ASV Machines & Sleep Apnea: Everything You Need to Know

Sleep apnea is a medical condition that causes intermittent pauses in breathing during sleep. It may be due to obstruction of the upper airway (obstructive sleep apnea) or failure of the brain to signal your respiratory muscles (central sleep apnea).

The first choice of treatment for sleep apnea is positive airway pressure (PAP) therapy. Usually, this involves wearing a mask during sleep to pump compressed air into the lungs and keep the airways open. The most common type of PAP device is a continuous positive airway pressure (CPAP) machine. 

Adaptive servo-ventilation (ASV) machines are also used to treat sleep apnea with PAP therapy. Learn more about the pros and cons of this treatment and its effectiveness.

Woman sleeping with sleep apnea mask

Yelena Rodriguez Mena / Getty Images

Sleep apnea is common, affecting around 22 million adults in the United States. Left untreated, sleep apnea can lead to symptoms like daytime sleepiness and fatigue, as well as serious medical complications like heart disease, stroke (a blockage of blood flow or bleeding in the brain), brain damage, and diabetes (chronic condition affecting the way your body processes glucose, or blood sugar). 

What Is ASV?

Adaptive servo-ventilation machines offer a newer kind of PAP therapy than traditional CPAP machines. 

People with sleep apnea experience apnea events, or pauses in breathing, throughout the night. These breathing interruptions typically cause loud snoring, gasping, and choking. They disrupt sleep and cause excessive daytime sleepiness.

ASV machines work to prevent these apnea events by monitoring a person’s breathing. They adjust automatically to deliver air pressure levels that fit the patient’s breathing patterns. This helps to stabilize airflow and improve blood oxygen levels during sleep.


Unlike CPAP machines, which provide the same level of air pressure during inhalation and exhalation, ASV machines automatically adjust in response to the user’s breathing patterns.

As a result, some people with sleep apnea find ASV treatment more comfortable and easier to tolerate on a regular basis. This may make them more likely to use their device regularly, which is key to managing sleep apnea.


Because ASV is a newer type of PAP therapy, researchers are still discovering some of its potential drawbacks.

In one study, patients who had both sleep apnea and known heart disease with congestive heart failure (in which the heart doesn't pump enough blood to meet the body's needs) were found to be more at risk of sudden death due to cardiac arrest. This led to concerns about the use of ASV treatment in sleep apnea patients with CHF.

ASV is contraindicated in patients with heart failure with reduced left ventricular ejection fraction. This was determined after a randomized controlled trial (study measuring the effectiveness of new treatments by randomly assigning participants into either an experimental group or a control group) showed 34% increased mortality (death rate) in the ASV treatment group compared with no-ASV group.


Research on the overall effectiveness of ASV machines is ongoing, but some results are promising. 

In one study, long-term use of ASV machines lowered the apnea-hypopnea index (AHI)—the number of breathing interruptions per hour—in patients who had sleep apnea due to prolonged opioid use. The patients in this study did not respond well to CPAP treatment.

Other research has suggested that ASV therapy could reduce daytime sleepiness, decrease the number of nighttime wakings, and improve sleep quality and oxygen levels in people with CPAP-resistant sleep apnea.

What to Expect

It can take several weeks or more to see consistent improvement in symptoms like daytime sleepiness and overall sleep quality with PAP treatment. It’s important to use your ASV machine every night for as many hours as possible to increase your chance of progress.

How Does ASV Differ From Other Treatment Options?

In many ways, ASV machines are similar to CPAP devices and other PAP treatments. However, because it automatically adjusts throughout the night to provide customized air pressure levels, ASV is particularly beneficial for patients with certain diagnoses. 

The most common kind of sleep apnea is obstructive sleep apnea (OSA). OSA is caused by partial or complete blockage of the upper airways. OSA patients typically benefit from treatment with a CPAP device or a bi-level positive airway pressure (BiPAP) machine, which uses two different pressure settings for inhalation and exhalation. 

ASV machines are often used to provide breathing support in patients with conditions that involve irregular breathing patterns. These conditions may include:

  • Central sleep apnea (CSA), in which breathing interruptions are caused by neurological dysfunction
  • Complex sleep apnea, which causes CSA symptoms to develop after an OSA patient receives CPAP treatment
  • Mixed sleep apnea, in which the patient has symptoms of both OSA and CSA

Who Should Not Use an ASV Machine?

There are some people who should not use an ASV machine. Talk to your healthcare provider first if you have heart disease or congestive heart failure.

