Used CPAP last night in lab, 1st time. Had major issues breathing with mask unless my head was elevated. Sleep tech seemed surprised. Is this normal?

CPAP. CPAP machines often cause problems with patients when they initially start using them I would continue to try to use it as the symptoms may resovlve themselves.
It can be. occasionally the use of CPAP can initially be difficult until you get use to it. The pressure in the nose and respiratory tree can feel smothery. With time and relaxation you should be able to tolerate the CPAP much better.