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How are Pulse Change events determined?
How are Pulse Change events determined?
I have been monitoring SpO2 for the last week using a Wellue O2ring.  Along with the charts of oxygen levels, pulse rate and movement, the Events tab in the Daily Sidebar lists "Pulse Change Events".  I am trying to understand the definition of these.  Specific questions are that I am trying to get answered are:

  1. Do these come from the O2ring, or are they generated by OSCAR?
  2. What is the definition of an event, i.e. how much of a change over what time?
  3. If I have a pulse spike, does that generate two events (one up and one down)?  In other words, is the number of spikes theoretically half the number of events?
  4. In the list of Pulse Change events, there is a number (8) in brackets after the time of the event.  What does this indicate?
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RE: How are Pulse Change events determined?
Hi StuartC

I used to track the PR changes hoping to find some correlation with machine settings etc.
I found no correlation: See Post #15 and so I stopped looking there.

You can change the filter for flagging the PR changes under File Preferences Oximetry and change your preferred Pulse Rate change and Duration.

From memory you will have to rebuild the data for this to be recalculated.

From what I see on the charts there may be two changes recorded: firstly an increase in PR and then followed by a decrease in PR, if both pulse rate changes take place within your preferred time frame.

If your pulse rate spikes up by say 15 bpm in a period of 10 seconds, you will get a flag, but if it decreases by 15 bpm over a period of greater than  your selected 10 seconds you may not get a second flag. I often saw PR changes in change of position and also at times of cessation of mask or mouth leaks, spikes in flow limitations, pressures spikes and in association with change in Insp times etc. So many variables.

Here is a chart where PR changed up and then down in the selected time frame.

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RE: How are Pulse Change events determined?
Thanks for the reply.  Pointing me to the preferences page answers most of most of my questions.  Then what you said about generating events for either increase or decrease answers the other - and matches what I thought so it is nice to have that confirmed.

The reason I asked is because I have been getting between 175 and 375 (!) per night.  It looks like I should change the settings to reduce that to a less spectacular and more meaningful indicator.  Or just to turn them off.

I have noticed some correlation between the larger pulse spikes and a disturbance in the breathing pattern shown in the Flow Rate trace.  Sometimes it is pretty subtle and the timing between the two is sometimes a bit variable, but I think it is generally there.  These are not disturbances that are detected in any other manner so I have been debating whether they might be indicate something like RERAs, which I can see that I used to get if I look back at the DS1 data that I imported (after I returned the machine) but do not see on in the data imported from my new AS10.  I can say with certainty that the day after the night that I had 375 pulse change events was an absolute shocker.  So I am not certain of what I see and I recognize that I could be seeing things that are not really there because I "want to", but I have not yet entirely discarded the possibility either.

I have attached a couple of screenshots, not to seek diagnostic advice because that is a topic for a different part of the forum, but just to show what I am seeing.  Perhaps it is of interest to you or others.

Attached Files Thumbnail(s)
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RE: How are Pulse Change events determined?
Apologies, OSCAR's calculation of PC and SD are pretty bad. They don't match any particular clinical measure, so take them with a very large grain of salt.

It's one of many improvements on our list, but we have a long list!

As you suggest, it's probably only helpful if you tweak the preferences to highlight a few big events, otherwise it's too noisy.
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RE: How are Pulse Change events determined?
(11-05-2021, 08:42 AM)sawinglogz Wrote: As you suggest, it's probably only helpful if you tweak the preferences to highlight a few big events, otherwise it's too noisy.

Thank you.  "A-tweaking" I will go!

I think I would like to set things so that I do still count the major changes because I remain interested in observing whether there is any correlation between number of pulse changes and how I feel in the morning.  As a non-medical person, it feels somewhat logical that a racing pulse could cause a sleep arousal, whether it is linked to a breathing anomaly or not.  And if sleep arousals are the "enemy", then they are worth knowing about.  Of course, what to about it becomes a whole different story ...
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RE: How are Pulse Change events determined?
Hi again StuartC,

Good luck in your quest. From one your zoomed in charts from the 31st one thing that jumps out is the cessation of leaks associated with incr. PR.

That was something I also saw early on in my struggles with mask leaks. I have marked up one of my older charts as an example.

Note the Flat areas in orange with low PR, these are deeper periods of sleep, these are what we want. Our muscles get rest when we sleep because they are not exercising, but the heart has to carry on beating. It gets its rest by slowing down during the night. That's what we want, long periods of rest for the heart muscle.

Notice I slept through the ridiculously large mouth leaks!

Then notice the arousals circled in black where the PR jumped up and the Resp Rate increased with wildly fluctuating breathing patterns (Minute Ventilations and Tidal volumes.) Even though there were no recorded OA, HA or RERA these are clearly disturbed sleep, or transitions from one sleep stage to another. Notice the rising PR just before waking up after 5:40 AM.

Then look at the green lines, whenever there was a termination of the large mouth leaks there was a spike in PR. 

Message to self: need to control the mouth leaks! they cause arousals, and disturb sleep, reflected in the marker of increased PR.
Just another piece of the puzzle.

You might find something equally useful by taking a bird's eye view of your charts, including Resp Rate, Tidal volume, Minute ventilation and Leaks for example.
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RE: How are Pulse Change events determined?
Thanks for that.  I have looked at several other charts and I agree that changes in leak rate appear to have correlating PR changes.  The opposite is not always true, but tackling the leak rate should make a difference.

I am seeing someone on Wednesday about different masks to trial.  I used tape last night with some success, though still some leaks with characteristics that I did not expect.  It is not something that the DS1 reported much until just a few months ago.  The AS10, which I have only had for a month, has consistently shown huge leaks.
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