Medical Myths - Cricoid Pressure

Medical Myths: Cricoid Pressure

Minh Le Cong MD and Anand Swaminathan MD 

Cricoid pressure was first described by Dr. Sellick in the 1960s. It refers to applying pressure over the cricoid cartilage, generally with two fingers, such as the thumb/index finger or thumb/middle finger. This provides direct posterior pressure backward onto the cricoid cartilage. The premise is to push the cricoid cartilage against the esophagus to occlude it and prevent regurgitation of stomach contents into the upper airway. The initial papers were small, non-randomized case series with the author as the main researcher. 

Le Cong. There are some studies that show that it can cause airway obstruction and does not reduce regurgitation. However, we haven’t been taught to do it properly or safely. If you do cricoid pressure on yourself, you will find that you will be unable to swallow at some point. It is a simple maneuver and you can remove it at any time. The data is not robust but there are some randomized controlled trials currently underway in Australia looking at this issue. 

Swaminathan. 

• There are a number of studies using MRI that show that in most people, the esophagus actually lies lateral to the cricoid cartilage. When cricoid pressure was applied under MRI, these studies found that the esophagus tends to be displaced laterally if it wasn’t already displaced. There is one study that refutes this. A study by Rice in 2009 found that cricoid pressure resulted in reduction of the diameter of the hypopharynx by 35%, and that the hypopharynx and cricoid ring moved together as a unit. This compression, and not displacement, of the esophagus was felt to decrease the risk of aspiration. 
• Rice MJ, et al. Cricoid pressure results in compression of the postcricoid hypopharynx: the esophageal position is irrelevant. Anesth Analg. 2009 Nov;109(5):1546-52. [PMID: 19843793] 
• A study by Jim Tsung found that visualization with ultrasound shows that the esophagus is lateral to the airway in 60 percent of patients. Cricoid pressure led to displacement in all. 

Tsung JW, et al. Dynamic anatomic relationship of the esophagus and trachea on sonography: implications for endotracheal tube confirmation in children. J Ultrasound Med. 2012 Sep;31(9):1356-70. [Open access link] 

• Cricoid pressure does not do what we have been told it does. Also, it probably decreases the tone in the lower esophageal sphincter, which may increase regurgitation. 
• Cricoid pressure decreases airway patency. There are multiple papers that show that cricoid pressure in intubated patients results in increased peak pressures. It may be more difficult to bag these patients. 
• Cricoid pressure obscures your view of the airway. Cricoid pressure can cause the vocal cords to close. 
• Oh J, et al. Videographic analysis of glottic view with increasing cricoid pressure force. Ann Emerg Med. 2013 Apr;61(4):407-13. [PMID: 23306455] This study showed that cricoid pressure worsened the glottic view. 
• There is no study that shows cricoid pressure reduces aspiration. An observational, retrospective chart review done in Africa looked at 4,891 patients who underwent C-sections. Cricoid pressure was applied in 61% of patients, and 24 vomited during induction. There were 11 deaths that were attributed to aspiration, and 9 of these were in the group with cricoid pressure. However, this is not a randomized controlled trial. 
• Fenton PM, et al. Life-saving or ineffective? An observational study of the use of cricoid pressure and maternal outcome in an African setting. Int J Obstet Anesth. 2009 Apr;18(2):106-10. [PMID: 19144507] 
• In summary, cricoid pressure doesn’t do what it is supposed to. It pushes the esophagus laterally. It relaxes the lower esophageal sphincter, which may make patients more likely to experience passive regurgitation. It makes ventilation and views of the airway more difficult. In 50 years, there is not a single, well-done, randomized, controlled trial showing benefit. 

Le Cong. Sometimes you don’t need great evidence to say that something is a reasonable idea because of the principle that we are trying to do the best for our patients in minimizing the harm for the procedure. This is similar to manual in-line stabilization for intubation in trauma patients; there is very little evidence supporting it, but it is considered the standard of care.