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APAP vs CPAP

Updated January 18, 2023

Written by

Jay Summer, Staff Writer

Jay Summer

Staff Writer

Jay Summer is a health content writer and editor. She holds a B.S. in psychology and master's degrees in writing and public policy.
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If you are wondering what the difference between an APAP and CPAP machine is, you or someone close to you has likely been diagnosed with sleep apnea. Sleep apnea is a potentially serious disorder that causes the body to repeatedly stop breathing during sleep. There are three types:

Obstructive Sleep Apnea (OSA): The muscles in the throat relax during sleep, in general or in a specific sleeping position, blocking the airway.
Central Sleep Apnea (CSA): The brain doesn’t send the proper signals to the muscles that control breathing during sleep.
Complex Sleep Apnea Syndrome: Sleepers experience a combination of obstructive sleep apnea and central sleep apnea.

Apneas, or pauses in breathing during sleep, often cause microarousals from sleep. Frequent waking from sleep, even if only for a small amount of time, can prevent a person from getting the healthy, restorative sleep that they need.

Sleep apnea affects approximately 2% to 9% of adults. Millions of Americans have been diagnosed with sleep apnea and are actively seeking treatment, while others may have undiagnosed or untreated sleep apnea.

If left untreated, sleep apnea can cause short-term symptoms such as intrusive snoring, morning headaches, sore throats, daytime fatigue, irritability, and disordered sleep patterns. It can also lead to long-term negative health outcomes such as an increased risk of cardiovascular disease, metabolic syndrome, type 2 diabetes, and liver disease, as well as potential surgery complications.

Once a doctor establishes that you are suffering from sleep apnea, they may initially suggest lifestyle changes, such as losing weight, quitting smoking, or discontinuing the use of alcohol or certain sleep medications. They may also treat underlying conditions like allergies. In addition to these potential changes, a doctor will usually prescribe the use of a device that can help open the airway during sleep. In some cases, other interventions, such as surgery, are necessary.

In the majority of sleep apnea cases, treatment usually includes one of two devices: a continuous positive airway pressure (CPAP) machine, or an automatic positive airway pressure (APAP) machine. There are similarities between CPAP and APAP machines, as both devices are designed to promote airflow to help relieve symptoms of sleep apnea. A CPAP machine is the standard treatment option in most cases, but some sleepers may respond better to an APAP machine.

What Is the Difference Between CPAP and APAP?

The main difference between a CPAP and an APAP machine is that an APAP machine automatically adjusts its settings as you sleep. This allows it to meet changing pressure needs throughout the night.

A CPAP machine is adjusted to one setting, usually during a PAP titration study at home or in a sleep study center, or by trial and error while using the machine. If the pressure is too high and causes exhalation discomfort, the CPAP can be manually adjusted to a new setting, but it will not adjust automatically.

Understanding the differences between these two machines can help sleep apnea sufferers work with a medical professional to find the right fit.

	CPAP	APAP
Common Applications	Experts recommend using a CPAP machine for a minimum of 6 hours each night, with regular use required for results Users wear a mask over the nose and secure it with straps The face mask is connected to the machine by a hose Older machine models were bulkier and made more noise, but newer machines are smaller and quieter	APAP machines should be used for at least 6 hours each night, with consistent use Similar to a CPAP machine, APAP machine include the machine, a hose, and a face mask APAP machines tend to be small and make minimal noise
Usage and Appearance	Experts recommend using a CPAP machine for a minimum of 6 hours each night, with regular use required for results Users wear a mask over the nose and secure it with straps The face mask is connected to the machine by a hose Older machine models were bulkier and made more noise, but newer machines are smaller and quieter	APAP machines should be used for at least 6 hours each night, with consistent use Similar to a CPAP machine, APAP machine include the machine, a hose, and a face mask APAP machines tend to be small and make minimal noise
Availability	Widely available and commonly prescribed	Increasingly common treatment for sleep apnea, but not as widely available as CPAP machines
Typical Cost	Average cost of $500 to $800 Most insurance plans cover CPAP machines Reduced-rate CPAP machines and rebates may be available through manufacturers, Medicaid, Medicare, or state-funded programs	Typically more expensive than CPAP machines, averaging $800 or more Many insurance companies will ask you to try a CPAP first, unless your doctor specifies your particular need for an APAP Individual insurance companies may not approve coverage
Success Rate	Most consistently successful treatment for sleep apnea, as well as the most extensively researched Success rate depends on consistency of use	Though there is still a need for more research on the success rate of APAP machines, the existing research is promising, particularly for people with sleep apnea related to sleeping position
Pros	May reduce swelling in the nose and throat Can help reduce or eliminate the vibration that causes loud snoring May clear out congestion along the top of the upper airway	Can respond appropriately to temporary airway blockages like allergies and colds May reduce disruptive snoring Can help clear congestion and reduce swelling
Cons	The mask may cause skin irritation The nose, mouth, and throat may feel dry or irritated May cause a choking sensation in some people, since air continues to blow while the sleeper exhales	Pressure sores or other skin irritation may occur Users may experience a dry mouth, throat, or nose Not programmed to respond effectively to certain sorts of sleep apnea
Generally Recommended For:	Those with sleep apnea, particularly OSA People whose apnea symptoms are disturbing their sleep	Sleepers who have trouble exhaling with the CPAP machine People who have specific forms of sleep apnea, as prescribed by a doctor
Generally Not Recommended For:	People who may be intolerant of wearing a face mask while sleeping	People with CSA, COPD, congestive heart failure, or apnea caused by opioid use Those who do not want to wear a mask when sleeping

