Awake periodic breathing/ desats, otherwise healthy? (+sleep apnoea)
Hi everyone - first post but I have been lurking for a while and am amazed at the communal knowledge here. I have been on APAP 6 weeks, for what I think has been lifelong sleep apnoea.
I'm wondering if anyone else has idiopathic daytime desaturations as part of their "sleep" apnoea? Apologies in advance for the long post to try to detail my unusual situation. I have been told I have sleep apnoea plus "awake periodic breathing", but no-one seems to have a good explanation for it.
I seem to be a mystery to my physicians, with awake desaturations as low as 92% in the absence of any other physical problem, apart from sleep apnoea. I have been specifically advised that I don't present like someone with central sleep apnoea??? I still haven't got a coherent explanation of whats going on, beyond, "it might get better with APAP"
I developed severe fatigue late last year (I have had long, lesser episodes of this life-long) and was found to be desaturating cyclically as low as 92% on room air while laying quietly awake. Full cardiac/ respiratory/ neurological workup was clear (cardiac and pulmonary angios/stress echo/ VQ scan / full pulmonary function tests/ MRI head). So no emboli/lung disease/ heart shunts and so forth. All blood work normal (including atypical haemoglobin). Cardiac MRI is pending, but expected to be normal.
My saturations at rest on room air (at sea level) still typically cycle between 93-97%, with a deep breath or two easily getting it up to 98-99%. I have had no altitude exposure.
Desaturations are confirmed on multiple professional/ hospital/ Resmed oximeters, and absolutely confirmed with arterial blood gases. My actual arterial oxygen on the blood gases was a bit better than it should be for the saturation (like normally happens with high altitude acclimatisation), but still a bit low. Normal blood carbon dioxide and pH.
The subsequent in-hospital sleep study wasn't all that great as I slept very poorly compared to usual (I don't suffer insomnia). There was only 80 minutes of level 1-2 sleep, 10 min level 3 sleep, zero REM.
Final diagnosis "moderate obstructive sleep apnoea with a respiratory disturbance index of 24", but events were almost all hypopnoeas and a single obstructive. Given I got almost no deep sleep, I guess it was presumed I probably would have a lot more obstructives normally, and I was put on APAP.
I started apparently effective APAP 6 weeks ago (AHI/ OI/ HI/ CA/ RERA -1.1/ 0.2/ 0.2/ 0.7/ 0).
Fatigue is starting to improve, but only to some degree. No leaks issues or significant comfort problems. 100% Compliance, 8.5 hours. My oximetry on APAP (Resmed) for a couple of days showed Min/ Med/ 95%/ Max - 90/ 93/ 95/ 98% asleep. Most flagged CA's are usually preceded by increased respiratory volume so artifact/ normal I guess. I get occasional OA's.
Much of the night flow-rate shows a cycling pattern (attached) but mostly not enough to trigger flags in Sleepyhead. The volumes seem to match O2 drops and pulse-rate rises that I guess might muck up my deep sleep??
I do have some periods of an hour or so early in the evening, where sleeping flow rates and tidal volumes are quite steady, albeit at around 93% sats, so I'm hoping that means my brain stem isn't irreversibly fried. My awake oximetry is still weird and not improved.
Otherwise, I am mid 50's, previously very physically active, BMI 33, no relevant regular medication. I have had long periods of unreasonable fatigue life-long, but never before to the point of becoming non-functional. There is no family history to suggest congenital hypoventillation, albeit genetic testing for Phox2B is pending.
Adding 2L oxygen into the circuit, and a 7 day one-off lot of zolpidem seemed to help fatigue enough so I could get back to work, but this could have equaly been coincidental. Nevertheless I am still not as good as I was, say, 6 months ago.
I do have another sleep study coming up at a different lab/ different physician soon to try to iron this out better.
It'd be nice to hear if anyone else has this idiopathic awake desaturation thing "that might get better with APAP" as I was advised, or does it just stay the same, or even get worse with time? It's kind of a worry to me - I'm too young to have to retire due to some problem that might get worse?