Mean blood pressure, pulse pressure and grade of hypertension in untreatedhypertensive patients with sleep-related breathing disorder

Objective To test the hypothesis that sleep-related breathing disorder (SRB D) is associated with increasing severity of cardiovascular risk markers. Design A cross-sectional study of sleep laboratory patients. Setting University Hospital Sleep Disorders Centre, Patients We studied 591 patients referred for a sleep study, all of them wi thout a history of systemic hypertension. Interventions Clinical interview, two unattended sleep studies, and assessm ent of office blood pressure, cholesterol concentration, alcohol and nicoti ne consumption and daytime blood gases. Main outcome measure Post-hoc analysis of different cardiovascular risk mar kers: mean blood pressure, pulse pressure, and the type and grade of system ic hypertension. Results Patients were classified as normotensive (blood pressure <140/90 mm Hg, n = 228) or hypertensive (blood pressure <greater than or equal to> 140 /90 mmHg, n = 363) according to office blood pressure measurements. Mixed ( systolic and diastolic) hypertension was the most common type of hypertensi on (n = 182), followed by isolated diastolic hypertension (n = 101), border line isolated systolic hypertension (n = 70), and isolated systolic hyperte nsion (n = 10). The frequency of mixed hypertension increased with SRBD act ivity (P < 0.05) and respiratory disturbance index (RDI; the number of brea thing disorders per hour of estimated sleep time) was increased in those wi th mixed hypertension compared with those with normotension (24.8 compared with 15,7; t test: P < 0,01). In hypertensive patients classified as having grades 1-3 of hypertension (n = 265, 80 and 18, respectively), there was a progressive increase in RDI (18.9, 27.2 and 30.3, respectively, P < 0,01), Mean blood pressure increased significantly with RDI, Pulse pressure incre ased significantly with age (P < 0.001), but was unrelated to the degree of SRBD. Conclusion We conclude that mean blood pressure and the severity of hyperte nsion, but not pulse pressure, increase with the severity of the SRBD. (C) 2001 Lippincott Williams & Wilkins.