(08-25-2013, 10:23 AM)PaBlum Wrote: Visually, everything is above the red (88%) line except for about 1:45 AM - 2:45 AM where it dithers up and down seemingly centered around that line. (I went to sleep at midnight so the time is correct). The pulse events correspond to AHI increases. The SpO2 events seem to correspond to pressure increases.
To those with experience in this, what you you think about it?
I think if our breathing during sleep is excellent, the SpO2 would stay above 92. Readings of 88 and below may be occasion for concern. Dipping below 80 into the 70s is even more concerning, of course. You will want to bring to your doctor's attention the statistics your Pulse-Oximeter is recording.
In the software for the pulseox, I think you can change the time scale so that only 10 minutes are shown across the screen, and can then hold down the mouse pointer on the horizontal scroll arrow, causing the waveforms for pulse and O2 to scroll quickly.
What I do: When I see an especially deep or long dip on SpO2 waveform I stop scrolling and note the time of the event. Then I go to that time using ResScan (or SleepyHead) to see what was happening CPAP-wise shortly before that exact time. For example, by looking at the Flow waveform I can see how long was the apnea that caused the dip in SpO2, was it an obstructive or central event, was the pressure max'ed out or low, etc.
Some comments regarding time synch between the CPAP data and the pulseox data:
1.) It is helpful if the clock in the pulseox is adjusted to closely match the clock in the CPAP machine, so the recorded times will match within a few seconds when comparing the pulseox data and the CPAP data.
2.) Keep in mind that, even if the clocks in the pulseox and CPAP were perfectly matched, the SpO2 waveform reported by the pulseox will appear to lag about 20 to 40 seconds behind the CPAP waveforms (of Flow, High Rate Pressure, etc), depending on how fast the heart is beating. That is, SpO2 waveform may lag only 20 seconds if pulse rate is 60 or may lag 40 seconds if pulse rate is 30. (My sleeping pulse rate sometimes drops as low as 30, which for me is of concern and I am keeping my cardiologist informed.)
The reason the SpO2 waveform will "lag" is because the blood is pumped earliest to the lungs and brain and only later reaches the fingers (where the P-O is located) about 20 to 40 seconds later, depending on pulse rate. An example of lag is if the CPAP "Flow" waveform shows an apnea ending with a lot of deep breathing, the SpO2 might not start rising until 20 to 40 seconds later.
Similarly, the Pulse Rate waveform may lag about 15 seconds, because the recorded pulse rate may actually be an averaged value and the averaging process may introduce a delay of perhaps 15 seconds in the reporting (waveform) of Pulse Rate.