PREDICTING DIFFICULT INTUBATION WITH INDIRECT LARYNGOSCOPY

Background: It is not always possible to predict when tracheal intubat ion will be difficult or impossible. The authors wanted to determine w hether indirect laryngoscopy could identify patients in whom intubatio n was difficult. Methods: Indirect laryngoscopy was done in 2,504 pati ents. The Wilson risk sum score and the modified Mallampati score mere also studied in a different series of 3,680 patients for comparison. These predictive methods were compared according to three parameters: positive predictive value, sensitivity, and specificity. Results: Of 6 ,184 patients studied, the trachea proved difficult to intubate in 82 (1.3%). Positive predictive value (31%) and specificity (98.4%) with i ndirect laryngoscopy were greater than the other two predictive method s (P < 0.01), whereas sensitivity with indirect laryngoscopy (69.2%) w as greater than that of the Wilson risk sum score (55.4%) (P < 0.01). Conclusions: Although in 15% of patients indirect laryngoscopy could n ot be performed because of excessive gag reflex indirect laryngoscopy cars serve as an effective method to predict difficult intubation.