ABSTRACT
To evaluate APTT for monitoring heparin neutralization and rebound following CPB. Method: Twenty patients undergoing cardiac valve replacement were randomly selected, APTT and activated clotting time (ACT) were measured 10 minutes following protamine in 0.5:1,0.7:1and 1:1 ratio to total heparin administered, and 3 and 6 hours after 1:1 ratio. Result: After the neutralization of the heparin/protamine at ratio of 0.5:1, the further doses of protamine (0.7: 1,1:1)decreased APTT markedly (P0.05). APTT with 0.5:1 or 0.7:1 ratio neutralization decreased significantly after in vitro protamine titration (P0.05). Conclusion= APTT is a better assay for monitoring both inadequate reversa. of heparin and heparin rebound,and is more sensitive to minimal dose heparin than ACT. The dose ratio of protamine to heparin at 1:1 may reverse heparin effect completely.