Both the SleepGuide Glossary of Terms and one of Carl's posts on an unrelated discussion note that CPAP use can promote central apneas.  I would love to find out what is known about this pathway.  Just for two examples: how frequently does this occur?  Are there warning signs (and just to anticipate the practical jokers who allude to my post of five minutes ago -- no, doubling of the respiration peak is not an obvious warning sign!)?