Cricoid pressure is a manual procedure performed on a patient’s neck during emergency airway management, typically before inserting a breathing tube into the trachea. The technique involves applying firm, downward pressure to a specific piece of cartilage in the throat. This intervention was designed to prevent stomach contents from entering the lungs, a complication known as pulmonary aspiration, which can lead to severe injury or death. Despite its decades-long history, the routine use of this maneuver is currently the subject of significant debate among medical professionals. This controversy stems from accumulating evidence suggesting the procedure may not be as effective as originally believed, and may even introduce new risks during the intubation process.
The Origin and Aim of the Maneuver
The practice of applying pressure to the cricoid cartilage gained widespread recognition following the work of British anesthesiologist Dr. Brian Sellick, who published his findings in 1961. His paper proposed this technique as a means to control the passive regurgitation of stomach contents during the induction of anesthesia. The procedure was quickly integrated into the standard protocol for rapid sequence intubation (RSI), a method used to secure the airway quickly in at-risk patients. The goal was to physically seal off the esophagus, which lies just behind the larynx, thereby creating a mechanical barrier against gastric reflux. This intent led to its near-mandatory inclusion in intubation protocols worldwide for many years.
Anatomical Basis and Technique
The technique is anatomically focused on the cricoid cartilage, which is the only complete ring of cartilage in the larynx. This structure provides a firm point for external pressure application, unlike other laryngeal cartilages which are incomplete rings. The physical mechanism requires an assistant to locate the cricoid ring and apply firm, posterior pressure. The pressure is directed backward, intending to flatten the esophagus between the cricoid cartilage and the rigid vertebral body of the neck.
The standard application involves a “three-finger” technique, placing the index finger directly over the cricoid cartilage, with the thumb and middle finger positioned on either side. The required amount of force is specific and changes based on the patient’s level of consciousness. Before the patient loses consciousness, approximately 10 Newtons (N) of light pressure is applied to prevent discomfort or vomiting. Once the patient is fully anesthetized, the force is increased to 30 N, a level thought sufficient to occlude the esophagus in most adults. This pressure must be maintained until the breathing tube is correctly placed and its cuff is inflated.
Scientific Scrutiny of Effectiveness
Modern imaging techniques have cast doubt on the procedure’s fundamental anatomical basis and effectiveness. Studies using ultrasound and magnetic resonance imaging (MRI) have demonstrated that the esophagus is not always positioned directly posterior to the cricoid cartilage. A significant percentage of patients have an esophagus that is displaced laterally, often to the left of the midline. When cricoid pressure is applied in these individuals, the force may simply push the esophagus further to the side, rather than compressing it against the vertebrae to achieve full occlusion.
Imaging research has also found that even when the force is applied correctly, the esophageal lumen may not be completely closed. In some cases, liquid has been observed passing into the esophagus despite the application of 30 N of pressure. Furthermore, the pressure may compress the hypopharynx, the lower part of the throat, instead of the esophagus itself. The utility of the maneuver is further undermined by the lack of high-quality, randomized controlled trials (RCTs) that prove a reduction in aspiration rates.
The application of pressure can also have unintended adverse effects by distorting the patient’s laryngeal anatomy. This distortion can impair the view during laryngoscopy, making the intubation procedure more difficult and potentially leading to a delay in securing the airway.
Current Clinical Guidelines and Application
The growing body of evidence regarding the maneuver’s ineffectiveness and potential complications has led to a significant shift in clinical practice guidelines. Major professional organizations, including the American Heart Association (AHA), have removed the routine use of cricoid pressure from their resuscitation algorithms. The American Society of Anesthesiologists (ASA) has also moved away from mandating its routine application, particularly when managing difficult airways.
Despite the move away from routine use, the maneuver has not been abandoned entirely and is now applied more selectively. In some high-risk situations, such as rapid sequence intubation for obstetric patients or when a proceduralist specifically requests it, cricoid pressure may still be considered. The modern consensus emphasizes that if cricoid pressure is used, it must be performed by a trained provider who can apply the correct force. This provider must be prepared to immediately release the pressure if it impedes ventilation or the visualization of the larynx. The overall trend is a shift from a mandatory, standardized step to a clinician-dependent, risk-benefit decision based on the individual patient and specific clinical circumstances.