Posture, Interface, and Peak Cough Flow

Cough is a key airway protective mechanism requiring coordinated neuromuscular function. Peak cough flow (PCF) is a simple, non-invasive measure widely used to assess cough effectiveness and guide clinical decisions. Current ATS/ERS guidelines recommend measuring PCF in a seated position using a mouthpiece with a nose clip; however, this setup is not always feasible in clinical practice. Some patients cannot maintain posture or ensure an adequate mouthpiece seal, making a facial mask a potential alternative. The influence of body position and interface on PCF measurements remains unclear, with limited evidence from randomized crossover studies. This study aims to evaluate the effects of body position (sitting vs standing) and measurement interface (mouthpiece vs facial mask) on PCF in healthy young adults. In a randomized within-subject crossover design, participants perform PCF measurements under four conditions (Sit-Mask, Stand-Mask, Sit-Mouthpiece, Stand-Mouthpiece) during a single session. The findings will help inform more flexible and standardized PCF assessment procedures in clinical practice.