What is Sleep Apnea?

mars 19, 2015

What is Sleep Apnea?

The most common sleep breathing disorder is Obstructive Sleep Apnea (OSA), which is caused when the upper throat muscles relax too much during sleep, cutting off or restricting the airway. (1-4) These episodes, which also cause the oxygen level in the blood to drop, last from 10 seconds to a minute or longer. (2,3) The brain registers lack of oxygen and the individual wakes up just enough to open the throat and begin breathing again, starting the cycle over. Most of the time, individuals don’t remember these episodes in the morning, but they severely disrupt the restorative effects of sleep. (3) People with moderate or severe sleep apnea may be waking up hundreds of times every night without knowing it. (2) Officially, about 4 percent of men and 2 percent of women in the United States have sleep apnea, but research shows that many more people are living with it. (1,3) One estimate put numbers at 24 percent in men and 9 percent in women; another said nearly 14 percent of adults have the disorder. (6)

“Sleep apnea is a major health concern worldwide,” says Edward Grandi, executive director of the American Sleep Apnea Association. “It’s common but under-diagnosed, and the effects of untreated sleep apnea can be quite serious.” Signs and symptoms of obstructive sleep apnea include loud and frequent snoring, including choking or gasping during sleep, sleepiness or fatigue during the day, and difficulty concentrating. (1,4,6) OSA doesn’t just cause annoying tiredness; it’s also the cause of several serious health problems. Untreated sleep apnea can cause or contribute to heart conditions such as heart attack, heart rhythm disorders and high blood pressure; it’s also associated with stroke, epilepsy and diabetes. (1,3,4) Poor alertness due to lack of quality sleep can cause reduced concentration, decreased productivity at work or school, and even motor vehicle accidents. (4,6)


Sleep apnea is diagnosed using an overnight polysomnogram (PSG), or sleep study. (1,2,3) A PSG is conducted overnight at a sleep laboratory. Several monitoring devices continuously measure breathing, blood oxygen levels, heart rate, limb movements and more. For adults, if breathing stops or is reduced more than five times per hour, OSA is diagnosed.  Even a mild case of OSA can cause health problems, but people with severe obstructive sleep apnea wake up more than 30 times every hour. (1,3) Other tests can support an OSA diagnosis, such as unattended polygraphy, which is conducted at home, or pulse oximetry, which monitors blood oxygen levels. (1,2,3) However, an overnight PSG in an accredited sleep center is considered the definitive test.

(1,2) The most effective treatment for OSA is the application of continuous positive airway pressure, or CPAP. A CPAP machine forces pressurized air through a nose or facial mask, preventing the limp muscles at the back of the throat from closing off the airway. (3,4) (See more information on CPAP in the Q &A below.) Sometimes, treatment can be a device for the mouth that helps keep the airway open (oral appliance). (1,3) Surgery may be an option in some cases. The doctor may also recommend lifestyle changes, such as weight loss, decreasing alcohol and caffeine, and quitting smoking. (3) “The ‘Breathe easy, sleep well’ theme of World Sleep Day 2012 is timely,” says Grandi. “Obstructive sleep apnea and other breathing-related sleep problems are fairly simple to diagnose and treat, but recognition of the problem needs to come first.”


Continuous positive airway pressure application is the gold standard treatment for obstructive sleep apnea, but there are many variations and customizations available. Here, two world leaders in sleep medicine, Antonio Culebras, M.D., and Liborio Parrino, M.D., answer the most common questions about the therapy. Dr. Culebras is professor of neurology at SUNY, Upstate Medical University, Syracuse, New York; Dr. Parrino is assistant professor of neurology at Parma University, Italy.

