I'm aware that I have a number of long, whiny threads open, complaining about my problems. I hope you will indulge me for what I hope will be the last time. I didn't really want to extend one of the other threads, because this is really a different train of thought completely. Basically, I've spent a month or so fiddling with my CPAP, with no enormous success. The reason, I think, is that I might not have any problem that CPAP can fix. So I'm trying to work out whether I need to continue with CPAP at all.
I'm aware that what I really need is an in-lab PSG. Realistically, though, that's not going to happen. The UK NHS is broken, my insurance won't pay for it, and I can't afford to. So I really need to decide what to do, based on the limited information I have.
By way of background: I was recommended CPAP because my doctors thought my cardiac arrhythmias might be caused by sleep apnea, and no other cause could be found. I've since discovered that I have a patent foramen ovale (PFO) -- a defect in the atrial septum that is very common, and usually asymptomatic. In my case, however, there is demonstrable right-to-left blood flow, so deoxygenated blood is bypassing my lungs. This effect is only present when I lay down (awake or asleep), and particularly when I lay on my left side (I have verified this with a camera). I've had huge numbers of heart and lung tests, and all are normal apart from the leaky PFO. Nevertheless, my oxygen saturation is abnormal of for extended periods of time, unless I'm upright.
I've arranged my thoughts in favour of, and against, continuing with CPAP.
In favour of CPAP:
1. I had a sleep study which said AHI ~20 and mean SpO2=90
2. Without CPAP, I do somtimes wake up at night, out of breath
3. The CPAP machine reports AHI always < 2 and usually < 1
4. The CPAP machine starts logging flow restrictions, almost as soon as I fall asleep, and adjusts the pressure. For my doctors, this alone is conclusive proof that I need CPAP
5. I'm a middle-aged man with a thick neck
6. Using the CPAP creates a modest improvement in my average SpO2, compared to before -- 1 to 2 percentage points
7. Some apneas and hypopneas are reported -- more than zero, anyway -- so something clearly is going in with my breathing
8. There's a small amount of research evidence that CPAP reduces the effect of a right-to-left intracardiac shunt, even in people who don't need it for OSA
9. I can tolerate CPAP. I can keep the mask on all night, every night.
Against CPAP:
1. My sleep study was only a WatchPAT. I'm not sure how reliable these are
2. I have none of the textbooks symptoms of sleep apnea -- my Epworth score is zero, and I don't have headaches, fatigue, etc.
3. Although the CPAP machine reports low AHI, it does this even when I set pressure to 4cm, which is usually sub-therapeutic. In addition, my AHI is highly variable from night to night even with constant machine settings, and does not seem to depend much, if at all, on those settings.
4. Although the CPAP machine logs flow restrictions, if I set the pressure to 4cm, so that these are not corrected, I do not show more breathing or SpO2 disturbances during these flow-restricted periods than elsewhere. They appear to be asymptomatic.
5. Although I have an "OSA neck", I don't snore. Not ever.
6. Although my average SpO2 is improved by CPAP, the time I spend with SpO2 in the 90% region is not. It's usually 1-2 hours every night. In addition, my SpO2 is highly variable from night to night, so comparison is difficult. Still, I know that periods of lowest SpO2 occur when I'm laying on my left side, when a right-to-left intracardiac shunt is most active. CPAP will probably not fix this.
7. The apneas and hypopneas that are reported are either (a) in clusters, when I'm laying on my back (i.e., positional) or (b) during periods of periodic breathing when I'm laying on my left side. CPAP will probably not fix either of these.
8. The small amount of research evidence that CPAP reduces the effect of a right-to-left intracardiac shunt is, in fact, just one published paper with a small sample size
9. Although I can tolerate CPAP, I hate it. It's uncomfortable, it disturbs my sleep, and it's trashed marital relations completely.
Needless to say, my doctors are completely baffled, and have nothing useful to suggest apart from "carry on with CPAP for another year and see how you feel". The fact is that I feel fine, with or without it. All my problems arise when I'm unconscious.
I confess that, to be honest, I've written this mostly to organize my thoughts for myself. I won't be offended if nobody has time to read it. But many thanks to anybody who does.
BW, DS