Pulse/Oxygen Metrics

[DHC]

I am curious if anyone has suggestions for which of the metrics collected from recording your pulse/oxygen levels overnight are the most *useful* to you - and why/how are they used?

[HoseCrusher]

Obstructive events usually result in O2 desaturation. Your airway closes and you don't get O2.

Monitoring with a pulse oximeter can identify gross obstructions.

I set the pressure on CPAP by reviewing the desaturations and slightly increasing the pressure until I have no desaturations below 90%. This was the first step.

The next step involved reviewing the O2 data and looking for the "saw tooth" pattern. The next step was to try to eliminate O2 events and eliminate the "saw tooth" pattern.

Then, you can adjust the scoring criteria from a 4% drop in O2 to a 3% drop in O2 over 10 seconds and work to minimize those events.

The pulse side gives you heart rate. You need both rate and rhythm, but if your oximeter has a pleth graph you can get an idea of rhythm. It is not the same as an ECG, but it can provide some information. Unfortunately, the pleth graph waveform is not stored and when you are sleeping you can't see it.

The way pulse events are set up, you score an event every time you move around. While there isn't a good correlation between pulse events and arousals, the goal is to minimize pulse events.

My cardiologist mentioned that a different scoring parameter is used for cardiac events. He suggested looking at what the results were when the parameters were changed to a change in pulse of 15 beats per minute over 30 seconds. This changes things a lot, but without the ECG it is just "interesting."

If you look at the data from holding your breath you will find that as you desaturate, your pulse increases. If you do this a few times you can get an idea of what a desaturation event looks like and look for that pattern in the data taken while you sleep.

In general, your O2 will drop, then your heart rate will increase in an effort to wake you up and force you to take a breath. When reviewing the O2 events, look at what your heart rate is doing and compare it to the pattern you saw while holding your breath.

You need oxygen to live. However, you can have good oxygen levels and still not get a good nights sleep. xPAP therapy does a good job of removing the obstructions to air flow and restoring oxygen levels to normal, but I am not sure that it can take care of the other causes of poor sleep.

[BusyLyn]

With all the desaturations most of us experience during the obstructive events, why don't most sleep doctors prescribe a pulse oximeter for use along with the xpap machine? Even better, why isn't it one of the functions of the xpap machine?

I only have the summary from my first study, which listed 'significant desaturation to a nadir of 61%. The longest event lasted 31-1/2 seconds.' I plan to ask my sleep doctor about the significant desats, and how he can be sure that I don't still have some amount of desaturation even with a low AHI. I see him on Wednesday, and I'll be getting full copies of the sleep studies.

[M.D.Hosehead]

Even better, why isn't it one of the functions of the xpap machine?

An excellent question; I don't know the answer.

One thing HoseCrusher didn't mention: the pO2 helps identify artifacts in the EV 2.0 report. For example, I usually have several hypopnea events falling asleep and waking up (which is pretty common). If there are no desats accompanying these hypopnea episodes, I feel confident they are artifacts. If these are excluded, my true AHI would be a little lower than reported by EV 2.0.

[RDawkinsPhDMPH]

DHC: I know I said I'd respond here but I put it back on the other thread because.... HoseCrusher said it better ... "sawtooth" pattern and heart rate ... sawtooth is a good marker for events ... and heart rate is a good marker for sympathetic activation ... so ... please see my other post to see why I agree with HoseCrusher