Hi PatientOrangeRedMoose. The Resmed Aircurve is capable of compensating for altitude. However, your body might need time to adjust. When I travel to higher altitudes with my Resmed, I do not experience problems with my treatment, but my breathing does change. At higher altitudes, I find I sometimes feel lightheaded, and I definitely seem to drink more water! I encourage you to speak to your sleep physician or you equipment provider if you do not think your machine is functioning properly. Wiredgeorge makes a good point as well about using Sleepyhead software to monitor your treatment. If you are interested, the software provides quite a bit of helpful data. Best wishes!