Bilevel vs. Autoset

[Possum]

I've noticed that many folks on here use a bilevel device. How do you know if you need, or would benefit from using one?

My device is self-setting, adjusting pressure based on my needs, and I believe that puts it under the APAP category. I also have the EPR setting which, as I understand, is supposed to mimic a bilevel. So, I guess I'm just wondering if I'm missing anything by using an Autoset vs. a true bilevel?

[Sleeprider]

Your pressures are relatively low and as long as you're getting good AHI results and low RERA I wouldn't worry about bilevel.

EPR works a bit differently from a true bilevel. It does provide up to 3 cm of exhale pressure relief, but the timing and implementation are not equivalent to a true bilevel. With an auto-bilevel machine, the minimum EPAP is set first to prevent OA. Pressure support (PS) is added to achieve an IPAP that controls H, FL and RERA. Too much PS can washout CO2 and result in CA. So really, bilevel is very easy to titrate, extremely comfortable, and much better for those who require high pressures or don't tolerate CPAP.

Lets consider your pressure settings, (7-12) and what they really mean. With EPR of 3.0 your effective EPAP pressure is 4-9. If you were titrating with bilevel, could you really prevent OA at only 4 cmH2O pressure? The pressure support of bilevel is what really makes the difference as it makes inhalation so much easier that is overcomes flow limitation. For people with upper respiratory airway resistance this makes breathing effortless. The machine rapidly detects the end of inhalation and switches to the EPAP pressure which is high enough to prevent respiratory collapse, but comfortable for breathing out.

I guess APAP is similar, but the feel is very different. I get very good AHI results on APAP and have one that I use as a standby. I don't "need" bilevel although it cuts my OA and RERA significantly, by 2/3. Still doesn't probably qualify as medically necessary. If you had a chance to get one, I wouldn't turn it down as it is an improvement over CPAP, but you describe your machine as comfortable and effective, so why worry about it?

[zonk]

How do you know if you need, or would benefit from using one?

People on higher pressure, hard to exhale against pressure, gas problems, pulmonary lung issues like COPD, can benefit from using bilevel

But for the majority with straight forward sleep apnea, CPAP/APAP is all that needed. I haven't seen any actual proof that bilevel is better than CPAP for this group of people. If something is better, has to produce better results, like improved sleep quality

[Possum]

Thanks for the thoughtful responses, zonk and Sleeprider. I'm not "worried" about my therapy - just wanted to make sure I'm not missing out on something even more awesome than what I'm already doing.

Sometimes I do find exhalation difficult, but since I've been losing weight and my Autoset has been steadily decreasing my average treatment pressure, it's been easier.

[Sleepster]

Bi-level machines can also be auto-adjusting. You don't have to choose one over the other. Since you already have an auto-adjusting machine, if you stepped up to an auto-adjusting bi-level it would lower the pressure more than by just the 3 cm or so that your EPR gives you. Plus, there are other tweaks.