What can cause an O2 drop without an OA/CA event?

[MyronH]

After switching to BIPAP for last 3 weeks, my AHI went way down. But I'm still having SpO2 desaturations during the night. Here is one desat that had no event flagged with it. Also at 5:36pm I had a 15sec UA, and that caused O2 drop to 84%, and HR went up to 97.

I know I need to get leaks under control, getting a new foam liner this week. I feel if i go to my sleep doctor about this, he would say "you're doing great", since AHI <1 most nights now. But those desats still wake me up.

Questions:
1. Why did O2 drop but no event flagged?
2. On the event at 5:36pm, is it normal for a 15sec event to cause a O2 desat to 84%?






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5:36am event.

[PaulaO2]

Hmm. A bad dream since your pulse rate went up. What was the respiratory rate during both events?

[Sleeprider]

That event at 02:59 was a pretty serious hypopnea, bordering on CA event and it lasted nearly 30 seconds. It probably was not flagged due to being in large leak. The flow rate shows you had a pretty good arousal which probably caused you to fix the leak. There is also a possible hypopnea a minute earlier.

You really need to deal with the leaks. The machine is showing possible events on the flow line, but not flagging them. Your leak rate is averaging and excess leak of 33 and a 95% much higher.

[Matt00926]

Don't those dark black bars on the SpO2 assistant software mean device artifact? Could just be a loss of connection or you moved around in your sleep causing the probe to falter for a bit. I don't think SpO2 would recover so sharply like that graph indicates.

[MyronH]

Hmm. A bad dream since your pulse rate went up. What was the respiratory rate during both events?

Looks like my normal Respiratory Rate is around 14-16 usually, looking back at all my data on CPAP and BIPAP. But during the event, it went way down to 6 at 2:58am and back up, then down to 4.40 at 2:59:30am, right before I woke up.

Tonight I'm going to try a mask liner, different hose, and a spare mask I have to see if it fixes leaks. Besides these events, I do feel much better on BIPAP. 

Could the large leaks, be masking other events? Could I really be having more OA/CA, and the machine cant detect them?
With my APAP, even with large leaks, it detected OA/CA just fine.

[Walla Walla]

I wouldn't worry about two quick dips in O2 as much as I would worry about the leaks. The leaks are affecting your treatment. Once you get the leaks fixed any O2 dips will be resolved with better treatment.

[pholynyk]

OTOH, that O2 dip and the hypoapnea/recovery are only a few minutes apart. Unless you are _very_ sure the two clocks are synchronised, they could be related. My AS10 loses time steadily, and my oximeter runs fast, and both are a PITA to correct. I never trust either one.

[Sleeprider]

We know that the real leak rate can approach zero when you are awake, because we see it on the chart, but a lot of the night is near 60 L/min. The desaturation event looks real enough to me, and corresponds to a very low respiratory rate, then recovers on the arousal and recovery breathing. I think it can't hurt to try to resolve the leaks.

[PaulaO2]

Leaks mean the machine is too busy maintaining some semblance of pressure. It cannot react to events because it cannot detect them. It is like trying to use a wind meter and figure out the speed of the wind from the west when you're standing in the middle of a whirlwind.

Fix the leaks. Put on the mask, turn on the machine, and lay down. Toss, turn, do all sorts of movement to figure out where it is coming from. Since you use a FFM, it can't be from mouth leaks. The only air you should feel outside the mask is from the vent holes. Anything else is a leak.

And no, your previous machine was NOT reporting correctly if the leaks were that high and that frequent.

[PaulaO2]

And here is how to use the attachment feature for the forum. It is a better way to present screenshots.

http://www.apneaboard.com/forums/Thread-...ttachments