Effect of N95 Filtering Facepiece Respirator on Venous Blood Carbon Dioxide Levels and Hemodynamic Changes in Health Care Workers.

Abstract

Background: N95 filtering facepiece respirators (FFR) are used by health care workers for prevention of airborne infection, and its use has increased manifolds during COVID-19 pandemic. Prolonged use may result in carbon dioxide (CO₂) accumulation, affect hemodynamics, and blood gas values. Although arterial blood gas values accurately measure the blood CO₂ levels, venous blood gas values also show acceptable correlation.

Aim: To evaluate the physiological impact of N95 FFRs on health care workers, including hemodynamic changes and venous blood levels of CO₂ during a period of 6 h.

Settings and design: Prospective observational study in a tertiary care hospital.

Methods: The study was conducted on 30 health care workers who performed routine duties while wearing N95 FFR. Venous blood gas values (CO₂, pH, and bicarbonate) and vitals (respiratory rate, heart rate, blood pressure, and saturation) were noted at baseline, 2 (T2), and 6 h (T6) after wearing the mask. Discomfort level was also measured on a Visual Analogue Scale (VAS) of 1-10.

Statistical analysis: Repeated measures analysis was done using repeated measures ANOVA or Friedman's test. Group comparisons for continuously distributed data were made using independent sample "t" test or Wilcoxon test.

Results and conclusion: Hemodynamic and blood gas values did not change over time. The VAS for discomfort because of respirator use was 1.33 (1.42) at T2 and 2.77 (1.91) at T6. This was a significant increase in discomfort over time (P = 0.001). About 80% of participants experienced discomfort during this period. N95 FFR did not lead to significant alteration in hemodynamics or change in blood gas values after 6 h of continuous usage. However, discomfort significantly increased over time.