ANALGESIA AFTER UPPER ABDOMINAL-SURGERY USING EXTRADURAL ADMINISTRATION OF A FIXED-DOSE OF BUPRENORPHINE IN COMBINATION WITH LIGNOCAINE GIVEN AT 2 INFUSION RATES - A COMPARATIVE-STUDY

Background: Extradural administration of combinations of local anaesth etics and opioids are frequently employed for postoperative pain relie f. There is a scarcity of data on the analgesic effects of variations of the dose of local anaesthetic drug admired to a fixed dose of opioi d. Methods: Twenty-four patients were investigated after elective uppe r abdominal surgery. During closure of the abdomen, 2% mepivacaine (8 mi) with buprenorphine 0.1 mg (0.5 mi) was given extradurally. After e xtubation, patients were randomly allocated to receive continuous extr adural infusion of a fixed dose of buprenorphine (0.017 mg/h) in combi nation with 2% lignocaine at either 2.1 ml/h (low rate group, n = 14) or 6.3 ml/h (high rate group, n = 10). Postoperative pain at rest was assessed using visual analogue scale (VAS) scores and pain at movement by Prince Henry Pain Scale (PHPS) scores. Venous plasma lignocaine co ncentrations were measured. Results: VAS scores at rest were similar i n the two groups at 3 h postoperatively, whereas at 6-24 h postoperati vely, VAS scores were higher in the low rate group than in the high ra te group. PHPS scores were similar in the two groups at 3 h and at 18 h postoperatively, whereas at 6, 9, 12 and 24 h postoperatively, PHPS scores were higher in the low rate group than in the high rate group. Plasma lignocaine concentrations were higher at 23 h postoperatively i n the high rate group than at 16 h in both groups, and at 23 h in the low rate group. At 3 h postoperatively, both the systolic and diastoli c arterial pressures were higher in the low rate group than control va lues obtained on admission. Side effects were observed in one patient in the low rate group who complained of dizziness, and in one patient in the high rate group who complained of nausea. Conclusions: When add ed to a fixed dose of buprenorphine, continuous extradural infusion of 2% lignocaine at high rate provides better postoperative analgesia th an when given at low rate without producing significant side effects.