Gallamine disposition in open-heart surgery involving cardiopulmonary bypass

Kinetics of gallamine, a neuromuscular blocker, were investigated in 22 adult patients undergoing surgery involving cardiopulmonary bypass (CPB). Approximately 60 min before CPB, 11 patients received 480 mg gallamine IV; the other 11 patients received an initial dose of 240 mg IV, followed by another 240 mg through the pump priming fluid at the start of CPB. In 14 of our patients, the time course of gallamine concentrations in the plasma before, during, and after CPB was similar to that in normal surgical patients, indicating little or no effect of cardiac disease or CPB. In the remaining patients, perturbations were not observed before CPB, but with its onset there were varying changes, typically, rises in gallamine concentration ranging from an alteration during the period of CPB only or during the elimination phase, to an alteration at all times after starting CPB. Although the mechanism for this rise in gallamine plasma concentrations during and after CPB is not known, computer simulations suggest that it is due to a contraction in blood volume or decreased tissue perfusion during the period of extracorporeal circulation. Gallamine disposition differed only moderately in our patients from that in control patients. Therefore, from a kinetic viewpoint, provided that renal function is not impaired, gallamine is not contraindicated in CPB surgery.