Since many years it is recommended for COPD patients to reduce the crossdiameter of the lips in order to improve the exhalation by means of so-called pursed-lips breathing (PLB). But the effects have never been studied quantitatively. In this study, the PLB effect is simulated during lung function diagnostics, using different sized resistors inserted into the routine mouthpiece of the flow sensor to resemble the effective airway resistances of a PLB maneuver. This prospective, randomized study includes 20 healthy subjects and 50 COPD patients, who will perform lung function testing with 4 different sized resistors.
