Journal article
Intubation Biomechanics: Laryngoscope force and cervical spine motion during intubation with Macintosh and Airtraq laryngoscopes
Anesthesiology (Philadelphia), Vol.121(2), pp.260-271
08/2014
DOI: 10.1097/ALN.0000000000000263
PMCID: PMC4110170
PMID: 24739996
Abstract
Introduction: Laryngoscopy and endotracheal intubation in the presence of cervical spine instability may put patients at risk of cervical cord injury. Nevertheless, the biomechanics of intubation (cervical spine motion as a function of applied force) have not been characterized. This study characterized and compared the relationship between laryngoscope force and cervical spine motion using two laryngoscopes hypothesized to differ in force.
Methods: Fourteen adults undergoing elective surgery were intubated twice (Macintosh, Airtraq). During each intubation, laryngoscope force, cervical spine motion, and glottic view were recorded. Force and motion were referenced to a preintubation baseline (stage 1) and were characterized at three stages: stage 2 (laryngoscope introduction); stage 3 (best glottic view); and stage 4 (endotracheal tube in trachea).
Results: Maximal force and motion occurred at stage 3 and differed between the Macintosh and Airtraq: (1) force: 48.8 ± 15.8 versus 10.4 ± 2.8 N, respectively, P = 0.0001; (2) occiput-C5 extension: 29.5 ± 8.5 versus 19.1 ± 8.7 degrees, respectively, P = 0.0023. Between stages 2 and 3, the motion/force ratio differed between Macintosh and Airtraq: 0.5 ± 0.2 versus 2.0 ± 1.4 degrees/N, respectively; P = 0.0006.
Discussion: The relationship between laryngoscope force and cervical spine motion is: (1) nonlinear and (2) differs between laryngoscopes. Differences between laryngoscopes in motion/force relationships are likely due to: (1) laryngoscope-specific cervical extension needed for intubation, (2) laryngoscope-specific airway displacement/deformation needed for intubation, and (3) cervical spine and airway tissue viscoelastic properties. Cervical spine motion during endotracheal intubation is not directly proportional to force. Low-force laryngoscopes cannot be assumed to result in proportionally low cervical spine motion.
Details
- Title: Subtitle
- Intubation Biomechanics: Laryngoscope force and cervical spine motion during intubation with Macintosh and Airtraq laryngoscopes
- Creators
- Bradley J Hindman - Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, U.S.ABrandon G Santoni - Foundation for Orthopaedic Research and Education, Tampa, FL, U.S.AChristian M Puttlitz - Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, Colorado State University, Fort Collins, CO, U.S.ARobert P From - Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, U.S.AMichael M Todd - Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, U.S.A
- Resource Type
- Journal article
- Publication Details
- Anesthesiology (Philadelphia), Vol.121(2), pp.260-271
- DOI
- 10.1097/ALN.0000000000000263
- PMID
- 24739996
- PMCID
- PMC4110170
- ISSN
- 0003-3022
- eISSN
- 1528-1175
- Language
- English
- Date published
- 08/2014
- Academic Unit
- Anesthesia
- Record Identifier
- 9984007165502771
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