Sodium citrate premedication in elective caesarean section patients

The pH and volume of gastric contents from thirty-three patients undergoing elective caesarean section with thiopentone, nitrous oxide, succinylcholine anaesthesia were examined. Twenty patients received Gelusil 30 ml by mouth and thirteen patients received 30 ml of a 0.15 molar solution of sodium citrate. Following tracheal intubation, gastric fluid was sampled through an 18 French Salem sump tube place orally. Mean pH following Gelusil was 4.54 +/- 2.45 (SD) and 2.29 +/- 1.77 following sodium citrate. This difference was statistically different (P less than 0.05). There was no difference in gastric volume between the two groups. Thirty five per cent of patients receiving Gelusil had a pH less than 2.5. This low pH was more likely to occur with prolonged intervals between drug administration and sampling. Significantly more patients receiving sodium citrate had a low pH (85 per cent) and this low pH was not related to the duration of interval between administration and sampling. This study demonstrates that 30 ml of 0.15 molar sodium citrate is not a satisfactory alternative to 30 ml of Gelusil for increasing gastric pH in the paturient when given sixty minutes before operation.