First night - leak and central apnea questions

I just completed my first night on CPAP with mixed success. I had no trouble wearing the mask all night, but I felt like I was awake a lot through the night. I downloaded the data and had a couple of questions on it.

First, is the leak that I had acceptable (see report below), or do I need to try to lower it? The medium pillows felt quite comfortable to me, and I don't think I was leaking from around my nose. I did feel some air escaping through my mouth a couple of times during the night, but it wasn't a full flow.

Second, I had what appeared to be several central apneas during the night, which I understand are sometimes possible when starting CPAP use. Should I expect these to go away, or do people keep experiencing a few of these each night?

Here's a report from last night:


For comparison, here are the numbers from my sleep study:
Diagnostic: Sleep time 257.5, No. of Respiratory Arousals 119, AI 0, AHI 27, Lowest O2 sat 95, Mean O2 Sat 96, Highest EtCO2 48, Mean EtCO2 38
Treatment (starting at 4cmH2O, ramping to 7cmH2O): Sleep time 83.8, No. of Respiratory Arousals 0, AI 0, AHI 0, Lowest O2 sat 95, Mean O2 Sat 97

It's interesting to me that the sleep study showed no apneas, but the S9 is seeing some (although the first one was when I was awake and held my breath for a short amount of time during mask fitting).

Based on the difference between your lab results and your first night AHI, I'd say your therapy is working fine. But I'm not a doctor, nor do I play one on TV, so take that for what it's worth.

Don't get too hung up on what you see after your first night. Those leaks are no biggie. They'll sort themselves out within your first week or two. I've had far worse many times. As you get used to sleeping on the hose you'll unconsciously adapt to it. Maybe you think you're not sleeping all that well, but most folks get used to it pretty quickly. A lot of the "getting used to it" for me was how to route the hose so it wasn't tugging on my nose or causing leaks. I ended up unclipping the hose from the velcro strap that held it to the headgear and simply let it flop around wherever it wanted to go. My mask has the hose connecting to the nasal pillows via a ball joint, so there's tremendous freedom of movement. I end up sleeping on my side with the hose lieing on my neck between my shoulder and earlobe. I'm not even aware that it's there now (after 6 weeks).

Seems like a lot of respiratory related arousals for as low an AHI as you initially had. Maybe something else is going on. Restless leg?

Your O2 saturation never drops very far, so you don't have the problem many of us do. My sat dropped as low as 66% prior to getting hosed.

Try zooming in on your breathing ("Flow" in ResScan) just before and just after an event is recorded. The peak shape described by the flow recorded will have a characteristic rounded top while you are awake, and a very different shape when you are asleep. Mine are more sawtooth shaped when I'm sleeping. If your flow rate peaks become rounded after an event is recorded that might indicate an arousal. You can have a lot of fun just looking at the flow recording on ResScan.

Keep us posted. There are plenty of people here who can provide some perspective for you.

Thanks for the info - it was very helpful (especially the graph shape part). It looks like a couple of the "apneas" were while I was awake (probably adjusting the mask).

Slartybartfast wrote: Seems like a lot of respiratory related arousals for as low an AHI as you initially had. Maybe something else is going on. Restless leg?

I had no PLMs during the sleep study, so apparently it was just hypopneas that were enough to cause an arousal without desaturation. The respiratory related arousal index was 27, so it was identical to my AHI.

Here's an excellent site http://www.osahelp.com/ that should really be of help. Scroll down to about #6 to view the flow traces. You can clearly see the differences in their profile. I'd like to learn more about those profiles. But this is a good place to start.

Hypopnea arousal with no corresponding desaturation? I wouldn't expect that, but then I'm still in learning mode.

Hope this helps.

cwied wrote:

I had no PLMs during the sleep study, so apparently it was just hypopneas that were enough to cause an arousal without desaturation. The respiratory related arousal index was 27, so it was identical to my AHI.

and Slartybartfast commented:

Hypopnea arousal with no corresponding desaturation? I wouldn't expect that, but then I'm still in learning mode.

Like cwied, my diagnostic sleep study showed no significant PLMs. I had a total of 14 obstructive apneas for the night, 0 hypopneas with desaturation, but also had 78 "hypopneas with arousal". My O2 numbers weren't quite as good as cwied's, but were still much better than most folks here: Min O2 saturation was something like 91% and my mean O2 sat was somewhere between 95% and 96%. The O2 saturation numbers on the titration study were pretty much the same with only a very slight increase. So my original sleep study listed my AHI = 3.9 where AHI=(apneas + hypopneas w/desat)/hour and my RDI = 23.something where RDI=(apneas + hypopneas w/desat + hypopneas w/ arousal). The diagnosis of moderate apnea was based on my RDI.

I have not really gotten anywhere it trying to figure out just what a "hypopnea with arousal" is and whether it is the same thing as a RERA---i.e. a respiratory event related arousal. But that's what I'm slowly beginning to conclude it must be.

