Comment on ‘A survey of self-reported use of cricoid pressure amongst Australian and New Zealand anaesthetists: Attitudes and practice’

We read with great interest the article, entitled ‘A survey of self-reported use of cricoid pressure amongst Australian and New Zealand anaesthetists: attitude and practice’. ¹ We compliment the authors for expending the time and effort to complete such an elucidative project. Since cricoid pressure (CP) was added to rapid sequence intubation (RSI) in 1961, surveys have been performed to assess its use and acceptance among clinicians. The current article presents the results of such a survey. The responses were mixed: 76.9% of responders indicated that they would routinely use CP in adults and children at increased risk of gastric regurgitation; 39.8% believed that the use of CP reduced the risk of gastric regurgitation; 36.3% were unsure; and 23.8% believed it did not. ¹ This lukewarm enthusiasm by responders to the survey suggests that their experience with CP was far from satisfactory. We believe that this can be explained primarily by a lack of proper training and an inattention to details by some of the CP users, rather than being a reflection of the inherent shortcomings of the technique itself.

The role of CP in preventing regurgitation requires an understanding of its theoretical underpinnings and a mastery of the skills involved for its effective and safe implementation. Moreover, the current practice of RSI consists of a cascade of identified interrelated components, based on sound anatomical, physiological and pharmacological principles. ² These components include: preoperative gastric tube placement when indicated, pre-oxygenation, intravenous induction, full muscular relaxation, use of CP and/or head-up position to prevent gastric contents from reaching the pharynx in case regurgitation occurs, tracheal intubation, cuff inflation and safe extubation.^2–4 The successful use of CP is contingent on all these steps being performed correctly.^3,4 Indeed, it is conceivable that the occurrence of aspiration is a consequence of faulty techniques such as failure to place a gastric tube preoperatively, incomplete muscular relaxation and premature extubation.^3,4 Ignoring these confounding variables could lead to the erroneous conclusion linking aspiration to a failed CP manoeuvre.

The advent of modern modalities has provided reliable evidence of the effectiveness of correctly applied cricoid force in occluding the conduit between the pharynx and the alimentary tract.^4,5 Yet various studies have documented the use of excessive or inadequate cricoid force and misapplication of the force by operators, which may explain the reported failure of CP to provide protection against aspiration and other associated complications. ⁴ Although regular training utilising technology-enhanced simulation can improve operators’ performance of the CP manoeuvre, it is time that clinicians seriously consider the utilisation of devices to ensure that the appropriate cricoid force is applied. ⁶ The progressive loss of force with prolonged application, the complications associated with excessive or inadequate force and the need to modify the force in women and morbidly obese patients, are all valid reasons why the cricoid force should be measured, rather than estimated.^6,7 The use of a 30 Newton force, the recommended force in adults, can cause compression and distortion of the child’s airway, leading to airway obstruction and difficult intubation.^4,8 Furthermore, the age-dependent cricoid force necessary to prevent regurgitation is far less than 30 Newtons.^4,8 Accordingly, proper use of CP in children demands accurate measurement of the force.

We propose that future CP surveys include additional information, such as measured cricoid force and how it was applied, and the extent of training of users, to gain further insight into the actual cause of the aspirations, thus providing a basis for corrective actions that can be taken to reduce the incidence of this tragic complication.