Nocturnal Blood Pressure Abnormalities in Obstructive Sleep Apnea - Clinical Predictors

Background: Hypertensive obstructive sleep apnea (OSA) patients are more likely to have nocturnal blood pressure (NBP) abnormalities than hypertensives without it. The establishment of predictors of NBP abnormalities would be of clinical significance. Aim: To determine the role of anthropometric, glucometabolic and sleep study parameters in the detection of OSA patients with NBP abnormalities. Materials and Methods: Eighty-seven patients with newly diagnosed OSA and hypertension participated in the study. OSA was verified by a polysomnography. An ambulatory 24-hour BP monitoring was done to discern (NH) - nocturnal hypertensives (NBP >120/70mmHg) from (NN) - nocturnal normotensives. Results: Risk factors of NH did not differ significantly from those in NN. From all the conventional cardiovascular risk factor parameters only the duration of sleep at SaO2<90% was significantly longer in NH ( p=0.009), as well as, the levels of HbA1C (p=0.024). After adjustment for confounding factors in a multiple regression model only the time of sleep at SaO2<90% remained as an independent predictor. HbA1C levels were of borderline significance. Conclusion: The time of sleep at SaO2 <90%may be applied for the detection of NBP abnormalities in severe OSA patients.