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How do I interpret my Oximetry Report?
#1
How do I interpret my Oximetry Report?
G'day,
Getting everything working on the CMS50D+ was a trip. It was complicated by my using it on XP running under VMWARE Fusion on my Mac. Reading this forum beforehand helped. I blew it the first night because I turned recording off when I awoke, not realizing that deleted what was stored. Nothing like counterintuitive software. I should have done a dry run first. I practiced prior to the second night.

Here's what I got for 4:48:19 duration:

Pulse events: 13 events; 8.6 mins in events; 39.9 secs avg duration; 2.7 index; 5.5% artifact; 2.9 adjusted index.

SpO2 events: 13 events; 12.2 mins in events; 56.5 secs avg duration; 2.7 index; 5.5% artifact; 2.9 adjusted index.

%SpO2 data: 95.2% Basal SpO2; 3.4 mins < 88%; 9 events < 88%; 76% min SpO2; 87.2% avg low SpO2; 85% avg low SpO2 <88%

Pulse Data: avg pulse rate: 49.2; low pulse: 42

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?

Thanks, in advance.
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#2
RE: How do I interpret my Oximetry Report?
(08-25-2013, 10:23 AM)PaBlum Wrote: I blew it the first night because I turned recording off when I awoke, not realizing that deleted what was stored.
It is my belief that the previous recording is deleted when a new recording session is started and not when a recording session is stopped.
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#3
RE: How do I interpret my Oximetry Report?
You may be correct about that. I did try for quite a while without success to coax it to download. Perhaps there was a trick I missed. Cooper's note does say that it is important to not turn off the recording until it is downloaded. If there is a way to do it, it would be useful to know. I'm hoping that someone(s) can give me interpret the data for me. Paul
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#4
RE: How do I interpret my Oximetry Report?
No, you can and must turn off the recording. It is stored automatically until the next session when it is written over. You must not turn off the device or the download connection until that is over.
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#5
RE: How do I interpret my Oximetry Report?
(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?

Hi PaBlum,

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.

Take care,
--- Vaughn
The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies.  Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.
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#6
RE: How do I interpret my Oximetry Report?
Thank you, Doc & Mark. What do you think of my readings?
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#7
RE: How do I interpret my Oximetry Report?
Well, it isn't great, but it also isn't all that bad - many people get around 92% or even less at night, not least because of slowed respiration and natural blockage by mucus. As a rule of thumb, so long as you stay above the magic 88% line, you are getting enough O2 to function, although I admit I have often questioned that over the years. If your spikes down line up more or less with your events in the CPAP readings, you can correlate the one to the other - you won't get an exact line up even if you correctly set the timer on the pulseox (which you will have to do each session). Be sure you are using a bit of tape to hold the device on the finger (not too tight, just enough so it won't shift as you toss and turn). A lot of what you see is also noise generated by the device, BTW, so the strip chart can be confusing. If you use Sleepyhead, you can import the readings for that night (providing you set the time clock correctly) and line it up with your CPAP readings and look at them together to suss out the event pattern. Highest events patterns often occur around the phase of falling deep into sleep, after the dozing segment has come close to an end.

Be aware that a cluster of events at some point early in the sleep process and then the rest of the night uninterrupted sleep is not considered harmful. Having your sleep continually interrupted is, however.
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#8
RE: How do I interpret my Oximetry Report?
Thank you, very much.

Paul
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#9
RE: How do I interpret my Oximetry Report?
I hate to ask another question, but I've followed this thread with interest and hope someone will be able to explain a few things to me about my pulse oximetry report. I am using the same pulse oximeter as PaBlum. I understand what constitutes an "event", but wonder if I should be alarmed (or not) at the number of events I am having.

Event Data
Sp02 Total Events: 15
Time in Events (min) 23.7
Avg. Event Dur. (sec) 94.7
Index (1/hr) 1.9
% Artifact 1.1
Adjusted Index (1/hr) 1.9
%Sp02 Data
Basal Sp02 (%) 95.4
Time (min) < 88% 0.0
Events <88% 0
Minimum Sp02(%) 91
Avg Low Sp02 (%) 93.1

Event Data Pulse
Total Events 93
Time in Events (min) 45.6
Avg. Event Dur. (sec) 29.4
Index (1/hr) 11.6
% Artifact 1.1
Adjusted Index (1/hr) 11.8
Avg Pulse Rate (bpm) 62.4
Low Pulse Rate (bpm) 48

I use an oxygenator at 2.5 (Liters? not certain what the unit is) when I sleep and I live at an elevation of 5,600'. My AHI is always below 5.0 (except when the power goes out and the oxygen/CPAP stops). I qualified for CPAP mostly because of A-Fib and my cardiologist is slowly reducing my digoxin and blood pressure meds at the moment.

Should I be concerned about the number of Pulse Events? Or is it fairly "normal" in the scheme of things?

Thanks!
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#10
RE: How do I interpret my Oximetry Report?
(08-25-2013, 03:50 PM)PaBlum Wrote: Thank you, Doc & Mark. What do you think of my readings?
I didn't think your report was overly troubling. But I would probably do 2 more nights then look at all three sets of numbers and determine if there is a consistency. I am assuming that your machine had a low AHI that night giving no reason for the dips. Certainly a more clinical instrument would be used to verify what the Contec PulseOx reported. If your AHI is very low and your SpO2 events increase over time, supplemental oxygen may be in your future while sleeping.

If the reports are consistent I would recheck on a monthly basis for 2 months then quarterly thereafter to watch for deterioration.
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