ASV Titration Tonight

Actually, if you can tolerate it (for example if you don't have complex sleep apnea) then you probably will have the maximum pressure set to 25cm H2O. The unit won't use that unless you stop breathing (due to a central apnea). In essence, it acts as a mini-ventilator to help sustain that exchange of CO2 for O2. In that case, it quickly ramps up the pressure to help sustain respiration to break the undershoot/overshoot cycle that causes central sleep apnea.

What is that undershoot / overshoot cycle? Well, during sleep we have chemoreceptors in our blood that measures the level of acidity in our blood. By inference our bodies determine when too much CO2 builds up in our blood (and it becomes slightly more acidic), then we are driven to breathe to exchange the CO2 for more O2.

Unfortunately, with central sleep apnea this normal mechanism does not work correctly at times. When that happens the CO2 builds up. That's the undershoot sice of the breathing cycle. CO2 builds up to the point where we MUST breathe. Sometimes it goes until we awaken gasping for air. Sometimes, we don't fully awaken, but it does cause an arousal (move from deeper to lighter levels of sleep). Sometimes our bodies just restart the breathing. But now we have too much CO2 in our blood, so our bodies tend to overcompensate. We breathe a little faster than normal and tend to blow off too much CO2. That's the overshoot side of the cycle.

And unfortunately, when we overshoot, we blow off too much CO2, which suppresses our normal breathing cycle. We have another central apnea until the CO2 builds up and we find ourselves in the undershoot side of the cycle again ... and so it goes ... over and over and over again.

The ASV therapy tries to break this cycle of undershoot / overshoot. By quickly ramping up the pressure, it helps sustain respiration. It's not a full ventilator, but it does help with the exchange of CO2 for O2. And that helps break the cycle.

So, unless you are sensitive to the higher pressures, they will almost certainly leave the maximum pressure at 25cm H2O to allow the machine to "do its thing" to help break that cycle.

Hope that helps briefly explain how ASV therapy works.