Airway/original researchLaryngeal View During Laryngoscopy: A Randomized Trial Comparing Cricoid Pressure, Backward-Upward-Rightward Pressure, and Bimanual Laryngoscopy
Introduction
Tracheal intubation by direct laryngoscopy is the primary means of airway management in cardiac resuscitation, emergency care, and general anesthesia. Laryngeal exposure is the main determinant of success or failure with this procedure.
The 3 commonly used techniques for manipulating the external anatomy to help improve laryngeal view are the Sellick maneuver (involving cricoid pressure), backward-upward-rightward pressure (BURP, involving thyroid cartilage pressure), and bimanual laryngeal manipulation. Sellick1 in 1961 described backward pressure on the cricoid cartilage as a method for preventing passive regurgitation of stomach contents and also facilitating endotracheal intubation. In 1993, Knill coined the term “BURP,” describing the direction and pressure exerted on the thyroid cartilage by an assistant to improve laryngeal view at laryngoscopy.2 Bimanual laryngoscopy involves operator-directed manipulation of the thyroid cartilage (Figure 1).3, 4 Unlike cricoid pressure and BURP, both done by an assistant, bimanual laryngoscopy coordinates manipulation by the operator’s right hand with simultaneous direct observation. After the view is optimized, laryngeal manipulation is then taken over by an assistant at that location, which frees the operator’s right hand to place the tracheal tube.
Cricoid pressure and BURP are widely taught and now a standard aspect of resuscitation and airway training and are included in the American Heart Association’s Advanced Cardiac Life Support materials, as well as numerous other reference texts in emergency care.5, 6, 7 Bimanual laryngoscopy has been previously shown to be a simple and effective method of improving the laryngeal view.8 However, no study has directly compared BURP and cricoid pressure with the bimanual laryngoscopy technique and evaluated their impact on laryngeal view.
The objective of this study was to compare laryngeal view percentage of glottic opening (POGO) scores obtained during direct laryngoscopy using no neck manipulation, cricoid pressure, BURP, and bimanual laryngoscopy on fresh non-fixed cadavers to determine the method that optimizes laryngeal view.
Section snippets
Study Design, Setting, and Selection of Participants
This was a randomized intervention study that was conducted using 104 physician participants in emergency airway workshops from December 2003 to November 2004. The courses were taught for 2 days by the authors (R.M.L., W.J.L.) and included a detailed lecture series followed by a cadaver session in which the various techniques were performed.
Interventions
Participants were informed of the study objectives and all of the neck manipulation techniques had been discussed in the lecture component of the course.
Results
There were 1,530 sets of comparative laryngoscopies. The mean number of different cadavers (laryngoscopy sets) per participant was 15. The Table shows the experience levels of the participants. The POGO scores varied substantially between neck-manipulation groups when examined by ANOVA (all laryngoscopies: F3,6116=121.4, P<.0001; initial POGO scores <100: F3,6116=121.4, P<.0001). Figure 3 shows the POGO scores across all laryngoscopy maneuvers. Use of the bimanual laryngoscopy technique
Limitations
Our study should be interpreted with the following limitations. First, the use of a cadaver model is not a substitute for a live patient. However, we believe the cadaver model does approximate the mechanical feel and performance during laryngeal exposure of newly dead patients, such as in traumatic or cardiac arrest situations. Furthermore, it would be difficult to justify in anesthetized patients or cardiac arrest cases 4 randomly assigned laryngoscopies to investigate this subject. Second, we
Discussion
This study entailed a large number of emergency airway providers and a large number of laryngoscopies that compare laryngeal views with no manipulation, cricoid pressure, BURP, and bimanual laryngoscopy. Our results support the work of Benumof and Cooper 3 and others who have concluded that optimal external laryngeal manipulation is done by the operator’s right hand, with simultaneous observation of laryngoscopic view.4, 15, 16, 17, 18 Despite the fact that optimal external laryngeal
References (42)
Cricoid pressure to control regurgitation of stomach contents during induction of anesthesia
Lancet
(1961)- et al.
Qualitative improvement in laryngoscopic view by optimal external laryngeal manipulation
J Clin Anesth
(1996) - et al.
Bimanual laryngoscopya videographic study of external laryngeal manipulation by novice intubators
Ann Emerg Med
(2002) - et al.
Predicting difficult intubation
Br J Anaesth
(1988) - et al.
Airway obstruction following application of cricoid pressure
J Clin Anesth
(1991) - et al.
Airway difficulties caused by improperly applied cricoid pressure
J Emerg Med
(2001) - et al.
Cricoid pressure applied after placement of laryngeal mask impedes subsequent fibreoptic tracheal intubation through mask
Br J Anaesth
(2000) - et al.
Effect of cricoid pressure on the ease of insertion of the laryngeal mask airway
Br J Anaesth
(1993) - et al.
Cricoid pressurecan protective force be sustained?
Brit J Anaesth
(1998) - et al.
Head-elevated laryngoscopy positionsimproving laryngoscopic exposure during laryngoscopy by increasing head elevation
Ann Emerg Med
(2003)
Difficult laryngoscopy made easy with a “BURP.”
Can J Anaesth
Difficult laryngoscopyobtaining the best view
Can J Anaesth
Airway
Advanced airway support
Assessment of airway visualizationvalidation of the percent of glottic opening (POGO) scale
Acad Emerg Med
Assessment of laryngeal view in direct laryngoscopythe percentage of glottic opening (POGO) score compared to Cormack and Lehane grading
Can J Anesth
Reliability of paramedic ratings of laryngoscopic views during endotracheal intubation
Prehosp Emerg Care
Advanced statisticsstatistical methods for analyzing cluster and cluster-randomized data
Acad Emerg Med
Adjustments for center in multicenter studiesan overview
Ann Intern Med
POGO score as a predictor or intubation difficulty and need for rescue devices
Ann Emerg Med
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2021, AORN JournalCitation Excerpt :This maneuver can be critical during intubation, particularly during rapid‐sequence induction and intubation when the patient may be at higher risk of aspiration. However, using improper technique when applying cricoid pressure (ie, incorrect amount of pressure, wrong location) can lead to patient injury, including ruptured esophagus and laryngeal damage,2,3 as well as poor visualization during laryngoscopy.4 The team members involved in induction and intubation should be aware of the potential for harm caused by the incorrect amount or placement of pressure during cricoid pressure, particularly in the patient with an existing airway injury.3
Supervising editors: Kathy J. Rinnert, MD, MPH; Michael L. Callaham, MD
Author contributions: RML, WCK, and WJL conceived, designed, and collected data for this study. RML and WWE analyzed and interpreted the data. WWE provided statistical advice. RML drafted the manuscript, and all authors contributed substantially to its revisions and intellectual content. RML takes responsibility for the paper as a whole.
Funding and support: The authors report this study did not receive any outside funding or support.
Financial disclosures: Dr. Levitan is a principal owner of Airway Cam Technologies, Inc. (Wayne, PA). Practical Emergency Airway Management courses during the study were run by Airway Cam Technologies, Inc. and sponsored by the American Academy of Emergency Medicine.
Reprints not available from the authors.
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Dr. Levitan is now with the Department of Emergency Medicine, Albert Einstein Medical Center, Philadelphia, PA.