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.