[Pressure] New xPAP user - Question about Centrals on OSCAR

[AeroM]

Ok, good to know

[AeroM]

Hi Guys, I have returned with an AirCurve 10 VAuto. 

Long story short, after two CPAP titrations, I was still experiencing too many central apneas with CPAP. In fact, my AHI with CPAP was occasionally worse than without CPAP due to experiencing more centrals with CPAP than apneas and hypopneas without CPAP. I am not sure that my sleep was fixed by moving to BiPAP because I am still waking up every 2 - 4 hours for unknown reasons (and my BiPAP titration showed a lot of spontaneous arousals even at the pressure that reduced my AHI to 1), and I haven’t woken up feeling amazing like some people report, but falling asleep with pressure has been more comfortable, and I am sleeping for significantly longer periods of time without consciously waking up than I could ever manage with CPAP. 

As some of you noticed, I was experiencing periodic limb movements during some of my sleep studies, and I occasionally had restless leg symptoms while falling asleep, especially when taking Benadryl. For this reason, my sleep doctor checked my blood iron ferritin levels and found that, while my ferritin levels were not low enough to indicate anemia, they were below the normal range for males my age (ferritin is a blood protein that stores iron in the body, making it useful as a measure of iron levels in the body). Raising iron levels in restless leg/PLMD patients with low iron seems to help prevent RLS/PLMD symptoms, so I’ve been taking iron supplements and my ferritin was back in the normal range the last time my blood was sampled. During my recent BiPAP titration, PLMD was low and not associated with arousals, so we seemed to have eliminated that as a cause of my waking up. 

Back to my current experience with BiPAP, which I have now been using for 2 weeks:

The first night home with default AirCurve VAuto settings at the pressure prescribed from the BiPAP titration, I experienced the same, if not worse, numbers of centrals as on CPAP (AHI ~24 for a couple hours that night, all centrals). However, searching the forum, I found some Apnea Board members were able to decrease their centrals on BiPAP by changing the trigger sensitivity on their BiPAPs from medium to high or very high. 

Fortunately, this also worked for me and I am now experiencing no more than 1-2 centrals an hour (often less than 1). I am still trying to decide whether setting trigger sensitivity to high or very high works better for me - right now I have been using very high.

To make breathing more comfortable, I also increased Ti max to between 3.0 and 3.5 and Ti min to 0.6. I am still experimenting with these settings, but they did not have as big an impact on my centrals as changing the trigger sensitivity. 

Decreasing cycle sensitivity below medium seemed to make my centrals significantly worse the one night I tried it, but I can’t say that was the cause for certain as I wasn’t interested in repeating the experience to establish a pattern. Your mileage may vary. Currently, my cycle sensitivity is set to very high as I have found breathing while falling asleep feels more comfortable when EPAP is very sensitive to detecting my exhalations.

While my AHI is generally below 1 thanks to eliminating centrals with high/very high trigger sensitivity, as I mentioned above, I am still waking up every 2-4 hours and finding it difficult to return to sleep with the mask on despite feeling tired. I have noticed my VAuto responding to flow limitations, and I am also seeing what looks to me like some really weird patterns of rising and falling breaths. I don’t know if these may be why I am waking up prematurely/not feeling great, or if they are normal. I will post screenshots of these tomorrow.

As a refresher, I am reposting my sleep studies and titrations here as a summary:

Initial Sleep Study: 
I was diagnosed with mild sleep apnea (AHI = 8.9; Supine AHI 11.3/h). My SPO2 went to a low of 91%. During the study, I slept for 6.3 hours and had 3 central apneas and 53 hypopneas. If obstructive apneas, mixed apneas, or RERAs happened, they weren't recorded. There were 0 periodic limb movements (PLM = 0), 14 limb movement events with an index of 2.2. Finally, there were 32 spontaneous arousals with an index of 5.1 arousals/hour of sleep. Snoring was noted. Heart rate was fine and everything else was normal.

1st CPAP Titration Sleep Study: 
Over the course of the night, my pressure was titrated up from 5 cmH2O to 9 cmH2O. The study states that I "responded well to 9 cmH2O, but there continued to be some respiratory events along with flow limitations, so a pressure of 10 may be more optimal." I slept for 7.2 hours with an AHI = 8.4. They noted 3 obstructive apneas, 0 mixed apneas, 55 central apneas, and 3 hypopneas. Total AI was 8.0. There were 5 RERAs for an RDI of 9.1. Cheyne Stokes was not noted. SPO2 went to a low of 88%. There were 48 periodic limb movement events (PLM = 6.6). 6 of these were associated with arousals (0.8 events/h) There were 108 limb movement events with an index of 14.9. Finally, there were 28 spontaneous arousals with an index of 3.9 arousals/hour. 

