Can anybody comment on this desaturation behaviour?

[desaturator]

If your awake average is actually 98% I would have a hard time believing your heart is bypassing a significant amount of deoxygenated blood as you would have me and most other members beat in that respect.

With the Wellue gadget I use, my awake average is, in fact, 97%-98%. My asleep average is actually 95-96% -- not much lower -- but I have periods every night where it's 88-90%. These periods are not hugely affected by the CPAP, although using the CPAP reduces the number of short-term desaturations I experience.

I understand that my cardiac shunt is posture-dependent. When upright, the effect of gravity keeps blood flow in the "proper" direction (essentially top-to-bottom). When I'm laying down, there's an increased tendency for blood to wander horizontally. There are also issues related to fluid balance and intra-atrial pressure differential that are affected by posture (they tell me).

So my main desaturation is nothing to do with sleep -- it's just posture; but I'm usually only horizontal when I'm asleep. Well, the only times I'm horizontal and not asleep, I'm not looking at my oximeter

I'm told that the only way to be certain if the shunt is causing my desaturations is to close it. I'll still have OSA, though :/

Best wishes, DS

PS. I reduced my EPR to 2 last night, and noticed a couple of central apnea's reported, for the first time. I'm not concerned about this, but it was the opposite effect to the one I expected.

PPS. I discussed my CPAP settings with the lung doctor, and his advise was to set everything to factory defaults, and check the results in a year. Although my SpO2 at night is crappy, the OSA is actually mild, and shouldn't be fussy to treat. Well, fingers crossed, anyway.

[Ratchick]

Wait... I thought they said your heart was just fine?

In general, yes, letting the machine make all the decisions should be fine. The problem is that sometimes it's not. If you (as it seems) have some tendency towards central events, letting the machine wide open could potentially push the pressure to a point where you start popping centrals all over the place. And especially, if the slightly higher minimum pressure helps with that desaturation some, then starting at 4 might be counterintuitive. He's basically just shrugging his shoulders and saying "don't even try to tweak it and hope that is good enough for a year". This is why I have fixed the pressure on mine because if I open it up (as it was when I got the machine at first), then it maxes out at 20 and my centrals go insane.

[SarcasticDave94]

If I could say this, don't form opinions or plans to change settings based on any one night trend, which isn't a trend really. The EPR 2 change with CA increasing is likely a coincidence. CA go up and down for no reason, hence the consistently inconsistent description.

How many CA events did it actually add? And over how much sleep time? For some, even doubling CA is pretty much nothing to be concerned over. Double your average person's normal CA rate and this may not be too bad a thing. Double mine though and there's big issues.

How long did the SpO2 drop to 88-90%? If it's just the spikey drops then it would likely be seconds at a time and very likely not an issue. When it's measured in minutes at a time then there's something to watch.

[Geer1]

I was confusing your data with another member. Your average SPO2 is very good, better than most on here. The examples you posted only show brief drops and not below 90%. Could those be related to heart? Maybe. Could they be related to sleep stage, position or probably a number of other things? Yes.

For the most part they don't worry about SPO2 levels at night unless you are spending significant time below 88% which it appears you do not do. 92-98% range is pretty much considered normal and is where you appear to fall the majority of the time. I think you are overthinking these desaturations a little bit and that they aren't as bad as you think. If you start seeing extended periods below 90% regularly then I would start looking into them more.

As for the heart side if you think it is actually an issue I would talk to a cardiologist about it and I assume a holter monitor would record it and determine if it is something that needs to be dealt with or not.

[desaturator]

Wait... I thought they said your heart was just fine?

It is. To have a patent foramen ovale (PFO) is not considered abnormal. In most people, in most circumstances, there's no right-to-left blood flow because the balance of atrial pressures favours the other direction. If blood flows left-to-right, you just end up with oxygenated blood being sent back to the lungs.

