An Observational Crossover Study of N95 Respirator with Surgical Mask and Visor in Various Combinations on Healthy Volunteers and Their Impact on Physiological Variables.

Background and aim: The COVID pandemic necessitated the use of masks to reduce the propagation of coronavirus by airborne transmission. This research was conducted in healthy volunteers to assess the changes in noninvasive measurable physiological variables over 45 min at rest.

Methods: This was a prospective randomized controlled crossover trial. Twenty-one healthy volunteers were monitored for pulse rate (PR), peripheral oxygen saturation (SpO₂), systolic blood pressure (SBP), diastolic blood pressure (DBP), respiratory rate (RR), inspired carbon dioxide and expired carbon dioxide (ECO₂), inspired (FiO₂) and expired oxygen (FeO₂), every 15 min for 45 minute (min) with N95 respirator, N95 respirator with surgical mask (SM), N95 with SM and visor (V), SM with N95, and N95 respirator with visor.

Results: Repeated measures analysis of variance (ANOVA) of PR, RR, SpO₂, SBP, and DBP over time within the group and intragroup was calculated and found statistically insignificant. P value for comparison of mean value within the group was calculated by paired t-test with Bonferroni correction. There was a significant rise in ECO₂ in the N95 group over time, and repeated measures ANOVA showed P = 0.04 at 30 min between the N95 + V group and the N95 + SM + V group. Inspired CO₂ was statistically significant over time in the N95 + SM + V with P = 0.02.

Conclusion: N95 alone or in combination with a SM and visor does not cause any clinically significant measurable physiological derangements. The inspired CO₂ may be implicated in the symptoms manifested by individuals.