Cricoid Pressure During Laryngoscopy – What Is It Good For?
Ali S. Raja, MD, MBA, MPH
Absolutely nothing. A small study finds that it is biomechanically impossible to maintain adequate cricoid pressure, even with real-time monitoring using a scale.
A number of studies have called into question the practice of cricoid pressure (CP) — meant to occlude the esophagus and prevent aspiration during intubation but often resulting in worsened glottis views and more difficult tube passage — during intubation (NEJM JW Emerg Med Mar 2016 and Br J Anaesth 2016; 116:413; NEJM JW Emerg Med Sep 2014 and Anaesthesia 2014; 69:878; NEJM JW Emerg Med Aug 2010 and Resuscitation 2010; 81:810). Australian researchers used weighing scales to measure CP in real time during direct laryngoscopy, randomizing CP operators to be able or unable to see the scale in order to achieve the target pressure of 30 to 40 newtons. Their primary outcome was the difference in pepsin detection rates as a marker of esophageal occlusion.
The study targeted inclusion of 212 patients but was terminated early after enrollment of only 70, once it was determined that neither group of CP operators could maintain the desired minimum 30 N of CP during direct laryngoscopy — despite both groups maintaining pressure in the target range during the induction phase (prior to insertion and elevation of the laryngoscope).
This should be the final nail in the coffin of cricoid pressure as it goes to dogma heaven (or in the other direction). The counterforce of direct laryngoscopy clearly makes application of adequate CP impossible, even with real-time monitoring. While video laryngoscopy might decrease the counterforce and allow for adequate CP to prevent aspiration, prior studies have already demonstrated that CP worsens the glottis view during intubation. Regardless of the laryngoscopic technique used, CP should not be.
Trethewy CE et al. Ideal cricoid pressure is biomechanically impossible during laryngoscopy. Acad Emerg Med 2017 Sep 28; [e-pub].(http://dx.doi.org/10.1111/acem.13326)
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