The unanticipated difficult intubation: rigid or flexible endoscope?

Unanticipated difficult intubation occurs with a frequency between 1.5% and 8.5%. The aim of this study was to compare the use of flexible versus rigid endoscopy in such a patient population, with respect to the preparation time and feasibility of each device.

During a four-year observational period, 116 patients with unanticipated difficult intubation were managed either with the flexible fiberscope (FFI group, n= 57) or the rigid Bonfils endoscope (RBI group, n= 59) on a randomized basis.

The time required for preparing and performing the intubation was significantly shorter in the RBI group: median (IQR) 160 s (118-209 s) as opposed to 229 s (162-326 s) in the FFI group (P=0.001). There were no significant differences with respect to endoscopic visibility or quality of the intubation manoeuvre (P>0.1 each). Causes of unanticipated difficult intubation were mainly as follows: restricted movement of the head and neck (39.7%), a Mallampati class > 2 (35.3%), a short neck (31%) or a thyromental distance < or = 5 cm (28.4%). Postoperative complications associated with the intubation maneuver included slight bleeding (FFI = 8.8% vs RBI = 8.5%; NS), technical problems (12.3 vs 10.2%, NS), hoarseness (15.8 vs 15.3%, P=0.946) and dysphagia (5.3 vs 16.9%, P=0.070).

Both endoscopic techniques enable quick and safe intubation. The Bonfils method could be the method of choice in cases of already relaxed patients with unanticipated difficult conventional laryngoscopy, presuming that the anaesthetist is familiar with this technique. Because the clinical re-evaluation for possible predictors of difficult intubation revealed no unknown new factors, the preoperative examination for anatomical peculiarities and being aware are the best protection against unanticipated intubation problems.