Comparison of a bupivacaine peripheral nerve block and systemic ketoprofen on peripheral inflammation and hyperalgesia in rats.

BACKGROUND AND OBJECTIVE: Local anaesthetics via a nerve block can attenuate inflammation. However, their effects have never been compared with the anti-inflammatory effects of systemic NSAIDs. The aim of this study was to compare the effects of bupivacaine via sciatic block with a systemic NSAID on oedema and hyperalgesia and on indices of systemic inflammation as measured by cytokines and prostaglandin E2 production in a model of peripheral inflammation in rats.

METHODS: Rats (n=56) randomly received three injections: a left subcutaneous hind paw injection (carrageenan or physiological saline); a left sciatic block (bupivacaine or physiological saline); and a systemic injection (ketoprofen or physiological saline). Six hours later, local oedema, thermal and mechanical hyperalgesia as well as cerebrospinal fluid prostaglandin E2 concentration and tumour necrosis factor-alpha and interleukin 1beta-stimulated production in whole blood cultures were measured.

RESULTS: A sciatic block with bupivacaine as well as a systemic injection of NSAID significantly decreased the oedema and the thermal and mechanical hyperalgesia induced by carrageenan. Oedema was decreased by approximately 12%, and thermal and mechanical thresholds were increased by three-fold to fourfold and 1.5-2-fold, respectively. They both inhibited the increased production of prostaglandin E2 in cerebrospinal fluid and tumour necrosis factor-alpha and interleukin 1beta in stimulated whole blood induced by carrageenan. There was no further benefit of the combination of a sciatic block and systemic NSAID.

CONCLUSION: In the current study, a bupivacaine block alone achieved the same anti-inflammatory effect as systemic NSAID or as when the same block is combined with a NSAID.