The Main Question: Is there any evidence for the efficacy of cricoid pressure in reducing aspiration?
The short answer is no.
A systematic review intended to answer this question was published in the Canadian Journal of Anaesthesia in 2007 and concluded,
“Following our analysis of the literature it was apparent that there was no evidence available that would allow the following question to be answered: “Does RSI reduce either the incidence or the adverse consequences of aspiration during emergency airway management?” In fact, there is no study, randomized, controlled, blinded, or otherwise, that measures the impact of any intervention on the incidence of aspiration, nor is there likely to be a statistically meaningful study conducted on this issue. Assuming that the incidence of aspiration during emergency surgery is 0.15%, a strategy that would simply reduce the incidence by 50% would require a study of approximately 50,000 patients to confirm that benefit (one-tailed hypothesis for improved outcome, α = 0.05, β = 0.20). Thus, the strength of any recommendation favouring the use of RSI for the prevention of aspiration would be Grade D.”