AirCurve VAUTO vs AST

[alshayed]

I strongly disagree with Sleeprider when oxygen concerns are related to OHS. Diagnosing OHS requires an elevated blood CO2 component (hypercapnia), which is caused by inadequate ventilation (aka shallow breathing). The first step of treatment is improving ventilation regardless of oxygenation by increasing EPR/PS. If that causes central apneas then you move to treatment with a backup rate. Even if the minute vent is stable and EPR/PS just raises the tidal volume (Vt) while lowering the RR, the volume of air reaching the alveoli is still improved due to anatomical deadspace. Only after ventilation is improved do you use other tools like PEEP/EPAP or supplemental oxygen if oxygen saturation is still too low.

In the latest screenshot median Vt is 360 @ RR of 15.4. Unless DayWalker (assuming male) is 5'4.5" or shorter that tidal volume is below the lower 6 mL/kg IBW target. Even if that 360 meets the 6 mL/kg IBW target remember median means half the time it's equal to or lower than that. DayWalker, if you give us your height we can calculate better numbers.

Now all things being equal in a person with normal levels of CO2 (no OHS or other hypoventilation) and high enough ventilation I totally agree with Sleeprider. EPR/PS at that point would be purely for comfort or other reasons and then you can use EPAP/PEEP to improve oxygenation.

DayWalker - I suggest you leave EPR at 3 and continue to tweak minimum pressure (aka EPAP).

[DayWalker]

Alshayed,

My height is 5'11"-ish and male. I did try lowering the EPR today and the SpO2 was dropping to 87-88 even when awake so I turned it back to 3. In any case here is something else I've observed. The position of my head (if tilted down a bit) makes a huge difference in SpO2. Here is a snapshot from this evening. Short nap... felt like it and half the time I was semi on my back with the head tilted a bit down (due to high pillow) and half is on my left side. You can clearly see the different periods in the saturation chart...

Please advise,

[Sleeprider]

What baffles me is why Daywalker is not using a bilevel. The use of a CPAP as a pressure support device is both confusing and contrary to what is being attempted by his medical team. As I said before, PEEP confers oxygenation and Pressure Support is ventilation. Both are deficient. We have not discussed a bicarbonate or PCO2 test, but it would be interesting to know if Daywalker is in the normal range ( 23–29 mEq/l) or has a high bicarbonate. Alshayed, I actually don't advocate reducing pressure or pressure support, rather increasing minimum pressure with EPR is a preferred solution, however if I had to choose between PEEP and pressure support, then based on the known low SpO2, I will take higher EPAP, however that is accomplished.

In bilevel terms Daywalker is currently using EPAP min 6.0, PS 3.0 (9.0/6.0) and Max pressure at 20, however the maximum pressure never comes into play. Compare that to my settings with EPAP min 9.0 (13.0/9.0) PS 4.0, an I'm not treating OHD. Bottom line is there are benefits to higher PEEP and more pressure support. You should certainly be able to talk to your doctor and have him argue that bilevel is medically necessary in this case. If you don't get that, then supplemental oxygen is probably warranted. Meanwhile increasing minimum CPAP pressure as you can tolerate it with EPR is the best way to go, however there are alternative ways of getting there.

[Dormeo]

Daywalker, one moral seems to be to use a flatter pillow. Another, to try to stay sleeping on your sides. Can you try either/both?

[DayWalker]

Dormeo, yes I will get a flatter 'non-thempur' pillow.

Sleeprider, I am on therapy since April 25th essentially. Given that we couldn't do ABG test at this time, the doctor suggested that I 'may need a bi-pap' but since he was unsure about the OHS, he suggested we try the APAP first and then see how this goes. The rest you know. In the meanwhile, I bought a VAUTO just because I was able to find a VAUTO from back home at a very decent price and because even though it could be overkill if not needed for OHS, I could still do what this APAP does for half of what they sell it here. It will arrive next month. Until then I am with that APAP rental unit.

[alshayed]

Sleeprider - I think he's got a VAuto on the way but he's borrowing a CPAP temporarily until it arrives. Basically just trying to use the CPAP as a bridge until then due to severe symptoms so min pressure 10 & EPR 3 may be the ticket. BTW with OHS there is a concern adding supplemental oxygen without adequate ventilation - there appears to be some risk of that worsening the hypoventilation so you have to be very careful with that. However I think most of the studies I've read all call for further research. I've wondered if using EPAP/PEEP to increase oxygenation without addressing ventilation would have the same concerns but haven't seen any research or even discussion about that at all. BTW2 bicarbonate >= 27 is highly correlated with OHS so you don't actually have to be technically out of the normal range there. Also FWIW there's now talk about OHS being divided into stages where only more advanced stages include daytime hypercapnia, see https://jcsm.aasm.org/doi/10.5664/jcsm.7318.

