Evaluation of respiratory disorders during sleep.

A respiratory sleep study should be performed in subjects suspected of having sleep apnea or in subjects suspected of hypoventilating during sleep who have unexplained hypersomnolence, erythrocytosis, pulmonary hypertension, or cor pulmonale. Sleep studies should include sleep staging, measurement of airflow, respiratory effort, oxyhemoglobin saturation, and electrocardiogram. Screening and at-home studies may be valuable, but further studies are necessary before they can be generally recommended. Analysis should include the number of apneas and hypopneas and an index of respiratory effort to determine whether the subject has obstructive, central, or mixed apnea. Oxyhemoglobin saturation should be analyzed quantitatively to note the degree of hypoxemia during sleep and to determine whether the subject could benefit from treatment to correct the hypoxia.