The Flex-it® Articulated Stylet Does Not Shorten Intubation Duration During Videolaryngoscopy Compared to the GlideRite® Rigid Stylet in Patients Wearing a Semi-rigid Cervical Collar: A Randomized Controlled Trial

Abstract

Introduction Compared to the GlideRite® rigid stylet used with the GlideScope® and its hyperangulated blade, the Flex-it® stylet permits a dynamic orientation of the endotracheal tube toward the glottic aperture. Our study compared the GlideRite stylet and Flex-it stylet on GlideScope intubation durations in patients wearing a semi-rigid cervical collar, simulating conditions of cervical instability. Methods Our institutional research ethics board approved the study protocol (Hôpital Maisonneuve-Rosemont IRB#14013) for this single-centre randomized controlled trial on 12/05/2014. Eighty patients between 18 and 70 years old were randomized into one of two interventions: intubation with GlideScope + GlideRite stylet (GlideRite) or intubation with GlideScope + Flex-it stylet (Flex-it). We used a hyperangulated blade, size 4. All included patients provided written consent, had American Society of Anesthesiologists (ASA) physical status I or II, and did not exhibit any difficult intubation criteria or known cervical spine anomaly. Following induction of anesthesia, a Philadelphia® semi-rigid cervical collar was installed to simulate conditions associated with cervical instability. One of the three anesthesiologists participating in the study performed the intubation. The primary endpoint was intubation duration in seconds, from the beginning of the laryngoscopy until detection of expired CO₂. Secondary outcomes were endotracheal tube handling duration in seconds, intubation failure, Intubation Difficulty Score, and ease of stylet removal. Variations in blood pressure, heart rate, O₂ saturation during intubation, postoperative hoarseness, and sore throat intensity were also compared between the interventions. Results Intubation was longer when using Flex-it vs. GlideRite (sec, Median [quartiles]), 71 [50-84] vs. 48 [39-60], P = .006). Kaplan-Meier curves showed that at 1 min, 20% of Flex-it patients were intubated vs. only 20% of GlideRite patients. The endotracheal tube (ETT) handling duration (sec, Median [quartiles]) was longer with Flex-it than with GlideRite, with 48 [33-66] vs. 34 [25-39], P = .007. The percent of failures was significantly higher with Flex-it (13/38, 32.5%) compared to GlideRite (1/38, 2.5%), P< .001. The Intubation Difficulty Scale score was significantly higher for Flex-it, with median [quartiles] of 6[5-7], compared to 2[2-5] for GlideRite, P< .001. There were no blood stains on the ETT or desaturations in either intervention. Ease of stylet removal, hoarseness, sore throat, blood pressure and heart rate measurements, and O₂ saturation after intubation were not different between the interventions. Conclusion Videolaryngoscopy intubation using the Flex-it stylet was slower, more difficult, and had more failures than the GlideRite stylet in patients with simulated cervical instability wearing a semi-rigid cervical collar.