Signs to Watch Out For

After starting ASV treatment, let your healthcare provider know right away if your sleep apnea symptoms don’t improve or if they get worse. You should also talk to your healthcare provider if you experience hyperventilation (breathing too fast or too deep), chest pain, dizziness, or a racing pulse.


Sleep apnea is a medical condition that causes intermittent pauses in breathing throughout the night. This can lead to daytime sleepiness and fatigue and potentially fatal medical complications like heart disease. 

The first treatment choice for obstructive sleep apnea (OSA) is continuous positive airway pressure (CPAP) therapy. CPAP machines blow compressed air into the lungs during sleep at a single, continuous pressure level. 

For patients with central sleep apnea, complex sleep apnea, or mixed sleep apnea, adaptive-servo ventilation (ASV) machines may be a better choice. ASV machines automatically adjust to the user’s breathing patterns throughout the night, which can be easier to tolerate for people with irregular breathing patterns.

People with both sleep apnea and congestive heart failure (CHF) should not use ASV devices, as some research suggests that it increases their risk of death from cardiac arrest.

A Word From Verywell

It can take time to decide which sleep apnea device best fits your needs. If you have sleep apnea and your symptoms aren’t improving with CPAP therapy, talk to your healthcare provider about whether an ASV device might be right for you.

Frequently Asked Questions

  • What is the difference between an ASV machine and a CPAP machine?

    Sleep apnea is typically treated with positive airway pressure (PAP) therapy. Both ASV and CPAP machines are PAP devices. They work by pumping compressed air into the lungs to keep the airways open during sleep.

    While CPAP machines provide a single level of pressure during both inhalation and exhalation, ASV devices adjust automatically to the user’s breathing patterns as they sleep.

  • Is sleep apnea curable?

    There is currently no cure for sleep apnea. However, sleep apnea symptoms can be managed effectively with treatment. The first choice of treatment for most types of sleep apnea is positive airway pressure (PAP) therapy.

  • How effective is ASV in treating sleep apnea?

    ASV machines are sometimes helpful in treating patients with sleep apnea who have not responded to CPAP or BiPAP treatment. Some patients find ASV machines easier to tolerate over a long period of time because of their variable pressure levels.

    ASV treatment is usually prescribed to patients with central sleep apnea, mixed sleep apnea, or complex sleep apnea.

14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Heart, Lung, and Blood Institute. Sleep apnea.

  2. Harvard Medical School Division of Sleep Medicine. Understanding PAP.

  3. American Sleep Apnea Association. Sleep apnea information for clinicians.

  4. National Institute of Neurological Disorders and Stroke. Sleep apnea information page.

  5. American Association of Sleep Technologists. What is ASV? Treating complex and central sleep apnea.

  6. American Sleep Association. Central sleep apnea treatment: Adaptive servo ventilation.

  7. Aurora RN, Bista SR, Casey KR, et al. Updated adaptive servo-ventilation recommendations for the 2012 AASM guideline: "The treatment of central sleep apnea syndromes in adults: Practice parameters with an evidence-based literature review and meta-analyses.J Clin Sleep Med. 2016;12(5):757-761. doi:10.5664/jcsm.5812

  8. Javaheri S, Harris N, Howard J, Chung E. Adaptive servoventilation for treatment of opioid-associated central sleep apneaJ Clin Sleep Med. 2014;10(6):637-643. doi:10.5664/jcsm.3788

  9. Muza RT. Central sleep apnoea-a clinical reviewJ Thorac Dis. 2015;7(5):930-937. doi:10.3978/j.issn.2072-1439.2015.04.45

  10. National Library of Medicine. Positive airway pressure treatment.

  11. Sleep Foundation. ASV machines.

  12. Wang J, Wang Y, Feng J, Chen BY, Cao J. Complex sleep apnea syndromePatient Prefer Adherence. 2013;7:633-641. doi:10.2147/PPA.S46626

  13. Sleep Foundation. Sleep apnea.

  14. American Association of Sleep Technologists. Pros and cons of adaptive servo-ventilation (ASV) for sleep apnea.

By Laura Dorwart
Laura Dorwart is a health journalist with particular interests in mental health, pregnancy-related conditions, and disability rights. She has published work in VICE, SELF, The New York Times, The Guardian, The Week, HuffPost, BuzzFeed Reader, Catapult, Pacific Standard,, Insider,, TalkPoverty, and many other outlets.