Cardiovascular effects and regional clearances of intravenous ropivacaine in sheep.

The purpose of this study was to determine the cardiovascular effects and the total body and regional clearances of ropivacaine during its continuous intravenous infusion to subtoxic levels in five conscious unrestrained sheep that had been previously prepared with appropriate intravascular cannulas. Ropivacaine HCl.H2O, 1 mg/min, produced constant arterial blood concentrations which ranged from 0.70 to 1.84 mg/L. This caused no appreciable cardiovascular effects. The mean total body clearance (+/- SD) of ropivacaine was 1.00 +/- 0.27 L/min. There was significant clearance of ropivacaine by the liver (0.85 +/- 0.32 L/min), gut (0.09 +/- 0.07 L/min), and kidneys (0.04 +/- 0.03 L/min). There was no significant clearance of ropivacaine by the lungs, brain, heart, or hindquarters. It was concluded that the liver accounts for the majority of ropivacaine clearance.