Exacerbation of sleep-apnoea related nocturnal blood-pressure fluctuations in hypertensive subjects

Obstructive sleep apnoea syndrome (OSAS) induces marked haemodynamic fluctuations during sleep that might be deleterious to the cardiovascular system. The influence of daytime blood pressure (BP) levels and aging on short-term BP variability during sleep in OSAS patients was investigated. Twenty-nine subjects with newly-diagnosed untreated OSAS were categorised into three groups: normotensive subjects aged <50 yrs (n=10); subjects aged <50 yrs with untreated hypertension (n=8); and normotensive subjects aged >50 yrs (n=11). Beat-by-beat BP was recorded with a Finapres device during polysomnography. The average values+/-SD of apnoea-related BP elevations and the values of the frequency distribution of all BP variations during sleep were assessed to estimate short-term BP variability. Apnoea-related systolic (or diastolic) BP elevations were significantly greater in hypertensives than in normotensives aged <50 yrs (50.3+/-4.88 versus 30.7+/-2.14 mmHg, p<0.001), as was the SD of systolic (or diastolic) BP variations during sleep (19.6+/-2.22 versus 11.1+/-0.73, p<0.001). Short-term BP variability was not significantly increased in normotensive elderly patients. To conclude, the results suggested that systemic hypertension is associated with a greater exacerbation of short-term variability during sleep in obstructive sleep apnoea syndrome patients.