Motion of a cadaver model of cervical injury during endotracheal intubation with a Bullard laryngoscope or a Macintosh blade with and without in-line stabilization

Background: Endotracheal intubation in patients with potential cervical injury is a common dilemma in trauma. Although direct laryngoscopy (DL) with manual in-line stabilization (MILS) is a standard technique there is little data on the effect of MILS on cervical motion. Likewise there is little data available regarding alternative airway techniques in this setting. This study compared intubations with and without MILS in a cadaver model of cervical instability. We also used this model to compare intubations using DL with a Macintosh blade versus a Bullard laryngoscope (BL). Methods: Complete C4-C5 disarticulations were surgically created in 10 fresh human cadavers. The cadavers were then intubated in a random order with either BL or DL with and without MILS. The motion at the unstable interspace was measured for subluxation, angulation, and distraction. Results: MILS did not significantly affect maximal motion of this model in any of the three measures using either DL or BL. There were no clinically significant differences in maximal median motion in any of the three measures when comparing the two blades. However, there was significantly more variance in the subluxation caused by DL than by BL. Conclusions: We were unable to demonstrate any significant effect of MILS on the motion of an unstable cervical spine in this cadaver model. The BL appears to be a viable alternative to DL in the setting of an unstable lower cervical spine.