At the present time, the typical procedure for confirmation of the diagnosis of OSA and its management is an in-laboratory PSG with application of CPAP. Portable monitoring systems have arisen to increase access to the diagnosis of OSA and to potentially reduce costs. A RDI > 5 in adults is used to confirm OSA unless the patient is asymptomatic, in which case a RDI > 15 is used to confirm OSA. For children, one or more apneas or hypopneas of at least two respiratory cycles in duration, or other evidence of respiratory disturbance (i.e., RERAs, arterial oxygen desaturation, snoring, hypercapnia, arousals) confirm OSA. Validation of a portable monitoring device should involve the assessment of sensitivity and specificity of the OSA diagnosis using the device under ideal conditions as well as in the intended environment (typically the patient's home) versus simultaneous comparison with attended PSG. At the present time, Level II and IV portable monitors are not sufficiently accurate or validated to recommend for use, particularly unattended in the home, while Level III monitors are useful attended in the laboratory and of possible usefulness unattended in either the laboratory or the home, with the proviso that careful follow-up and usually a PSG is necessary to fully evaluate the patient with a negative or nondiagnostic study. The role of PSG as a reference standard is limited given issues such as the lack of standardized scoring of hypopneas and the night-to-night variability of the AHI or RDI; however, features such as sleep stage, body position, and all currently recommended respiratory event data are typically found in PSG systems but are lacking in portable monitors. Complicating these issues is the fact that current Medicare guidelines make it difficult for portable monitors to adhere to Medicare criteria for OSA diagnostic devices, and portable monitors are not the best choice for confirming the OSA diagnosis in patients with COPD or who have significant daytime sleepiness from causes other than OSA. The type of electrodes or sensors, oximeter sampling rate, and manual versus computerized scoring are technical factors that should be considered in the selection of the portable monitoring device. The most appropriate use of an attended Level III portable monitor appears to be the diagnosis of OSA rather than the exclusion of patients with OSA based on both evidential and strategic analyses. Lastly, the cost effectiveness of portable monitoring compared to in-laboratory PSG studies is a complex issue that at the present time has not been resolved.
Was this article helpful?