[Analgesia after laparoscopic cholecystectomy by intraperitoneal administration of bupivacaine].

OBJECTIVES: The aims of this study were to assess the analgesic effect of the intraperitoneal topical administration of 0.375% bupivacaine in patients undergoing laparoscopic cholecystectomy and to carry out a pharmacokinetic study of bupivacaine administered topically by intraperitoneal route.

STUDY DESIGN: Randomized, double-blind controlled trial.

PATIENTS AND METHODS: Twenty-four patients of ASA physical status 1 or 2, undergoing elective laparoscopic cholecystectomy, were included. Anaesthesia technique was the same for all patients. At the end of surgery, they were randomly assigned to one of two groups. Patients in group bupivacaine were administered 0.375% bupivacaine, 0.6 mL.kg-1 intraperitoneally in both subdiaphragmatic areas and the cholecystectomy wound, those of the control group were given the same volume of NaCl 0.9%. Analgesia was provided by morphine PCA. Postoperative pain, assessed on a 100 mm visual analogue pain scale (VAS), and administered morphine were recorded 30 min after extubation, and 0.5, 1, 2, 3, 6, 12, 24, 36 and 48 hours later. Blood samples were collected 2, 5, 15, 30, 60, 90, 120, 180, 300 and 480 min after the intraperitoneal administration of bupivacaine to measure bupivacaine plasma concentration. Statistics included Student t test and Chi square test. P < 0.05 was considered significant.

RESULTS: There was no significant difference between the two groups with regard to VAS scores during the first 48 postoperative hours. Morphine requirements (total and at each point) were also similar. Plasma bupivacaine concentrations reached a plateau at 10-20 min, and then decreased slowly. The median plasma peak concentration was 0.94 +/- 0.47 microgram.mL-1. In one patient toxic concentrations (> 1.6 micrograms.mL-1) during the first 60 min after intraperitoneal administration were obtained, while in another patient a concentration of 1.58 micrograms.mL-1 was reached twice.

CONCLUSIONS: Intraperitoneal administration of 0.6 mL.kg-1 of 0.375% bupivacaine is ineffective in reducing postoperative pain after laparoscopic cholecystectomy. Furthermore these high doses of bupivacaine may result in toxic plasma concentrations. This technique is not safe and cannot be recommended.