Differences in respiratory oscillometry measurements using mouthpiece, mouth, and nasal mask in healthy adults.

Airway resistance measurements using oscillometry provide a potential alternative to spirometry in assessing airway obstruction and dynamics due to measurements taken during tidal breathing. Oscillometry typically requires participants to form a tight seal around a mouthpiece that can prove challenging for some people. To address this challenge, we conducted a prospective study to evaluate the effect of different interfaces like mouthpiece, mouth mask, and nasal mask on respiratory impedance results from oscillometry in a cohort of healthy adults. Ten healthy adults [7 females; mean age: 38.9 yr (SD ±15.5)] underwent oscillometry using each of the three interfaces. We measured resistance at 5 Hz (Rrs), frequency dependence of resistance at 5-20 Hz (Rrs), and reactance area (Ax). Rrs was not different when using the mouthpiece compared with the mouth mask [mean 2.98 cmHO/L/s (SD ±0.68) vs. mean 3.2 cmHO/L/s (SD ±0.81); = 0.92; 95% CI -0.82 to +0.38], respectively. Nasal mask Rrs measurements were significantly higher than mouthpiece measurements (mean 7.31 cmHO/L/s; SD ±2.62; < 0.01; 95%CI -6.91 to -1.75). With Ax, we found a mean of 4.01 cmHO/L (SD ±2.04) with the mouth mask compared with a mean of 4.02 cmHO/L (SD ±1.87; = 1.0 95% CI -1.86 to +1.87) for the mouthpiece, however, we found a significant difference between the mouthpiece and nasal mask for Ax (mean = 10.71; SD ±7.0 HO/L; = 0.04, 95% CI -12.96 to -0.43). Our findings show that oscillometry using a mouth mask may be just as effective as using a mouthpiece in assessing airway dynamics and resistance. This is the first study to compare the use of different interfaces: mouthpiece, mouth mask, and nasal mask, for oscillometry in an adult population. We report that using a mouth mask in oscillometry may provide a valid alternative to a mouthpiece in cohorts who may struggle to form the required tight seal that is typically required in oscillometry or spirometry.