How effective is CPAP?
Continuous Positive Airway Pressure (CPAP) refers to a medical device used primarily for the treatment of sleep apnea. Sleep apnea causes interruption of natural breathing during sleep. The CPAP uses compressed air to keep the air passage open so breathing continues normally.
CPAP treatment involves a CPAP machine, which has three main parts:
and A mask or other device that fits over your nose or your nose and mouth. Straps keep the mask in place while you’re wearing it.
and A tube that connects the mask to the machine’s motor.
and A motor that blows air into the tube.
Continuous positive airway pressure (CPAP) machine 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. CPAP uses air pressure to hold the tissues open during sleep. The CPAP device does not breathe for you. Instead, it creates a flow of air pressure when you inhale that is strong enough to keep your airway passages open.
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.
The CPAP machine blows 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 not heavy, may be 1kg. It is portable and can be taken on trips.
Titration of CPAP (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 during sleep study. It can be performed during the same night as the initial sleep study 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 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. 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.
When adjusted properly and tolerated, it is 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.
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 .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.
The auto-titrating CPAP machine is an Auto 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.
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.
CPAP versus Surgery
As an ENT Surgeon I prefer to remove the obstruction first and the patient may not need a CPAP at all. Sometimes, removing obstruction by surgery, make the patient more comfortable to use the CPAP. There are patients who are not fit for sleep surgery and I do indeed prescribe CPAP which is the only life saver for them.