POSTOPERATIVE ANALGESIC REQUIREMENT AFTER CESAREAN-SECTION - A COMPARISON OF ANESTHETIC INDUCTION WITH KETAMINE OR THIOPENTAL

In a randomized, double-blind study, we compared postoperative pain an d analgesic requirement in patients who underwent elective cesarean se ction under general anesthesia induced with thiopental 4 mg/kg (n = 20 ) or ketamine 1 mg/kg (n = 20). Anesthesia was maintained with nitrous oxide and isoflurane. Postoperative analgesia was provided by patient -controlled analgesia (PCA) using morphine. Median (range) time to fir st PCA demand was greater in the ketamine group (28 [3-134] min) compa red with the thiopental group (20.5 [3-60] min; P = 0.04). Median (ran ge) morphine consumption over 24 h was less in the ketamine group (24. 3 [3-41] mg) compared with the thiopental group (35 [4-67] mg; P = 0.0 17). Visual analog scale pain scores were similar between groups. No p atients had recall of intraoperative events or unpleasant dreams. Two patients in the thiopental group and one patient in the ketamine group had pleasant intraoperative dreams. Apgar scores were similar between groups. Median umbilical venous pH was higher (7.33 vs 7.31; P = 0.04 ) and attributable to lower median umbilical venous PCO2 (5.72 vs 6.14 kPa; P = 0.02) in the ketamine group compared with the thiopental gro up. Induction of anesthesia for cesarean section using ketamine is ass ociated with a lower postoperative analgesic requirement compared with thiopental. Implications: Patients who had anesthesia for cesarean se ction induced with ketamine required less analgesic drugs in the first 24 h compared with patients who received thiopental. Ketamine, unlike thiopental, has analgesic properties that may reduce sensitization of pain pathways and extend into the postoperative period.