The Wonders of CPAP


Continuous positive airway pressure (CPAP) is probably the best, non-surgical treatment for any level of obstructive sleep apnea. In finding a treatment for obstructive sleep apnea, the primary goal is to hold the airway open so it does not collapse during sleep. The dental appliances and surgeries (described later) focus on moving the tissues of the airway. CPAP uses air pressure to hold the tissues open during sleep.
CPAP was first used in Australia by Dr. Colin Sullivan in 1981 for obstructive sleep apnea. It delivers the air through a nasal or face-mask under pressure. As a person breathes, the gentle pressure holds the nose, palate, and throat tissues open. It feels similar to holding your head outside the window of a moving car. You can feel the pressure, but you can also breathe easily.

The CPAP machine blows heated, humidified air through a short tube to a mask. The mask must be worn snugly to prevent the leakage of air. There are many different masks, including nasal pillows, nasal masks, and full-face masks. The CPAP machine is a little larger than a toaster. It is portable and can be taken on trips.

Determining CPAP pressure: With CPAP it is important to use the lowest possible pressure that will keep the airway open during sleep. This pressure is determined by "titration." Titration frequently is performed with the help of polysomnography. It can be performed during the same night as the initial polysomnography or on a separate night. In the sleep laboratory an adjustable CPAP machine is used. A mask is fit to the person and he or she is allowed to fall back asleep.

During baseline sleep the apneas and hypopneas occur, and the the technician then slowly increases the CPAP pressure until the apneas and hypopneas stop or decrease to a normal level. A different pressure may be needed for different positions or levels of sleep. Typically, laying on the back and REM sleep promote the worst obstructive sleep apnea. The lowest pressure that controls obstructive sleep apnea in all positions and sleep levels is prescribed.
  • Effectiveness of CPAP

    CPAP has been shown to be effective in improving subjective and objective measures of obstructive sleep apnea.
    - It decreases apneas and hypopneas.
    - It decreases sleepiness as measured by surveys and objective tests.
    - It improves cognitive functioning on tests.
    - It improves driving on driving simulation tests and decreases the number of accidents in the real world.
    When adjusted properly and tolerated, it is nearly 100% effective in eliminating or reducing obstructive sleep apnea. An important clinical outcome of CPAP use is in the area of prevention of the potential complications of obstructive sleep apnea. Studies have shown that the proper use of CPAP reduces hospitalization for cardiac and pulmonary causes in people with obstructive sleep apnea. More generally, treating obstructive sleep apnea with CPAP can reduce the risks of conditions related to obstructive sleep apnea, such as, ischemic heart disease, abnormal heart rhythms, stroke, hypertension, and insulin dependence.
  • Problems with CPAP

    The first 2-4 weeks is the crucial time to become a successful CPAP user. During this time, it is important to try to sleep as many hours a night as possible with the mask on. If the mask does not fit properly or the machine is not working it is important to have it fixed immediately. It is also helpful to remember all of the increased risks of untreated obstructive sleep apnea (decreased productivity, heart attacks, strokes, car accidents, and sudden death) as an incentive to continue using CPAP.

    People with severe obstructive sleep apnea, never get a normal night of sleep. They often put on the CPAP mask and think it is the best thing ever. They quickly get used to it because it allows them to sleep. They take it on vacations because without it they have no energy and are always sleepy.

    However, CPAP is not always easy to use. People with only mild to moderate sleep apnea often have a harder time using CPAP. About 60% of people with CPAP machines report that they use them, but only 45% of them actually use them more than four hours per night when the actual use time is measured. Between 25% and 50% of people who start using CPAP, stop using it.

    It is not easy to sleep with a mask that is blowing air into your nose. Some people are claustrophobic and have difficulty getting used to any mask. If a patient has nasal congestion or a septal deviation; it is important to have these evaluated since they can be treated (as discussed later). Some people do not like the inconvenience of sleeping with the mask or traveling with the machine. Others do not like the image of having to sleep with a mask. The noise of the machine blowing air can also be bothersome to some people using the CPAP or their bed partners.
  • Bi-level positive airway pressure (BiPAP)

    Bi-level positive airway pressure (BiPAP) was designed for people who do not tolerate the higher pressures of CPAP. It is similar to CPAP in that a machine delivers a positive pressure to a mask during sleep. However, the BiPAP machine delivers a higher pressure during inspiration, and a lower pressure during expiration, which allows the person not to feel like they are breathing out against such a high pressure, which can be bothersome. It is most helpful for people who require a higher pressure to keep their airway open. BiPAP was designed to improve CPAP compliance; however it is difficult to measure an increase in compliance when compared to standard CPAP. BiPAP is often only approved by insurance companies after documentation that a patient cannot tolerate CPAP.
  • Auto-titrating continuous positive airway pressure

    The auto-titrating CPAP machine is a "smart" CPAP machine that makes pressure adjustments throughout the night. As discussed above, different pressures are needed for different levels of sleep and positions. The goal of auto-titrating CPAP is to have the lowest possible pressure for each position or sleep level. At a given pressure, if a person starts to have an apnea or hypopnea, the machine adjusts the pressure higher until the episodes are controlled. If a person is in a sleep level or position that doesn't need a higher pressure, the pressure is reduced. The benefit is when a lower pressure is all that is required, the machine is not stuck at the highest pressure needed. The down side is, if the machine does not adjust, a person can be stuck at a lower pressure having episodes of sleep apnea.

    With auto-titrating CPAP, the mean pressure throughout the night is lower and 2/3 of the night is spent below the set CPAP pressure. The machine also can adjust for the changes in pressure that are needed to overcome the effects of weight gain and alcohol or sedative use. It may also improve compliance; however, this has not been measured. The disadvantages of auto-titrating CPAP are that leaks may underestimate pressure or airflow. Each company has a different algorithm for adjusting the pressure and adjusting for leaks. It is unclear which company has the best algorithm, but studies are on-going.
  • Why is it important to treat obstructive sleep apnea?

    When a person with obstructive sleep apnea considers all the options for treatment, he or she may be tempted to not choose any of them. The masks and dental appliances have to be worn every night and the surgeries are painful and have no guarantee that they will be successful. When considering the consequences of all the treatments; however, it is important to remember that there are consequences of not receiving treatment. It is estimated that only 10% of patients with obstructive sleep apnea are being treated. Some of the remaining 90% know that they have a problem, but they choose not to pursue treatment. People with obstructive sleep apnea may have a right to accept the risks to their health that refusing treatment poses; however, when they drive they put everyone else at risk as well. People who refuse treatment for their obstructive sleep apnea should be reported to the DMV, which often will suspend their driver's licenses. Untreated obstructive sleep apnea also increases the risk of:
    - heart attacks,
    - strokes,
    - high blood pressure,
    - decreased productivity at work,
    - decreased attentiveness at home, and
    - sudden death.
    If you think that you or someone you know may have obstructive sleep apnea, please discuss the symptoms with your doctor as soon as possible.
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