Standard clinical risk factors for difficult laryngoscopy are not independent predictors of intubation success with the GlideScope

Study Objectives: To determine whether the first-attempt tracheal intubation incidence using the GlideScope videolaryngoscope is higher in patients with predicted increased risk of difficult laryngoscopy, and to assess the ability of other a priori defined standard risk factors to predict first-attempt intubation success, in aggregate and by forming scores. Design: Prospective study. Setting: Operating room in a tertiary-care academic center. Patients: 357 patients intubated with the GlideScope for nonemergent general anesthesia. Interventions and Measurements: Mallampati airway class was used to create two groups of patients, one with higher and the other, lower, potential difficult laryngoscopy (Mallampati classes 3-4 and 1-2, respectively). Intubation success on the first attempt with the GlideScope videolaryngoscope in patients with a Mallampati class 3 or 4 airway versus those with Mallampati class 1 or 2 airway was tested. We also evaluated the predictive ability of the Mallampati airway class (1 and 2 vs 3 and 4) along with 9 other possible predictors of difficult intubation on first-attempt intubation success: gender, age, body mass index, level of training within our anesthesia residency program (Clinical Anesthesia Resident years 1, 2, and 3), ASA physical status, mouth opening, thyromental distance, neck flexion, and neck extension. Main Results: None of the standard predictors of difficult intubation was significantly associated with outcome after adjusting for other predictors. A multivariable model containing the aggregate set of variables predicted outcome significantly better than a risk score formed as the sum of 10 predictors ("Risk 10"; P = 0.0176). Conclusions: With GlideScope-assisted tracheal intubation, Mallampati airway class is not an independent risk factor for difficult intubation. Other standard clinical risk factors of difficulty with direct laryngoscopy also do not appear to be individually predictive of first-attempt success of tracheal intubation.