Holiday at high altitude (7, 000 to 8, 000 ft). what effect will this have on my sleep apnea?

High altitude: It is difficult to predict what will happen to your sleep apnea at high altitudes. People without sleep apnea can develop cheyne stokes respirations (a form of central sleep apnea) at high altitudes. The lower oxygen levels at high altitude alter respiratory drive with wake and sleep. This heightened drive could theoretically improve your obstructive events but i recommend wearing your cpap.

Not a problem: Assuming your general health is good enough to permit higher altitudes, just use your CPAP machine as usual. It will work as it always does. Of course, you will have less oxygen in the ambient air, but it will continue to do it's job. If you don't have a cpap, get one, or if intolerant of its use, see your dentist about having an oral appliance made as an alternative.