(05-02-2014 06:11 PM)jbuchanan6196 Wrote: For example, last night it showed I had 7 centrals while the night before just I had one. ...
My body definitely feels like I had that many apneas today more than other days, even with using CPAP.
If you slept 7 hrs the 7 CA events would represent a Central Apnea Index of 1.0, which I think the health profession in the USA would consider completely negligible, especially since all were fairly short.
However, if you continue to definitely feel worse after nights when larger numbers of central events occur, you definitely should not ignore these events. Keep an eye on them and see what you can come up with, to minimize them.
(05-02-2014 06:50 PM)SnuffySleeper Wrote: Don't worry too much about central apneas in rescan/sleepyhead as these programs can only use air resistance recorded in wavforms to measure such events.
This in turn gives false positives as all the machine knows is that it sent a puff of air and never got anything back. This can be caused by many things, like changing position, breathing goes out of sync for a bit, mask leaked for a little bit..etc.....
Actually, I think ResMed's Forced Oscillation Technique (FOT) is quite accurate, unless unintentional leak is too high (more than 24 Liters per minute) or is varying quickly.
Please see "Central Sleep Apnea Detection and the Enhanced AutoSet Algorithm" white paper; the link is at the bottom of the following ResMed webpage:
(05-02-2014 06:50 PM)SnuffySleeper Wrote: My observation as I am a low pressure guy like you, is that resscan/sleepyhead reports CA events that are really hypopneas (shallow breathing) but because the pressure is low it doesn't have as much air resistance to read and marks it a central apnea.
As far as I know, it is excessive Leak or quickly varying Leak, not low or high pressure, which limits the accuracy of ResMed's central apnea detection algorithm.
(05-02-2014 08:12 PM)jbuchanan6196 Wrote: I was taken off AutoPap when they determined that a straight pressure of 7 was effective for me. I just went through some of the data and noticed the median was more around 8-9. I may try to bump it up a notch.
If a long term average of the nightly Median Pressure was 8-9 during your APAP trial, then 7 would probably have been lower than optimal as a fixed CPAP setting. I doubt it, but maybe your doctor or therapist was giving you time to adjust to the pressure and was planning to increase your pressure in future, after watching the data for a while. If using a fixed CPAP pressure, I think somewhere around the 95 percentile APAP pressure would be more appropriate, or possibly higher, unless problems appeared like aerophagia or headache or hearing/dizziness issues or excessive central apneas, or excessive daytime sleepiness.
Further, if using the machine in CPAP mode (a fixed pressure all night), for some patients changing the amount of EPR (Exhalation Pressure Relief) can affect treatment efficacy, so ideally the APAP trial would be repeated using the new EPR setting. Having an APAP machine allows this re-titration to be done easily and without extra cost, merely by changing the operating mode of the machine to APAP for a time. For some patients who are on a fixed-pressure machine, increasing the EPR setting (which decreases EPAP, the pressure during exhalation) may tend to allow more obstructive apneas to occur unless the Pressure setting is raised an equal amount to compensate, to raise the EPAP back to the previously titrated setting.
(05-02-2014 11:50 PM)herbm Wrote: BTW: You can also get these by just holding your breath while turning over ...
Whenever we "hold" our breath I think our airway tends to get closed off, making this effectively obstructive. When we stop breathing while turning over, rather than this mimicking a central apnea, I suspect we tend to create a brief obstruction which usually is not scored by the machine (because it lasts less than 10 seconds).
(05-03-2014 12:15 AM)Sleepster Wrote: Are you new to CPAP therapy? If so, that is most likely the cause, and they will soon fade away. Your body is not used all the extra oxygen you're supplying, and those elevated oxygen levels trick your brain into thinking you don't need to breathe.
I've heard that usually the frequency of central apnea events decreases during the initial weeks or months of CPAP therapy as we become accustomed to CPAP therapy, as we become accustomed to the changed level of CO2 in our blood.
(05-03-2014 12:15 AM)Sleepster Wrote:
Quote:However, some nights they are more frequent than others. For example, last night it showed I had 7 centrals while the night before just I had one. So is there any reason that these apneas occur more frequently some nights than others? I'm wondering what caused me to have more last night than previous nights.
Nothing is causing this, it's just a natural variation. It's like asking why it rains more on some days than others. That's just the way it is.
I agree with Sleepster that a variation of 1 per night compared to 7 per night may simply be natural variation, especially since both numbers are still very low and are usually considered insignificant.
At the same time, many things can affect the frequency of central apnea events. For example: how many hours we are sleeping, what time we go to bed, stress and anxiety, common non-prescription medications, changes in diet and exercise, developing or recovering from anemia, developing or recovering from heart conditions, changes in what time we drink caffeinated drinks, etc., all these things may have an influence.