Vasoconstrictive effects of levobupivacaine on the basilar artery in the rabbit

INTRODUCTION Spinal anesthesia is a widely used technique of the modern practice of anesthesia. Spinal cord ischemia is a rare but catastrophic complication of spinal anesthesia which may be caused by a direct vasoconstrictive effect of the local anesthetic. Although the vasoconstrictive effects of levobupivacaine have been widely studied, the vasoconstrictive effects of this drug on the intradural arteries have never been studied. The aim of this study is to evaluate whether levobupivacaine has vasoconstrictive effects on the basilar artery in rabbits. MATERIAL AND METHODS Thirty male New Zealand white rabbits were divided randomly into three groups of ten rabbits each: group 1 (control); group 2 (0.125% levobupivacaine); group 3 (0.25% levobupivacaine). The cisterna magna was punctured as described below, then 1 ml of saline or 0.125% or 0.25% levobupivacaine was injected into the cisterna magna in 10 min by an infusion pump in groups 1, 2 and 3 respectively. All animals were euthanized by perfusion-fixation 30 min after the procedure. The luminal area and the size of the cross-sectional area for each basilar artery were measured. RESULTS Both 0.125% and 0.25% levobupivacaine infusion caused significant vasoconstriction. Vasoconstriction was more significant for the 0.125% concentration. CONCLUSIONS The results of this study indicated that both 0.125% and 0.25% concentrations of levobupivacaine caused significant vasoconstriction of the basilar artery when administered into the subarachnoid space. This may constitute proof that subarachnoid administration of levobupivacaine may diminish the spinal cord blood flow, causing ischemia.