DayWalker, are you saying that SpO2 on your back is lower vs on your side or did I get it backwards? If I'm interpreting that correctly I think that could be consistent with expectations of OHS too, but note I don't recall seeing any research comparing body positions. However in general OHS research says the additional weight puts more pressure on your ventilation system and makes it harder to breathe adequately, eventually leading to reduced tidal volume, higher RR, more stress on body, retained CO2, etc. So I suspect if you are on your side that would offload some of the weight and make it easier to breathe.

I think until you receive the VAuto basically my recommendation would be to keep EPR at 3 and use the highest min pressure you can tolerate, so I'm not sure there's much more PAP therapy tweaking to be done.

At 5'11" for a male you would want tidal volume to be between 450 and 600. When you get the VAuto you'll probably want to shoot for a median Vt a little higher than 450, maybe 480 would be a good starting point. Please remember you may eventually be looking at moving from the VAuto to a ST/ST-A with iVAPS. The international Lumis 150 ST has iVAPS where the US AirCurve 10 ST doesn't and you have to get the AirCurve 10 ST-A for iVAPS. Also the Lumis 150 ST has AutoEPAP which last I knew the US AirCurve 10 ST/ST-A did not yet. But the myAir website doesn't seem to support Lumis 150 for some reason, only AirSense & AirCurve if that's important to you.

Best,
Alshayed

[DayWalker]

Alshayed

Thanks for the reply. My breathing and SpO2 saturation is lower on my back than on my left side. The right side is somewhat in the middle. I also think that this foam mattress is also contributing to the whole problem as I tend to sleep awkward positions and it seems that my head always tilts toward my body thus causing further ventilation issues. My shallow breathing has been an issue during my awake time too. I used to have random episodes of tachycardia which no one could explain why was happening, ice-cold limbs, etc and everyone was blaming it on stress, although most of the time there was not a stress factor. For that reason, even though my extended heart exam showed nothing and the cardiologist didn't want to prescribe anything, but my old endocrinologist and the ophthalmologist (both of whom I fired already) insisted on putting me on valsartan and beta-blockers. Both of those are out the door after less than a year of treatment (after my sleep study showed severe bradycardias) and as I do not believe I should walk around with BP of 106/70 and pulse under 50 all the time and feel like s*it all the time. Not to mention that they were causing bradycardia events during sleep with pulse dropping to 39-42. In any case, I has been almost 1 1/2 months since I stopped them (gradually of course) along with Glucophage (as I don't need metformin to further cause hypoxemia and with a1c only 6%), my saturation improved a bit and there are no more bradycardias or tachycardias. I have BP of 115/80 to 129/89 at most, which is not bad at all for my height and weight of 280lbs. I also think that this shallow breathing is due to me playing basketball in high school/college and having larger than normal shoulders and chest capacity and the fact that I carry all my extra weight above the waist too. From the waist down you cant say I am overweight, so there is some reaffirmation as of what you say in regards weight on ventilation.

As of Vauto, do you think it won't help much either and I need to start looking for an iVaps machine? I can care less for myAir access as it doesn't give much info either to me or my pulmonologist and they always want the SD cards. What it would do better or more than VAUTO?

Cheers,

[alshayed]

It's really hard to predict if the VAuto will work for you or not. If it does I think you'll like the smoothness of the breathing with it a lot better. The iVAPS mode doesn't let you use the easy breathe setting, you have to set rise time and fall time is fixed. So especially going from inhale to exhale is somewhat abrupt.

OTOH iVAPS mode let's you have variable pressure support so it adjusts constantly keeping your ventilation at a minimum rate regardless of what position you're sleeping in. Also it has a backup rate to deal with or prevent central apneas. And if you get a version that has AutoEPAP then it adjusts for obstructive events automatically though I think I like the VAuto better on that front too.

The VAuto is the correct next step, and definitely more comfortable. I just wanted to make sure you are aware that there's a chance it's just a waypoint here so you aren't surprised later. 

Also FWIW even if you get the VAuto and then switch to iVAPS there's a chance you could go back to VAuto at some point. There's a study that showed a significant percentage of patients were able to go back to CPAP after 3 months treatment with NIV (presumably bilevel with backup rate). I'm not aware of any way to predict that though. However there are studies that say if your OSA is mild or moderate and you have OHS then you should always start on bilevel rather than CPAP.

[alshayed]

I should have said hard to predict without a titration study. A titration study done correctly should be able to tell you definitively what you need.

[Sleeprider]

We are getting way ahead of ourselves. Vauto should be a good solution. We don't even have a diagnosis to support the rest of the options.