The Takeaway

"Routine stylet preparation may not be necessary for elective videolaryngoscopic intubations with a Macintosh blade in patients with a longer sternomental distance, increased thyromental height, and normal cervical spine mobility"

Study Design

• Prospective observational study
• 224 adult patients scheduled for elective videolaryngoscopic intubations using a Macintosh blade
• Exclusion Criteria: cervical spine issues, airway disease, anticipated difficult intubation, BMI > 35 kg·m^-2, or required rapid sequence induction
• Primary outcome: incidence of first-pass success for videolaryngoscopic intubations without a stylet

Abstract

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.

Excerpts

A recent systematic meta-analysis indicated that videolaryngoscopy with a Macintosh or hyperangulated blade offers better glottic visualization than direct laryngoscopy

improved glottic views do not always ensure a successful videolaryngoscopic intubation with a Macintosh blade because of challenges with tube passage to the glottis

stylet use can lead to rare but serious complications, such as soft tissue perforations, and minor issues, such as postoperative pharyngeal pain and sore throat, reported in up to 50% of cases

systematic reviews and closed claim analysis revealed that laryngeal injuries account for up to 33% of postoperative airway complications

Not using a stylet with a hyperangulated blade during videolaryngoscopic intubation may prolong intubation duration and require more attempts, while with a Macintosh blade, it may increase both intubation duration and difficulty

Videolaryngoscopes with Macintosh blades often allow successful intubation without a stylet, while hyperangulated blades typically require one owing to their steep curvature

The first-pass success rate of videolaryngoscopic intubations without a stylet was 80% (180/224). This success rate increased to 96% (215/224) for second attempts without stylet use but with laryngeal manipulation. A stylet was necessary in 9/224 (4%), and there was one case of total intubation failure, even with a stylet, due to prolonged intubation duration exceeding 120 sec.

Given the low overall stylet requirement, clinicians might consider preparing stylets as needed rather than routinely. Conventional airway assessments may suffice for identifying patients likely to require a stylet, particularly in settings without ultrasonographic equipment.

Our study revealed a significant association between stylet use and postoperative hoarseness. Nevertheless, hoarseness may result from either stylet use or multiple intubation attempts without using a stylet. This highlights the need to balance the benefits of successful intubation without a stylet, cautious stylet use, and minimizing multiple intubation attempts

While stylets and bougies are commonly used for intubation assistance, both can potentially cause airway trauma if used improperly

Citation

Song SE, Jung JY, Jung CW, Park JY, Kim WH, Yoon HK. First-pass success rate and predictive factors for stylet use in videolaryngoscopic intubations with a Macintosh blade: a prospective observational study. Can J Anaesth. 2025 Apr 25. English. doi: 10.1007/s12630-025-02952-0. Epub ahead of print. PMID: 40281329.

Article Link