Effects of interpleurally administered bupivacaine 0.5% on opioid analgesic requirements and endocrine response during and after cholecystectomy: a randomized double-blind controlled study

In 30 patients undergoing cholecystectomy, a randomized double-blind saline-controlled study was performed using interpleural 0.5% bupivacaine with or without epinephrine (5 micrograms.ml-1) in combination with 0.8% halothane inspired concentration in oxygen. The aim of the study was to investigate whether interpleural 0.5% bupivacaine could decrease the intraoperative opioid requirements and attenuate the metabolic endocrine response to surgical stress. Patients were randomly allocated to one of three groups: Group 1: 0.5% bupivacaine; Group 2: 0.5% bupivacaine with epinephrine (5 micrograms.ml-1); and Group 3: saline. The interpleural catheter was inserted after induction of anesthesia in the spontaneously breathing patient. The study drug was injected 30 min prior to surgery. Peak plasma bupivacaine concentrations in the respective groups were 1.30 +/- 0.78 and 1.16 +/- 0.48 micrograms.ml-1. In all patients concentrations were below suggested convulsive level. Two patients in Group 1 and two in Group 2 required intraoperative fentanyl (0.1 mg each). In contrast, eight patients in the saline group received an average of 0.21 mg (range 0.1 +/- 0.4 mg) fentanyl (P less than 0.05). Postoperatively, a second dose of the study drug was given. Subsequently, pain was assessed using a visual analog score and a verbal rating scale. Pain scores decreased significantly 30 min after the interpleural injection in both bupivacaine groups and remained unchanged in the saline group (P less than 0.05). Pain management by means of interpleural bupivacaine was successful in 17 of the 20 patients. In the saline group seven out of ten patients needed additional analgesics (P less than 0.05). Cortisol levels increased in response to surgery in all groups: maximum levels in Groups 1, 2 and 3 were: 1.09 +/- 0.29, 1.11 +/- 0.20 and 1.19 +/- 0.16 mumol.l-1, respectively. Plasma glucose concentrations increased significantly in all groups: maximum levels in Groups 1, 2 and 3 were: 7.6 +/- 1.3, 7.3 +/- 1.7 and 8.3 +/- 1.7 mmol.l-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)