proven to be related to various symptoms, including headaches, dizziness, facial skin disease symptoms, and other occupational disturbances . Our previous research found that among healthy anesthesiologists with normal weight, wearing a Surgical mask for more than 2h can significantly reduce peripheral blood oxygen saturation (SpO2) and increase respiratory rate (RR). Rebmann et al. investigated the physiological effects of N95 masks on healthcare workers, and the results showed a statistically significant increase in end-tidal CO2 pressure （PetCO2）among 10 intensive care unit nurses who used N95 masks on a 12 hour shift. Recently, it has been confirmed that prolonged use of N95 masks can cause changes in gas exchange, including a decrease in plasma pH and venous partial pressure of oxygen (PvO2), and a slight increase in PetCO2.

Obesity is defined as abnormal or excessive fat accumulation that poses a risk to health and can cause baseline lung function impairment and decreased immune function. According to the standards of the World Health Organization (WHO), people with a body mass index (BMI) greater than 30 kg/m2 are classified as obese. Research shows that obese patients are the population with the highest risk of SARS CoV-2 infection related incidence rate and mortality. Research has shown that healthcare workers who work long hours are more likely to become obese due to changes in body regulation, metabolism, and stress. Long term use of N95 masks by medical staff may lead to a certain degree of insufficient ventilation and/or CO2 re breathing. Obesity itself has a significant impact on the heart and lungs, but the potential physiological effects of long-term wearing of N95 masks on obese healthcare workers have not been studied. The purpose of our study is to determine the abnormal gas exchange and physiological changes of obese doctors and nurses in the operating room who wear Surgical mask and N95 mask for 4 hours.

We plan to recruit 20 non-smoking and healthy obese medical staff, regardless of gender, from the anesthesia doctors and nurses in the operating room, who sign written informed consent forms.

This is a prospective, randomized, cross controlled trial. Develop a sequence number for 20 participants in the order of enrollment. The participants were randomly assigned to the N95 mask group (n=10 cases) and the Surgical mask group (n=10 cases) using the random number method. Before the participants are grouped, group concealment is performed and the random grouping scheme is saved using a shaded envelope. Open the envelopes in the order of the participants joining the group, and determine the grouping situation based on the allocation plan inside the envelopes. The N95 respirator group and the Surgical mask group were used in the two stages of cross operation. When the first round of test was completed and after a 24-hour washing out period, the subjects in the Surgical mask group and the N95 respirator group were exchanged for the second round of test. The steps and methods were the same as those in the first stage.

During the study, each candidate must correctly wear a disposable bandage type medical Surgical mask or a disposable N95 mask. After wearing, it is necessary to check whether it is worn properly and whether there is air leakage. At the beginning of the test, participants are required to avoid using masks for at least 10 minutes, measure their right index finger in a sitting position, and collect baseline (T1) data under normal breathing, including SpO2, Pulse rate (PR), RR, PetCO2, blood pressure (BP). Collect 1ml of venous blood to measure the baseline venous blood gas value.

All subjective sensations were rated using a 10 point VAS digital scale for subjective sensations such as headache, dizziness, difficulty breathing, and facial discomfort. A score of 0 indicates no discomfort, while a score of 10 indicates the most severe imaginable discomfort. Then participants were asked to wear Surgical mask or N95 mask for 4 hours to start medical work. Subsequently, immediately after using masks (T2) and continuously wearing masks for 1 hour (T3), 2 hours (T4), 3 hours (T5), and 4 hours (T6), the above data was collected using the same method. In order to minimize data variability, data was collected twice at each time point and the average was taken. After continuous wear for 4 hours, 1ml of venous blood was taken for blood gas analysis.

If the subject is unable to persist, they can immediately remove the cover and abandon the experiment; Researchers monitored these subjects until symptoms improved. Second round test: After the first round of test is completed, the second round test is conducted after a 24-hour washing period. In the second round of test, the subjects of N95 mask group and Surgical mask group in the first round of test were exchanged, and the test was conducted according to the steps and data collection methods of the first round of test.

Inclusion criteria： anesthesiologists or nurses working in the operating room, aged 20-60 years old, body mass index (BMI)>30kg/m2, clearly healthy, and without any history of chronic diseases.

Exclude criteria： recent acute or chronic respiratory disease, recent history of headache and dizziness, pregnancy or lactation, rhinitis, Nasal polyp or poor breathing, facial skin inflammation and skin laxity.