Controversies in monitoring and testing for sleep-disordered breathing.

Despite significant advances in the understanding of the pathophysiology of the obstructive sleep apnea syndrome, the best index to classify the severity of sleep-disordered breathing has not been established. The use of new measurement techniques suggests that subtle changes in airflow not detected by conventional thermal sensing devices may signal events associated with significant sleep disruption. Recurrent increased respiratory efforts without discernable changes in airflow, which are currently reliably detectable only by invasive means, also may be important. However, it is still uncertain which events should be considered clinically significant, and the correlation of the frequency of various types of respiratory events with long term physiologic consequences is not clear. Outpatient screening with multichannel portable devices or pulse oximetry has important limitations. However, in combination with the clinical pretest probability of significant sleep-disordered breathing, such screening may correctly classify a large proportion of patients. Combining a partial night diagnostic sleep study with a therapeutic titration of continuous positive airway pressure seems to provide adequate information for appropriate management of many patients with obstructive sleep apnea and reduces time between presentation and initiation of treatment.