Effect of the Measurement Interface on Maximal Expiratory Pressure During Voluntary Cough in Young Adults

Background/Objectives: To determine whether there are differences between a nozzle and an oronasal mask in the measurement of maximal expiratory pressure (MEP) during a voluntary cough maneuver in young university students. Methods: Forty university students aged 20–25 years were recruited, comprising 20 males and 20 females. Forced vital capacity and MEP were measured during a voluntary cough maneuver. All participants were assessed using both interfaces. The order of the interfaces used to measure MEP during the voluntary cough maneuver was randomized, once the order was determined, the evaluations were conducted on two separate days: one for the nozzle and another for the oronasal mask. Subsequently, participants were asked to report their perception of air leakage and comfort associated with each device. Results: There was no significant main effect of the interface on MEP after adjusting for gender, peak expiratory flow (PEF), and body mass index (BMI) (F(1.36) = 3.285; p = 0.078; η2p = 0.084). There was a significant interaction between interface and BMI (F(1,36) = 6.391; p = 0.016; η2p = 0.151). Gender and PEF were significantly associated with MEP (gender: F(1,36) = 16.698; p < 0.001; η2p = 0.317; PEF: F(1,36) = 8.985; p = 0.005; η2p = 0.200). Conclusions: In young adults, the measurement interface alone did not significantly alter MEP. The relationship between BMI and MEP varied according to the interface used, as evidenced by the interface × BMI interaction; gender and PEF were significantly associated with MEP.