Publication
Baroreflex sensitivity during rest and pressor challenges in obstructive sleep apnea patients with and without CPAP
Publisher:
Elsevier BV
Date:
09-2022
DOI:
10.1016/J.SLEEP.2022.05.846
Abstract: Obstructive sleep apnea (OSA) increases sympathetic vasoconstrictor drive and reduces baroreflex sensitivity (BRS), the degree to which blood pressure changes modify cardiac output. Whether nighttime continuous positive airway pressure (CPAP) corrects BRS in the awake state in OSA remains unclear. We assessed spontaneous BRS using non-invasive continuous BP and ECG recordings at rest and during handgrip and Valsalva challenges, maneuvers that increase vasoconstrictor drive with progressively higher BP, in untreated OSA (unOSA), CPAP-treated OSA (cpOSA) and healthy (CON) participants. In a cross-sectional study of 104 participants, 34 unOSA (age mean±std, 50.6±14.1years Respiratory Event Index [REI] 21.0±15.3 events/hour 22male), 31 cpOSA (49.6±14.5years REI 23.0±14.2 events/hour 22male self-report 4+hours/night,5+days/week,6months), and 39 CON (42.2±15.0years 17male), we calculated BRS at rest and during handgrip and Valsalva. Additionally, we correlated BP variability (BPV) with BRS during these protocols. BRS in unOSA, cpOSA and CON was, respectively (mean±sdv in ms/mmHg), at rest: 14.8±11.8, 15.8±17.0, 16.1±11.3 during handgrip 13.3±7.6, 12.7±8.4, 16.4±8.7 and during Valsalva 12.7±8.0, 11.5±6.6, 15.1±8.9. BRS was lower in cpOSA than CON for handgrip (p=0.04) and Valsalva (p=0.03). BRS was negatively correlated with BPV in unOSA during Valsalva and handgrip for cpOSA, both R=-0.4 (p=0.02). BRS was negatively correlated with OSA severity (levels: none, mild, moderate, severe) at R=-0.2 (p=0.04,n=104). As expected, BRS was lower and BPV higher in OSA during the pressor challenges, and disease severity negatively correlated with BRS. In this cross-sectional study, both CPAP-treated (self-reported) and untreated OSA showed reduced BRS, leaving open whether within-person CPAP improves BRS.