CPAP: Continuous Positive Airway Pressure

People who are diagnosed with a sleep-related breathing disorder are often prescribed a treatment called positive airway pressure (PAP) therapy Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source . Although there are multiple ways of delivering PAP therapy, continuous positive airway pressure (CPAP) is a common sleep apnea treatment.

Consistent use of a CPAP machine provides both short- and long-term benefits to people diagnosed with sleep apnea. Learn about using a CPAP machine, choosing the right machine for you, and tips to help you get the most out of CPAP therapy.

What Is a CPAP Machine?

A CPAP machine is a bedside device that delivers positive airway pressure Trusted Source National Heart, Lung, and Blood Institute (NHLBI) The NHLBI is the nation's leader in the prevention and treatment of heart, lung, blood and sleep disorders. View Source and is used to treat obstructive sleep apnea (OSA) and other breathing problems. People with OSA experience an abnormal number Trusted Source American Academy of Sleep Medicine (AASM) AASM sets standards and promotes excellence in sleep medicine health care, education, and research. View Source of shallow breaths or complete lapses in breathing while asleep. Abnormal nighttime breathing can result in snoring, daytime tiredness, nighttime awakenings, and a variety of other health complications Trusted Source National Heart, Lung, and Blood Institute (NHLBI) The NHLBI is the nation's leader in the prevention and treatment of heart, lung, blood and sleep disorders. View Source .

CPAP therapy may also be prescribed to treat central sleep apnea (CSA) Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source , another sleep-related breathing disorder. In people with CSA, breathing slows or stops due to a lapse in the signals from the brain Trusted Source Medline Plus MedlinePlus is an online health information resource for patients and their families and friends. View Source that regulate breathing.

To help reduce periods of abnormal breathing in people with sleep apnea, a CPAP machine pushes air into a person’s airway, keeping it open as they sleep. As a result, sleepers treated with CPAP should experience fewer obstructive apneas Trusted Source Merck Manual First published in 1899 as a small reference book for physicians and pharmacists, the Manual grew in size and scope to become one of the most widely used comprehensive medical resources for professionals and consumers. View Source and central apneas during sleep.

Read: At-Home Sleep Study

How Do CPAP Machines Work?

A CPAP machine operates by pushing air through a tube into a sleeper’s nose, mouth, or both as they sleep. This air applies pressure to the airway, reducing the likelihood the airway will collapse and obstruct breathing. With a traditional CPAP machine, air is pushed out continuously at one fixed rate of pressure.

CPAP machines are not the only machines that can provide positive airway pressure. Understanding the differences among the various machines that deliver PAP therapy may help shed light on why a certain type of machine is recommended by a doctor or sleep specialist.

CPAP vs APAP

CPAP machines may deliver air at a fixed rate, or may continually change the rate of airflow based on internal technology that senses changes in a person’s breathing during sleep. When a CPAP machine emits air at varying levels of pressure, it is called an auto-titrating CPAP (APAP or auto-CPAP).

Instead of emitting a fixed rate of air, an APAP machine senses when a person’s airway is likely narrowed or blocked, then increases pressure to open the airway. On average, an APAP delivers air at a lower rate than a CPAP machine that uses a fixed rate of airflow. As a result, people using an APAP may be better able to tolerate therapy.

BiPAP vs CPAP

Unlike a fixed-rate CPAP machine that delivers air at a constant pressure, a bilevel positive airway pressure (BiPAP) machine pushes out air at different rates, depending on whether a sleeper is breathing in or breathing out. Generally, the rate of airflow is higher as a person inhales and lower as a person exhales.

In addition to releasing air at two fixed rates of airflow, some BiPAP machines are capable of releasing air at an adaptable rate based on what the machine determines is necessary to reduce abnormal breathing. In these instances, the machine is called an auto-titrating BiPAP.

Generally, a CPAP machine is the first type of treatment prescribed to a person with obstructive sleep apnea (OSA). BiPAP may be recommended to people with OSA who do not respond well to a CPAP machine. BiPAP therapy may also be prescribed to people who have both OSA and another type of sleep-disordered breathing.

CPAP vs ASV

An adaptive servo-ventilation (ASV) machine is primarily used to treat people with central sleep apnea when a CPAP machine is not effective in reducing abnormal breathing . Like a BiPAP machine, an ASV releases air at different rates of pressure when a person breathes in and when they breathe out. Also, the machine delivers air at a pre-set rate of pressure when it detects the person has stopped breathing.

