Would it be possible that a sleep apnea test be dangerous for a 92 year old woman?

It's relative: It is all relative to her condition. If she is a "healthy" 92 yo than there is no reason she could not sleep overnight in a sleep center to properly diagnose osa, which if positive, she may benefit from treatment, and feel well for several years still to come.

Yes: Sleep apnea is dangerous at any age. At 92, she has probably developed other health problems as a result. At any age it can lower the quality of life. And increase expenses for health care.

Shouldn't: The test are very non invasive and psg are done with someone actually monitoring the pt.