Agreement of Spirometry Parameters Between Facemask and Flanged Mouthpiece in Healthy Individuals and Patients with Perioral Muscle Weakness

<bold>Background:</bold> Flanged mouthpiece interface is used for patients who cannot tightly seal conventional mouthpiece during spirometry maneuver. However, leakage is still observed in patients with perioral muscle weakness (POW). Using a facemask, instead of a mouthpiece interface could minimize air leakage in these patients. <bold>Aim:</bold> We aimed to evaluate the agreement of spirometry parameters obtained with facemask and flanged mouthpiece interfaces in both healthy individuals and patients with POW. <bold>Method:</bold> This was a randomized crossover study that enrolled healthy subjects and POW patients to perform spirometry with both flanged mouthpiece and facemask interfaces in a randomized order. Intraclass correlation coefficients (ICC) and Bland-Altman plots were used to assess agreement between interfaces for forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEF) and other parameters. Paired t-tests were used to compare parameter differences. <bold>Result:</bold> A total of 32 healthy subjects and 22 patients with POW participated in the study. Excellent agreement was observed between both interfaces, for FVC (ICC = 0.992) and FEV1 (ICC = 0.972), in normal group, and also in the POW group, FVC (ICC = 0.986) and FEV1 (ICC = 0.948). There were no significant differences in FVC and FEV1 between the interfaces. In the POW group, the mean(SD) of PEF was significantly higher with flanged mouthpiece, 5.06 (1.89) L/s, compared to facemask, 4.05 (1.85)L/s, (P < 0.001). <bold>Conclusion:</bold> Both facemask and flanged mouthpiece interfaces yielded excellent agreement for most spirometry parameters in both healthy and POW patients.