Cervical Spine Biomechanics During Endotracheal Intubation

August 3, 2012 updated by: Bradley J. Hindman, University of Iowa

Intubation Mechanics of the Stable and Unstable Cervical Spine

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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

14

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Iowa
      • Iowa City, Iowa, United States, 52242
        • University of Iowa Hospitals and Clinics

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 80 years (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Patient Height: 5-feet, 0-inches to 6-feet, 0-inches
  • Patient body mass index: less than 30 kg/m2
  • Planned surgery requires use of C-arm fluoroscopy
  • Planned surgery to take place at University of Iowa and requires general anesthesia and orotracheal intubation

Exclusion Criteria:

  • The patient is a prisoner
  • The patient is pregnant
  • The patient is not competent to personally give consent
  • Neurological signs and symptoms indicating cervical spinal cord myelopathy
  • Cervical spine images demonstrating anatomic instability, traumatic injury, significant cervical stenosis, and/or spinal immobility
  • Condition associated with cervical spine anatomic abnormalities such as Rheumatoid arthritis, Down Syndrome, Ankylosing spondylitis, Osteogenesis imperfecta
  • Prior cervical spine surgery of any type
  • History of difficult endotracheal intubation
  • Currently symptomatic gastroesophageal reflux disease
  • Currently symptomatic asthma or other reactive airway disease
  • Any history of coronary artery disease
  • Any history of cerebral aneurysm(s)
  • History of vocal cord and/or glottic disease or dysfunction
  • Contraindication to receiving 100% oxygen
  • Systolic blood pressure greater than 180 mmHg
  • Diastolic blood pressure greater than 100 mmHg
  • American Society of Anesthesiologists Physical Status class of 4, 5, or 6
  • Known allergy or other adverse response to study drugs: midazolam, lidocaine, fentanyl, propofol [eggs, soy beans], rocuronium, or sevoflurane.
  • Mallampati oropharyngeal class of III or IV
  • Thyromental distance less than 6.0 cm
  • Sternomental distance less than 12.5 cm
  • Maxillary incisors loss or in poor condition

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: BASIC_SCIENCE
  • Allocation: RANDOMIZED
  • Interventional Model: CROSSOVER
  • Masking: DOUBLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: Airtraq laryngoscope
The Airtraq is an alternative indirect laryngoscope that appears to cause less cervical spine motion during intubation that conventional direct laryngoscopy (Macintosh blade)
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.
ACTIVE_COMPARATOR: Macintosh laryngoscope
This arm constitutes intubation with a conventional direct laryngoscopy with a Macintosh blade which has been shown to result in cervical spine extension, particularly in the upper cervical segments.
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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cervical spine segmental intervertebral motion
Time Frame: Data collection takes place during two sequential endotracheal intubations (40-45 seconds), with follow-up assessments on postoperative days 1, 3, and 7.
Lateral fluoroscopy is used to measure cervical spine motion during endotracheal intubation.
Data collection takes place during two sequential endotracheal intubations (40-45 seconds), with follow-up assessments on postoperative days 1, 3, and 7.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Laryngoscope blade force distribution
Time Frame: Data collection takes place during two sequential endotracheal intubations (40-45 seconds), with follow-up assessments on postoperative days 1, 3, and 7.
"Pressure-mat" technology is used to measure spacially distributed forces applied by the laryngoscope blade during endotracheal intubation.
Data collection takes place during two sequential endotracheal intubations (40-45 seconds), with follow-up assessments on postoperative days 1, 3, and 7.
Glottic visualization
Time Frame: Data collection takes place during two sequential endotracheal intubations (40-45 seconds), with follow-up assessments on postoperative days 1, 3, and 7.
An image of the glottis during intubation is obtained for off-line measurement of the percentage of glottic opening as seen by the laryngoscopist.
Data collection takes place during two sequential endotracheal intubations (40-45 seconds), with follow-up assessments on postoperative days 1, 3, and 7.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Iowa

Collaborators

National Institute for Biomedical Imaging and Bioengineering (NIBIB)
Colorado State University

Investigators

  • Principal Investigator: Bradley J Hindman, M.D., University of Iowa

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

December 1, 2011

Primary Completion (ACTUAL)

July 1, 2012

Study Completion (ACTUAL)

July 1, 2012

Study Registration Dates

First Submitted

May 31, 2011

First Submitted That Met QC Criteria

June 7, 2011

First Posted (ESTIMATE)

June 8, 2011

Study Record Updates

Last Update Posted (ESTIMATE)

August 7, 2012

Last Update Submitted That Met QC Criteria

August 3, 2012

Last Verified

August 1, 2012

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 201102721
  • R01EB012048 (NIH)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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