Dose of Protamine for Heparin Reversal in CABG Surgery

Objective: To determine the dose of Protamine required for reversal of Heparin effect in Coronary Artery Bypass Grafting (CABG). Study Design: Quasi-experimental study. Place and Duration of Study: Adult Cardiac Surgery Unit, Armed Forces Institute of Cardiology/National Institute of Heart Diseases, Rawalpindi Pakistan, from May to Dec 2022. Methodology: Total 382 patients were included in this study through consecutive sampling and were divided into two groups (n=191 participants in each group). After induction of anesthesia, baseline Activated Clotting Time (ACT) was measured. About 300units/kg of unfractionated Heparin was given non-randomly before establishing Cardiopulmonary Bypass (CPB). After termination of CPB, Protamine was administered in doses of 1 mg/kg and 1.5 mg/kg to Group-A and Group-B respectively. Protamine was diluted in 20ml of saline, and administered at a rate of 100ml/hr. Once Protamine was administered, blood sample was taken after 5min for ACT measurement. If this ACT was within 10% of baseline, it was taken as sign for reversal of Heparin effect. Student t-test and Chi-square test were applied to compare the groups and level of significance taken was p<0.05. Results: Majority cases were males 287(75.1%), whereas 95(24.9%) were females. Statistically significant mean differences were noted between Cardiopulmonary Bypass (CPB) time, ACT after Protamine administration, and requirement for extra Protamine administration between two groups (p<0.05). However, no significant differences were noted between age, weight and ACT before Heparin administration ....  Conclusion: Classical doses of 3mg/kg of Protamine in CABG patients may actually be exposing patients to higher than required ..........