Predicting difficult intubation--a comprehensive scoring system.

A study was conducted in an attempt to devise a simple and more accurate method of predicting difficult intubation. Prospective assessments were made in 282 patients and retrospective assessment in 16 patients with regard to 21 anatomical factors which were correlated with the laryngoscopic view at intubation. Twelve factors correlated significantly with difficult intubation. Four of these were eliminated after multifactorial analysis. A scoring system was devised, assigning points to each variable based on its discriminative value. A score of 6 or more correctly identified 22 out of the 23 difficult intubations and there were 50 false positives (sensitivity, specificity and PPV of 96%, 82% and 31% respectively). When negative scoring was done for factors favouring easy intubation, false positives were reduced to 36, but only 20 difficult cases could be identified correctly.