Journal Club Podcast #47: January 2019
A brief look at whether cricoid pressure (AKA the Selleck Maneuver) decreases aspiration risk or impedes airway visibility…
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Article 1: Bohman JK, Kashyap R, Lee A, He Z, Soundar S, Bolling LL, Kor DJ. A pilot randomized clinical trial assessing the effect of cricoid pressure on risk of aspiration. Clin Respir J. 2018 Jan;12(1):175-182. Answer Key.
Article 2: Turgeon AF, Nicole PC, Trépanier CA, Marcoux S, Lessard MR. Cricoid pressure does not increase the rate of failed intubation by direct laryngoscopy in adults. Anesthesiology. 2005 Feb;102(2):315-9. Answer Key.
Article 3: Birenbaum A, Hajage D, Roche S, et al. Effect of Cricoid Pressure Compared With a Sham Procedure in the Rapid Sequence Induction of Anesthesia: The IRIS Randomized Clinical Trial. JAMA Surg. 2018 Oct 17. Answer Key.
You are working a shift in TCC one day when the level 1 pager goes off. EMS is bringing in a forty-year-old male involved in a rollover MVC. He was unrestrained, has a blood pressure of 70/40, and has been intermittently combative. You gather your team, grab the ultrasound, and make sure the CMAC is in the room and ready for intubation.
The patient arrives in extremis. His combativeness has resolved as he is now unresponsive. He is breathing spontaneously, does not respond to questions, and has sonorous respirations. His GCS is 5. As the team continues the primary survey, all are in agreement that the patient requires intubation to secure his airway.
A quick assessment from the head of the bed, as the nurses draw up medications, reveals a large laceration to the left parietal scalp with minimal bleeding, left periorbital ecchymosis and edema, and 4 mm pupils that are round and reactive to light. He has no signs of neck or intraoral injury. His O2 sat is 98% on a nonbreather and his blood pressure is now 82/38.
The meds are ready and the team is prepared for the intubation. As he is paralzyed and sedated, you gently remove the cervical collar and ask your colleague to provide inline stabilization. As you open the airway and begin to insert the laryngoscope, you hear somebody question why no cricoid pressure is being administered. As you are busy trying to keep the patient alive, you ignore the ensuing argument and insert a endotracheal tube between the vocal cords without incident.
Later, the team discusses the utility of cricoid pressure (aka the Sellick Maneuver) while the patient is undergoing CT scans of his entire body. You have been taught that cricoid pressure is not really helpful, but wonderful if there is actual evidence to back this up. As you begin to search the internet, you find a very recent article published on the topic, with some very in-depth reviews. Not content with this single article, you diver deeper into the subject...
Population: Adults patients requiring endotracheal intubation under RSI in the emergency department for any reason.
Intervention: Cricoid pressure (AKA the Sellick Maneuver).
Comparison: No cricoid pressure.
Outcome: Aspiration pneumonitis, hospital-acquired pneumonia, ventilator associated pneumonia, ease of intubation, hypoxia during intubation attempt, failed intubation.
A PubMed search using the terms "cricoid pressure" OR "Sellick maneuver” resulted in 472 citations (https://tinyurl.com/ycb6v3dl), from which the 4 most relevant articles were selected. The Cochrane Database of Systematic Reviews was also searched; this resulted in a single systematic review. As this review only included one article, the review was omitted.
For years after Dr. Sellick first described his maneuver in 1961 (Sellick 1961), cricoid pressure was touted for use during endotracheal intubation to theoretically prevent the aspiration of stomach contents by compressing the upper esophagus. Despite a lack of clinical evidence, this maneuver was widely used by both anesthesiologists (Howells 1983, Thwaites 1999) and emergency physicians (Kovacs 2004, Gwinnut 2015). Over the years, several studies have evaluated the efficacy and harm associated with cricoid pressure, with varying results.
In 2005, Turgeon et al performed a randomized controlled trial evaluating the effect of cricoid pressure on failure to intubate within 30 seconds among patients undergoing elective procedures in the operating room (Turgeon 2005). They found no significant differences in failure rates (RR 1.2, 95% CI .058 to 2.5) with and without cricoid pressure.
A cross-sectional study published in 2013 (Oh 2013) evaluated the effect of cricoid pressure on glottic view by recording images of the glottis at varying degrees of cricoid pressure using a video laryngoscope. While they did find a decrease in the medial area of the glottic view with increasing pressure, they did not evaluate the effect of this on the ease or success of intubation.
More recently, two randomized controlled trials were undertaken to assess the effect of cricoid pressure on rates of aspiration. In the first of these (Bohman 2018), patients undergoing elective surgical procedures were randomized to receive or not receive cricoid pressure. Following intubation, all patients had 5 mL of sterile saline infused into the endotracheal tube, followed by aspiration via a sterile suction catheter. Pepsin A testing was then performed on the aspirate to determine whether micro-aspiration had occurred or not. The presence of significant pepsin A was similar between the groups (RR 0.77, 95% CI 0.33 to 1.8) suggesting to difference in micro-aspiration rates. There was also no difference in the incidence of healthcare-associated pneumonia or ventilator-associated pneumonia.
The second trial published last year (Birenbaum 2018) also randomized patients undergoing surgery to cricoid pressure or sham cricoid pressure. Pulmonary aspiration was defined as either visual detection of aspiration during laryngoscopy or by tracheal aspiration following tracheal intubation. Again, the incidence of aspiration was not difference between the two groups (RR 0.90, 95% CI 0.33 to 2.38). Unfortunately, the study was designed as a noninferiority trial, but the incidence of aspiration was much lower than anticipated (0.5% overall). This resulted in the upper limits of the 1-sided 95% confidence interval exceeding the a priori noninferiority margin of 1.5, and the study could not conclude that omitting cricoid pressure was not inferior to its use.
Unfortunately, none of the studies we reviewed was conducted in the emergency department (all were conducted in the operating room) and questions of external validity make it difficult to generalize these results to our patient population. Additionally, while these four studies only represent a small portion of the literature on this topic, there has been no direct evidence that cricoid pressure reduces the risk of patient-centered outcomes (i.e. aspiration pneumonitis, healthcare-associated pneumonia, ventilator-associated pneumonia, ARDS).