AHI spikes at about 0300

[FeelingBetter]

another question. I have been have a recent onset of edema and my echocardiogram showed significant pulmonary arterial hypertension. I had a right-sided heart cath done and they said it was only slightly elevated, which I don't believe for many reasons but that's another story in and of itself. My night o2 sat was 95% most of the night, still having edema but interestingly enough my AHI most of the night is less than 5 until~0300 then it spikes as high as 36 (so far) which ends up giving me an average AHI for the night of anywhere from 10-14. I have been on CPAP since this past August and now the doc is sending me back to the lab. Does this ring a bell with anyone?
FYI, 1 month ago my night o2 said I spent 66% of the night below 90% lowest 81%but I was very edematous then and they've since started me on Lasix which is why I think my o2 sat improved so much.
Thanks in advance.

[NightMonkey]

What are your pressure settings?

What does the detailed leak line look like?

What position do you sleep in?

Do you have any idea if you are changing sleeping positions around 0300?

[FeelingBetter]

I've had two spinal fusions and am a dedicated side sleeper. I can't stand to be on my back for more than about 5 minutes, if that. My current pressure is 14 and my leak runs about 30 and the sleep doc said anything less than 40 is accpetable.
Does this help?

[FeelingBetter]

I also forgot to tell you my snores are minimal in my acclaim 2 nasal mask and I usually have one EP I a night if that.

[NightMonkey]

Side sleeper - good.

Leak rate - good.

Is there any chance you are mouthbreathing for part of the night (0300)? Do you get dry mouth?

[robysue]

Another possibility is that 3:00AM may be roughly corresponding to the end of your longest REM cycle of the night. Did your diagnostic PSG show a substantially higher REM AHI than NREM AHI?

[FeelingBetter]

They were titrating me from 1230 on and when I first started CPAP my numbers were beautiful the first couple of months. They did state that I had more central apneas then they would've expected from just getting used to breathing with CPAP. They said most people "over breathe" when they are first started which causes central apneas but apparently I had a lot of CAs. I also have an intrathecal pain pump for my back which delivers morphine and marcaine directly into my spinal nerves (really bad back) but the neurosurgeon doesn't think that should cause it as it is non-systemic and doesn't reach my blood stream. Anyway the sleep doc is sending me back to the sleep lab. He's thinking I need either cpap with o2, bipap, or an as.
I hate the sleep lab. The beds are too soft and kill my back.

[Janknitz]

You have so many overlying conditions and meds it's just hard to tell, but I suspect Roby Sue is on the right path. That's why some of us NEED APAPs--big difference in our REM. pressure needs.

[MaxDarkside]

Another possibility is that 3:00AM may be roughly corresponding to the end of your longest REM cycle of the night. Did your diagnostic PSG show a substantially higher REM AHI than NREM AHI?

In my case, I do have AHI spikes at about 0300 as well. Around that time I have one of my REM periods and a cluster of apneas. This was also seen during my sleep study. I'm guessing robysue may be right in your case as well.

[FeelingBetter]

I was on autopap but my AHIs were worse. The sleep doc thought I'd be better off setting my pressure higher but constant. He said with apap the machine has to detect the event, then respond to it and often times by the time the machine responds, the event is over and the pressure drops again. Any thoughts?

[NightMonkey]

I was on autopap but my AHIs were worse. The sleep doc thought I'd be better off setting my pressure higher but constant. He said with apap the machine has to detect the event, then respond to it and often times by the time the machine responds, the event is over and the pressure drops again. Any thoughts?

Just my guess that the doctor has a poor understanding of APAP machine algorithms. Many doctors have a poor understanding.

APAPs do take some time to respond to events. If they did not the pressure would be ramping up and down disturbing sleep when it was not necessary to do so.

In very general terms (detailed algorithm descriptions are available for some machines on the net), APAP will respond to obstructive breathing events by slowly raising the pressure until the events are treated. They will stay at the higher pressure for some extended minutes with no events present. The APAP will then gradually lower the pressure ever alert to reverse course if events occur.

At certain times of the night I need more pressure and my machine does an excellent job of raising the pressure and taking care of the events. Your doctor is correct if he means that the machine might allow a few events until it gets the pressure up to the "new" therapeutic pressure. But it does not immediately drop the pressure.

My machine very nicely and slowly raises the pressure about 4 cm during what may be long REM periods. I have very few events and usually have an AHI < 2.0. That is proof for me that my APAP algorithm is a big benefit and close to perfect at least for my therapy.

Now I have read in this forum of many doctors sending a patient home with an APAP set to min 4/max 20 and my first sleep doc did this to me. With this setting if you need for example 12 cm pressure, the machine will allow you to have many apneas while it is raising the pressure from 4 to 12. The minimum is set too low!!! Repeating myself, doctors do this so this is proof they do not understand the APAP algorithm.

More light might be shed on this if we knew what your APAP settings were and what your current CPAP settings are??

Footnote: In REM your muscles, including those in the airway, are at a maximum state of relaxation and that is why some people need higher pressures during REM.

[MaxDarkside]

I was on autopap but my AHIs were worse. The sleep doc thought I'd be better off setting my pressure higher but constant. He said with apap the machine has to detect the event, then respond to it and often times by the time the machine responds, the event is over and the pressure drops again. Any thoughts?

This fits with many recommendations to raise the lower Auto-PAP pressure a bit to enable the machine to "get there faster" (does not have as far to adjust), but I think that has a lot to do with the Auto-PAP algorithm (unknown, mysterious) in the machine one is using. I've seen my ResMed scoot from 7 cm to 13 cm H2O in about 60-90 seconds in response to events and in that case it might take an event's time to "get there". Other times it has taken 7 minutes to go from 7 to 15, stopping along the way to sense whether one event after another, after another, after... along the way is a central or obstructive. CPAP needs not pause. It's there. I prefer Auto because I want a blast when I need it and a smaller range becomes "more CPAP-like" in behavior.

[FeelingBetter]

Nightmonkey,
My apap pressures were a floor of 10 and a Max of 18. With this my nightly AHIs were running about 14-18. Now with a pressure of 14, my AHIs are a little better then on the apap but no where near where it needs to be.
Thanks all.

[NightMonkey]

Can you post the one page detail graphs from a typical night?

You will need to upload an image to a host site, such as Photobucket, and then post the link here as an image.

[FeelingBetter]

I can't figure out how to put a screen shot of my nightly data in my post. Can someone help me?