In patients with obstructive sleep apnea, is continuous positive airway pressure or nocturnal oxygen therapy better for reducing blood pressure than usual care alone?
The use of continuous positive airway pressure (CPAP) in addition to education on sleep hygiene and healthy lifestyle led to lower mean arterial blood pressures in patients with obstructive sleep apnea (OSA) after 12 weeks as compared with either education alone or nocturnal oxygen therapy plus education, even in patients with well-controlled blood pressure at baseline. The absolute reduction was modest (~ 2.5 mmHg), but observational studies associate this level of reduction with a significant reduction in the likelihood of cardiovascular events. This study, however, was not powered to detect any change in patient-oriented outcomes. (LOE = 1b)
Gottlieb D, Punjabi N, Mehra R, et al. CPAP versus oxygen in obstructive sleep apnea. N Engl J Med 2014;370(24):2276-2285.
|Study Design Randomized controlled trial (nonblinded)||Funding Government|
|Setting Outpatient (specialty)||Allocation Concealed|
Patients at 4 cardiology clinics with established cardiovascular disease (CVD) or CVD risk factors were screened for OSA with the Berlin questionnaire (which assesses the presence of snoring and cessation of breathing, daytime sleepiness, and obesity or hypertension), the Epworth Sleepiness Scale (which measures daytime sleepiness), and home sleep testing. The researchers randomized 318 patients with moderate to severe OSA to receive education on sleep hygiene and healthy lifestyle, education and CPAP treatment, or education and nocturnal oxygen therapy. Eligible patients were aged between 45 years and 75 years, scored positively on at least 2 of 3 domains on the Berlin questionnaire, and experienced 15 to 50 events per hour on the apnea-hypopnea index. The primary outcome was 24-hour mean arterial blood pressure. After excluding patients who did not complete blood pressure measurement at baseline and at 12 weeks, 281 (88%) participants were eligible for analysis. Baseline patient characteristics were similar across all 3 groups, save for the ratings of daytime sleepiness and the proportion of patients using alpha-adrenergic blockers. Half the participants had established CVD, 88% had hypertension, and the average 24-hour blood pressure was 124/71. After 12 weeks, both the CPAP and supplemental oxygen groups demonstrated greater than 60% reductions in the frequency of desaturation events. Mean duration of oxygen therapy use was significantly greater than CPAP use (4.8 ± 2.4 versus 3.5 ± 2.7 hours). The mean arterial blood pressure at 12 weeks was significantly lower in the CPAP group than in the education-only group (?2.4 mmHg; 95% CI, ?4.7 to ?0.1) and the supplemental oxygen group (?2.8 mmHg; ?5.1 to ?0.5). The authors suggest that this study offers no support for the largely untested clinical practice of salvage oxygen therapy in OSA patients.