The age-related effects of epidural lidocaine, with and without epinephrine, on spinal cord blood flow in anesthetized rabbits

The effect of epidural or spinal epinephrine when added to local anesthetic s on spinal cord blood flow (SCBF)are controversial. We evaluated the effec ts of epidural Lidocaine, with or without epinephrine, on spinal cord blood flow in young and adult rabbits receiving 2% plain lidocaine, 2% lidocaine with epinephrine (1:200,000), or saline epidurally. Colored microspheres w ere injected through the left ventricle 10 min before and 7.5 and 30 min af ter epidural injection. The organs (brain, heart, kidneys, and the L6-7 seg ment of the spinal cord) were analyzed for regional blood flow determinatio n. A significant decrease in mean arterial pressure was observed after the administration of lidocaine, with or without epinephrine, in both adult and young animals compared with saline. SCBF did not change over time in adult rabbits. Conversely, a significant decrease in SCBF was observed in the tw o groups of young rabbits receiving lidocaine. This decrease correlated wit h the decrease in mean arterial pressure but did not correlate with the use of epinephrine. We conclude that any reduction in blood pressure occurring in pediatric patients receiving a combined epidural-general anesthetic may result in decreased SCBF. Implications: In young rabbits, any decrease in blood pressure was followed by a decrease in spinal cord blood flow, a decr ease that did not correlate to the use of epinephrine and was not observed in adult animals. These data suggest that blood pressure should be monitore d closely to promptly treat any decrease in blood pressure when combined ep idural-general anesthesia is used in children.