Colleague of mine was doing a case and thought it was interesting to present to the students.

66 y/o F presents for ERCP, easy DL, positioned prone and procedure started. Plan to do a sphincterotomy as well to pull out some junk in the duct. As they are finishing up the CRNA cycles a pressure and gets 60/30, ETCO2 goes from 35 to 20 then to the low teens. IV is running fine with no air bubbles, surgeon did not push anything anywhere...

What are you differentials STUDENTS for this sudden drop in BP and ETCO2 and what are your first interventions for this patient?