<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=1717549828521399&amp;ev=PageView&amp;noscript=1">

«  View All Posts

Blog Feature

By: AAST Associate Editor on April 9th, 2021

Print/Save as PDF

CPAP Machines/CPAP Masks: What You and Your Patients Need to Know

CPAP | cpap machine | cpap mask

A continuous positive airway pressure (CPAP) machine is the most commonly prescribed device for treating sleep apnea and associated sleep-related breathing disorders, delivering a steady flow of pressurized air into a patient's nose and mouth as they sleep. This keeps airways open and helps normalize breathing. Recent research has shown that patients with obstructive sleep apnea (OSA) exhibited improvements in sleepiness and depressive and anxiety symptoms after three years of CPAP use. Another study found that patients with OSA and a history of cardiovascular disease treated with CPAP therapy reported 20% higher levels of moderate physical activity compared with non-CPAP users, with these patients also more likely to exercise at levels meeting clinical recommendations.

As with other treatments, there are drawbacks associated with the use of a CPAP machine, including discomfort and difficulty falling asleep, especially in the beginning. A major issue with CPAP is non-adherence. Studies published in the European Clinical Respiratory Journal, Journal of Otolaryngology – Head & Neck Surgery and CHEST Journal showed that some users either abandon the use of CPAP, and/or use CPAP for only a fraction of the night. Prospective candidates are often reluctant to use this therapy, since the nasal mask and hose to the machine look uncomfortable and clumsy. Overcoming these hesitancies should be a priority.

A sleep technologist should explain some of the problems that may be faced but should stress that the benefits of CPAP use increase with long-term use. The importance of CPAP education cannot be undervalued. Once the patient has been educated and agreed to CPAP therapy, the next step is to choose the right device.

The Differences Between CPAP, AutoCPAP and BiPAP1

The CPAP machine is the most basic flow generator and the device most often prescribed first, many times because of insurance requirements, since it costs less, and most patients do well with it. If challenges arise, then an AutoCPAP or BiPAP may be prescribed. One of the biggest challenges adjusting to CPAP is the feeling of claustrophobia, or choking, caused by the continuous flow of air pressure upon exhalation. With many machines, pressure can be adjusted or ramping, or other features can be employed to reduce discomfort.

Automatic titrating (another name for auto adjusting) continuous positive airway pressure machines, also known as AutoCPAP or APAP, use a high- and low-pressure range that adjusts delivered pressure based on varying needs. The range is predetermined by the physician but is most often not limited. An APAP machine can detect how much inhalation pressure a patient needs with each breath. Pressure requirements can be impacted by things like sleep position, sleep stage, nasal conditions or even alcohol use. An AutoCPAP set at the lowest pressure of 4 and the highest of 20 is helpful when APAP is used to determine the CPAP pressure needed to maintain an open airway. APAP in patients who have a known CPAP pressure based on an in-lab titration, the setting range is often tightened a bit closer to the average known CPAP pressure for the patient.

BiLevel positive airway pressure (BiPAP), or BPAP, machines have a flow generator that delivers two distinct pressures, one for inhalation and one for exhalation. It is the most complex of these three devices, and therefore the most expensive, and is typically reserved only for those with special needs. Most BiLevel devices offer a high setting of 25 cm H2O versus CPAP and APAP which typically top out at 20 cm H2O. BiLevel best serves those who require mid to high range inhalation pressure needs. Since BiLevel works similarly to a ventilator, it is commonly used for patients with other disorders such as amyotrophic lateral sclerosis (ALS), Parkinson’s or other diseases in which patients need assistance with breathing. It is also frequently prescribed for patients who have central sleep apnea, although many with central apnea do quite well with CPAP or APAP.

Which Interface Is Best for Your Patient?2

Interface Types

  • Traditional nasal masks: Nasal masks are the most common type of interface used by patients and, as the name suggests, just cover the nose. Most have additional forehead braces with pads that lay above the eyebrow area to add stability. This mask works best for patients who sleep with their mouths closed and are able to inhale and exhale well through their nostrils only.
  • Nasal pillows: Nasal pillows are also a popular choice. Like their traditional counterparts, they work best for patients who sleep with their mouths closed and are able to inhale and exhale well through their nostrils only. They are a better choice for patients who have a narrow nose bridge or short face. And since nothing lays above the nostrils, these masks work well for patients who may otherwise be intimidated by the size of traditional masks or who have claustrophobia issues.
  • Full face masks: Full face masks cover both the nose and the mouth and are prescribed for those who breathe through their mouth when they sleep. Components include a hard plastic-like frame which holds a softer inner cushion that lies against the face.

Mask Sizing

There is no industry standard for mask sizing. Thus, brand to brand, and even within manufacturers, sizing can greatly vary. It is important for the patient to try on different masks to see which works best. Sizing choices can be found to include petite, extra small, small, medium, large and extra-large. Many masks also come with a variety of mask cushions. Most masks include the strapped headgear that is adjustable and comes in “one size fits most." Smaller and sometimes larger sizes are available upon request or special order to accommodate patients with a small or large head circumference.

