Randomized crossover trial comparing cervical spine motion during tracheal intubation with a Macintosh laryngoscope versus a C-MAC D-blade videolaryngoscope in a simulated immobilized cervical spine

BACKGROUND: Maintaining cervical immobilization is essential during tracheal intubation in patients with unstable cervical spines. When using the Macintosh laryngoscope for intubation in patients with cervical immobilization, substantial neck extension is required for visualization of the glottis. However, the C-MAC D-Blade videolaryngoscope may require less neck extension due to its acute angulation. We hypothesized that C-MAC D-Blade videolaryngoscopic intubation would result in less cervical spine movement than Macintosh laryngoscopic intubation. We compared the effects of C-MAC D-Blade videolaryngoscopic intubation and Macintosh laryngoscopic intubation in terms of cervical spine motion during intubation in patients with simulated cervical immobilization. METHODS: In this randomized crossover study, the cervical spine angle was measured at the occiput–C1, C1–C2, and C2–C5 segments before and during tracheal intubation with either a C-MAC D-Blade videolaryngoscope or Macintosh laryngoscope in 20 patients, with application of a neck collar for simulated cervical immobilization. Cervical spine motion was defined as the change in angle measured before and during tracheal intubation. RESULTS: The cervical spine motion at the occiput–C1 segment was measured at 12.1 ± 4.2° and 6.8 ± 5.0° during Macintosh laryngoscopic and C-MAC D-blade videolaryngoscopic intubation, respectively, corresponding to a 44% reduction in cervical spine motion when using the latter device (mean difference, − 5.3; 98.33% CI: − 8.8 to − 1.8; p = 0.001). However, there was no significant difference between the two intubation devices at the C1–C2 segment (− 0.6; 98.33% CI: − 3.4 to 2.2; p = 0.639) or C2–C5 segment (0.2; 98.33% CI: − 6.0 to 6.4; p = 0.929). CONCLUSIONS: The C-MAC D-Blade videolaryngoscope causes less upper cervical spine motion than the Macintosh laryngoscope during tracheal intubation of patients with simulated cervical immobilization. TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov on June 26, 2018 (NCT03567902).