Ideal Cricoid Pressure Is Biomechanically Impossible During Laryngoscopy

Abstract

Study Objective

A prospective, randomised controlled trial of Rapid Sequence Intubation (RSI) with Cricoid Pressure (CP) within the Emergency Department (ED). The primary aim of the study was to examine the link between ideal CP and the incidence of aspiration.

Method

Patients >18 years of age undergoing RSI in the ED of two hospitals in New South Wales, Australia, were randomly assigned to receive Measured CP using weighing scales to target the ideal CP range (3.060kg – 4.075kg) or Control CP where the weighing scales were used, but the CP operator was blinded to the amount of CP applied during the RSI. A data logger recorded all CP delivered during each RSI. Immediately after intubation, tracheal and oesophageal samples were taken and underwent pepsin analysis.

Results

Fifty four RSIs were analysed (25 Measured/29 Control). Macroscopic contamination of the larynx at RSI was observed in 14 patients (26%). During induction (0 – 50 seconds), both groups delivered in-range CP. During intubation (51 – 223 seconds), laryngoscopy was associated with a reduction in mean CP below 3.060 kg in both groups. When compared, there was no statistically significant difference between the groups. For eleven patients, pepsin was detected in the oropharyngeal sample, whilst 3 were positive for tracheal pepsin. Seven patients (4 Control / 3 Measured) were treated for clinical aspiration during hospitalisation. As a result of the finding that neither group could maintain ideal range CP during laryngoscopy, the trial was abandoned.

Conclusion

Laryngoscopy provides a counter force to CP which is negated in order to facilitate tracheal intubation. The concept that a static 3.060 kg- 4.075kg CP could be maintained during laryngoscopy and intubation was rejected by our study. Whether a lower CP range could prevent aspiration during RSI was not explored by this study.

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