Pursed-lips breathing improves inspiratory capacity in chronic obstructive pulmonary disease

BACKGROUND: In patients with severe chronic obstructive pulmonary disease (COPD), pursed-lips breathing (PLB) improves the pulmonary gas exchange and hyperinflation measured by electro-optic coupling. The response to PLB in inspiratory lung function tests is not known. OBJECTIVES: The purpose of this study was to measure the effect of PLB on inspiratory parameters. METHODS: Thirty-five subjects with stable COPD and a forced expiratory volume in first second (FEV(1)) <50% of the predicted value were tested for the following primary parameters before and immediately after PLB, and 5 min later: forced inspiratory vital capacity, inspiratory capacity (IC), forced inspiratory volume in first second, maximal inspiratory flow at 50% of vital capacity, and peak inspiratory flow. Patients were also tested for the following secondary parameters: vital capacity, FEV(1), breathing frequency, end-tidal CO(2) tension, and oxygen saturation. RESULTS: Of all the primary parameters only IC (p = 0.006) improved significantly; with regard to the secondary parameters, the mean oxygen saturation was improved by 1% (p = 0.005) and the mean end-tidal CO(2) tension and breathing frequency decreased significantly (p < 0.0001 for both) to 3.2 mm Hg and 3.1 breaths/min, respectively. After 5 min the effects diminished. CONCLUSION: Improved IC after PLB indicates less hyperinflation in patients with severe COPD; there was no effect on parameters of flow