Inducers of post-apneic blood pressure fluctuation monitored by pulse transfer time measurement in obstructive sleep apnea varied with syndrome severity.

Abstract

This study investigated the properties of blood pressure (BP) fluctuation and sympathovagal imbalance with the severity of OSAS. Nocturnal BP was continuously monitored by polysomnography for mild (n = 33), moderate (n = 34), and severe (n = 37) OSAS patients. Apnea-related systolic BP elevation (△SBP) indicated the amplitude of BP fluctuation. The SBP index, number of △SBP > 10mmHg/h of sleep, indicated the frequency of significant BP fluctuations. The low frequency/high frequency (LF/HF) ratios indicated heart rate variability and sympathovagal imbalance. △SBP and the SBP index were the highest in severe OSAS (12.9 ± 2.3mmHg and 33.7 ± 14.7/h), followed by moderate OSAS (9.5 ± 2.6mmHg and 7.1 ± 4.4/h), and mild OSAS (8.3 ± 1.6mmHg and 3.4 ± 2.1/h). The LF/HF ratios in severe OSAS were significantly higher than that in moderate and mild OSAS. In mild OSAS, arousal played a more important role in BP fluctuation. In moderate OSAS, the oxygen desaturation index (ODI) and the SBP index were correlated. The difference in △SBP induced by hypoxia or by arousal was not significant. In severe OSAS, the apnea-hypopnea index (AHI) and LF/HF ratio were correlated with the SBP index, and △SBP was larger with hypoxia than arousal. BP fluctuation and sympathovagal imbalance were both related to obstructive sleep apnea severity. The influence of arousal and hypoxia on BP fluctuation varied with OSAS severity. NCT02876471.