My dad just got out of the hospital after a 25-day stay. He's been recovering from COVID, and now he's dealing with fibrosis. His oxygen saturation levels are hanging around 89-90, and he's doing his lung exercises about 34 times a day. We have a concentrator at home, and his oxygen level is 93 at 1.5 liters per minute. I'm worried and wondering how often we should give him oxygen support and if we should adjust the liters. Any advice?