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An ASV (adaptive servo-ventilation) machine is a specialized bilevel PAP device that adjusts pressure support breath by breath, with a built-in backup rate, to stabilize breathing. It is used mainly for central sleep apnea, complex (treatment-emergent) sleep apnea, and Cheyne-Stokes breathing, not for ordinary obstructive sleep apnea [1]. It is prescription-only, and there is one group it must NOT be used in: people with symptomatic heart failure and a low ejection fraction (see below).
ASV Machines at a Glance
- What it is: a bilevel PAP that auto-adjusts pressure support in real time with a backup rate [1].
- Who it is for: central, complex (treatment-emergent), mixed, and Cheyne-Stokes breathing, and some treatment-resistant OSA {C(1)}.
- Who it is NOT for: symptomatic chronic heart failure with a left ventricular ejection fraction of 45% or less and predominant central sleep apnea [2][3].
- Prescription: required, after a sleep study and specialist review.
- Cost: the most expensive PAP type, roughly $1,800 to $4,000+ (often covered as durable medical equipment).
What Are ASV Machines?
Adaptive servo-ventilation (ASV) machines are non-invasive positive airway pressure (PAP) devices designed to treat sleep apnea, especially when conventional treatments such as CPAP machines are not effective. Unlike a CPAP, an ASV is a bilevel device: its algorithm reads your own minute ventilation and respiratory rate and delivers changing pressure support to stabilize your breathing through the night [1].
These machines have three main components:
- Face mask: worn over the nose, or nose and mouth, to deliver pressurized air into your upper airway.
- The machine: the motor unit that generates the pressurized air and runs the ASV algorithm.
- Flexible hose: connects the mask to the machine.
How To Use An ASV Machine
If you are new to an ASV machine, the routine is simple: before bed, fit the mask comfortably over your nose (or nose and mouth) to prevent leaks, turn on the machine so it can monitor and support your breathing, and sleep. Your specialist sets the pressure-support range for you in advance.
How Do ASV Machines Work?
The core of an ASV machine is its ability to adjust the delivered pressure in real time through a servo algorithm. Instead of a single target pressure, ASV tracks your recent minute ventilation and respiratory rate and aims to keep your breathing near your own normal [1]. By monitoring you all night, it detects when your breathing slows, pauses, or becomes irregular and increases pressure support to normalize it [1].
What sets ASV apart from a simple auto-adjusting CPAP is the backup rate: if you stop making breathing effort, as happens in central apnea, the machine delivers a timed breath for you {C(1)}. When your breathing is steady again, it eases the pressure back toward baseline, so support rises and falls with your need rather than staying fixed. That closed loop is why ASV suits central and Cheyne-Stokes patterns that a fixed pressure cannot fix.
Difference Between ASV Machines, CPAP Machines and BiPAP Machines
Choosing the right PAP device starts with understanding how the three types differ. Here they are side by side:
| Feature | CPAP | BiPAP | ASV |
|---|---|---|---|
| Pressure delivery | One fixed pressure (APAP adjusts within a set range) | Two fixed levels (higher in, lower out) | Auto-adjusts pressure support breath by breath |
| Backup rate (breathes for you during a pause) | No | Only on ST models | Yes, built in |
| Primary use | Obstructive sleep apnea | OSA needing higher pressure, or trouble exhaling | Central, complex, and Cheyne-Stokes breathing |
| Adjusts in real time | No | No | Yes |
| Relative cost | Most affordable | Mid-range | Most expensive ($1,800 to $4,000+) |
| Prescription required | Yes | Yes | Yes |
Continuous Positive Airway Pressure (CPAP) Machines
CPAP machines deliver a fixed, constant pressure all night, which works well for straightforward obstructive sleep apnea. Auto-adjusting (APAP) models like the ResMed AirSense 11 or AirSense 10 vary the pressure within a preset range based on your breathing, but they do not add breaths or target ventilation the way ASV does. Explore all auto-adjusting CPAP machines or compare the types of CPAP machines.
