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META-ANALYSIS OF THE USE OF IV PROTON PUMP INHIBITORS (PPI) OR H2-BLOCKERS (H₂RA) PRIOR TO ANESTHESIA TO DECREASE RISK OF ASPIRATION

J Soo, S Veldhuyzen van Zanten
University of Alberta, Edmonton

BACKGROUND: Gastric aspiration is an infrequent but serious complication of general anaesthesia. Gastric pH of <2.5 and gastric volume >25mL are risk factors for aspiration. This meta-analysis evaluated evidence whether use of intravenous H₂RA or PPI reduce the risk.

                                    

Results	PPI vs. placebo #studies/#patients	H2RA vs. placebo #studies/#patients	PPI vs.H2RA #studies/#patients
µ pH WMD (95% CI)	2.8 (1.56-4.06) n=2/n=100	2.8 (2.28-3.33) n=14/n=952	-0.02 (-0.54-0.51)* n=2/n=100
µ vol. WMD (95% CI)	-13.47(-20.3,-6.67) n=1/n=60	-8.07(-11.8,-4.34) n=1/n=718	-7.43 (-14.27,-0.59) favors H2RA n=1/n=60
# with at risk pH OR (95% CI)	0.19 (0.04-0.82) n=2/n=142	0.04 (0.02-0.08) n=15/n=950	1.80 (0.39-8.32)* n=1/n=60
# with at risk volume OR (95% CI)	0.44 (0.19-1.02) n=2/n=142	0.31 (0.18-0.52) n=9/n=596	2.25 (0.51-9.99)* n=1/n=60
# with both OR (95% CI)	0.24 (0.07-0.77) n=2/n=142	0.20 (0.10-0.38) n=7/n=495	3.22 (0.32-32.89)* n=1/n=60

METHODS: A Medline search was performed looking for RCTs comparing treatment to placebo. The five outcome measures of interest were proportion of patients with pH < 2.5 and/or gastric juice < 25 ml alone or together, mean pH (reported as difference between groups) and mean volume. Results are expressed as Odds ratios (OR) and weight mean differences (WMD). Three groups were analyzed; PPI or H₂RA compared with placebo/no treatment, and PPI compared to H₂RA. Subgroup analysis was performed for duration of time between drug administration and timing of gastric sampling and for treatment dosage. Study quality was assessed using the Jadad score. There were 16 studies with N = 35-150, the average Jadad score was 2.2, (range 0-4). Subgroup analysis yielded similar results.
CONCLUSION: There is good evidence to support that the routine administration of intravenous H₂RA or PPI prior to anesthesia reduces the risk factors associated with gastric aspiration. However the chosen endpoints are substitutes for aspiration. A study with aspiration as endpoint would require a very large sample size.

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