Cervical Spine Biomechanics During Endotracheal Intubation

Summary

Current methods for endotracheal intubation in the presence of cervical spine (c-spine) instability are not evidence-based. This is so because the relationships between the forces applied during intubation (by the laryngoscope) and the resulting c-spine movement have not yet been quantitatively characterized. As a result, with the current level of knowledge, it is not known, and it is not possible to predict, which types of c-spine instability have the greatest risk of cervical spinal cord injury with intubation. This shortcoming makes it impossible to know which intubation devices and techniques are likely to be safest in the presence of c-spine instability.

To address this critical lack of knowledge, the overarching purpose of the proposed research is to: 1) quantitatively relate c-spine movement that results from the forces applied to the peri-airway tissues during intubation (force-motion relationships), and 2) use these data to develop a mathematical model of the c-spine that will predict which types of c-spine instability result in the greatest amount of abnormal c-spine motion and associated spinal cord compression during intubation.

This clinical study will utilize laryngoscope blades that are instrumented with a high resolution pressure mapping system to make high-resolution measurements of the forces and pressures of intubation while making simultaneous measurements of c-spine motion. In this study, study subjects will be intubated using both a conventional (Macintosh) laryngoscope and an alternative (Airtraq) laryngoscope. By using two different laryngoscopes, we, the investigators, will introduce forces of differing magnitudes and distributions to peri-airway tissues. The Airtraq does not require a direct line of sight to visualize the vocal cords, and among the various new alternative laryngoscopes it is the only one that has been shown to result in 30-50% less cervical motion than a conventional (Macintosh) laryngoscope. Accordingly, we hypothesize 1) 30-50% less force will be applied with the Airtraq laryngoscope than with the conventional (Macintosh) laryngoscope and 2) 30-50% less c-spine motion will occur with the Airtraq. By studying (intubating) each subject twice, any differences in the c-spine force-motion relationships between devices will be due to the devices themselves. By studying each subject twice, we can account for (and eliminate) differences among study subjects in c-spine biomechanical properties.

Conditions

• Spinal Diseases
• Other Biomechanical Lesions of Cervical Region
• Tracheal Intubation Morbidity

Interventions

PROCEDURE

Endotracheal intubation

Study patients undergo endotracheal intubation using both a conventional direct laryngoscope (Macintosh) and an alternative indirect laryngoscope (Airtraq). The order of intubation (Macintosh then Airtraq--or--Airtraq then Macintosh) is randomized.

Sponsors & Collaborators

• National Institute for Biomedical Imaging and Bioengineering (NIBIB)

  collaborator NIH

• Colorado State University

  collaborator OTHER

• University of Iowa

  lead OTHER

Principal Investigators

• Bradley J Hindman, M.D. · University of Iowa

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

80 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2011-12-31

Primary Completion

2012-07-31

Completion

2012-07-31

Countries

• United States

Study Locations