Circadian Rhythm of Blood Pressure in Patients with Obstructive Sleep Apnea

Aims: The aims of this study were to examine the circadian variation in blood pressure (BP) in obstructive sleep apnea (OSA) and to compare this between normotensive and hypertensive subjects.Methods: We measured 24-hour ambulatory BP (ABP) in 72 men (mean age 51±8 years), with OSA diagnosed on overnight sleep study. Measurements of BP were made at 15 min intervals for 24 h using either an Oxford Medilog ABP or Spacelabs 90207 recorder. All recordings were performed after ≥ 3 week washout of anti-hypertensive drugs. The day-time monitoring period was defined as 07:00 hrs to 22:00 and night-time 22:00 to 07:00. The ratio of night: day systolic and diastolic BP was calculated.Results: The patients were obese (mean body mass index 33 ± 5 kg/m2) with a central pattern of obesity (waist:hip ratio 0.99 ± 0.14, normal < 0.94). The mean 24-h ABP (systolic/diastolic) was 138 ± 18/88 ± 12 mmHg. The mean daytime ABP was 143 ± 18/93 ± 12 and night-time ABP 128 ± 20/80 ± 12 Hg. The night: day BP ratio was 0.90 ± 0.07 ...