Moving from Dreamstation to Aircurve

[PartsGuy]

Hi everyone,
 
I am a 66 year old male, 5'10" 205 lbs and in reasonably good health.
 
I have been reading everything that I can find on here but I am at a loss.
 
For several years I was using a  Dreamstation Bipap Auto with an average AHI below .5 almost every night with 99% of events being obstructive. I had changed the settings on it to Min EPAP 12.0 Max IPAP 15.0 with a pressure support of 0. I figured that it would operate basically as a CPAP that could automatically adjust the pressure. I used these settings for years and always had a very good AHI. The few events that I did have were almost always obstructive.
 
I am now using an AirCurve 10 VAuto. With Min of 10 Max of 13 with PS of 2. My AHI is still pretty good although almost all events are now clear airway. When looking at my charts I need help understanding why a couple of things have changed and what changes that I should try. The Insp time and Exp between the machines are totally opposite of each other with the Dreamstation having a long Insp time and a short Exp time and the Aircurve having a long Exp time and a short Insp time.
 
Notice in the attachments that my Insp time and Exp time have basically flipped between the two machines and that the flow rate patterns are very different.
 
All of these years I have only paid attention to AHI and considered everything was good if it was low. I have also attached a chart of a bad night where I had several clear airway apneas with the Aircurve.
 
1. Why would the Insp and Exp times be so greatly different between the machines?
2. Why would there be so much difference between the Flow rate highs and lows between the machines?
3. Is there some other data that is needed to make a judgement?

Any help would be very much appreciated.
 

[Sleeprider]

The insp/exp times being displayed for the Philips device is inaccurate due in part to the rapid exhale with extended null flow ahead of inspiration and the Philips Dreamstation consistently reports longer inspiration times than expiration time. Looking at the chart, we can tell your inspiration time is much shorter than expiration time. The Aircurve appears to accurately report insp time of 1.2 and exp time of 2.7, which is normal. The flow rates between both machines are very similar with tidal volume in the 440 mL range and minute vent near 7 L/min and breath rate of 15-16 bpm. The shape of the flow rate curves appear different, and that may be due to the 25 Hz recording rate for Resmed vs the 5 Hz for Philips4

From what I can see your results look better with the Resmed. I would be tempted to let the Vauto do an auto-titration rather than limit it to fixed pressure. We can clean up the CA events using the trigger sensitivity to trigger IPAP a little faster to stimulate a breath. My suggestion is to try Vauto mode with EPAP min 8.0, IPAP max 14.0 and PS 3, trigger sensitivity high. This range will lower pressure slightly and give the machine some room to respond to events. This will yield a range of 11/8 to 14/11 (inhale/exhale) which brackets your current settings and affords an opportunity to evaluate lower pressures. Unlike the Philips the Resmed is very responsive to flow limitation and obstruction and better at preventing events.

[PartsGuy]

Thank You for the quick reply!!!

I am relieved that most of my concerns are just differences in how the two machines calculate the data.

Thanks also for the much appreciated advice on which changes to try.

[Sleeprider]

The way Philips reports inspiration and expiration times has been frustrating to me. I think that the timing may actually be calculated by Oscar, while I:E times are directly reported and graphed by Resmed. With Philips, as soon as the flow rate rebounds from negative (expiratory flow) to zero, inspiration time begins. That results in completely unreliable results. I tried working with the Oscar development team to find a way to refine the algorithm to wait until at least x-milliseconds of positive flow was recorded, but my recollection is that we just didn't get it done. We can verify whether I:E has a normal profile by looking at zooms of the flow rate as you provided, and there we certainly verified that IE time is probably properly reported for your Resmed and is not significantly different.

We can take a look at results from the revised settings tomorrow. Be sure to post the full-night as well as any segments of concern, and let us know how you feel with the new settings.

[PartsGuy]

Here are my results from last night but take into account that I probably didn't go to sleep until sometime between 12:3-1:00. It was an extremely bad reflux night and I had to sleep sitting in a chair. It may be a few nights before I can get back to sleeping in bed. The new chart with only one CA looks good though. From past experience, I think sitting in a chair must help with my OA.
Thanks for helping

[Sleeprider]

Once you settled down, your pressure was near the bottom of the range and nearly event-free. I don't think our revised settings are related to the GERD. I'm mostly looking to get you in a more comfortable place, and this looks like a move in the right general direction. We have many options with the Vauto to make you more comfortable, but we have the challenge of dealing with GERD in addition to the sleep therapy settings. If you would like to experiment with higher pressure support and lower overall pressure, I would suggest EPAP min 7.0, IPAP max 13.0, PS 3.6, however there is no rush at all to try this alternative as you let things settle down.

[PartsGuy]

I was able to move back to my bed last night and here are what the numbers look like. I haven't changed the settings since the initial changes that you recommended. I am including a close up view of flow rate in an area that is what the majority of my night looked like while I was sleeping as well as the overall view. 
Thanks for any help!!!

[Sleeprider]

That looks like textbook sleep breathing. Hope if feels as good as it looks.

[PartsGuy]

Thanks for the help that you are giving me.

With your recommendations my AHI has been either 0 or near 0 for a few nights. I know that every breath cannot be perfect all night long but I figure the closer that I can get, the better that I will sleep. I am noticing a lot of near events but they don't last long enough to trigger an event. I will attach a snapshot of what these events normally look like.

You had recommended also that I might try EPAP min 7.0, IPAP max 13.0, PS 3.6. I figured that I might "ease" into these settings a little at a time, that is the reason that I was at PS 3.0 over 7.8-14.0 last night. I thought that I would keep lowering the EPAP min number and increasing PS a little at a time.
Thanks for helping

[Sleeprider]

Minor arousals or position shifts like the one in your chart are not something we would adjust settings for. It may help to know that when we subconsciously move in our sleep, that is what it looks like. Note the breathing pause is actually a breath-hold with inhale and no exhale. If you have reached a point in your settings that you are happy with the results, there is no need to do anything else. By getting there slowly, you have self-titrated to an effective and comfortable therapy.