On Cricoid Pressure: “May the Force Be with You”

Abstract

Jerrold Lerman, MD, FRCPC, FANZCA*† Cricoid pressure has become the quintessential cornerstone of the rapid sequence induction of anesthesia in patients at risk for passive regurgitation of gastric fluids. Despite an almost 5-decade history, the level of evidence to support its effectiveness in preventing passive regurgitation is a paltry 4 or 5, resulting in a Grade D recommendation for its use. However, guidelines in anesthesia and other medical specialties endorse its use, and the legal community exploits its omission from the anesthetic record as evidence of a practice below the “accepted” standards. In this month’s issue of Anesthesia & Analgesia, Rice et al. explore the cricoidhypopharyngeal unit to determine whether cricoid pressure occludes the esophageal lumen when the latter is displaced lateral to the cervical spine. The time has come to critically review what we know and what we do not know about cricoid pressure and to set the record straight once and for all. Cricoid pressure was first reported by Sellick in 1961 for use at induction of anesthesia. His seminal report in which he established the effectiveness of cricoid pressure in 26 patients who required emergency surgery transformed the practice of anesthesia. However, several details in his report are not well known and merit our consideration. First, each patient in his report was positioned “head down slightly with the head turned” for induction of anesthesia. Upon release of the cricoid pressure, he noted that 3 of the patients (12%) regurgitated. Some readers may be surprised that such a large proportion of patients regurgitated when cricoid pressure was released (it contrasts sharply with our clinical experience), whereas others might attribute the high incidence of regurgitation simply to the patients’ head-down position. The pervasive fear of regurgitation and aspiration during induction of anesthesia with the early ether anesthetics led to this positioning to direct regurgitant fluids away from the larynx. Currently, the head-down position is never used at induction of general anesthesia; moreover, Sellick’s study has never been repeated with patients in the supine position. Second, Sellick suggested that “firm” pressure be applied to the cricoid ring after positioning the neck in the “tonsil” position (in which the neck is fully extended). Sellick never determined how much force was required to occlude the lumen of the esophagus. Currently, a minority of anesthesiologists and assistants are aware of the magnitude of the force required to occlude the esophageal lumen. Many more apply an insufficient force (although some apply excessive force) to occlude the lumen of the esophagus and prevent passive fluid regurgitation (a force of 30–44 N is required with loss of consciousness, where 10 N is the force of gravity on an object with a mass of approximately 1 kg). Although Sellick recommended that the tonsil position be used when performing this maneuver, the majority of patients are positioned with the head in the “sniffing” or “neutral,” but not tonsil, position. Third, Sellick claimed that a nurse or assistant could be instructed in this maneuver in “a few seconds.” Currently, anesthesiologists infrequently instruct others in the correct technique for applying cricoid pressure. If the principles espoused by Sellick were followed, then anesthesiologists need to revisit the details of how we perform this maneuver: we must agree on a uniform position for the patient’s head and neck and ensure that all From the *Department of Anesthesiology, Women and Children’s Hospital of Buffalo, State University of New York at Buffalo, Buffalo; and †Strong Memorial Hospital, University of Rochester, Rochester, New York. Accepted for publication August 1, 2009. Supported by Department of Anesthesiology, Women and Children’s Hospital of Buffalo, State University of New York at Buffalo and Strong Memorial Hospital, University of Rochester, Rochester, NY. Address correspondence and reprint requests to Jerrold Lerman, MD, FRCPC, FANZCA, Women and Children’s Hospital of Buffalo, 219 Bryant St., Buffalo, NY 14222. Address e-mail to jerrold.lerman@ gmail.com. Copyright © 2009 International Anesthesia Research Society