To investigate the effects of different intermittent hypoxemia (IH) properties on blood pressure (BP) and short-term blood pressure variability (BPV) in severe obstructive sleep apnea (OSA) patients.
Nocturnal BP was continuously monitored by measuring pulse transmit time. Apnea-related systolic BP elevation values were used to reflect BPV. Beat-to-beat RR interval data were incorporated in polysomnography for heart rate variability analysis. The LF/HF band ratio was used to reflect sympatho-vagal balance.The rate of SpO₂ decrease was counted as the change in the percentage of SpO₂ per second after obstructive apnea and expressed as the oxygen desaturation rate (ODR). Severe OSA subjects (n=102) were divided into two groups according to the median ODR: faster ODR (FODR group: ODR>0.37, n=50) and slower ODR (SODR group: ODR≤0.37, n=52).
Comparisons between the two groups showed significantly higher systolic BP (SBP) values in the FODR group than in the SODR group (awake SBP 149.9±18.3 vs.131.8±15.6 mm Hg; asleep SBP: 149.6±19.9vs.128.7±15.6 mm Hg; both p<0.001), as well as short-term BPV (15.0±4.8 vs. 11.6±3.6 mm Hg; p<0.001), and the prevalence of hypertension (74.0% vs. 26.9%; p<0.001). Multiple linear regression analyses revealed that after adjusting for BMI, FRC, ERV and baseline SpO ODR, as assessed by △SpO₂/△t, had the strongest association with both BP and short-term BPV. Correlation analysis showed that ODR was positively correlated with the LF/HF band ratio (r=0.288, p=0.003).
ODR, as a novel hypoxemia profile, was more closely associated with the elevation of BP and BPV in patients with severe OSA. FODR might be associated with enhanced sympathetic activity.

© 2020 American Academy of Sleep Medicine.