First-pass success rate and predictive factors for stylet use in videolaryngoscopic intubations with a Macintosh blade: a prospective observational study.

Purpose: The aim of this study was to evaluate the first-pass success rate of videolaryngoscopic intubations without a stylet using a Macintosh blade and to identify predictive factors for successful intubation.

Methods: We conducted a prospective observational study of 224 adult patients scheduled for elective videolaryngoscopic intubations using a Macintosh blade. We excluded patients who had cervical spine issues, airway disease, anticipated difficult intubation, or a body mass index > 35 kg·m^-2, or who required rapid sequence induction. We initially attempted intubations without a stylet, with laryngeal manipulation on the second attempt if needed, and a stylet added after two failures. We evaluated the first-pass success rate and identified predictive factors using multivariable logistic regression, incorporating demographic, conventional, and ultrasonographic airway parameters. We performed ultrasound examination after induction of general anesthesia. We developed and evaluated a prediction model using receiver operating characteristic curve analysis.

Results: The first-pass success rate was 80% (180/224), increasing to 96% (215/224) after laryngeal manipulation on the second attempt. Nine patients (4%) required a stylet. Longer sternomental distance (odds ratio [OR], 1.24; 95% confidence interval [CI], 1.01 to 1.53; P = 0.04) and increased thyromental height (OR, 1.14; 95% confidence interval [CI], 1.07 to 1.21; P < 0.001) were associated with first-pass success without a stylet. Limited (OR, 0.39; 95% CI, 0.16 to 1.00; P = 0.049) or severely limited (OR, 0.05; 95% CI, 0.01 to 0.19; P < 0.001) cervical spine movement negatively affected success.

Conclusions: Routine stylet preparation for elective videolaryngoscopic intubations with a Macintosh blade may not be necessary, as only a small percentage of patients required it.