For the students...
I came in to relieve one of our Anesthesiologists for a break on an umbilical hernia repair under general. He turns to me and asks if I had any problems with the anesthesia machine earlier in the day because he is not able to acheive the set tidal volume. It is set at 850 and it is delivering 420. The peak airway pressure is 15 and I think I smell agent.

Tell me what you think is the problem, what
would you do and how many different things should you evaluate?