Summary

Background and objective:Only regular training of anaesthetic personnel ensures safe and reliable application of cricoid pressure during rapid sequence induction of anaesthesia. Previously described training devices are either complicated, too expensive and usually unavailable, or they are very simple and do not correctly simulate the process of applying cricoid force. We designed and tested a cricoid pressure trainer with real-time display of applied force. The device is easy to assemble at relatively little cost with material widely available. It allows effective biofeedback training of the force required during the Sellick manoeuvre and can be used for routine staff assessment.

Methods:Thirty-six anaesthesia assistants were assessed for their correct application of cricoid pressure. Previous training in, and knowledge of, applying cricoid pressure was first evaluated by a questionnaire. We designed a model for testing the application of cricoid force. Pre-training cricoid forces were obtained by asking the subjects to apply ‘awake’ (10 N = 1.020 kg) and ‘asleep’ (30 N = 3.060 kg) cricoid pressure on our model while blinded to the actual pressure produced. The volunteer was then trained to apply correct pressure employing real-time biofeedback. Post-training values were later determined with the subject again blinded to the actual applied pressure.

Results:Post-training performance showed significant improvement in the application of the correct cricoid force (P<0.0005). Only 8% (3/36) of subjects applied incorrect ‘awake’ cricoid pressure after training vs. 56% (20/36) before training. All participants applied correct ‘asleep’ cricoid pressure after training vs. 72% (26/36) failing before training.

Conclusions:Our biofeedback cricoid pressure trainer is effective in the assessment and training of correct cricoid pressure application by anaesthetic personnel.

Summary

Background and objective: The application of cricoid force is central to techniques that reduce the risk of gastric regurgitation and the subsequent pulmonary aspiration associated with obstetric and emergency anaesthesia. The discomfort associated with cricoid force in awake preoperative patients increases the incidence of coughing, struggling and pain during induction of anaesthesia. This study determined if increasing the surface area of a cricoid yoke reduced the associated discomfort in volunteers.

Methods: Fifty volunteers participated in a randomized single-blinded study. The cricoid yoke was positioned using standard anatomical landmarks and forces of 10, 20, 30 and 40 N were applied in a random order for 20 s, using two different yoke attachments with surface areas of 3 and 10 cm2. A rest of 30 s was allowed between the application of forces. Discomfort was graded by volunteers on a scale from 0 to 10 (0: no discomfort; 10: worse discomfort imaginable). A score of 10 was allocated if the volunteers could not tolerate the applied force for 20 s.

Results: Median scores for the small yoke were always higher than those for the large yoke at each force. There were significant differences between the scores for the small and large yokes at 10 and 20 N (P < 0.001) and 30 N (P = 0.0233), but there was no significant difference at 40 N.

Conclusions: The larger yoke was tolerated better by volunteers when clinically relevant cricoid forces were applied.