2nd CPAP Titration Sleep Study: 
My pressure was titrated starting from a minimum CPAP pressure of 8* cmH2O up to a maximum pressure of 11* cmH2O. The study states the “optimal CPAP pressure was noted at 11 cmH2O.” I slept for 7.5 hours. I had a total of 37 respiratory event(s) for an AHI of 5.0 per hour. There were - obstructive apnea(s), - mixed apnea(s), 33 central apnea(s) and 4 hypopnea(s). These respiratory events were associated with arousals and oxygen desaturation to a low of 90.0%. A total of 9 RERAs were noted for a RDI of 6.2. Cheyne Stokes was not noted. There were a total of 18 periodic limb movement events with a PLM Index of 2.4, 5 of which were associated with arousals, which calculated to 0.7 event(s) per hour during sleep. There were a total of 61 limb movement events with an index of 8.2. There were 107 spontaneous arousal(s) noted with an index of 14.3 arousal(s) per hour of sleep.

1st BiPAP Titration:
During this titration study, BPAP pressures between 8/4 cwp and 11/5 cwp were used. I slept for 5.8 hours. The study states that “at BPAP pressure of 11/5 cwp, the best sleep was noted, and the AHI was 1/hr with a TST of 208 minutes at this pressure.Transitional central respiratory events were noted at lower BPAP pressures.”

The apnea/hypopnea breakdown was as follows: 34.1% obstructive (1 apneas, 13 hypopneas), 63.4% central (26 centrals), 2.4% mixed (1 event). AHI for the night = 7/hr) During sleep, the baseline Sa02 was 98% with an Sa02 nadir of 91%. The desaturation index was 4/hr. The arousal index was 20/hr for the night and the spontaneous arousal index was 14/hour during the 208 minutes that I achieved an AHI of 1. The overall periodic limb movement index was 3/hr with a periodic limb movement arousal index of O/hr. 

[SarcasticDave94]

Do you have an OSCAR shot for us? I think what's going to occur is the VAuto will need tuned, likely editing pressures with change to Trigger High to modify things to avoid CA. You'll need to determine how good the therapy is considering rest and comfort. Normally, a person with idiopathic pre-dominant Central Apnea will do worse on a BPAP without backup breath rate like the VAuto than they did on CPAP.

Besides, this is the expected path to ASV. Test, get CPAP, fail. Test, get BPAP without backup breath rate, fail. Unless you put up resistance, next is ST a BPAP with backup breath rate, fail. Then they'll want to test yet again then issue ASV and then you'll pass finally.

Tests are money grabs. Highlight the CA on your current tests. If you must test, accept ASV Titration, skip the rest of them.

[AeroM]

Here are progressively zoomed images of the centrals from the first night with trigger sensitivity at default medium. After seeing this, I changed the trigger sensitivity to high, and I have not had this problem again. Although, I am wondering whether the trigger sensitivity change to high/very high is causing what seems to be some kind of periodic breathing.

[AeroM]

Here are various examples of what I guess is some kind of periodic breathing? Note, these are not from the night with all the centrals, which had trigger sensitivity set at medium - the  trigger sensitivity in the following shots was set at very high. This series of shots I have termed fanged breathing because of the sharp breaths. The shots are 30 minute, 15 minute, and 3 minute zoom, respectively.      ,      ,     

[SarcasticDave94]

PS of 6. Why? This is in dire need to be reduced. I'm quite sure that is inducing at the very least about half the Centrals that were out in force in 12/16.

[AeroM]

I am also seeing less crazy patterns of rising and falling breathing. The following image has what may be asleep periodic breathing and then awake breathing at the end (based on the irregularity of the breaths at the end?).

[SarcasticDave94]

I'm not at all certain, but it's something like a sleep to wake pattern is my guess. Others that's much better at the trace patterns will be along to help.

[AeroM]

The PS of 6 was based on the BiPAP titration. At lower PS, I was having centrals at a rate of up to 75 per hour. AT PS 6, I had one event/hour for the final 208 minutes of the titration, and only one desaturation per hour. For what its worth, I still woke up prematurely, unprompted and didn't feel great. It sounds like the AASM BiPAP titration protocol is to treat flow limitations and hypopneas with increased PS once apneas are eliminated with EPAP, so I'm guessing that's why they kept raising PS even though I had so many centrals    I am definitely still seeing flow limitations at a PS of 6 at home, and I am waking up every couple hours as well, although I can't say for sure that is because of the flow limitations. I also set up OSCAR to flag 30% and 50% flow rate limitations lasting at least 7.5 seconds, and I am having 3-8 of those per hour depending on the night. I know user flagged flow limitations are an experimental feature in OSCAR, so I don't know how accurate the flags are, but if they are accurate, maybe some of those are the reason I'm waking up?

Here is a scanned image of the summary of the BiPAP titration pressures and their corresponding number of events. Apologies for the low resolution of the image, unfortunately, the sleep center provided a really low res image.

[AeroM]

Here is an example of flow limitations at increasing zoom that my AirCurve responded to.