The study investigated reducing the protamine-to-heparin ratio (P-to-H) from 1:1 to 0.9:1 and 0.8:1 in cardiac surgery patients to determine its effect on post-operative bleeding. Results showed a significant reduction in the actual protamine dose without an increase in post-op bleeding, suggesting that a ratio as low as 0.75:1 might be sufficient for effective neutralization of heparin.