CMS 50E showing O2 increases?

[jonquiljo]

I again tried my CMS 50E O2 monitor last night and noticed when I looked at the report yesterday that the most profound changes were when my O2 increased, not decreased!

I have to widen out the graph to make them clear - so here is a screen shot of a typical 2 hour time frame. On this shot, especially around 6:00am, my O2 jumped to 98 or 99% a few times. That's my waking O2%, not sleeping O2% ( which is more in the range of 93-94%). In fact the monitor was reading 99% when I first put it on before going to sleep ...



Now these spikes in O2 happened throughout the night and are the only really prominent events. My pulse at the time did not change and was in the mid 50's - normal for my sleep.

Are these artifacts? Or am I waking up? Unfortunately my SD card was not seated in the machine as I had read it the day before and obviously not plugged it in all the way - so I have no data for that day. But all my nights are pretty uneventful at least as far as the System One and Encoreviewer is reporting (avg. AHI is around 0.3).

The reason I am curious is since I have been using CPAP, I sleep much better and feel better during the day. Lately, however, I seem to sleep for about 5 hours and tend to wake up on and off for the last 2 hours - not many events get reported by the System One during this time - and I am not really tired that day as I used to be before CPAP. I wonder if I am not waking during the night too and just don't know it and these are "unreported events".

So basically I don't know whether to trust my CPAP machine, my O2 monitor, or anything to tell me what is going on. Given what I've seen in some threads lately - it seems that each brand of machine wants to tell you what it wants to tell you - and that may be a whole lot of BS in terms of reality. If so, what can you trust? Thanks.

[HoseCrusher]

As I understand it...

When looking at a O2 saturation chart you are looking for several things. One is the "sawtooth" pattern, another is the magnitude of the desaturation, and another is the time frame over which the event occurred. In addition, you are looking for around a 15 - 20% change in heart rate. When your O2 level drops and causes an increase in heart rate that rapidly falls off after your saturation level increases, you have a good probability of having a waking moment. This has to be confirmed with the EEG reading, but it is a reasonable indicator.

The more awake you are, the more rapid you breath and the steadier the O2 line will be. As you fall deeper and deeper into sleep, your respirations slow down, and you will see more variation in the O2 levels. One of the limits with the pulse oximeter is that it averages the readings in order to give a smoother presentation. This average ranges from 3 - 7 seconds, but there are times when it is recovering from a lost signal that it can take longer.

Your data looks like normal variations. At around 5:20 you almost had a desaturation, but it didn't amount to anything. When I am driving I range between 92 and 99% and I am awake. I find that if you use the pulse oximeter during various day to day tasks you begin to see normal patterns and may be able to recognize irregular patterns easier.

[jonquiljo]

When your O2 level drops and causes an increase in heart rate that rapidly falls off after your saturation level increases, you have a good probability of having a waking moment. This has to be confirmed with the EEG reading, but it is a reasonable indicator.

Yes, but I am wondering if I am not being wakened (woken?) by external events. I call it "CPAP-nea", and it can be totally unrelated to apnea - more like events that wake you as a result of sleeping with a mask and hose, etc. Now my dogs (according to my wife) barked for a minute at around 6am. I may have been aroused from this or other events - and just don't know. It's complicated by the fact that I still need Ambien to sleep with all this junk on. Ambien will not make you sleep after a while, but it will make you forget if something else wakes you. It may have nothing to do with apnea directly - but hey are still arousals.

If my resting HR should have gone up with O2 - then where are these anomalies coming from? Others are also skeptical of these home O2 devices. If this means nothing going in the upward direction - then does it mean much in the downward as well? I guess I am searching for something that actually reflects reality.

[mreewh]

These seem like fairly normal variations to me. I have similar spikes during REM sleep. Also, when I look at the graph you posted, there seems to be a pulse variation for about half of the O2 spikes.

Since you feel well rested even with just 5 hours of sleep, and your AHI is 0.3, I'm not entirely understanding your concern - ?

[jonquiljo]

I'm not entirely understanding your concern - ?

I feel better, but know I could feel a whole lot better than I do now. Some part of the puzzle is really wrong. I'm just trying to figure out what it may be.

[Calist]

If only we had an expert on this kind of thing.

[HoseCrusher]

Jonquiljo,

Who says those are anomalies. Perhaps they are normal. A good way to look at this is to consider driving your car. A while back digital speedometers were the new thing. The first ones were a royal pain because they fluctuated a lot. We think that we are driving at 60 mph, but the gauge was reading 56, 59, 58, 60, 62, 59, 63, 60, 57, and so on. This is the same thing you are reading with your pulse oximeter. The way around this is to do a moving average over a longer period of time, but this reduces sensitivity to rapid occurring events. Since we are looking at events that occur within a 10 second window, you can expect some variability.

If you want to play... You can load your data into Excel and run a moving average over a period of 60 seconds and smooth that data out.

To gain confidence in your pulse oximeter you need to compare it to the ones the paramedics use, or the ones that the sleep lab uses, or the ones the hospital uses. Then you have to wear it during a variety of activities. After reviewing the data collected during walking, reading, driving, eating, and so on, you will gain a perspective on what is normal. Now you can record data during sleeping and look at that data.

The body has the ability to store a small amount of O2. You can get a feel for this by looking at your data while holding your breath and while hyperventilating. While holding your breath you should see a drop in pulse rate just prior to the drop in saturation. Then the pulse rate will increase as the saturation level drops. Finally when you breath again you will see the pulse rate settle down and the saturation go back up. While doing this note the lag between when you are struggling holding your breath and when the recorded data actually shows a desaturation. If you exhale and then hold your breath you should see the pulse rate change in 30 - 45 seconds, and the desaturation will occur shortly after that. Once you resume breathing it will take 10 - 15 seconds before the data will show your saturation increasing and you heart rate slowing down. If you do this a few times, you can get a good idea of what your body goes through during a desaturation. You can also look at the up side of this by doing controlled breathing. My normal level is around 97% so I don't have a lot of room for increased saturation, but you can still get an idea of how your body works and how the oximeter records this increase.

As your oximeter slips around on your finger there is lots of opportunity for artifacts. If you practice you will be better able to recognize those artifacts and be able to separate them from the real data.