Effect of continuous positive airway pressure on blood pressure in hypertensive patients with coronary artery bypass grafting and obstructive sleep apnea

Background: Previous studies have documented that obstructive sleep apnea (OSA) increases the incidence of hypertension, respiratory failure and unexpected post-operative deaths during night in coronary artery bypass grafting (CABG) patients. We hypothesized that continuous positive airway pressure (CPAP) reduces blood pressure in these patients. Methods: We conducted a prospective, controlled study in 51 patients. The subjects received CPAP treatment were defined as CPAP group, whereas those refused to use CPAP were served as controls. Blood pressure was measured by 24 h ambulatory blood pressure at baseline and at six months. Results: Fifty-one patients completed the study. CPAP group and controls had similar characteristics. Compared with the control group, the 24-h SBP and 24-h DBP in the CPAP group had a tendency towards lower levels, but the differences were not statistically significant. But the change of SBP in CPAP treatment was significantly higher than controls (CPAP: 10.0 +/- 13.5 mm Hg vs. Control: 2.9 +/- 10.5 mm Hg, P = 0.040). The rate of hypertension control was improved in the CPAP treatment, but had no statistical difference compared to the controls (CPAP, 76.0% vs. Control, 61.5%; P = 0.260). Compared with controls, the proportion of non-dipping hypertension had a markedly improvement in the CPAP group (Control, 46.2% vs. CPAP, 16.0%; P = 0.034). Conclusions: CPAP therapy decreased SBP and improved the status of non-dipping hypertension and alleviated daytime somnolence in hypertensive patients with CABG and OSA on standardized antihypertensive treatment. But DBP and hypertension control did not significantly change compared with the control group.