Blood pressure change after treatment for Obstructive Sleep Apnoea (OSA) with Continuous Positive Airway Pressure (CPAP)

It is unclear whether OSA is an independent risk factor for hypertension and whether CPAP treatment reduces blood pressure (BP). We conducted a randomised parallel controlled trial of 4 weeks therapeutic versus sub-therapeutic CPAP treatment (as a control) in men with OSA (Epworth Score (ESS) >10, >4% SaO2 dips >10 per hour). We measured 24-hour BP at home using the TM-2420 ambulatory BP monitoring system before and after treatment. Diary cards were used to report sleep and wake periods. BP changes with treatment were compared between groups using independent samples T-Tests. 85 patients completed the trial. Median (range), age 50 (33-73) years; Body Mass Index 33.7 (24.9-53.9); ESS 16 (10-24); SaO2 dip rate 32.1 (10.6-101.3) and similar between groups. Machine use hours CPAP per night was equivalent between therapeutic 5.4 (2.3-9) and control groups 5.5 (0.4-10). The groups had similar baseline 24 hour BP, mean (SD) therapeutic 132.7 (14.5) / 85.3 (9.5), controls 132.5 (16.6)/84.5 (9.1). Change in BP with Treatment Systolic(mmHg) Diastolic(mmHg) Overall Wake Sleep Overall Wake Sleep Therapeutic -2.4 -1.4 -5.8 -1.6 -1.9 -2.0 n=41 (1.4) (1.4) (1.8) (1.3) (1.4) (1.4) Control +1.4 +2.8 -0.4 +0.6 +1.5 -0.8 n=44 (1.3) (1.4) (1.7) (0.8) (.86) (1.3) p value <0.05 <0.05 <0.04 ns <0.05 ns Mean change (SEM) in Systolic and Diastolic BP by treatment group. Post treatment, sleep period systolic BP was also significantly different on a between groups comparison of means, therapeutic mean (SD) 118.1 (13.3) mmHg versus control 125.6 (18.4), p<0.05. These results support OSA as an independent risk factor for the elevation of blood pressure in men, and shows a blood pressure fall with CPAP treatment.