Pain management after lumbar spinal fusion surgery using continuous subcutaneous infusion of buprenorphine.

PURPOSE: The continuous subcutaneous infusion (CSI) technique is a simple, inexpensive method for managing postoperative pain. We examined the analgesic effects of CSI of buprenorphine in patients undergoing lumbar spinal fusion surgery. METHODS: The patients were randomly assigned to one of three groups for postoperative pain management: control group (n = 17), high-dose buprenorphine group (BH group, n = 17), and low-dose buprenorphine group (BL group, n = 16). Infusion solutions containing buprenorphine at concentrations of 25.0 and 16.7 microg x ml(-1) combined with droperidol at a concentration of 52.0 microg x ml(-1) were used in the BH and BL groups, respectively; and an infusion solution containing droperidol at a concentration 52.0 microg x ml(-1) was used in the control group. CSI of each solution was started at a rate of 1 ml x h(-1) and was continued for 48 h. RESULTS: The BH and BL groups showed significantly lower scores than the control group on the Visual Analogue Scale. There were significantly fewer administrations of flurbiprofen as a supplemental analgesic in the BL and BH groups than in the control group. The incidences of sedation and nausea were comparable in the three groups. The median number of administrations of flurbiprofen was significantly less in the BH group than in the control group on the day of the operation and on the first postoperative day, whereas the number in the BL group was less than that in the C group only on the day of the operation. CONCLUSION: CSI of buprenorphine effectively reduces pain after lumbar spinal fusion surgery without apparent side effects. This technique is simple and useful for postoperative pain management.

The anticonvulsant action of propofol on epileptiform activity in rat hippocampal slices.

We used extracellular electrophysiological recordings from the CA1 region in rat hippocampal slices to investigate the effects of propofol on the field excitatory postsynaptic potential (fEPSP), population spike, and epileptiform activity induced by a Mg(2+)-free condition. Propofol depressed the population spike, fEPSP, and epileptiform activity. Both aminophylline, a nonselective adenosine receptor antagonist, and 8-cyclopentyl-1,3-dipropylxanthine, an A(1) receptor antagonist, significantly reduced the effect of propofol on fEPSP amplitude. However, 3,7-dimethyl-1-propagylxanthine, an A(2) receptor antagonist, did not alter the effect of propofol on fEPSP amplitude. Picrotoxin, a specific chloride channel blocker, partly reduced the effect of propofol on epileptiform activity, but bicuculline, a competitive gamma-aminobutyric acid(A) receptor antagonist, failed to antagonize it. Aminophylline significantly reduced the action of propofol on the epileptiform activity. The anticonvulsant action of propofol was partly reduced by 8-cyclopentyl-1,3-dipropylxanthine, whereas 3,7-dimethyl-1-propagylxanthine failed to affect it. Adenosine depressed the amplitude of fEPSPs in a dose-dependent manner, and propofol enhanced this inhibition. The results demonstrated that, in rat hippocampal slices, propofol inhibits epileptiform activity. In addition, adenosine neuromodulation through the A(1) receptor may contribute to the anticonvulsant action of propofol.