My father had stage 4 COPD. He was just released from the hospital and now needs oxygen. We had a follow up appointment yesterday, and they indicate he needs 2L of pulse flow, after a 6 minute walk that really only lasted 2 minutes due to fatigue and SOB. What I am not clear on, is how they determine if he needs it at night. He takes his 02 level upon awakening and it is always above 90...but. of course, we have no idea what happens in the middle of the night. Thank you in advance!