"The HeartBEAT Study" finds that continuous positive airway pressure is a superior therapy for reducing blood pressure in patients with sleep apnea, compared with supplemental oxygen.
In the early 1980s, doctors began to notice that a high proportion of patients with obstructive sleep apnea were also presenting with clinical hypertension, or high blood pressure. Over the next 20 years this association caused a great amount of debate between physicians, with research unable to conclude whether sleep apnea causes high blood pressure.
Research was inconclusive as sleep apnea and high blood pressure share a large number of risk factors, including obesity, age, alcohol consumption, smoking, exercise levels and caffeine consumption.
Researchers writing in the BMJ's specialist journal Thorax called 2000 "a bumper year for high quality studies on sleep apnea and hypertension," concluding in 2001 that:
"It now seems almost beyond all reasonable doubt that [obstructive sleep apnea] is an independent risk factor for diurnal hypertension, and that this has more than trivial consequences at a public health level."
In people who have obstructive sleep apnea, the muscles in their throat close in and block the airway while they are sleeping. This results in heavy snoring interrupted by long silent periods when their breathing stops, followed by loud snorts and gasps as they attempt to breathe again.
These gaps in breathing cause blood pressure to go up, because the oxygen level in the body falls and the brain sends signals to the blood vessels to "tighten up" so that oxygen flow to the heart and brain is increased.
Continuous positive airway pressure (CPAP) is the most commonly prescribed treatment for obstructive sleep apnea. This involves the patient wearing a mask while they sleep, connected to a small machine that pumps air into the patient's airway, which helps prevent the airway from closing.
The 'HeartBEAT Study' investigates prevention of heart problems in sleep apnea patients
In the new Heart Biomarker Evaluation in Apnea Treatment (HeartBEAT) randomized, single-blind clinical trial, researchers from Brigham and Women's Hospital in Boston, MA, tested the effectiveness of CPAP at lowering blood pressure in obstructive sleep apnea patients against the effectiveness of nocturnal supplemental oxygen and educational control treatments.
Lead author Dr. Daniel Gottlieb, from Brigham and Women's Hospital's Division of Sleep and Circadian Disorders, explains the relevance of this study:
"The effect of CPAP on blood pressure in this study is important for both physicians and their patients. Previous studies have demonstrated that a decrease in blood pressure of this magnitude is associated with up to a 20% reduction in mortality from stroke and a 15% reduction in cardiovascular mortality."
In the study, 318 patients ages 45-75 with at least moderately severe obstructive sleep apnea were randomized to receive a lifestyle and educational treatment alone or in combination with either CPAP or nocturnal supplemental oxygen.
The participants' blood pressure was measured over a 24-hour period before and after 12 weeks of treatment. The researchers published their findings in the New England Journal of Medicine.
Although Medical News Today does not have access to the full data, the HeartBEAT researchers report that CPAP "performed significantly better than either control or supplemental oxygen on lowering blood pressure."
The effect of CPAP on lowering blood pressure was greatest at night, the researchers observed, and the reduction was greater in diastolic than systolic blood pressure. Also, CPAP proved effective at lowering blood pressure even in participants who had generally well-controlled blood pressure.
"Studies like HeartBEAT provide an opportunity to rigorously test apnea treatment options, which should help physicians determine best treatments for individual patients," says James Kiley, PhD, director of the Division of Lung Disease at the National Heart, Lung, and Blood Institute, who supported the study.