Physiological Impact of N95 Masks on Obese Operating Room Staff: A Randomized Crossover Trial

Abstract

Background Obesity and mask both may increase the cardiopulmonary burden on medical staff. The physiological impact of surgical masks (SMs) and N95 masks on obese operating room staff remains uncertain. This study aimed to determine whether wearing N95 masks for 4 hours significantly affected physiological indices in obese medical staff compared to surgical masks (SMs). Methods In this randomized controlled two-phase crossover trial, the physiological impacts of wearing SMs and N95 masks for 4 hours was analysed among 20 obese operating room staff. The primary outcome was the change in venous carbon dioxide partial pressure (PvCO2) levels at 4-hour intervention. Secondary outcomes included venous oxygen pressure (PvO2), bicarbonate (HCO3−) and pH levels at 4-hour intervention, end-tidal carbon dioxide partial pressure (PetCO2), peripheral oxygen saturation (SpO2), respiratory rate (RR), pulse rate (PR) and blood pressure (BP) at immediately, 1 h, 2 h, 3 h, and 4 h after mask wear. Dyspnoea, palpitations, headache were assessed with the visual analogue scale (VAS) score. Linear mixed models were used for comparative analysis. Results Twenty participants (age 32.2 [6.0] years; BMI 32.8 [2.1] kg/m2; 45% female) completed the study. Compared with the no-mask condition, both SM and N95 masks wearing for 4 hours caused PvCO2, HCO3−, PetCO2, and RR levels increased slightly in obese operating room staff. N95 masks had a statistically significant rather than clinically significant impact on PvCO2 (mean [95% CI], 1.4 [0.8, 1.9], P < 0.001) and RR (0.6 [0.1, 1.1)], P = 0.023) compared with SM. There was no significant difference between the two types of masks in terms of PvO2, pH, SpO2, PR, and BP. The three subjective VAS scores gradually increased over wear time. After more than 2 hours, the N95 group showed significantly increased than SM group. Conclusion Obese operating room staff continuously wearing SM or N95 masks 4 hours showed almost no difference in physiological impacts. It is recommended to wear N95 masks under high-risk conditions for better protection. Clinical trial registration: NCT05950256.