ASV stands for Adaptive Servo-Ventilation

ASV is one of the latest products released by ResMed, it was specifically designed with central sleep apnea in mind (including it’s complex or mixed apnea forms), although it can also be used to treat obstructive sleep apnea.

How does ASV work?

ASV works by constantly monitoring a patients breathing, whenever a reduction or pause in breathing is detected the machine intervenes with just enough breathing support to maintain the patients breathing at 90% of what it should be. When the patients breathing problems for that ‘episode’ end the machine slowly backs off it’s breathing support. When no support is needed the machine provides just enough pressure to keep airway patency (to keep the airway free from obstruction). This provides up to a 50% reduction in the work of breathing.

Because ASV machines conterminously adjusts itself to what the patient requires most people find these extremely comfortable and easy to wear while wearing.

How effective is ASV treatment?

A 2001 study (Teschler H et. al. Adaptive Pressure Support Servo-Ventilation. A Novel Treatment for Cheyne-Stokes Respiration in Heart Failure. Am J Resp & Crit Care Med 16: 614-619, 2001)
produced the following results:

ASV was the only sleep apnea device which was able to bring the number of apneas and hypopneas into the normal range (anything under 7 per hour is considered ‘normal’). It was also able to reduce the number of arousals per hour the most and increase the amount of time spent in the ‘vital’ (REM & deep slow wave sleep) stages of sleep by the most.

Issues With ASV

The biggest issue with ASV machines is currently the cost, these machines cost upwards of $4,000 each and are sometimes not covered by health insurance. Other issues include the noise of the machine itself and trouble fitting the mask correctly. These can usually be sorted out by trying out different masks, or having a custom one made.

Before you can start using an ASV machine, you’ll need to make an appointment with a sleep specialist and most likely need to spend at least one night under observation (this is so the settings on the computer can be set correctly). In most cases several sleep studies will need to be conducted before the machine is working at it’s full potential.