The feasibility of injecting protamine via left atrium after cardiopulmonary bypass

Objective To investigate the feasibility of injecting protamine via left atrium after cardiopulmonary bypass.Methods Thirty-six patients undergoing open heart surgery were allocated randomly to three groups with 12 cases each.Protamine was injected via central vein in group A,via left atrium in group B and via aortic root in group C.At the end of CPB,protamine in a dose of 1.5 times of heparin used before CPB was administered at the speed of 1 mg·kg-1· min-1.MAP,CVP and airway resistance(AWR)were recorded before and after protamine injection.Blood sample of 5 ml from the right atrium was taken for detecting thrombxane B2(TXB2)and histamine.Activated cloting time(ACT)was examined at 5 min after protamine injection.Results At 1,3,5 min after protamine,MAP in group A was decreased obviously and lower than that in group B and C(P0.05 or P0.01).After protamine,CVP and AWR began to increase at 1 min in group A,which was lower than those in group B and C at 3 min(P0.05).The levels of TXB2 and histamine in group A began to increase earlier and lasting for 10 min after protamine,which was delayed with less degree in group B and C(P0.05).Conclusion As injected via aortic root,protamine may be given via the left atrium after CPB with less effect on the hemodynamics and lung ventilation than that via peripheral vein.