A randomized controlled trial on ambulatory blood pressure lowering effect of CPAP in patients with obstructive sleep apnea and nocturnal hypertension

Abstract

Objective: In a randomised controlled trial, we investigated the blood pressure (BP) lowering effect of continuous positive airway pressure (CPAP) in patients with moderate-severe obstructive sleep apnoea syndrome (OSAS, an apnoea-hypopnoea index, AHI of 15 or higher) and nocturnal hypertension (night-time systolic/diastolic BP ≥120/70 mmHg).

Methods: Sixty patients were randomly assigned to CPAP or sham CPAP, while maintaining their antihypertensive treatment. Ambulatory BP monitoring was performed at baseline (first run-in visit) and the end of follow-up. Clinic and home BP were measured at baseline and each of the monthly follow-up visits.

Results: Of the 60 patients, 47 completed the 3-month study. CPAP (n = 26), compared with sham CPAP (n = 21), slightly and non-significantly reduced 24-h systolic/diastolic BP by −2.8/−2.5 mmHg (p ≥ 0.27), with a slightly greater between-group difference in the daytime (−4.0/−2.8 mmHg, p ≥ 0.29) than night-time (−0.2/−1.5 mmHg, p ≥ 0.50). The CPAP treatment did not significantly influence clinic or home BP during follow-up (p ≥ 0.27). Nonetheless, simple and partial correlation analyses showed that the ambulatory BP lowering effect was dependent on the daytime pulse rate at baseline (r ≥ 0.47, p ≤ 0.01). In patients with a daytime pulse rate greater than 85 beats/min, the mean changes in daytime systolic BP were significantly greater in the CPAP (n = 10) than sham CPAP group (n = 11), with a between-group mean difference of −10.1 mmHg (p = 0.048).

Conclusions: The CPAP treatment did not show significant ambulatory BP lowering effect in patients with moderate-severe OSAS and nocturnal hypertension. However, it may be effective in lowering daytime BP in patients with a faster pulse rate.

Keywords:

• Nocturnal hypertension
• obstructive sleep apnoea
• continuous positive airway pressure
• ambulatory blood pressure
• home blood pressure

Acknowledgement

The authors gratefully acknowledge the participation of all patients and expert technical help of Yi-Ni Zhou (The Shanghai Institute of Hypertension, China).

Disclosure statement

Dr Wang reports having received lecture and consulting fees from Bayer, Daiichi-Sankyo, Novartis, Omron, Pfizer, and Servier. Drs Shen and Yin are employees of Philips Research. The other authors declare no conflict of interest.

Additional information

Funding

The present study was financially supported by grants from the National Natural Science Foundation of China [grants 81270373, 81470533, 91639203, and 81770455] and Ministry of Science and Technology [grants 2015AA020105-06 and 2018YFC1704902] and Ministry of Health [grant 2016YFC0900902], Beijing, China and from the Shanghai Commissions of Science and Technology [grant 15XD1503200], Education [Gaofeng Clinical Medicine Grant Support 20152503] and Health [grants 15GWZK0802 and 2017BR025 and a special grant for “leading academics”] and by a grant from Philips (Shanghai, China).