Q. What is CPAP?

Dr. Culebras: Continuous positive airway pressure applies a constant stream of air pressure to the throat, working as an air splint that helps keep the airway open during sleep. (3,4) It also improves lung function, decreases the work of breathing during sleep, and improves heart function in people with obstructive sleep apnea. (4)

Q. What are the benefits of using CPAP for obstructive sleep apnea?

Dr. Parrino: Not only does CPAP reverse or correct many of the signs and symptoms of sleep apnea, such as sleepiness and snoring, but it also decreases the risks of associated conditions. Studies have shown that CPAP can lower blood pressure, decrease insulin resistance, and lower the risk of heart attack, stroke and epilepsy in people with obstructive sleep apnea. (1)

Q. Are there different kinds of CPAP?

Dr. Culebras: Yes, there is standard CPAP, auto-CPAP and bi-level PAP. The standard CPAP delivers a constant level of air pressure. The auto-CPAP takes into account that the need for air pressure can vary throughout the night depending on sleep position, stage of sleep and other factors. The auto-CPAP measures how much air pressure is needed to keep the throat open and adjusts accordingly. The bi-level positive airway pressure, or bi-PAP, has two levels of adjustable pressure: higher pressure while inhaling, and lower pressure while exhaling. The auto-PAP and bi-PAP options can be tried if adjusting the pressure settings on a standard CPAP do not  alleviate discomfort. (1,3,4)

Q. What other modifications are available?

Dr. Parrino: CPAP has become highly customizable, with more options available than ever before. There are literally hundreds of CPAP masks available, including many different variations of straps, tubes and apparatuses that fit to the face differently. Some masks can be worn like a hat; some don’t have straps at all, while others cover the entire face. Some only have what are called nasal pillows instead of a mask; even cloth masks are available for people whose skin is sensitive to plastics. (1) Dr. Culebras: CPAP is the best therapy for obstructive sleep apnea, but the most significant challenge is to ensure that patients are actually using it. If people find it uncomfortable or otherwise difficult to use, CPAP use can become inconsistent. In addition to the many mask options, there have also been advances in technology to make CPAP machines smaller, quieter and overall more friendly. Certain medications can be prescribed for some patients to help with comfort. Sometimes using an auto-PAP or bi-PAP can help, as can adding humidification to the machine to replicate the nose’s job of warming and humidifying the air. (1,3)

Q. How can I find the right CPAP for me?

Dr. Parrino: An accredited sleep laboratory is the first place to start. The sleep medicine specialist who interprets the sleep study results and discusses treatment options will also follow up later, making adjustments to masks, equipment and medication as appropriate. Many sleep laboratories allow patients to try out several masks before purchasing to find the best, most comfortable option for them. (1,3)


Why is heated humidification such an effective tool in CPAP treatment? Up to 75 percent of those using non-humidified CPAP report a dry, congested and sore nose and throat. (7,8) The use of a heated humidifier with CPAP has been shown to: -Increase compliance  (9-1) -Decrease abandonment of CPAP therapy (10,11) -Decrease nasal symptoms (12-14) -Decrease mouth leak  (15) For many people, heated humidification makes CPAP a more natural and comfortable experience; for others, it is about more than just a comfort. The following criteria make patients more likely to require heated humidification: -Patients over 60 years are five times more likely to require heated humidification. (9) -CPAP users taking two or more medications are six times more likely to require heated humidification. (9) -Patients with chronic mucosal disease (defined as subjective chronic nasal obstruction, chronic sneezing, nasal discharge and postnasal drip, abnormal appearance of the turbinate mucosa, and polypsis) are four times more likely to require heated humidification. (9) -Patients who have undergone uvulopalatopharyngoplasty surgery are four times more likely to require heated humidification. (9) Even if a patient doesn’t fit into any of the categories listed above, he or she may still benefit from heated  humidification.  Mouth leak on CPAP treatment has been shown to occur for up to 31% of total sleep time. (15) Even relatively minor or infrequent dryness may become a significant comfort issue.

 Why did humidity for CPAP treatment need revisiting? Conventional heated humidifiers (CHH), defined as any heated humidifier that does not employ a heated breathing tube, are a well-proven tool. However, like many new product introductions, there was considerable room for improvement. The amount of humidity that a CHH can provide to the patient is limited by ambient room temperature. As a result, a humidity setting that may have been perfectly tuned to the room temperature at the beginning of the night may cause water to accumulate in the CPAP tube as room temperature drops. The benefits of the humidifier may be outweighed by the issues that result from condensation. The advent of the heated breathing tube resolved many of these problems. 

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