If she does to to NJC/NJH, they will evaluate her for need of supplemental O2 soon after she arrives at their clinic, since many patients do find they need supplemental O2 there (and for flying which is pressurized to 8000 feet) even if they don’t normally need O2 at their lower elevation home.

If the doctor has access to a High Altitude Simulation Test (HAST), your mom can have it simulated as to how she will do while flying and at 5000 foot Denver, NJH/NJC. If there is no access to the test, she and a loved one could drive to a mountain in OR and use an oximeter to check her saturation rates at different altitudes. Most phones will be able to have an app to tell you your altitude. If she’s fine at 5000 and 8000 feet, she should be OK. If she’s not, she needs to work with her PCP to get supplemental O2 for the flight and for her time in Denver.