Low blood oxygen not being compensated by increased Blood Pressure?

[Peter Charlton]

Bit of a technical question.
I attribute my brain fog to beta blockers damaging my autonomic nervous system as it was the day they put me on Bisoprolol that I complained I could no longer feel my lungs working and I felt like a drunk zombie.
The hospital SATS showed my blood oxygen to be 87% when awake, so I bought my own oximeter, this showed I was spending half the night asleep with a blood oxygen level of 85%.
13 months after being off beta blockers, my autonomic nervous system finally seemed to have recovered its oxygen sensing abilities, and I no longer get the low blood oxygen or breathlessness, so I wonder why my brain fog is getting so much worst, I feel as if I have had anesthetic injected into my brain.
So I just read that the body can cope with SATS of 85% because it gets the blood pressure to increase so that more of that blood reaches the organs to make up for its oxygen deficiency, so it has just occurred to me that this increasing the blood pressure is another job of my compromised Autonomic Nervous System, so if that's not working properly, my bodies mechanism for making up the oxygen shortfall will not be in operation, so the 85% SATS might be more damaging to me, than to somebody with a healthy Autonomic Nervous System?

Or to sum it up, whilst 85% SATs might be compensated for by an increased blood pressure so the health service are not too worried, might Dysautonomia stop this compensatory mechanism so our low SATs are more serious than somebody with a good ANS?

Apologies if I dont react right away to your replies, it is quite involved for me to get on this site as I always have to reset my password.