Abstract

A randomized double-blind comparison of bupivacaine spinal anesthesia with or without epinephrine was performed in 40 patients age 46-93 years. Three milliliters of hyperbaric 0.5% bupivacaine, with or without 0.3 ml epinephrine, were injected in the subarachnoid space at the second or third lumbar intervertebral space. The dermatomal levels of sensory blockade and the quality of motor blockade were assessed every 5 minutes until 30 minutes and every 15 minutes thereafter. Heart rate and blood pressure were measured at the same intervals, while electrocardiogram (ECG) readings were monitored continuously from induction up to recovery time. The mean cephalad spread of sensory loss was similar in the two groups. There was no significant difference in the time to reach higher level of sensory blockade, but time for two segments regression and for sensory recovery was significantly longer in the epinephrine group. Indeed, the time to onset of complete motor blockade was shorter, although its duration was longer with epinephrine. It was concluded that epinephrine enhanced the duration of sensory and motor blockade when it was added to spinal hyperbaric bupivacaine. The mechanisms of action of vasocontrictors in modifying the effects of local anesthetics remain controversial.