If you have been diagnosed with obstructive sleep apnea (OSA), your doctor likely has recommended you use a continuous positive airway pressure (CPAP) machine to ensure that you sleep soundly at night. In OSA, soft tissue at the back of the throat essentially “collapses” while you sleep, blocking your airway. This interrupts breathing, resulting in low blood oxygen levels (called hypoxia) and increased levels of carbon dioxide that alert the brain to awaken you to open your upper airway muscles. At this point you start to breathe again, often making a loud gasp or choking sound in the process. You may not even be aware of awakening, but these episodes can happen 30 times or more per hour during the night.
OSA can cause daytime drowsiness (see our page 4 article on napping) and increases the risk of high blood pressure, heart attack, and stroke. Research also has pointed to links between OSA and diabetes, weight gain, cancer, memory impairment, and depression. Clearly, controlling OSA is important, and a CPAP machine can help you do that. Considered the gold standard for relieving moderate to severe OSA, CPAP works by delivering a steady flow of pressurized air that prevents the tissues of the throat from collapsing. This keeps your airway open and ensures that you get sufficient oxygen while you sleep.
Selecting the Right Machine
A CPAP machine is considered to be medical equipment and requires a prescription. Ideally, your prescribing doctor should guide you when it comes to selecting the machine and mask that best suits you, although David M. Rapoport, MD, professor of medicine/pulmonary, critical care and sleep medicine at Mount Sinai, says a respiratory therapist from the practice or a “CPAP coach” may assist you. “The focus is on getting the right mask fitted, adjusting the tightness of the straps, balancing the humidity of the airflow from the machine, and answering any questions you may have about how to use and maintain the machine,” Dr. Rapoport says.
CPAP machines have undergone numerous design changes since they were first introduced as a therapy for OSA in the 1980s. “For example, all current machines have built-in humidifiers,” Dr. Rapoport says. “About onethird or more of my patients need this.” A humidifier is useful because it can help you avoid waking with a dry, sore throat after using the machine overnight. Dr. Rapoport notes that some machines also have auto-adjusting pressure (APAP), meaning that they monitor your individual breathing pattern and vary the pressure of the flow of air from the machine to match it. Dr. Rapoport is one of the initial inventors of this mode, but says it should be used only if prescribed by your doctor. “It can be used either in the initial period of CPAP use, to determine the fixed pressure that best suits you, or used as ongoing adapting therapy,” he explains. “The problem with the latter is that while it does work in more than 80 percent of cases, it has never been shown to be ‘better’ overall. There also is a risk it may not work properly, especially if there is some other disruption to sleep.”
Choosing a CPAP Mask
As with CPAP machines, you need a prescription to obtain a mask. There are three types: full face, nasal-only, and nasal pillows. Full-face masks tend to be bulkier and have more straps to deal with, but because they cover the nose and mouth, they may be the most practical option if you breathe through your mouth while asleep. Nasal-only masks are smaller and, as their name suggests, cover the nose only. Nasal pillows sit just under the nose and have the smallest profile of all three mask styles.
Some people report that your favored sleep position is an important factor to consider when narrowing down your choice—for example, a full-face mask may be too large for side-sleepers. Overall, Dr. Rapoport says that comfort is the main issue. “The major companies make very good fits available, but there is no single ‘best mask’ any more than one type of shoe fits everyone best,” he observes. “In general, nasal-only masks work better than the full-face ones, but many clinicians start with either.”
Dr. Rapoport says that some of his patients immediately adapt to CPAP and wake up from their first night of use feeling energized and refreshed. “Most people with OSA are somewhat or very tired when they first try CPAP, and this can help them in the first few nights of use,” he notes. “Others are more neutral, but recognize the benefits after a few nights. A sizable number have difficulty with the treatment, although most establish a set pattern of use within the first two weeks of CPAP therapy.” He adds that if you don’t see the expected improvement in your symptoms after about two weeks of using the machine, a follow-up visit to the prescribing doctor is warranted. “It’s possible changing the settings on the machine may help,” he says.
The benefits of sticking with CPAP treatment are significant. For example, there is evidence that high blood pressure decreases after two weeks of CPAP use. The devices also reduce daytime sleepiness, and are associated with fewer hospital readmissions and emergency department visits, and reduced mortality in people with OSA.