Did you ever try wearing a pulseox and seeing what your sat looked like? As long as sats aren't ever dipping below (NOT medical advice, but I'm being conservative here), say, 90%, brain damage is very remote. Plenty of COPD patients walking around with sats in the 80s, or even 70s.
But as someone with bad lungs...yeah, you only get one set and most meds/treatments are partial symptom relief at best.
Hey, I happened to try this recently when I was holding my breath for another reason! It hit 70% or a little lower by the end*, but that was after having exhaled for a while. I do wonder what effect that kind of thing can have, even minor.
* sensor accuracy not guaranteed
Were you engaging in a highly scientific study of the deco song whip it?
Close! Avoiding wildfire smoke.
Not the OP but I used to do breathe hold training for surfing and bought a pulse oximeter. I don’t think I ever got below 90%.