The sizing gauges offered by most manufacturers are useful as a starting point in determining mask size but not always completely accurate. Facial features to consider when choosing a mask include the length of the nose from the nose bridge to the base, width of the nose base and width of the nose bridge; surface area of the upper lip; distance between the eyes and overall circumference of the head.

Once a mask has been chosen by a patient, it must be adjusted to fit properly before sleep. A sleep technologist should have the patient sit, turn the CPAP machine on at a low pressure and place the mask on their face with the straps loose. The patient should then lie down in their normal sleeping position and slowly pull the straps until a good seal is achieved. If the mask has a dual cushion, it will need to be set by gently pulling the mask straight out and away from the patient's face to allow the cushions to inflate properly.

Some Common Problems and Solutions3,4

  • Trouble getting used to using the CPAP device

First, encourage the patient to wear just the CPAP mask for short periods of time while they are awake, including with the CPAP device turned on at a low pressure. Also, encourage the patient to wear the CPAP device every time they sleep, including during naps, to help them get acclimated to it.    

  • Difficulty tolerating air pressure

This can be overcome by using a machine with a "ramp" feature. This setting allows the machine to start with low air pressure. The machine then automatically and slowly increases the air pressure to the prescribed setting as the patient falls asleep. There are also devices that automatically and constantly adjust the pressure during sleep. An example is a BiPAP machine that delivers more pressure during inhalation and less during exhalation.

  • Dry, stuffy nose

Check to make sure the mask fits well. A loose-fitting mask can dry out a patient's nose. If tightening the straps does not work, or the straps have to be retightened often, try a different mask or another interface. Another solution is an inline heated humidifier. Using a nasal saline spray at bedtime also can help.

  • Dry mouth

If a patient breathes through their mouth at night or sleeps with their mouth open, CPAP use may worsen dry mouth. A chin strap may help to keep the mouth closed and reduce the air leak if a nasal mask is worn. A full-face-mask that covers the mouth and nose also may work, as can a heated humidifier that attaches to the PAP device.

  • Difficulty falling asleep

PAP devices with a ramp feature that slowly and gradually increases the air pressure to the prescribed pressure setting as a patient falls asleep may improve comfort at bedtime. Sleep technologists should advise good general sleep habits, such as regular exercise, as well as the avoidance of caffeine and alcohol before bedtime.

  • Unintentionally removing the CPAP device during the night

If a patient moves a lot during sleep, a full-face mask should be considered. If this doesn't resolve the issue, advise the patient to consider setting an alarm for some time in the night, to check whether the device is still on.

  • Bothersome noise

Most CPAP devices are almost silent, but if the device's noise proves bothersome for the patient, first check to make sure the device air filter is clean, unblocked and working correctly. If the device is in proper functioning order, advise the patient to try wearing earplugs or using a white noise sound machine to mask the noise. Placing the machine as far away from the bed as possible also may help.

  • Aerophagia

CPAP users who experience excessive belching, stomach bloating, stomach distension and gas pains may be suffering from aerophagia, which is caused when air enters the esophagus, goes into the stomach and causes bloating. Aerophagia can occur when air from a CPAP device enters the esophagus and goes into the stomach, rather than into the airway and lungs. This can cause gas pains and distension of the stomach. It is common and can happen to anyone who uses CPAP, but when it becomes chronic, it’s a red flag. This is a problem that can be easily overcome when the cause is properly determined. Causes include pressure settings that are too high or too low, nasal congestion, mouth breathing during sleep or difficulty exhaling against the constant pressure of the air delivered by CPAP.

In Conclusion

CPAP treatment is widely used to treat sleep apnea, but patients require encouragement and education regarding long-term benefits that outweigh any short-term discomforts. Sleep technologists should work closely with their patients to overcome any hesitancies, walking them step by step through the protocols for control of the device and proper mask fitting. Remind the patient that adherence is key, and that with successful adherence to therapy, this treatment can not only result in a better night's sleep, but can also help improve health and resolve any associated symptoms, such as depression and anxiety.


  1. Nasca, T.R. Difference Between CPAP, AutoCPAP and BiLevel. American Sleep Apnea Association. https://www.sleepapnea.org/treat/cpap-therapy/choosing-a-pap-machine/difference-between-cpap-auto-cpap-bilevel/
  2. Which CPAP is Best for Me? American Sleep Apnea Association. https://www.sleepapnea.org/treat/cpap-therapy/choosing-a-mask/which-cpap-is-best-for-me/
  3. CPAP machines: Tips for avoiding 10 common problems. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/sleep-apnea/in-depth/cpap/art-20044164
  4. Aerophagia Causes and Resolutions. American Sleep Apnea Association. https://www.sleepapnea.org/treat/cpap-therapy/troubleshooting-guide-for-cpap-problems/aerophagia-causes-and-resolutions/