The efficacy of pursed-lips breathing in patients with chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease have a limited ventilatory reserve. With increasingly severe disease, patients become unable to maintain ventilation adequate to prevent hypoxia and hypercapnia. Since the altered mechanics of ventilation are largely due to irreversible changes in the lung parenchyma and airways, effective forms of therapy are limited. One of the cornerstones in the treatment of chronic obstructive pulmonary disease is the use of breathing exercises designed to increase tidal volume and diminish uneven ventilation. The most widely used breathing exercise utilizes prolongation of expiration with and without the active use of diaphragmatic muscles (1, 2). A commonly employed method to achieve this prolongation is expiration through pursed lips. There have been no studies, by means of blood gases and ventilatory measurements as to whether the employment of pursed-lips expiration is beneficial to patients with chronic obstructive pulmonary disease. It is a matter of common clinical observation that many patients with severe emphysema spontaneously expire through pursedlips, especially when they become unusually short of breath. Aside from theoretical considerations on how this form of breathing may improve the ventilation of these patients, the frequent teaching of this method of breathing has no firm basis in physiologic studies. Accordingly, this study has been conducted to elucidate the efficacy of pursed-lips breathing and the mechanism of the presumed improvement in ventilation.