Bilevel Positive Airway Pressure (BiPAP or BPAP) Machines
BiPAP machines provide two pressure levels: higher for inhalation and lower for exhalation. This can be more comfortable for people who struggle against the constant pressure of CPAP, or who need higher pressures. See CPAP vs. BiPAP and the best BiPAP machines, or shop bilevel machines.
ASV Machine
ASV devices finely adjust pressure support in real time to your breathing pattern, which can feel more natural for people with central or irregular breathing. They adjust more finely than any other PAP type, and are usually the most expensive option. The main models are the ResMed AirCurve 11 ASV (the newer generation) and the ResMed AirCurve 10 ASV (the established, proven version). If you were prescribed a bilevel but not ASV, the AirCurve 11 VAuto is the standard bilevel.
If you are considering an ASV machine, confirm with your sleep-medicine specialist that it is the right, and safe, option for you.
Who Can and Can’t Use ASV Therapy
ASV is built for specific breathing disorders, and it is not right for everyone. Who benefits and who must avoid it comes down to the type of apnea and, critically, your heart.
Who Can Use ASV Machines
Central Sleep Apnea
In central sleep apnea (CSA) the brain does not reliably signal the muscles to breathe, causing pauses. ASV is a leading treatment for CSA because it provides pressure support and a backup breath when your own respiratory drive drops out [6]. Learn more about central sleep apnea causes and treatment.
Complex (Treatment-Emergent) Sleep Apnea
Complex sleep apnea, now called treatment-emergent central sleep apnea, is when central apneas appear in an OSA patient who has just started CPAP. It often resolves on its own within weeks of continued CPAP, but when it persists, ASV adapts to the changing pattern.
Mixed Sleep Apnea
Mixed sleep apnea combines obstructive events (a blocked airway) with central events (no breathing effort) in the same night. That combination is hard for a single fixed pressure to manage: enough pressure to hold the airway open does nothing for a central pause. ASV addresses both, holding the airway open and adding a supported breath when effort drops.
Cheyne-Stokes Respiration
Cheyne-Stokes respiration is a cyclical crescendo-decrescendo breathing pattern linked to heart failure, stroke, and high altitude [6]. ASV is designed to smooth this pattern by adding support during shallow phases and easing off during hyperventilation [6]. (Important safety exception for heart-failure patients below.)
Treatment-Resistant Obstructive Sleep Apnea
Some people with severe OSA and a high apnea-hypopnea index (AHI) do not get their events under control on standard CPAP, even at higher pressures, sometimes because central events emerge or because their breathing is unstable. When conventional therapy repeatedly falls short, ASV can be a valuable next option, and your sleep specialist will decide based on your titration data.
Opioid-Induced Sleep Apnea
Chronic opioid use can cause central and complex sleep apnea that is often resistant to CPAP; research shows these central apneas persisted on CPAP but resolved with adaptive servo-ventilation [5]. ASV may be the best option in these cases.
Who Can’t Use ASV Machines
Symptomatic Heart Failure With a Low Ejection Fraction
This is the most important safety rule for ASV. ASV is contraindicated in people with symptomatic chronic heart failure (NYHA class 2 to 4) and a reduced left ventricular ejection fraction of 45% or less who have moderate-to-severe, predominantly central sleep apnea [3]. In the SERVE-HF randomized trial, this group had significantly higher all-cause and cardiovascular mortality on ASV, not just no benefit [2]. Because of that finding, both the AASM and the device manufacturer recommend against ASV in these patients [3][1].
Ejection fraction is the percentage of blood the left ventricle pumps out with each beat; a normal EF is about 50% to 70% [4]. The 45%-or-less figure is the specific threshold set for ASV safety after SERVE-HF, so if you have heart failure, your EF must be confirmed before ASV is even considered [3].
Chronic Obstructive Pulmonary Disease (COPD)
People with COPD often struggle to exhale, and the pressure swings of ASV can worsen that. ASV is generally not the right tool for COPD-related breathing problems, which are usually managed with other forms of ventilation.
Chronic Hypoventilation
Hypoventilation usually needs treatment aimed at its underlying cause, so these patients may not respond well to ASV alone. As with every case, a specialist decides.
