Effect of Wearing a Surgical Mask or N95 Mask in Patients With Stable Chronic Hypercapnic Respiratory Failure

Background: Surgical and N95 masks are commonly used in the prevention of respiratory virus transmission. The safety of wearing masks is well documented in healthy individuals but is unclear in people with chronic hypercapnia. In addition, masks are often poorly tolerated in this population. The present study assessed the effect of surgical and N95 masks in people with stable chronic hypercapnia using noninvasive ventilation (NIV). Methods: A randomized crossover trial was performed. S pO 2 and transcutaneous CO 2 ( P tcCO 2 ) were measured in participants wearing a surgical mask, an N95 mask, and no mask for a 20-min period at rest. Secondary outcomes included heart rate, breathing frequency, the A1 scale from the Multidimensional Dyspnea Profile (MDP), and the modified Borg dyspnea scale (mBORG). Results: 24 participants (50% female; mean [SD] age 61 [13] years) were randomized and completed data collection. Over the 20-min study period, when compared with no mask, the mean differences for S pO 2 in surgical and N95 masks were 0.0% [95% CI: −1.0–0.9] and 0.3% [95% CI: −0.6–1.3]. For P tcCO 2 surgical mask, the mean difference was 0.0 mm Hg [95% CI: −1.3–1.3], and for N95 mask, the mean difference was 1.0 mm Hg [95% CI: 0.3–2.3]. There was no effect on heart rate or breathing frequency. Masks increased the mBORG (surgical mask median difference 0.75 points [95% CI: 0.25–2.00]; N95 mask median difference 1.50 [95% CI: 0.75–2.25]) and MDP (surgical mask median difference 1.5 points [95% CI: 0.5–2.5]; N95 mask median difference 2.5 points [95% CI: 1.0–3.0]) compared with no mask. Three participants requested to remove one or both masks early. Conclusions: Wearing a surgical mask and N95 mask did not significantly affect gas exchange in subjects with chronic hypercapnia using NIV. However, dyspnea and breathing discomfort did increase.