Use of i.m. ranitidine for the prophylaxis of aspiration pneumonitis in obstetrics.

Twenty patients who underwent elective Caesarean section received ranitidine 150 mg by mouth 8-14 h, and 50 mg i.m. 90 min, before surgery. Intraoperative gastric aspiration resulted in contents with a pH greater than 2.5 and volume less than 25 ml in all patients (mean pH 6.5 (SD 0.8); mean volume 9.0 (SD 7.2) ml). Sixty patients in labour, who received ranitidine 50 mg i.m. 6-hourly, underwent emergency surgery. Half of this group received, in addition, a single preinduction dose of either 15 or 30 ml of sodium citrate 0.3 mol litre-1. A further 30 patients who remained unmedicated during labour and required emergency surgery received a preinduction dose of 15 or 30 ml of sodium citrate 0.3 mol litre-1 alone. Ranitidine medication resulted in a mean aspirated gastric volume of 31.4 (26.6) ml and pH of 5.3 (2.1); five of 30 patients had a pH less than 2.5. The addition of sodium citrate 0.3 mol litre-1 resulted in gastric pH greater than 2.5 in all patients and a mean gastric volume of 43.2 (38.3) ml. The group who received only sodium citrate 0.3 mol litre-1 had a mean pH of 5.3 (1.1) and a mean volume 122.7 (98.2) ml.