Central Apnea

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
zmbee
Posts: 31
Joined: Mon Apr 07, 2014 6:23 pm

Central Apnea

Post by zmbee » Mon Jun 29, 2015 10:54 pm

I have been using CPAP for about one year with good success. However, this morning I had a strange experience for the first time and I'm wondering if others have had a similar experience. Sometime early this morning, I awoke and found myself inhaling deeply, perhaps as though I was gasping for air. (I was only half awake at the time.) I also noticed that I felt as though my brain had been without oxygen (not surprisingly, I suppose) - like the feeling one gets after standing quickly and having a head rush. That said, I was half asleep and I almost immediately fell back asleep.

After getting up today, I checked the data form my CPAP machine and I found that I had 3 central apneas last night, one for 12 seconds, one for 13 seconds, and another for 14 seconds, the last being the one that woke me. I don't recall seeing central apneas in my data before, but I also have not checked my data too often as things have been going pretty well with my CPAP therapy. I did have a leak prior to the 14 second central apnea and, in fact, I had many leaks throughout the night, several of which exceeded the 24 L/min threshold. The leak just prior to the event I've described above exceeded the 24 L/min threshold and, since it went off the graph, I don't know exactly how large it was.

My questions:
1. Since this is the first time I've experienced something like this, I'm trying to figure out what may have caused this. I suppose my fear is that this occurs more often than I'm aware of and I have just slept through other similar events. What may cause this type of event? Can leaks cause such an occurrence?
2. Under Statistics in Resscan, my Central Apnea Index says 0.5, while my Obstructive Apnea Index says 0. Is a Central Apnea Index of 0.5 considered normal?
3. Are occasional central apneas common with people who have a sleep apnea diagnosis? From information I've read on the net, this seems to be caused by improper signaling from the brain to the respiratory muscles, which is concerning.
4. How accurate is the sleep data? In other words, is it possible that this was due to obstructive apnea, but my CPAP machine logged it as central apnea?

Any assistance would be greatly appreciated. Thank you very much.

JDS74
Posts: 3397
Joined: Sun Jan 23, 2011 2:57 pm
Location: South Carolina

Re: Central Apnea

Post by JDS74 » Tue Jun 30, 2015 6:23 am

zmbee wrote:... My questions:
1. Since this is the first time I've experienced something like this, I'm trying to figure out what may have caused this. I suppose my fear is that this occurs more often than I'm aware of and I have just slept through other similar events. What may cause this type of event? Can leaks cause such an occurrence?
Leaks can cause the machine to be confused as to what is happening. If the leaks occurred and ended prior to the event, then the leak is not the cause of the report. The leaks may have caused an arousal but not an awakening like you experienced with the last event. It is common to have events just after an awakening and usually they are ignorable as part of the wake-sleep transition. 15 seconds is a little long but not worrisome.
zmbee wrote:2. Under Statistics in Resscan, my Central Apnea Index says 0.5, while my Obstructive Apnea Index says 0. Is a Central Apnea Index of 0.5 considered normal?
The index is reporting the number per hour. In this case, the number is one event per each 2 hours.
zmbee wrote:3. Are occasional central apneas common with people who have a sleep apnea diagnosis? From information I've read on the net, this seems to be caused by improper signaling from the brain to the respiratory muscles, which is concerning.
Yes, occasional centrals are common for some sleep apnea patients. But they are not common as part of the experience for obstructive apnea patients. When they occur together with obstructive and/or hypopnea events, the diagnosis is complex sleep apnea. If they occur outside of the sleep-wake transition periods, then they are likely caused by some communications issue. In the wake-sleep transition periods, they are likely caused by a differential in the control of breathing between the detection of the SpO2 level and the CO2 level. One controls awake breathing rate and the other asleep breathing rate (I don't remember right now which is which.) In the awake-sleep transition period, your brain is switching between these two and may have a short period where breathing is suspended for a short period of time until the other triggers a breath. That is why such events are ignored in sleep studies and categorized as "sleep-wake trash."
zmbee wrote:4. How accurate is the sleep data? In other words, is it possible that this was due to obstructive apnea, but my CPAP machine logged it as central apnea?
Any assistance would be greatly appreciated. Thank you very much.
If they occur during a large leak, then the report may not be accurate. If they occur outside of a large leak, then the machines are quite accurate. However, the machine cannot tell if you are awake, asleep, or in transition so the meaning depends on what state you are in. I use a Respironics machine and Encore reporting software. After a very long time of looking at the breathing data, I have a pretty good idea of which of these states I am in at any point in the night. I don't know what ResScan reports for breathing data but would suggest that if you are interested, look at your breathing data each day for several months and see if you can see patterns in how your breathing changes that might suggest when you were awake or partially aroused and when you were asleep.
I tend to be a little OCD about looking at my data but most folks aren't. If things seem to be going well, they, like you, don't spend much time looking at the reports.

One last comment, central events that last only 13-15 seconds are not long enough to have any real effect on blood oxygen levels. Most machines won't report them at all until they exceed 10 seconds. So, three of these relatively short ones in a night shouldn't be much of a concern.

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zmbee
Posts: 31
Joined: Mon Apr 07, 2014 6:23 pm

Re: Central Apnea

Post by zmbee » Tue Jun 30, 2015 10:07 pm

Wow, thank you so very much for your very complete reply, JDS74! I really appreciate it. I will be meeting with my sleep physician in a couple of weeks and I'll talk with him about how I might ascertain which states I'm in at various points during the night. Thank you again for your help!