Validity and intra-class reliability of spirometry using a mask instead of a mouthpiece

Introduction: The objective of this study was to perform lung function measurements using a facemask in place of a cylindrical mouthpiece and to investigate the validity and intra-class reliability of the results. Methods: The subjects were 48 healthy university students. Spirometry was performed twice for the subjects, using a cylindrical mouthpiece (mouthpiece spirometry, MS) and a facemask (facemask spirometry, FS) in random order. We fitted a spirometer with either a spirometry conical mouthpiece (30 ml of dead space) or an airtight cardiopulmonary exercise test facemask (210 ml of dead space). The measurement parameters were vital capacity (VC), tidal volume (TV), inspiratory capacity (IC), forced expiratory volume in 1 second (FEV1), and forced expiratory volume % in 1 second (FEV1%). FS validity was verified by investigating the correlation between the measurement data for each parameter and MS and FS in terms of Spearman9s rank correlation coefficient. Intra-class reliability was verified by calculating the intra-class correlation coefficient (1, 1) between the first and second measurements of each parameter by FS. Results: There was a strong correlation between the measurements of VC, TV, IC, FEV1, and FEV1% obtained with MS and those obtained with FS. There also was a strong intra-class correlation between the first and second measurements of VC, TV, IC, FEV1, and FEV1%. Conclusion: Our results confirmed the validity and intra-class reliability of lung function measurements performed using a facemask instead of a cylindrical mouthpiece. This suggests that it may be possible to substitute a facemask for a cylindrical mouthpiece during spirometry.