Comparison of two different shapes of stylets for intubation with the McGrath MAC® video laryngoscope: a randomized controlled trial

Abstract

Objective This study was performed to compare two different shapes of stylets, 60° and J-shaped stylets, for intubation using the McGrath MAC® video laryngoscope (MVL). Methods Two hundred twenty-two patients undergoing surgery under general anesthesia were randomly allocated to Group J (n = 111) or Group 60° (n = 111) and intubated using the MVL with the stylet bent into the allocated shape. The time to intubation (TTI) and other intubating profiles were compared between the groups. Multivariate regression analysis was used to determine the relationship between factors related to difficult intubation and TTI. Results The TTI was not different between the two groups. There were also no differences in the intubating profiles between the two groups. In both groups, the TTI was longer with a modified Mallampati score (mMS) of ≥3 and percentage of glottic opening (POGO) score of <50. In Group J, the TTI was longer with a body mass index (BMI) of ≥30 kg/m2. Conclusion The TTI during tracheal intubation with the MVL was not different between the two groups. The TTI was longer with an mMS of ≥3 and POGO score of <50. In Group J, the TTI was longer with a BMI of ≥30 kg/m2.

A Paradigm Shift of Airway Management: The Role of Video-Assisted Intubating Stylet Technique

“…The shape of the stylet may affect the effectiveness and performance of VL in patients with normal airways [234]. The combined use of VS and VL has been helpful in patients with normal [235] and difficult airways [14,34,35,236].…”

A double-curved tube for McGrath® MAC videolaryngoscope-guided tracheal intubation

“…We have been using the McGrath® MAC (Covidien, Tokyo, Japan) videolaryngoscope routinely, and have found, as reported, 5 , 6 that tracheal intubation was frequently not easy (incidence of 10–30%), even when the distal side of a tracheal tube (with a style inserted) was curved at several different angles. It was frequently difficult to drive the tip of the tube toward the glottis, whereas the tube frequently obscured the glottic view seen on the video monitor.…”

“…4 This difficulty may occur when the laryngoscopist is inexperienced, the camera of a videolaryngoscope is positioned too close to the glottis (which negates the space needed for tube passage), a tracheal tube without a stylet is used, or when a tracheal tube is not formed to an optimal shape. 4e6 We have been using the McGrath® MAC (Covidien, Tokyo, Japan) videolaryngoscope routinely, and have found, as reported, 5,6 that tracheal intubation was frequently not easy (incidence of 10e30%), even when the distal side of a tracheal tube (with a style inserted) was curved at several different angles. It was frequently difficult to drive the tip of the tube toward the glottis, whereas the tube frequently obscured the glottic view seen on the video monitor.…”

“…4 This difficulty may occur when the laryngoscopist is inexperienced, the camera of a videolaryngoscope is positioned too close to the glottis (which negates the space needed for tube passage), a tracheal tube without a stylet is used, or when a tracheal tube is not formed to an optimal shape. 4 , 5 , 6 …”

Are we there yet? The long journey of videolaryngoscopy into the mainstream

“…The authors make a convincing argument for this difference in approach, leaning onto past studies demonstrating improved success rates of videolaryngoscopy sensu lato with concurrent use of stylets. Furthermore, given the McGrath's slightly increased angulation at the tip compared with the classic Macintosh direct laryngoscope blade, the difference appears clinically plausible, provided we extrapolate evidence from hyperangulated devices [9]. While stylet use in the direct laryngoscopy group was not mandated, it is not clear from the manuscript in how many cases a stylet was in fact used, nor is there any mention of the use of tracheal tube introducers (or bougies) as a rescue technique, making interpretation challenging.…”