The efficacy of a single oral dose of 0.3M of sodium citrate alone as a prophylaxis against acid aspiration syndrome in obstetric patients undergoing LSCS (elective and emergency) was compared with that of intravenous ranitidine. One group of patients was given 30 ml of 0.3M sodium citrate orally just before the induction of anaesthesia while the other group was given 50mg of ranitidine intravenously together with the 30ml of 0.3M sodium citrate. This was done for both the elective and the emergency groups of patients. There was no significant difference in the mean pH of the gastric aspirate obtained from those given sodium citrate alone and those given sodium citrate and ranitidine in either the elective or the emergency group. However, in the emergency group, those who were given sodium citrate alone tend to have a larger volume of gastric aspiration when compared with those given ranitidine together with the sodium citrate. There were significantly more patients with gastric aspirates of more than 25ml in the emergency group to which sodium citrate alone was given. It would appear that supplementing an intravenous dose of ranitidine with the oral dose of sodium citrate is useful in emergency LSCS as a prophylaxis against acid aspiration syndrome.
The severity of pulmonary aspiration depends mainly on the acidity of the aspirate. Mist magnesium trisilicate (MMT) has been used for many years at the maternity unit in General Hospital, Kuala Lumpur, to neutralise the acidic gastric contents in all obstetric patients requiring caesarian section. This preliminary study shows that a single dose of 15 mls of MMT before general anaesthesia raises the intragastric pH to above the critical level of 2.5 in 80% of the patients. Recently there have been doubts over the protective role of MMT. Sodium citrate which is the other antacid available may be a better alternative.