A Cochrane review [Abstract] 1 included 22 studies with a total of 2 658 women. All but two of the studies included women who had caesarean section under general anaesthesia. When compared to no treatment or placebo, there was a significant reduction in the risk of intragastric pH < 2.5 with antacids (RR 0.17, 95% CI 0.09 to 0.32, 2 studies, n=108), H2 antagonists (RR 0.09, 95% CI 0.05 to 0.18, 2 studies, n=170) and proton pump antagonists (RR 0.26, 95% CI 0.14 to 0.46, 1 study n=80). H2 antagonists were associated with a reduced risk of intragastric pH < 2.5 at intubation when compared with proton pump antagonists (RR 0.39, 95% CI 0.16 to 0.97, 1 study, n=120), but compared with antacids the findings were unclear. The combined use of 'antacids plus H2 antagonists' was associated with a significant reduction in the risk of intragastric pH < 2.5 at intubation when compared with placebo (RR 0.02, 95% CI 0.00 to 0.15, 1 study, n=89) or compared with antacids alone (RR 0.12, 95% CI 0.02 to 0.92, 1 study, n=119).
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment and lack of blinding).
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