CPAP Basics

CPAP machines are the most commonly prescribed treatment for sleep apnea, and have been in use since the 1980s. CPAP machines, which stands for continuous positive airway pressure machines, work by pushing a steady stream of pressurized air through the nostrils, opening up the muscles that improperly relax in people with sleep apnea.

The machine takes in air through a filter, often passing it through a heated humidifier so that it’s easier on the nose and throat. It then uses a built-in motor to push the filtered, humidified air through a tube attached to the machine. At the end of the tube is a CPAP mask that is worn over the nose and affixed to the head with straps.

When the mask is placed over the nose, the steady stream of air goes into the upper airway, essentially creating a cushion or air splint that prevents the throat muscles and tissues from relaxing and collapsing the airway. The continuous airflow also helps keep the soft palate, the uvula, and the tongue from blocking the airway. This helps prevent the pauses in breathing that cause many sleep apnea sufferers to wake up throughout the night.

For people with mild to moderate sleep apnea, particularly OSA, the CPAP can have immediate benefits. Studies have shown that CPAP machines can be effective for many people in reducing or eliminating the risk of both short-term symptoms and long-term health complications.

That said, there are several factors that may impede someone’s ability to benefit from a CPAP machine. Since the air continues to flow in a steady stream, it can cause an uncomfortable choking feeling when users try to exhale. If this happens, the machine can be set to a lower pressure.

Additionally, some users find it hard to get comfortable enough to fall asleep or stay asleep while wearing the mask. In many cases, this is because the mask has not been sized or adjusted to fit them properly. This can cause discomfort, in addition to air leaks, which may decrease the machine’s overall effectiveness. Users should find the best CPAP machine for them because an improperly fitting CPAP mask can cause other complications, such as irritation and pressure sores where the mask is rubbing against the skin.

An example of an APAP machine next to a CPAP machine.

APAP Basics

An APAP is an automatic positive airway pressure machine. Like CPAP machines, APAP machines work by taking in air through a filter (often with heating and humidification), and then using a motor to push the air through a tube that is connected to a face mask. APAP machines create an air splint by cushioning the airway and propping it open, while keeping the soft palate, uvula, and tongue from obstructing or collapsing the airway.

While a CPAP has one continuous setting, an APAP is able to respond to changing pressure needs by constantly measuring how much resistance is present in your breathing. The technology in an APAP machine allows it to remain on a low setting until a change in breathing is detected and more airflow is needed.

APAP machines are often prescribed to people who do not get the desired results from a CPAP machine, or to those who have specific issues with the CPAP’s unchanging pressure level. They may be prescribed before CPAP machines in specific instances, such as sleep apnea that is comorbid with other sleep disorders, or sleep apnea that only occurs when the body shifts into a specific position. APAPs may work better for those who are prone to allergies, colds, or other temporary airway blockages, as they can adjust pressure as needed and then return to a lower setting when the flare-up has passed.

Additionally, APAP machines can be set to perform like a CPAP by setting the machine to a continuous mode.

APAP machines do have some drawbacks that should be considered. Like CPAP machines, they may cause skin irritation, especially if the mask is not properly fitted. They are not recommended for people with CSA, chronic heart failure, COPD, or obesity hypoventilation syndrome, nor are they recommended for use in people who have sleep apnea related to opioid use.

APAP vs CPAP: Which is Best for You?

When it comes to choosing between a CPAP and an APAP, you can start by performing an at-home sleep study or consulting with a sleep specialist or doctor to find the right machine for you. In many cases, finding the right PAP machine is a matter of trial and error. Many people start with a CPAP machine as prescribed by a doctor, but may switch to an APAP if they are not getting the desired results. Others may find that neither PAP machine is the right choice for them, and go with an alternative treatment. Discussing your symptoms and needs with your doctor will help you determine the best treatment plan for your individual case.