Incidence of unanticipated difficult airway in obstetric patients in a teaching institution

PURPOSE: Our aim was to determine the incidence of difficult intubation during pregnancy-related surgery at a high-risk, high-volume teaching institution. METHODS: Airway experience was analyzed among patients who had pregnancy-related surgery under general anesthesia from January 2001 through February 2006. A difficult airway was defined as needing three or more direct laryngoscopy (DL) attempts, use of the additional airway equipment after the DL attempts, or conversion to regional anesthesia due to inability to intubate. Airway characteristics were compared between patients with and without a difficult airway. In addition, pre- and postoperative airway evaluations were compared to identify factors closely related to changes from pregnancy. RESULTS: In a total of 30,766 operations, 2,158 (7%) were performed with general anesthesia. Among these, 1,026 (47.5%) were for emergency cesarean delivery (CD), 610 (28.3%) for nonemergency CD, and 522 (24.2%) for non-CD procedures. A total of 12 patients (0.56%) were identified as having a difficult airway. Four patients were intubated with further DL attempts; others required mask ventilation and other airway equipment. Two patients were ventilated through a laryngeal mask airway without further intubation attempts. Ten of the 12 difficult airway cases were encountered by residents during their first year of clinical anesthesia training. There were no maternal or fetal complications except one possible aspiration. CONCLUSION: Unanticipated difficult airways accounted for 0.56% of all pregnancy-related surgical patients. More than 99.9% of all obstetric patients could be intubated. A difficult airway is more likely to be encountered by anesthesia providers with <1 year of experience. Proper use of airway equipment may help secure the obstetric airway or provide adequate ventilation. Emergency CD did not add an additional level of difficulty over nonemergency CD.