Oximeter Info

[app1nag]

[attachment=2049] Based on recommendations posted here, I recently purchased a CMS 50D+ oximeter. I finally got things up and running and was wondering if I could get some feedback from users that have been using an oximeter for a period of time. I've attached last nights results and am concerned about the drop in oxygen around the 2am time period. There are also gaps in the graph where oxygen levels are at zero. Is that a software issue or am I actually getting no oxygen during that time? AHI for the night was less than 2.

Thanks in advance for all your great advice.

[app1nag]

[attachment=2050] I guess looking at the data itself (not in graph form), makes it look like I had a decent night, oxygen-wise.

[Possum]

Overall your oxygen levels are excellent. You only have one "witching hour" starting around 1:50 AM and ending around 2:30 AM, but it actually doesn't correlate very well with features in the flow rate graph. You had a couple of hypopneas, but not until around 2:15 AM - I wonder if the clocks on your CPAP and oximeter are out of sync? You might want to check that, as both have a tendency to drift. In any case, once the machine caught the hypopneas and started increasing pressure, your witching hour ended, but it seemed to take a little longer than it should have. As for the gaps and spikes, those are probably just interruptions in signal from the oximeter. Your SP02 levels don't reach 0, unless you're dead.

In short, it appears that your therapy is going well, and I wouldn't be too concerned. If you really want to nitpick, you could consider raising your minimum pressure slightly to see if cleans up some of the H and OA events.

[app1nag]

That's excellent news...thanks ! My at-home sleep test showed oxygen levels in the 75% range for far too long of a time frame. I thought a zero oxygen level may have meant I stopped breathing for a bit.
I will try a higher minimum pressure this evening. Lastly, I wonder if there is a way to better sync up the two devices.

[Possum]

Sleepyhead gives you the option to sync CPAP and oximetry data with respect to time by either relying on the internal clocks of the CPAP and oximeter, which is generally not recommended unless you are prisitine about ensuring the time is correct on both devices, or you can sync the data manually by simply starting the two devices at the same time.

[membus]

Hi app1nag,

I also got the CMS 50D+ and used it twice in 2 weeks. The second was last night. I had woken up at 5 am and was awake for an hour and then had another hour to sleep. I decided to sleep without APAP and see how my SpO2 would be.

When importing the data to SleepyHead I chose the option where you can select a previous sleep session, as I started them both at the same time. When checking the graphs I see that the synch is fine.

As Possum already mentioned 0 oxygen levels means you are dead. Just try this if you want (I did try): With the oximeter attached to your finger, hold your breadth for as long as you can without pushing too hard and you'll see the drop in SpO2 levels maybe after 10-15 seconds.

Regarding the drop in SpO2 levels during 2am, I can only say that they may be due to some misreadings caused by the oximeter moving on the finger. I you haven't done it, I suggest you fix the unit to your finger with a medical tape which won't leave any adhesive residues once off. This will ensure a better reading throughout the night.

[nsherry61]

All the big spo2 drops are also associated with gaps in the data for both pulse and spo2, so the advice from membus above is right on. You are almost surely dealing with instrumental artifacts that will likely not occur once the instrument is stabilized on your finger.

[Possum]

I was also tempted to dismiss the drop around 1:50 to 2:30 AM as artifactual due to the probe moving out of a good reading position, but artifacts don't typically last that long nor do they suddenly recover unless you wake up and reposition the probe on your finger. And you're male, so I don't imagine you have residual nail polish that's interfering with the readings intermittently.

I would continue to gather additional oximetry data, at least a week's worth. That will give you a better sense of what's actually going on with your SPO2 levels during therapy. Also, I'm not sure which finger(s) you use for the probe, but I've found that my middle finger generates the cleanest signal with the fewest artifacts.

[app1nag]

I had a small rubber band around the device and my pointer finger. Sometime during my sleep, my finger became irritated so I quickly shifted it to my index finger, but did not secure it with the rubber band. I will try with medical tape tonight.

[membus]

I will try with medical tape tonight.

What I did was not only tape the oximeter, but also made one round around my finger and tied it to the oximeter, so it wouldn't come out. Did it like this because my first time I had only taped the oximeter to have a firmer grip but that didn't help and it came off.