I have moderate COPD and secondary mild Pulmonary Hypertension. My pulmonary function tests this past October showed some improvement. tResults from a 6 minute walk showed that my oxygen levels were above 88 during exercise and supplemental o2 for exertion would not be needed. I still use 4 ltrs of o2 in cpap at night. I've noticed more shortness of breath in the last few weeks (no coughing) and my oxygen has dropped below 88 with slow to moderate recovery. My pulmonologist's Nurse practitioner says I still don't meet the requirements for supplemental o2. I feel like I'm talking to a wall. I would like to request another 6 minute walk. I've been on supplemental oxygen for 8 years. No big changes other than a moderate weight loss and increased activity. Believe me I happily gave up walking around with 50 ft of oxygen tubing but I'm frightened of not having it if I need it. Thank you for any assistance you may have.