[Chronic obstructive pulmonary disease and sleep apneas]

Sleep quality is lower in patients with chronic obstructive pulmonary disease (COPD) than in healthy individuals. Hypoventilation during sleep is the most important cause of hypoxemia and the presence of ventilation/perfusion alterations and reduced functional residual capacity probably also plays a significant role. Although episodes of nocturnal saturation can reasonably be supposed to increase morbidity and mortality in these patients, the diagnostic importance of these desaturations has not been demonstrated. However, desaturation episodes must be detected in patients with COPD and sleep apnea-hypopnea syndrome (SAHS), since morbidity and mortality are higher when these two entities are combined than when they occur separately. Polysomnography is only indicated when the association of COPD and SAHS is suspected. Nevertheless, in some patients, respiratory behavior during sleep must be evaluated and techniques such as pulse oximetry, capnography and/or respiratory polygraphy and, if necessary, subsequent polysomnography may be useful. Further studies are required to elucidate the role of physiopathological alterations during sleep, the importance of nocturnal desaturations and the role of oxygen therapy and ventilatory support, as well as the utility of some drugs that could improve sleep quality and gas exchange in these patients.