Case 23: An Unusual Capnograph Tracing

Abstract

You have anesthetized a healthy 24-year-old man (ASA 1E) for an emergency laparoscopic appendectomy. He has no history of previous anesthetic nor does he take medication regularly and has no history of allergy to medication. There is no family history of any problems with anesthesia. He is 75 kg and 6 feet. After rapid sequence induction, you secure the airway and see a CO₂ waveform on the capnograph (which incorporates a sidestream CO₂ monitor [Datex Capnomac Ultima, Datex, Helsinki, Finland]), confirming bilateral air entry. The endotracheal tube is taped at 23 cm. The vital signs are normal. However, on closer inspection of the capnograph waveform, you now notice that the capnograph is very different to what you normally see (Fig. 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 24 cm. The patient’s vital signs remain normal. You have not seen anything like this before, and since you have checked the Narcomed 2B, North America Dräger anesthesia machine prior to the anesthetic, you are now wondering what this trace could mean.