Mixing of antacids with stomach contents. Another approach to the prevention of the acid aspiration (Mendelson's) syndrome.

An investigation was carried out into the readiness with which magnesium trisilicate mixture BPC, Andursil suspension (Geigy) and 0.33 M aqueous sodium citrate mixed with gastric contents, to evaluate their suitability for use as an antacid before the induction of anaesthesia in obstetric patients. Laboratory investigations demonstrated that magnesium trisilicate and Andursil did not mix adequately with gastric contents, whereas sodium citrate mixed readily. A clinical investigation of sodium citrate revealed significant improvement in the mixing of gastric juice with the antacid if the patient was turned into the right lateral position following its administration (p < 0.05), but highly significant improvement followed a rotation through 360 degrees (p < 0.005). It was thought that these findings were caused by the division of the stomach into two sacs, a phenomenon confirmed by radiological studies and the use of a pig's stomach as a model of the human stomach.