Portable monitoring for the diagnosis of obstructive sleep apnea. 
The demand for expedient diagnosis of suspected obstructive sleep apnea (OSA) has increased due to improved awareness of sleep disorders.  Polysomnography (PSG) is the current preferred diagnostic modality but is relatively inconvenient, expensive and inefficient.  Portable monitoring has been developed and is widely used in countries outside the United States as an alternative approach.  A portable monitor records fewer physiologic variables but is typically unattended and can be performed in the home.  Numerous portable monitor studies have been performed over the past two to three decades.  The US government and medical societies have extensively reviewed this literature several times in an attempt to determine if portable monitoring should be more broadly used for diagnosing OSA.  In March 2008, the US Centers for Medicare and Medicaid Services released a statement allowing the use of portable monitoring to diagnose OSA and prescribe continuous positive airway pressure.  This has potentially opened the door for more widespread use of these devices.  This review will focus on the literature that has examined portable monitoring as a diagnostic tool for OSA.  It is anticipated that portable monitoring as a diagnostic modality for OSA will be used more frequently in the United States following the Centers for Medicare and Medicaid Services ruling.  Physicians and others considering the use of portable monitors should thoroughly understand the advantages and limitations of this technology.