What Is ASV?

Medically Reviewed by Jennifer Robinson, MD on November 15, 2022
Written by Susan Bernstein
3 min read

Adaptive-servo ventilation, or ASV, is a device that treats sleep apnea. It’s a newer, non-invasive option to help you breathe in a steady pattern during the night.

ASV is similar to continuous positive air pressure (CPAP) devices, but it’s a newer technology. These devices track how you breathe while you sleep. They react to your breathing pattern and adjust air pressure to help you breathe more normally during the night.

Your doctor will set the original air pressure on your ASV. This “smart” machine has technology that allows it to change how much air pressure it gives you and how often to keep your airways open so you can breathe.

An ASV unit tracks if you stop breathing for a moment as you sleep. That pause is called an apnea.

If the ASV senses your breathing rhythm is off, it responds with extra air pressure. Once your breaths are steady again, the ASV gently adjusts its air pressure to normal levels. When you’re breathing at a stable rate, your ASV gives you just enough pressure to keep it that way.

You might try ASV if you have one of these types of sleep apnea:

Your doctor may prescribe an ASV for you if your CPAP hasn’t worked for your sleep apnea, or if using a CPAP or bilevel positive air pressure (BiPAP) device led to complex sleep apnea.

ASV can also help if you have sleep-related breathing disorders from taking opioids for chronic pain.

The advantages of ASVs include:

  • Comfort. Some people find them more comfortable to use than a CPAP. ASVs change air pressure levels on an ongoing basis to adapt to your breathing patterns through the night.
  • Easier to use. Since ASV works better for some types of sleep apnea, you may be more likely to stick with it.
  • Better for certain types:
  • Central sleep apnea. If you have central sleep apnea, an ASV can tell when your breathing pattern changes while you sleep. It gives you air when you need it, so you breathe more easily. It also makes sure you get enough oxygen during the night.
  • Complex sleep apnea. ASVs are more effective than CPAP for relief of complex sleep apnea. They can restore normal, stable breathing and improve your ability to have sound sleep.

ASVs may have some downsides, too. Don’t use them if you have one of these conditions:

Cost. ASVs usually cost more than CPAPs. You and your doctor will want to make sure you need the device before you spend money on one.

ASVs work in the same way as CPAP machines. When you’re ready to go to sleep, you’ll slip on a face mask that fits securely over your nose, or your nose and mouth. A flexible hose connects the mask to the motorized ASV unit to provide pressurized air

A few tips for using your ASV:

  • Make sure your mask is snug and won’t slip off as you move while you’re asleep.
  • If you breathe through your mouth when you sleep, you may want to use a mask with a chinstrap.
  • Wear your ASV and mask every time you sleep, even when you nap. This will help you get used to it.

Many people with ASVs find them comfortable. They can restore your normal breathing pattern, stabilize your breathing, and reduce how many times you wake up during the night.

These are the main differences between ASV and CPAP:

  • ASV pressure adjusts to your breathing as it changes during sleep. CPAP air pressure is constant.
  • ASVs are a more reliable treatment for breathing problems in people with complex sleep apnea than CPAP.
  • ASV units are more expensive than CPAPs. Not everyone needs to use an ASV instead of a CPAP.
  • Many people stop using their CPAPs because they’re uncomfortable. ASVs are easier to wear and quickly relieve symptoms. This may make you more likely to stick to using your ASV if you’ve given up on a CPAP in the past.