low oxygen levels on walking

[Holiday12345]

hi I had a respiratory oxygen sat walking test yesterday. I have high heart rate on standing, mild PoTs, so heart rate standing at start stubborn at 110 fir a while eventually got it down to 99 to start test about 20seconds in alarm on monitor goes off HR dropped to 51 and oxygen down to 68. It rose back up to normal on stopping. This kept happening till I had to stop test early very breathless and exhausted. Respiratory consultant said it’s not normal but doesn’t at present know what’s causing it. He looked up PoTs to see if this could happen with it but none of the literature mentions this. Any thoughts? My GP found my O2 sat dropped to 84 almost a year ago which got me referred to respiratory.

Thanks

[Izb1]

Sorry cant help you with this query Holiday12345 but am hoping your consultant gets to the bottom of it soon x