A Comparison of 4 Airway Devices on Cervical Spine Alignment in Cadaver Models of Global Ligamentous Instability at C1-2

Abstract

Background The effects of advanced airway management on cervical spine alignment in patients with upper cervical spine instability are uncertain. Methods To examine the potential for mechanical disruption during endotracheal intubation in cadavers with unstable cervical spines, we performed a prospective observational cohort study with three cadaver subjects. We created an unstable, type II odontoid fracture with global ligamentous instability at C1-2 in lightly embalmed cadavers, followed by repetitive intubations with four different airway devices (Airtraq laryngoscope, Lightwand, intubating LMA, and Macintosh laryngoscope) while manual in-line stabilization was applied. Motion analysis data were collected using an electromagnetic device to assess the degree of angular movement in three axes (flexion-extension, axial rotation and lateral bending) during the intubation trials with each device. Intubation was performed by either an emergency medical technician or attending anesthesiologist. Results Overall, 153 intubations were recorded with the four devices. The Lightwand technique resulted in significantly less flexion extension and axial rotation at C1-2 than with the intubating LMA (mean difference in flexion-extension 3.2 degrees [95% CI 0.9 to 5.5], p=0.003; mean difference in axial rotation 1.6 degrees [95% CI 0.3 to 2.8], p=0.01 and Macintosh laryngoscope (mean difference in flexion extension 3.1 degrees [95% CI 0.8 to5.4], p=0.005; mean difference in axial rotation 1.4 degrees [95% CI 0.1 to 2.6], p=0.03. Conclusions In cadavers with instability at C1-2, the Lightwand technique produced less motion than the Macintosh and intubating LMA.

Intubation Biomechanics

“…Recently, two cadaver intubation studies utilized an electromagnetic motion analysis device to simultaneously quantify intervertebral rotations and translations in the sagittal plane (flexion – extension), coronal plane (lateral bending), and axial plane (axial rotation). 31,32 These studies showed that, during intubation, angulation occurred in all three planes, but that sagittal motion (extension) was the greatest. 31,32 This observation is consistent with other clinical studies.…”

“…31,32 These studies showed that, during intubation, angulation occurred in all three planes, but that sagittal motion (extension) was the greatest. 31,32 This observation is consistent with other clinical studies. 33 In in vitro isolated spinal segments, flexion/extension is the most sensitive load direction for disco-ligamentous instability.…”

A comparison of classic laryngeal mask airway insertion between lightwand- and standard index finger–guided techniques

“…Lightwand is a rapid, effective, and safe tool for facilitating intubation in patients with difficult airway and in patients required for minimal neck movements through transillumination in the neck [14,19]. Whether lightwand-guided technique can also be used for guiding real-time insertion of the cLMA remains unclear.…”

Secondary cervical spine injury during airway management: beyond a ‘one-size-fits-all’ approach

“…Cervical spine trauma tends not to be isolated to simply a fracture site. Ligamentous injury [5], surrounding tissue oedema and haematoma formation all play a role in the trauma patient. Transection of the cord or contusion during airway manipulation may also be important.…”