Prevention of aspiration pneumonia in obstetrical anesthesia with the effervescent combination of cimetidine and sodium citrate

The effect of an oral effervescent formulation combining 200 mg cimetidine and 1.8 g sodium citrate on gastric pH and volume were studied in patients undergoing caesarean section. Seventy-four patients undergoing elective (group 1) or emergency caesarean section (group 2) were included. Before entering the operating theater (5 to 60 min before intubation), they were given the tablet dissolved in 15 ml of water. Induction and maintenance of anaesthesia were carried out with conventional techniques. The patient's gastric content was aspirated just after endotracheal intubation, and before extubation. its pH and volume were measured at both times. Mean pH was similar in the two groups after intubation (6.07 +/- 1.13 in group 1; 5.52 +/- 1.14 in group 2) and before extubation (6.32 +/- 1.08 vs. 5.85 +/- 1.02 respectively). Gastric pH was therefore greater than 2.5 in all 74 patients at both times. Mean volumes of gastric content after intubation were greater in group 2 (32.7 +/- 23.9 ml vs. 21.6 +/- 15.8 ml; p less than 0.02). However, just before extubation, these were similar (15.0 +/- 15.4 ml in group 1, 20.1 +/- 14.9 ml in group 2). The percentage of patients in the 2 groups with gastric volumes greater than 25 ml at the time of intubation were not significantly different (29.7% vs. 45.9% respectively). No patient was at risk of developing pneumonitis in case of aspiration (gastric content pH less than 2.5 and volume greater than 25 ml), either during endotracheal intubation or extubation.