A machine that delivers air through a nasal mask worn during sleep can reduce daytime sleepiness and other symptoms associated with sleep apnea, but apnea patients are not always happy with the treatment, according to two new reviews of recent studies.
In apnea patients, the airway in the nose and throat periodically narrows or closes off during sleep, stopping breathing for seconds at a time. People with apnea usually snore and feel sleepy and less alert in the daytime. Some studies suggest apnea can contribute to high blood pressure, heart disease and stroke and may be a factor in traffic accidents.
The reviews appear in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Air mask treatment, also known as continuous positive airway pressure or CPAP, is the main treatment for apnea. In their review, Tammie Giles of the Queen Elizabeth Hospital in Adelaide, Australia, and colleagues concluded that CPAP can significantly improve apnea symptoms compared to no treatment or treatment with less invasive methods, such as oral spacers or tongue depressors worn in the mouth to open up the airway.
Patients using CPAP reported feeling less sleepy and more physically and mentally healthy than those not using CPAP. They also had 17 fewer apnea episodes per hour of sleep, the researchers found. CPAP patients in several of the studies also lowered their blood pressure after starting the treatment.
“The overall results demonstrate that in people with moderate to severe sleep apnea CPAP can improve measures of sleepiness, quality of life and mood and associated daytime sleepiness,” Giles said.
In a second review, Jerome Lim and colleagues found that spacers and other oral appliances can improve apnea symptoms compared to no treatment, but they do not work as well as CPAP for most patients.
Lim and colleagues say their findings suggest oral appliances should not be used as “first choice therapy” for people with severe apnea.
However, “it would appear to be appropriate to recommend oral appliance therapy to patients with mild symptomatic obstructive sleep apnea and those patients who are unwilling or unable to tolerate CPAP therapy,” Lim says.
Despite CPAP’s benefits, “certain people tend to prefer oral appliances to CPAP where both are effective. This could be because they offer a more convenient way of controlling obstructive sleep apnea,” Giles said, explaining that many patients find the nasal mask uncomfortable to wear and the CPAP machine too noisy.
Tricia Haynes, a psychiatry professor at the University of Arizona who has studied patients’ reactions to apnea treatment, says the average person may think “the cons of using CPAP outweigh the perceived benefits.”
Haynes said many people with apnea are used to daytime sleepiness by the time they start therapy, “and CPAP is uncomfortable, unwieldy, and inconvenient. Moreover, it is a nightly reminder that one has a chronic medical illness. When operating in a sleep-deprived state, it’s often easier to put the machine in the closet permanently and avoid thinking about it than to problem-solve obstacles with CPAP use.”
The Giles review included 36 studies of 1,718 people, mostly middle-aged and overweight. The Lim review included 16 studies with 745 people, mostly middle-aged men.
According to the National Heart, Lung and Blood Institute, 18 million Americans have sleep apnea. The majority of adult apnea patients are obese, which may make weight loss an important behavioral component of treatment, although the short-term effects of weight loss on apnea symptoms are still uncertain, Giles says.
The Giles and Lim studies were supported by the Garfield Weston Foundation, UK. The Lim study also received support from the National Health Service Research and Development, UK.