Study objectives: The significance of residual excessive daytime sleepiness (EDS) on cardiovascular markers in patients with adequately treated obstructive sleep apnea (OSA) remains unclear. The objective of this study was to investigate flow-mediated dilatation (FMD) and inflammatory markers (C-reactive protein [CRP], tumor necrosis factor [TNF]-alpha, and interleukin [IL]-6) in continuous positive airway pressure (CPAP)-compliant patients with residual EDS compared with CPAP-compliant patients without residual EDS.
Methods: FMD of the brachial artery was measured by ultrasound in 12 CPAP-compliant patients with OSA who had residual EDS and 12 age-, sex-, and body mass index-matched CPAP-compliant patients with OSA who did not have residual EDS on week 8 after initiation of CPAP. Twelve otherwise-healthy subjects without sleep disordered breathing were used as control subjects. Serum concentrations of CRP, TNF-alpha, and IL-6 were quantified by enzyme-linked immunosorbent assays.
Results: Baseline FMD was comparable among CPAP-compliant patients with residual EDS (7.2 +/- 2.3), CPAP-compliant patients without residual EDS (8.6 +/- 2.1), and control subjects (7.7 +/- 1.4) (p = 0.37). The concentrations of CRP, TNF-alpha, and IL-6 were also not significantly different between subjects with CPAP-compliant residual EDS and those without residual EDS (p = 0.44, p = 0.37, and p = 0.42; respectively).
Conclusions: Residual EDS in patients with adequately treated OSA may not represent a risk factor for cardiovascular diseases.