GASTRIC FLUID PH AND VOLUME IN GYNECOLOGICAL OUT-PATIENTS - INFLUENCES OF CIMETIDINE AND CIMETIDINE-SODIUM CITRATE COMBINATION

Eighty consecutive ASA physical status 1 women scheduled for day-case gynaecological laparoscopy under general anaesthesia were randomly all ocated during the pre-operative visit to receive one of four premedica tion regimes. Patients in group 1 received hydroxyzine 100 mg; patient s in group 2 received hydroxyzine 100 mg and cimetidine 400 mg; patien ts in group 3 received hydroxyzine 100 mg and effervescent cimetidine (cimetidine 200 mg+sodium citrate 1.8 g). All were given orally in 30 ml of water, 90 min before anaesthetic induction. Patients in group 4 received effervescent cimetidine orally in 30 ml of water 5 min before anaesthetic induction. Following induction of anaesthesia, gastric pH and residual volume (phenol red dilution technique) were measured. Ga stric pH was higher (P < 0.05) in groups 2, 3 and 4 (medians: 5.71, 4. 84, 6.07, respectively) than in group 1 (2.18). No patient had a gastr ic pH less-than-or-equal-to 2.5 in group 4 compared with 13/14 n group 1, 1/1 5 in group 2 and 2/14 in group 3 (P < 0.0001). Mean gastric vo lumes were higher (P < 0.05) in group 4 (30.4+/-23.2 ml) than in group s 1, 2 and 3 (11.8+/-6.4, 15.8+/-11.2, 17.2.+/-24.4 ml, respectively). Nine of the 1 9 patients in group 4 had a volume higher than 25 ml. O nly one patient in group 1 had both gastric pH less-than-or-equal-to 2 .5 and volume greater-than-or-equal-to 25 ml. The administration of ef fervescent cimetidine 5 min prior to anaesthetic induction seems to be an easy and effective method of decreasing the acidity of gastric con tents in day surgery.