An Unusual Capnograph Tracing

You have anesthetized a healthy 24-yr-old man (American Society of Anesthesiologists physical status 1E) for an acute laparoscopic appendectomy. He has no history of previous anesthetic, he does not take medication regularly, and he has no history of allergy to medication. There is no family history of any problems with anesthesia. He is 75kg and 6′0″ tall. After rapid sequence induction, you secure the airway and see a CO₂ wave form on the capnograph (Datex Capnomac Ultima; Datex, Helsinki, Finland; incorporates a sidestream CO₂ monitor), confirming bilateral air entry. The endotracheal tube is taped at 23cm. The vital signs are normal. However, on closer inspection of the capnograph waveform, you now notice that the capnograph is very different than what you normally see (Fig. 23.1). The tracing starts from a zero and a normal plateau is reached, but just before the trace should normally go to zero, there is a marked peak in the tracing before rapidly returning to zero. Tidal volumes, respiratory rates, and minute volume are within normal limits. The peak pressure is 24cm. The patient’s vital signs remain normal. You have not seen anything like this before, and because you checked the Narcomed 2B (North America Dräger) anesthesia machine before administering the anesthetic, you are now wondering what this trace could mean. Should you be concerned? What do you think the problem is? What, if anything, can you do?