The Properties Of Nocturnal Blood Pressure Fluctuation And Associated Factors Of Secondary Hypertension In Severe Obstructive Sleep Apnea Hypopnea Patients

Objective Obstructive sleep apnea hypopnea syndrome(OSAHS)is closely associated with the incidence of hypertension.Its unique blood pressure properties could result in multiple system damages.The present study was to investigate the properties and associated influential factors of BP fluctuation in severe OSAHS with and without hypertension.Methods One hundred and twenty-five severe OSAHS patients were divided into hypertensive and normotensive groups.BP was continuously monitored via measurement of pulse transmit time(PTT).The value of apnea-related systolic BP elevation(?BP)was used to reflect the amplitude of BP fluctuation,and the BP index(the number of ?BP >10 mm Hg per hour of sleep time)was used to stand for the frequency of significant BP fluctuations.Results Compared with the normotensive group,the hypertensive group had a more severe sleep disturbance.? BP and BP index were higher in the hypertensive group(?BP,13.8±4.4mm Hg vs 10.9±3.1mm Hg;BP index,44.8±21.3 vs 26.8±15.8 events/h,all p<0.001).Regression analysis showed that BP index and the percentage of sleep time with oxygen saturation <90%(TST90)correlated more with mean level of BP than the other sleep disorder parameters.Analysis of all apnea events demonstrated that ? BP were more remarkable following hypoxia than following arousal(hypertensive group:15.4±4.9 mm Hg vs 11.9±3.8 mm Hg,P<0.001;normotensive group:10.6±3.1 mm Hg vs 9.5±2.4 mm Hg,P<0.001).Conclusions In severe OSAHS patients,BP levels are associated more with the nocturnal hypoxic duration and BP fluctuation than with the other sleep disord er parameters.Nocturnal BP fluctuation can be induced by both hypoxia and arousal,and especially by hypoxia.Background: Recent studies have suggested that the blood pressure variability was closely correlated with the severity of obstructive sleep apnea hypopnea syndrome(OSAHS).For the limitation of experimental techniques,the properties of transient blood pressure(BP)fluctuation induced by sleep apnea were rarely studied.The dominant inducers of post-apneic blood pressure fluctuation were still on controversial.This study investigated the properties of BP fluctuation and sympathovagal imbalance with the severity of OSAS.Methods: Nocturnal BP was continuously monitored by polysomnography for mild(n=33),moderate(n=34),and severe(n=37)OSAHS patients.Apnea-related systolic BP elevation(? BP)indicated the amplitude of BP fluctuation.The BP index,number of ? BP > 10 mm Hg/h of sleep,indicated the frequency of significant BP fluctuations.Nocturnal heart rate variability was analyzed.The low frequency/high frequency(LF/HF)ratios indicated heart rate variability and sympathovagal imbalance.Results: ? SBP and the SBP index were the highest in severe OSAHS(12.9±2.3 mm Hg and 33.7±14.7/h),followed by moderate OSAHS(9.5±2.6 mm Hg and 7.1±4.4/h),and mild OSAHS(8.5±1.6 mm Hg 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.Conclusions: 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.Sympathovagal imbalance played an important role in blood pressure variability.