Effects of cardiac surgery with cardiopulmonary bypass on lidocaine disposition

We investigated lidocaine kinetics after cardiac surgery to elucidate the effects of cardiopulmonary bypass (CPB) and major surgery on its disposition. In five patients lidocaine kinetics were unchanged 15 min and 1 day after CPB, but lidocaine clearance decreased 42% and volume of distribution was reduced by 40% in eight patients 3 days after surgery. Seven days after surgery lidocaine kinetics had returned to baseline in five patients. These changes correlated with a doubling of the alpha 1-acid glycoprotein concentration and a 46% decrease in lidocaine free fraction on day 3, effects that persisted on day 7. Our results suggest that the use of lidocaine need not be altered in the first day after uncomplicated coronary artery surgery, but, in light of our findings the use of lidocaine and the interpretation of measured total lidocaine concentrations 3 to 7 days thereafter should be reexamined.