Like APAP and some BiPAP machines, ASV machines can also be auto-titrating. The auto-titrating ASV machines use technology to determine how much air a sleeper needs to keep their airway open as they breathe out. As a result, the auto-titrating ASV machines release air at varying pressure during exhales.

Components of CPAP Machines

Although CPAP machines can vary somewhat depending on the manufacturer, they generally contain these components Trusted Source National Center for Biotechnology Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source :

• Mask: A mask sits over the sleeper’s nose or both their nose and mouth, creating a seal so air can be pushed into the airway without escaping.
• Mask straps: Straps help keep the mask in position, so it remains on a person’s face as they sleep.
• Tubing: A plastic tube or hose connects the mask to the CPAP machine’s motor that pushes out air. Air moves from the machine, through the tube, and into the mask and the airway.
• Motor: The CPAP machine motor blows air into the connected tube. Most machines must be plugged into an electrical outlet to power the motor, but some battery-operated CPAP machines are available. The motor component of the machine also often contains an air filter and, in some cases, a heated humidifier.

Types of CPAP Masks

CPAP masks designed for at-home use come in a variety of styles. A doctor can help choose the mask that offers the best fit Trusted Source Medline Plus MedlinePlus is an online health information resource for patients and their families and friends. View Source .

• Nasal mask:  A nasal mask pumps air through a mask that covers just the nose.
• Nasal pillow: A nasal pillow delivers air through two prongs that extend into the nose Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source .
• Full face mask: Most full face masks cover the nose and the mouth, but some may cover the full face.
• Oral mask: An oral mask is an uncommon style that covers just the mouth.

While not typically used in a person’s home, other types of CPAP masks may be used in hospitalized patients. For example, a nasopharyngeal mask involves inserting tubes into the nose that extend into the throat.

Benefits of CPAP Machines

The primary benefit of using a CPAP machine is a reduction in episodes of abnormal breathing Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source during sleep. As a result, CPAP therapy may improve symptoms associated with sleep-disordered breathing, resulting in:

• Improved sleep quality
• Reduced snoring
• Less daytime sleepiness
• Increased work productivity
• Improved mood

Consistently using a CPAP machine overtime can provide additional benefits. For example, CPAP use may:

• Lower high blood pressure
• Reduce risk of stroke
• Improve memory
• Improve cognitive ability

Related: Best CPAP Machines

Potential Side Effects

Although CPAP machines are very useful for treating sleep-disordered breathing, many people do not use their prescribed machine as much as recommended. Using a CPAP machine may produce side effects, such as:

• Congestion
• Runny nose
• Irritated eyes
• Dry mouth
• Sore throat
• Nosebleeds
• Redness or irritation on top of the nose
• Bloating or nausea
• Respiratory infection

When a person first begins using a CPAP machine, they might find the mask uncomfortable. They may also feel embarrassed or claustrophobic while wearing it. A person’s doctor or sleep specialist can help to minimize side effects by making adjustments or trying another mask type, or by offering suggestions to make using a CPAP machine more comfortable.

Tips for Comfortably Using a CPAP Machine

Fortunately, there are ways to make using a CPAP machine feel more comfortable if you experience discomfort or side effects at first.

• Ask about a humidifier: If your CPAP machine does not have a heated humidifier, switching to one that does may reduce the likelihood of dry mouth, nosebleeds, and congestion.
• Try another mask: There are multiple styles of CPAP masks. If one feels uncomfortable or allows air to escape, another type might be a better fit.
• Clean your CPAP machine: Be sure to clean your machine regularly, as directed by the manufacturer. A clean machine can reduce the chance of infection.
• Adjust machine settings: If you have trouble sleeping because the air coming out of the CPAP machine feels too forceful, see your sleep specialist. They may adjust the airflow rate or have the machine begin at a lower rate and ramp up over time.
• Consider an APAP machine: When the air of a fixed-rate CPAP feels uncomfortable, an APAP machine that automatically adjusts the rate of airflow to your needs might be a better fit.
• Wear earplugs: If the sound of your CPAP machine makes it difficult for you to fall or stay asleep, consider wearing earplugs to block out the sound.

How to Select the Right CPAP Machine for You

CPAP machines are classified as medical devices, so they are only available with a prescription Trusted Source American Academy of Sleep Medicine (AASM) AASM sets standards and promotes excellence in sleep medicine health care, education, and research. View Source . If you are diagnosed with sleep-disordered breathing and your doctor or sleep specialist wants you to try CPAP therapy, they will likely prescribe the best CPAP machine for you. Of course, you can ask questions and give feedback if you feel the machine they choose is not a good fit.