What Are the Advantages of Using an ASV Machine?
For the right patient, ASV can meaningfully improve sleep and breathing. The main benefits:
- Fewer apnea episodes: by adapting to your breathing in real time, ASV is designed to preempt pauses and keep breathing stable; in clinical review it reduced the apnea-hypopnea index substantially over baseline [3].
- Less daytime sleepiness: steadier nights can mean less fatigue and more alertness during the day.
- Better oxygen stability: keeping a steadier breathing pattern can help hold overnight oxygen levels in range.
- More natural comfort: the moment-to-moment pressure changes feel smoother than fixed pressure for many users.
- Better adherence: that comfort can improve how consistently people stick with therapy.
- Versatility: ASV handles several apnea types, which helps people who did not improve on other PAP devices.
Side Effects of ASV Machines
Like any PAP therapy, ASV has some potential side effects, usually minor and manageable: skin irritation from the mask (fix the fit or try a softer cushion), dry mouth (add a heated humidifier), aerophagia or swallowing air with bloating (adjust pressure and mask fit), nasal congestion (humidification helps), and claustrophobia (acclimate by wearing the mask for short awake periods first).
How Do You Get an ASV Machine? Prescription, Sleep Study, and Cost
ASV is prescription-only. You cannot buy one without a prescription, because the settings have to match your specific breathing disorder. The path is: a sleep study confirms the type of apnea, and if ASV is appropriate, a specialist sets your pressure-support range, usually during an in-lab titration study where they dial in the minimum and maximum support while you sleep. This attended setup matters more for ASV than for a standard CPAP, because there are more variables to tune.
On cost, ASV machines are the most expensive PAP category, typically from about $1,800 to over $4,000 depending on the model and bundle. Because they are durable medical equipment (DME), private insurance and Medicare Part B often cover part of the cost when you meet the documentation and diagnosis requirements. If you are choosing a unit, the ResMed AirCurve 11 ASV and the AirCurve 10 ASV are the most widely used options, and the Sleeplay team can help you match one to your prescription.
Frequently Asked Questions
Is an ASV machine the same as a BiPAP?
Not quite. ASV is a type of bilevel machine, but unlike a standard BiPAP it does not use two fixed pressures. It auto-adjusts pressure support breath by breath and adds a backup breath if you pause, which is why it treats central and complex apnea, not ordinary OSA.
How effective is ASV for central sleep apnea?
ASV is very effective at controlling central and Cheyne-Stokes breathing and usually normalizes the apnea events. The key exception: it is not safe or recommended for people with heart failure and a low ejection fraction (45% or less).
Do you need a prescription for an ASV machine?
Yes. Like all PAP devices, ASV requires a prescription. You need a sleep study to confirm the type of apnea and a sleep specialist to set your pressure support, usually during an in-lab titration study.
How much do ASV machines cost?
ASV machines are the most expensive PAP category, typically from about $1,800 to over $4,000 depending on the model. Because they are durable medical equipment, insurance or Medicare Part B often covers part of the cost.
What is the best ASV device?
The right one depends on your prescription, but the ResMed AirCurve 11 ASV and the AirCurve 10 ASV are the most widely used and well-regarded options.
Does Medicare cover ASV machines?
ASV machines are durable medical equipment, so Medicare Part B may cover a portion of the cost once you meet the diagnosis and documentation requirements. Check your specific plan for details.
Can central sleep apnea go away?
Sometimes. Treatment-emergent central apnea that appears when you first start CPAP often resolves within a few weeks. Central apnea caused by an underlying issue, such as heart failure, opioids, or a stroke, usually improves when that cause is treated.
References
- ResMed AirCurve 11 ASV (official)
- Cowie et al., SERVE-HF, New England Journal of Medicine 2015
- AASM 2016 Updated ASV Recommendations (Aurora et al., J Clin Sleep Med)
- Cleveland Clinic: Ejection Fraction
- Javaheri & Patel, J Clin Sleep Med 2017 (opioid-induced central apnea)
- AASM Practice Parameters: Central Sleep Apnea Syndromes
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