Objective: To investigate the effects of Intralipid injection on hemodynamics and pharmacodynamics of mongrel dogs with bupivacaine-induced cardiac depression.
Methods: Fourteen dogs were randomly divided into Intralipid injection group (the experiment group) and normal saline group (the control group). 0.5% bupivacaine was administrated at a constant rate until the mean arterial pressure (MAP) decreased to 60% of the basic value. Intralipid injection was administered in the experiment group. The hemodynamic parameters were recorded and blood samples were taken from femoral artery at 0, 5, 10, 15, 20, 30, 45, 60, 90, 120, 180, 240 min after stopping bupivacaine infusion for determination of plasma concentration by HPLC. The pharmacokinetic parameters were calculated by Drug and Statistics soft version 2.0.
Results: After the treatment of Intralipid injection, MAP, CO, HR increased significantly, compared to those of the control group (P < 0.05). The AUC(o-t) was (192 +/- 34)mg x L(-1) x min(-1) versus (271 +/- 81) mg x L(-1) x min(-1) and the AUC(0-infinity) was (231 +/- 62) mg x L(-1) x min(-1) versus (368 +/- 140) mg x L(-1) x min(-1) in the experiment group and the control group respectively. Vz (4.5 +/- 1.1 L/kg versus 3.3 +/- 0.9 L/kg) of bupivacaine in the experiment group was significantly higher than that in the control group (P < 0.05).
Conclusion: Intravenous infusion of Intralipid have beneficial effects on the hemodynamics of mongrel dogs with bupivacaine-induced cardiac depression. One of the mechanism of the beneficial effects was probably that Intralipid injection increases the apparent volume of bupivacaine distribution and that decreases blood concentration. [Key words]