Fibreoptic assessment of laryngeal aperture in patients with difficult laryngoscopy

Purpose: To determine the relationship between the area of the laryngeal ap erture (LA) seen fibreoptically during laryngoscopy and the difficulty of t racheal intubation in patients with difficult laryngoscopy Methods: In 587 adult patients after induction of general anesthesia and mu scle relaxation, the best laryngoscopic view of the larynx using a Macintos h 3 blade was classified according to Cormack. When the LA could not be see n, with laryngoscope blade in place, the LA view provided by a fibreoptic b ronchoscope (FOB)-camera passed nasally was photographed. Then, the laryngo scopist attempted to intubate the trachea using the Macintosh blade. Trache al intubation requiring more than three attempts was defined as difficult. After the third attempt, the trachea was intubated orally aided by FOE. The LA view after jaw thrust during FOB-aided intubation was photographed, Results: Laryngoscopy was difficult in 17 of 587 patients. In four, intubat ion was difficult. In the remaining 13 patients the trachea was easy to int ubate. The LA area obtained by the FOE in the difficult group (median, 0.19 ; intra-quartile range, 0.14 to 0.39 cm(2)) was smaller than that: in the e asy group (2.43; 1.84 to 2.93 cm(2))(P = 0.003), In contrast, the LA area p rovided by jaw thrust during the FOE-aided intubation in the difficult grou p (2.28; 1.99 to 2.73 cm(2)) was similar to that during laryngoscopy in the easy group. Conclusion: Inability of the laryngoscope to provide an adequate LA view is one cause of difficult intubation with the Macintosh laryngoscope in patie nts with difficult laryngoscopy.