Abstract

Thirty-two healthy term parturients undergoing elective cesarean section randomly received either no antacid (n = 10), 30 ml of 0.3 molar sodium citrate less than 60 min preoperatively (n = 11), or 30 ml of 0.3 molar sodium citrate longer than 60 min preoperatively (n = 11). Immediately after delivery, the stomach was emptied as completely as possible through a #18 Salem Sump tube passed orally. Mean gastric pH in the three groups was 1.8 +/- 2.7 (SD), 5.0 +/- 1.5, and 2.7 +/- 1.2, respectively. Gastric pH was significantly higher in the short interval group than in either the control group or in patients receiving their sodium citrate more than 60 min in advance. Gastric volumes were similar. All control patients had a gastric pH less than 2.5. Nine percent of patients receiving sodium citrate less than 60 min in advance and 50% of patients receiving their sodium citrate longer than 60 min in advance had a pH of less than 2.5. Volumes exceeding 25 ml occurred with equal frequency. No patient in the short interval group had a combination of both pH of less than 2.5 and a volume exceeding 25 ml. This combination occurred with equal frequency in control patients (64%) and in those patients receiving their sodium citrate more than 60 min in advance (50%). We conclude that sodium citrate effectively increases gastric pH when given less than 60 min prior to the induction of anesthesia.