• Bharati Prasad, David W Carley, and James J Herdegen.
• Sleep Science Center, University of Illinois at Chicago, Chicago, IL 60612, USA. bpradsad@uic.edu
• Sleep Breath. 2010 Jun 1; 14 (2): 101-7.

PurposeObstructive sleep apnea (OSA) is a common health problem that affects more than 2-4% of the US population. Polysomnography (PSG) is the gold standard for diagnosing OSA. PSG is, however, expensive, time-consuming, and not always readily accessible. Hence, alternative diagnostic methods such as home-based testing have been evaluated. We studied the ability of the REMstar Pro (RSP2, a brand of continuous positive airway pressure (CPAP) device) to identify abnormal breathing events in subjects with OSA and compared this with breathing events simultaneously determined by laboratory-based PSG.MethodsWe evaluated 10 subjects previously diagnosed with OSA (apnea hypopnea index (AHI) > 15, known therapeutic level of CPAP). Subjects underwent attended PSG using the REMstar Pro M series machine and their prescribed interface/mask type. The first 3 h of the study were conducted using a subtherapeutic CPAP (4 cm H2O). The last 3 h or remaining portion of the PSG was completed using the previously determined therapeutic CPAP. Comparison of respiratory events detected by PSG vs the RSP2 was performed.ResultsSubjects included four men and six women, aged 32 to 57 years and with a body mass index ranging from 29.5-66.4. The baseline AHI ranged from 18.3-93.1, with the AHI at therapeutic CPAP ranging from 0-3. Apnea counts at baseline and at therapeutic CPAP by manually scored PSG and REMstar were not significantly different (mean at subtherapeutic 11.7 vs 12.5, p = 0.76; median at therapeutic CPAP 2.0 vs 4.5, p = 0.15). Hypopnea counts at baseline and at effective CPAP by PSG and REMstar were not significantly different (mean at subtherapeutic 38.1 vs. 40.9, p = 0.72; median at therapeutic CPAP 5.0 vs. 2.5, p = 0.34). The correlation coefficient of REMstar and PSG for apnea and hypopnea was significant in subtherapeutic phase only (apnea r = 0.78, p = 0.007; hypopnea r = 0.76, p = 0.01). Agreement between the two methods declined for hypopnea detection at therapeutic CPAP.ConclusionsThe monitoring of residual sleep-disordered breathing on treatment, in addition to adherence, is an important objective therapeutic target in OSA. The REMstar Pro detects sleep-disordered breathing events similar to that of a manually scored PSG-for apnea but not for hypopnea-and merits further investigation as a device to determine disease severity and treatment efficacy.

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