Anesthesia Circuit

Case Synopsis

A 57-year-old woman who is a heavy smoker experiences a difficult endotracheal intubation during induction of anesthesia. Mask ventilation also is difficult, partly because of the high inspiratory pressures required and partly because of a poor mask fit, with a resulting considerable leak between the mask and face. The first and subsequent attempts at intubation are greeted with a stiff bag and a lack of a CO ₂ waveform on the capnograph; each time, a tentative diagnosis of esophageal intubation is made, and the tube is quickly removed. After each intubation, mask ventilation becomes progressively more difficult. Throughout this episode, the patient also becomes intermittently hypotensive. About 30 minutes after induction, an observer notices that the expiratory check valve of the anesthesia breathing system remained seated during the entire breathing cycle. Replacement of the valve solves the problem; ventilation becomes possible, and the subsequent intubation is successful. Thus this “cannot ventilate, cannot intubate” scenario had an unexpected twist.