Response to CPAP withdrawal in patients with mild versus severe obstructive sleep apnea/hypopnea syndrome

Abstract

Background: Patients with obstructive sleep apnea/hypopnea syndrome (OSAHS), even those generally compliant with CPAP therapy, often intermittently discontinue CPAP.

Study objective: Examine the impact of CPAP withdrawal on sleep, sleep disordered breathing (SDB), and daytime function in subjects with varying severity of OSAHS.

Patients and interventions: Forty-two subjects (26M/16 F) with OSAHS (AHI4% = 45.2 ± 35.5/h pretreatment) on CPAP for 4 months were evaluated on the second night of CPAP withdrawal. Sleep architecture, SDB indices, and subjective/objective daytime function were assessed pretreatment, on CPAP therapy, and after CPAP withdrawal. Comparisons were made between pretreatment and CPAP withdrawal for the entire group, and for subgroups of mild/moderate (AHI4% < 30/h, n = 22) and severe (AHI4% > 30/h, n = 20) SDB.

Results: Overall, and for mild/moderate subjects, SDB indices returned to pretreatment values on CPAP withdrawal but with fewer apneas and more hypopneas/RERAs. For severe SDB, the event frequency (AI, AHI4%, and RDI) was lower and O2 desaturation was improved on CPAP withdrawal. Across SDB severity, sleep architecture showed lower %REM (15.6% vs 12.9%, P = 0.009) on the CPAP withdrawal compared to pretreatment. Stanford Sleepiness Score, MSLT, and PVT measures were not significantly different between pretreatment and CPAP withdrawal.

Conclusions: Over a wide range of SDB severity CPAP withdrawal results in recurrence of SDB, albeit with less severe O2 desaturation. Subjective/objective daytime function returned to pretreatment levels. Sleep architecture changes on CPAP withdrawal (acute SDB) may reflect reduced sleep pressure compared to pretreatment chronic SDB. Our data suggest detrimental effects of even brief withdrawal of CPAP in subjects with both mild and severe OSAHS.

Citation: Young LR; Taxin ZH; Norman RG; Walsleben JA; Rapoport DM; Ayappa I. Response to CPAP withdrawal in patients with mild versus severe obstructive sleep apnea/hypopnea syndrome. SLEEP 2013;36(3):405-412.

Keywords: CPAP withdrawal; daytime sleepiness; sleep disordered breathing.

Figure 1

Outline of study protocol. Daytime function assessments included the multiple sleep latency test (MSLT), psychomotor vigilance test (PVT), Stanford Sleepiness Scale score (SSS), Epworth Sleepiness Scale score (ESS), and functional outcomes of sleep questionnaire (FOSQ). ESS and FOSQ were not administered at CPAP withdrawal, as they do not accurately assess acute sleepiness.

Figure 2

Figure plots RDI, AHI4%, and AI obtained on the pretreatment NPSG (x-axis) versus CPAP withdrawal NPSG (y-axis) along with the line of identity. Each point represents one subject and shows that there is little difference in RDI between pretreatment and CPAP withdrawal NPSG at all SDB levels. In subjects with severe SDB, the AHI4% and AI are lower on the CPAP withdrawal NPSG as seen by the predominance of data below the line of identity.

Figure 3

Pretreatment SDB severity assessed by AHI4% is plotted against the difference in %REM (pretreatment minus CPAP withdrawal NPSG). Each point represents one subject. Overall, subjects had higher %REM (2.8% ± 6.5%) on the pretreatment NSPG, and there was no clear effect of SDB severity.