And in poking around the AASM site at http://www.aasmnet.org/ , it looks to me like there's some kind of relatively new consensus that's been building for the last couple of years that frequent respiratory event related arousals (hypopneas with arousal, but not desat?) are just as disruptive to normal sleep as those that involve desaturation numbers. The Clinical Guideline for the Evaluation, Management and Long-term Care of Obstructive Sleep Apnea in Adults published in 2009 defines OSA in terms of RDI=(#apneas + #hypopneas + #respiratory event related arousals)/hour. So maybe it's only now becoming more common to add the number of this kind of respiratory arousals into the decision to diagnose sleep apnea/sleep disordered breathing and treat with CPAP.

In case you're interested, the Clinical Guideline is posted as a pdf on the AASM site. When I try to link it here, I get an error on submission. The link is at http://www.aasmnet.org/Resources/Clinic ... OSA_Adults dot pdf , but you need to replace the " dot " with a standard period and no blank before or after it. The OSA definition starts right at the bottom of the first column and continues onto the top of the second column of page 267; the article starts on page 263.

But then again, I'm a lowly college professor of mathematics, not a medical doctor. So what do I know anyway?

Thanks a lot to both of you for those links. They are very interesting.

I think my sleep study report doesn't include an RDI number. I did find a document that says that a hypopnea is defined as a reduction of flow >= 50% with either a desaturation >= 3% or an arousal. I think my hypopneas were scored based on the latter definition.

I found a copy of the AASM titration guidelines on binarysleep.com, here's the definition for an RERA: "As specified in the AASM Scoring Manual, a respiratory effort-related arousal (RERA) in adults is defined as a sequence of breaths lasting at least 10 sec characterized by increasing respiratory effort or flattening of the nasal pressure waveform leading to an arousal from sleep when the sequence of breaths does not meet criteria for an apnea or hypopnea."

The titration guidelines are in this thread: http://www.binarysleep.com/phpbb2/viewtopic.php?t=6534

Finally here is the document I found that appears to summarize the 2007 AASM Scoring Manual: http://www.n2sleep.com/Portals/408/Skin ... 0SLEEP.pdf.

Don't worry - the sleep study report is actually fairly straightforward. The charts in the document I linked are the raw charts that are used to calculate the scores in the report. The report itself is just a summary of the whole thing and doesn't include that level of detail. The most important part of my sleep study was summarized on one page of text by the interpreting sleep specialist.

I'm just diving down into details because I like to (and I'm a little obsessive about this kind of stuff ).

cwied wrote:I just completed my first night on CPAP with mixed success.

Hi,

This is not "mixed success". This is totally smashingly fantastic. In comparison, I was too chicken to use the machine the first night I had it, I only lasted 2 hours the 2nd night, and I wanted to chuck the whole thing through the window by the end of the first week. In comparison, you are doing remarkable. An AHI under 1.0 the first time flying solo is nothing short of amazing.

While it is great that you have the software day one and know how to download your data, please do give yourself a week to 10 days before diving in too far. One key thing that you did mention is a bit of air leaking from your mouth. You don't ever want mouth leaks--it throws off the machine and can skew the data, plus it can leave you untreated or under-treated. I'd look into that first.

Did your sleep study report any centrals? If not, then I wonder if this was your machine being confused, or if you really are having centrals, or if something that you were doing tricked the machine into scoring a central. For example, when I roll over from side to side, I hold my breath, and my machine scores a hypo for that. On my S8, I'd expect to see no centrals and more hypos. I don't know how the S9 works. But if you really are having centrals, then maybe your sleep doctor needs to know about this. A few central events can be normal for some people, even those without a sleep disorder. They can also be an indicator of a more complex version of apnea. Give it a week or so, and see if this continues, or if this was just a first night artifact.

-john-

jweeks wrote: This is not "mixed success". This is totally smashingly fantastic.

Thanks for the perspective. I probably was over-optimistic about how quickly I would be able to adjust since I the mask didn't bother me at all during the sleep study.

I know it's still early times - I have an appointment with my sleep doctor in a few weeks so I'm going to get a chance to go over all of this data with her. I've managed to catch a cold anyway, so I'm going to have to wait for that to pass before getting baseline data.

jweeks wrote: Did your sleep study report any centrals?

It did not. In fact I had no apneas of any kind - just hypopneas.

I think the S9 has a newer scoring algorithm. The way centrals are detected is by fluctuating the pressure after the first 4 seconds of reduced flow. If there is no obstruction, the flow reflects the fluctuations and it's scored as a central. In my case, I seem to go through periods where I take longer breaks between breaths. Here's an example of a central from two nights ago that's surrounded by some other pauses that are too short to be scored as an apnea:

cwied wrote:... I had what appeared to be several central apneas during the night, which I understand are sometimes possible when starting CPAP use. Should I expect these to go away, or do people keep experiencing a few of these each night? ...

Some central apneas are perfectly normal. If you had slept for ten hours you would have had a total of four. There are numerous reasons this might happen. For example, when you toss and turn in bed it is normal to hold your breath for a few seconds while doing this. The machine would register this as a "Clear Airway (CA)". It's not a central apnea, but it would score it as that. Also, if you awaken slightly (enough to be awake, but then fall back asleep), you go through the transition from awake to sleep. During this time "central apneas" are normal, but not considered to be "central apneas", since it is very normal for everyone to have some breathing instability when we transition from wakefulness to sleep.

So, those numbers are not unusual and are nothing to worry about.