Bipap Pressure Support - Dynamic or Fixed

[microvax]

Does anyone have any belief as to whether fixed pressure support in an auto bilevel in auto mode is better than Dynamic pressure support in an auto bilevel in auto bilevel mode? Resmed ps=x vs Phillips Psmin-PSmax or Psmin=PSmax where min and max are an equal non zero number. I normally would believe in most things Dynamic would be better, but in this case, I wonder if deterministically setting the pressure support to a fixed amount might address partial events turning into full-blown events and handling the arousal before it happens rather than waiting for it to happen and possibly being awoken if the machine even compensates for let say a random single apnea, which I don't believe mine does?

[Sleeprider]

If the Philips algorithm was actually fast enough to work, it's not a bad idea, but the problem is...it isn't. Static pressure support in combination with a basic pressure algorithm that detects flow limitation and responds appropriately is far better. In addition BiFlex is a complete waste of time compared to Easybreathe™. Prove me wrong.

[microvax]

Thanks, Sleeprider, I appreciate your input. I am not sure it's just speed either. It seems to me, as I have the latest models of each manufacturer, that because each has to follow rules on what is an event, both major brands don't deal with events that don't rise up to the full definition of the event type, until they do, then it's too late and you may already be awake. So in your experience, you believe regardless of which platform, it's better to have a fixed pressure support number that goes up to your typical worst case. This model is working great for me right now with Resmed Aircurve 10 vauto, and all things being equal I think that's a better machine from a build perspective, except perhaps the humidifier tank, but I want to get  some use out of my dreamstations since Philips was nice enough to replace my old system ones with new dreamstations. So, in this case, I was going to set them up essentially like my Resmed to a fixed min=max pressure support same as on the Resmed and give that a go. My only concern is with dynamic pressure support neutered will it still boost epap and then ipap simultaneously if there is a treatable cluster of apnea or something else up to ipap max pressure, like Resmed? Thanks again.

[Sleeprider]

Like yourself I have used both Resmed Aircurve 10 Vauto and the System One DS760, which is equal to the Dreamstation 700 series. The feel and efficacy was so much better on the Resmed, I simply abandoned and gave away the Philips. I think with any machine, an individual will benefit from optimizing pressure to an effective minimum, and while the idea of variable PS seemed like a good idea to me, I never found it to work that well. In theory, we want an increase in EPAP to prevent obstruction, and increase in PS for hypopnea or flow limitation. The Philips is not very good at detecting or responding to flow limits before they manifest as a full hypopnea event, at which point the damage (sleep disruption) is done. I also detest the constant sampling of higher pressure of the Philips algorithm. In coaching hundreds, if not thousands of people here over the years, I am yet to see where variable PS in a spontaneous bilevel has any advantage over static PS.

That said, a Philips BiPAP can be setup for static PS by setting the minimum the same as maximum, and I still prefer the "feel" of the Aircurve with Easybreathe, and I think that might be the bigger magic. Take a look at the mask pressure graph of a Philips (if you can), and you will see a basically square wave.

[microvax]

Thanks again, I tend to agree with your comments. As far as the feel. I like the Resmed feel just like you indicated. On the Philips I turn off biflex as I think it makes my therapy worse and I am okay with the feel like that, but I really think the Resmed does feel better. I have a strange issue with the Phillips maybe you have a thought on. I run out of a full humidifier tank every night if I turn on the humidifier to level 1, this is in less than seven hours. Resmed uses half a tank at its setting one. Both using the same mask and indicating zero or close to it in leak rate. I changed the seals to new ones on the humidifier and replaced the drybox as well in the Phillips. I can find no visible leaks and this was with both the humidifier with the new seals and one fresh out-of-the-box humidifier from Philips. Now I know I live in the desert, but I find it hard to believe the Resmed uses half a tank on setting one and the Philips tank is gone by one night. Another interesting behavior that makes me think there is a leak somewhere is both Resemd and Philips are set to autostart. With airtouch f20 mask on the Resmed, it will start from the first breath. the Philips wearing the same mask will rarely start by breathing. Maybe I should try a different dreamstation unit, maybe there is an issue with the unit itself, but it indicates zero leak when I use it all night and the elbow on it was the same one I was using on the Resmed and it seems to work fine there.

[Sleeprider]

I can't explain the difference in humidity water consumption, other than they both blow air over a warmed container of water. The surface area, turbulence, temperature and control differences probably account for your experience. Philips auto-start and stop has always been balky going back to the System One. It's not just your machine. The Resmed will start with just a hint of pressure change.

[microvax]

Thanks again Sleeprider, have a great evening.