My Mom has COPD and some days her saturation levels drop to the low 80s to high 70s with even a tiny amount of exertion, like going to the kitchen to get a glass of water. Is this normal? It can go on for a week or more. When we ask her lung dr about it he saids it is normal for the saturation levels to go down, but this is really affecting her quality of life.

Her normal saturation levels are between 89-92 and she is on O2 full time.