But in some people, in some circumstances, it seems that things like fluid balance, body shape, heart shape, and a bunch of other things I don't understand, can cause a right-to-left shunt. The problem isn't just that lying down prevents gravity doing its work, but that lying down causes fluid from your legs and abdomen to be redistributed to your torso. This causes the right atrium to stretch, so that its contraction is more forceful, and the balance of pressure between the left and right heart is disturbed.

But, while 30% of the population has a PFO, almost none of them result in a right-to-left shunt, whatever the circumstances. I don't know why I have this problem -- just bad luck, I guess.

The problem with shunting is that it can be treated externally -- you can't give additional oxygen, or improve ventilation, because deoxygenated blood is being put directly into the arterial circulation. The only solution is to close the hole. But... I just read a research paper from 2012 (the only one I could find) that said that sometimes CPAP treatment itself can reduce the shunting, whether or not sleep apnea is present, by reducing the hypertrophy of the right atrium. That makes sense for me, because my overnight SpO2 was an average 90% before I started CPAP, and now it's ~95%.

Best wishes, DS

[desaturator]

As for the heart side if you think it is actually an issue I would talk to a cardiologist about it and I assume a holter monitor would record it and determine if it is something that needs to be dealt with or not.

I did that -- it was a cardiologist that recommended CPAP in the first place. The heart guy recommended not closing my atrial septal defect in the first instance, in the hope that CPAP would get my oxygen saturation up enough to control the problem. Since I was going to need CPAP anyway, because of sleep apnea, there would be no point in having the closure procedure if CPAP fixed the problem.

But the lung guy recommended closing the defect immediately, without even waiting to see whether CPAP improved things in the long term.

It seems that many people tolerate SpO2 levels way worse than mine, and have no heart problems. It isn't even certain that my heart problems are related to SpO2. The problem is that the only way to find out for sure is to close the defect. Still, the procedure is relatively straightforward and has a low-ish risk and, best of all, my insurers will pay for it, when they wouldn't pay for anything to do with sleep disorders.

Best wishes, DS

[Geer1]

You are definitely a special case with CPAP for these heart reasons. If it were me I would probably get a 2nd cardiologist opinion to decide on how to proceed.

[Sleeprider]

Adding to Geer1's comment. Regardless of how you and your doctor(s) proceed with this common PFO, nothing you have posted suggests a medical need to do anything. Your CPAP therapy is effective, and you don't have anything that a medical professional will recognize as an issue with SpO2. I don't see what else the forum can do outside of emotional support. Of course you can tell from my avatar, that is a specialty!

[desaturator]

Your CPAP therapy is effective, and you don't have anything that a medical professional will recognize as an issue with SpO2.  I don't see what else the forum can do outside of emotional support.

Sure. I never expected a forum to offer anything except a place to compare my moans and grumbles with everybody else's. And I would agree -- as do my doctors -- that the weird desaturation behavior could be written off as a medical curiosity except that I have bursts of ventricular tachycardia and atrial fibrillation every night, at about the same time the desaturations occur. Of course, the causative relationship could be the other way around. Or might not even exist -- it might just be coincidence.

None of my doctors (and I have a whole posse of them now) thinks that the arhythmias are safe to ignore. Unfortunately, they don't seem to have a plan other than to close the PFO -- which is demonstrably leaky -- and hope that helps. It seems to me that I have little to lose, except a day of my time, by having this procedure, and potentially something to gain. Nobody seems to have any better ideas, anyway. The arhythmias don't respond to any drug that wouldn't create even more risks.

Best wishes, DS

[pholynyk]

>>> plan to close the PFO --- I have little to lose, except a day of my time,

That's a bit optimistic, I think. My quadruple bypass took a day - counting prep and waiting time - and then I was in the CICU for four days, recovery floor two more, and finally the rehab hospital for three weeks.

I can't imagine fixing a PFO while be less invasive...

OTOH, my resting SpO2 went from about 94-95% to 98%, among other things that got better