CPAP: Continuous Positive Airway Pressure
General information about continuous positive airway pressure (CPAP), a common treatment for obstructive sleep apnea.
What CPAP Is and How It Works
Obstructive sleep apnea happens when the throat (upper airway) repeatedly narrows or collapses during sleep, briefly interrupting breathing. These pauses can lower oxygen levels, fragment sleep, and cause loud snoring, gasping, and daytime sleepiness.
CPAP is a machine that gently blows a steady stream of pressurized room air through a tube and mask into the airway. This air acts like an invisible splint, holding the throat open so breathing is not interrupted. CPAP does not breathe for the person or add extra oxygen; it simply keeps the airway from collapsing. It is considered the most established and effective treatment for obstructive sleep apnea, and it works only on the nights and hours it is actually worn.
Who Commonly Uses CPAP
CPAP is commonly used by adults diagnosed with obstructive sleep apnea on a sleep study, especially those with moderate to severe disease. It is also used for milder obstructive sleep apnea when there are symptoms such as excessive daytime sleepiness, poor concentration, or mood changes, or when there are related conditions such as high blood pressure or heart disease. A diagnosis and prescription are needed before starting therapy.
Types of Devices
Fixed-pressure CPAP: Delivers one constant, preset pressure throughout the night.
Auto-titrating CPAP (APAP): Automatically raises and lowers the pressure within a set range as breathing needs change during the night (for example, with body position or sleep stage).
BiPAP (bilevel PAP): Delivers a higher pressure when breathing in and a lower pressure when breathing out. It may be used for people who need higher pressures or who find breathing out against steady pressure difficult.
Many machines also offer a "ramp" feature that starts at a low pressure and gradually increases to the prescribed level over about 20 minutes, which can make falling asleep more comfortable.
Types of Masks
The mask (also called the interface) is often the most important factor in comfort and success. Common options include:
Nasal pillows: Soft tips that rest just inside the nostrils. They are lightweight and have little facial contact, which some people prefer, and they can help those who feel closed in by larger masks.
Nasal masks: A cushion that covers the nose only, resting on the bridge and sides of the nose and the upper lip.
Full-face (oro-nasal) masks: Cover both the nose and mouth. These are often used by people who breathe through the mouth at night or have frequent nasal congestion.
Masks come in different sizes, shapes, and materials (often silicone or gel). Finding the right style, size, and fit usually involves some trial and adjustment.
Heated Humidification
Because CPAP moves a lot of air, it can dry out the nose, mouth, and throat. Most machines include a heated humidifier, and many use a heated tube, to warm and add moisture to the air. Humidification is generally used to reduce side effects such as dry or stuffy nose, runny nose, nosebleeds, and dry mouth or throat. Sometimes water droplets can form in the tubing or mask ("rainout"); adjusting the humidity or temperature settings or using a heated tube can help.
Getting Started and Adapting
Adjusting to CPAP takes time, and an adjustment period of several days to weeks is normal. General approaches that many people find helpful include:
Wearing the mask for short periods while awake (for example, while watching television) to become familiar with the sensation before using it for sleep.
A mask that is snug enough to seal but not overly tight.
Use of the ramp feature and humidifier, if the machine has them.
Regular use, every night and for the whole night, since benefits depend on consistent use.
Common Problems and General Troubleshooting
Mask leak: Air escaping around the mask (sometimes blowing into the eyes) often means the mask needs refitting, a different size, or replacement of a worn cushion. A different mask style may help if leaks persist.
Dry or stuffy nose: Adding or increasing heated humidification is a common approach; some people use saline sprays or rinses. Persistent congestion may be related to underlying nasal airflow problems that a clinician can evaluate.
Aerophagia (swallowing air): Air entering the stomach can cause bloating, belching, or gas. Changes in pressure settings, position, or device type are sometimes considered.
Feeling closed in (claustrophobia): A smaller or less intrusive interface, such as nasal pillows, and gradual practice while awake can help some people become comfortable.
Skin irritation or pressure marks: Redness or soreness, often on the nose bridge or where the mask contacts the skin, may improve with refitting, a different size or style, or cushioning products. Nasal pillows avoid contact with the nose bridge.
Many problems can be improved by adjusting the mask, fit, humidification, or pressure comfort settings, and equipment and sleep providers can help troubleshoot.
Cleaning and Maintenance
Regular cleaning helps keep equipment working well and hygienic. General practices include:
Rinsing the mask and cushion regularly and washing them (often with mild soap and water) as directed by the manufacturer.
Cleaning the tubing and humidifier chamber regularly and letting them air dry.
Using only distilled water in the humidifier if recommended by the manufacturer.
Replacing filters, cushions, tubing, and other supplies on the schedule recommended by the manufacturer, as they wear out over time.
Instructions vary by device, so the manufacturer's guidance is the best reference.
How Use and Benefits Are Monitored
Most modern CPAP machines record how many hours they are used and can send this information wirelessly to the care team for review. They also track information such as air leak and the number of remaining breathing events per hour, which helps show whether the settings are effective. More hours of use per night are generally linked to greater improvement in sleepiness and other symptoms. Symptoms such as daytime alertness, snoring, and sleep quality, along with the device data, are commonly used to judge how well therapy is working. The initial diagnosis of obstructive sleep apnea is typically made with an in-lab polysomnogram or a home sleep apnea test.
Potential Risks
CPAP is generally very safe. Most issues are the comfort-related side effects listed above, such as nasal dryness or congestion, mask discomfort, skin irritation, eye irritation from leaks, and bloating from swallowed air. Serious problems are rare. As with any therapy, benefits come only with consistent use.
Alternatives When CPAP Is Not Tolerated
When CPAP is not tolerated or preferred, other options may be considered depending on the type and severity of obstructive sleep apnea and individual factors:
Oral appliances: Custom dental devices, usually mandibular advancement devices, that hold the lower jaw forward to keep the airway open. Often considered for mild to moderate obstructive sleep apnea or for people who cannot use CPAP.
Positional therapy: Methods that discourage sleeping on the back, used when apnea occurs mainly in the back-sleeping position.
Weight loss: Lifestyle changes, and in some cases medications or bariatric surgery, can reduce obstructive sleep apnea severity in people with excess weight and support overall health.
Hypoglossal nerve stimulation: A surgically implanted device that stimulates a nerve to the tongue during sleep to keep the airway open, considered for selected people with moderate to severe obstructive sleep apnea who cannot use CPAP.
Surgery: Various procedures on the nose, throat, soft palate, or jaw may be options for certain people, sometimes to improve tolerance of other therapies.
Each option has its own benefits, limitations, and candidacy requirements, and choices are typically made together with a qualified clinician.