The Main Concerns and Implications of Cricoid Pressure Implementation

CP is considered a standard of care in many areas of the world, especially in the UK, North America, and Australia. However, it is not a standard practice elsewhere and maintains a controversial issue. Its performance seems to be in decline in Europe, and some pre-hospital organizations do not approve its use. CP may also not be common practice in regions where there are not skilled healthcare providers to assist the anaesthetist. In general, concerns in the implementation of CP include difficulties in laryngoscopy, lack of solid evidence of its effectiveness, potentially increased reflux risk and deterioration of unnoticed trauma in larynx or cervical spine. Moreover, concerns about the accurate cricoid force application, patient discomfort, and increased physical and cognitive workload on the part of the healthcare professionals make CP anything but a “simple maneuver that can be taught to an assistant in a few seconds,” as once perceived. In recently released guidelines by various international societies, including the 2015 Guideline on Airway Management by the Board of the German Society of Anesthesiology and Intensive Care Medicine, and the 2015 European Resuscitation Council Guidelines for Resuscitation, the routinely use of CP is no longer recommended. It is clear that these guidelines reflect the skepticism of the corresponding medical societies regarding the safety and efficacy of this technique.

This could have significant medicolegal implications since a physician could not anymore be accused of not having used CP. Based on results of non-RCT trials, a recent Cochrane systematic review concluded that CP may not be essential to perform RSI safely. It is acknowledged that there are two schools of thought on the benefits of CP. It is true that there are no randomized controlled trials that prove the favorable results of CP in patient safety and efficacy, and the level of evidence to encourage the application of CP is poor. Due to ethical constraints, such trials are highly unlikely to gain approval. Even if such a study was conducted, it would not reveal much information because of practical issues. Thus, the efficiency of CP should be evaluated through other means. On the other hand, reports of the preventive role of CP in gastric insufflation make it difficult to safely argue against its efficacy. We recognize that the use of CP could impede some aspects of airway management, especially when it is poorly applied; however, any complications are reversible as soon as it is removed. One of the principal issues in assessing the overall efficiency of CP is investigating whether CP successfully fulfills its primary goal of reducing the risk of gastric regurgitation and pulmonary aspiration. It is evident that CP cannot completely eliminate that risk. In a number of studies, regurgitation still occurred even with the application of CP. We cannot deny that, ideally, the regurgitation situations should be eliminated. Yet, those high expectations are not necessary to be met in order to prove the efficacy of CP. As long as CP can be proved to result in decreased incidence of regurgitation without causing any complications, this approach may continue to be considered a beneficial maneuver. Fundamentally, CP is a technique that completely occludes the hypopharyngeal lumen, impeding the passage of gastroesophageal content. The rationale behind CP has been verified by advanced imaging techniques.

Eventually, this fact is one of the most cogent arguments supporting CP. The evident, tangible effect of the compression of the esophageal entrance provides substantial credibility to the procedure. At this point, critics and doubters might wonder why there are so much evidence against effectiveness of CP and objections to its application. The answer could lie in the nature and history of CP research. Since its first publication in 1961 and not until the 21st century, a safe and widely-accepted CP protocol was lacking. For almost forty years, the efficacy of CP was under debate in absence, though, of a standardized procedure. In their attempt to build on previous literature, researchers usually used imprecise magnitude of cricoid force, followed invalid start/stop times, and applied CP on patients who nowadays would be unsuitable for this technique. Thus, early trials on CP should be dissected to warrant the accuracy of the conclusions. If CP is to be used during RSI, the maneuver must be performed in a safe and standardized manner, minimizing the risk of harm. This goal could be best achieved by reviewing the various differentiations in CP protocols and creating uniform guidelines. In the past, physicians argued over many details of the procedure. Nevertheless, after years of research, there is a general agreement about some of the more critical points. Regarding the cricoid force, it is now commonly accepted that 10 N of CP should be used just before induction in conscious adult and adolescent patients. On loss of consciousness, the cricoid force should be raised to maximum 30 N and maintained until successful intubation. However, this is a general guidance that cannot address individual or situational issues.

Therefore, the safe implementation of CP should also factor in the patient’s health conditions. Moreover, clinicians should not scruple to refrain from CP if it is suspected to hinder intubation. In addition, there is a large number of other issues that lack extensive research, like the proper CF for morbidly obese patients or the combination of CP with other anaesthetic procedures. Yet, the establishment of a standard protocol for CP does not ensure per se the clinical safety and efficacy of the procedure. Good practice must be secured by the dissemination of knowledge to the relevant healthcare professionals through training programmes and ongoing education. The majority of the current instructions referring to CP have been available in the literature for more than a decade. Nevertheless, frontline physicians still apply CP with inconsistent, even inappropriate, modifications in the maneuver. As an example, concerning the timing of CP, it is established that light pressure should be applied before induction. A survey, however, showed that almost 50% of the healthcare providers waited to perform CP until the patient was completely unconscious. More worrying is that over 30% of the anaesthetists reported that they removed CP precipitously before the confirmation of successful intubation. Correspondingly, theoretical knowledge concerning cricoid force has not always led to practical implementation among physicians. It has been well evidenced that a significant proportion of fully licensed and certified airway management providers are not aware of the appropriate amount of cricoid force. Even among those who know, many do not often calibrate their technique to make sure that the generated force is accurate. Such misapplications are not approved by existing protocols.