INTRODUCTION: The protamine is the antidote universally used to neutralize the heparin at the end of the cardiopulmonary bypass; however there isn't a consensus about the ideal necessary dosage so far. OBJECTIVE: To evaluate the effectiveness of the neutralization of heparin, with variable dosages of protamine after cardiopulmonary bypass, using three different protocols. MATERIAL AND METHODS: From April to August 2000, 45 patients were randomized prospectively, and divided into three Protocols: I, II e III with 15 patients each. The protocol I evaluates the neutralization of heparin, with dosage of protamine calculated by the initial dosage of heparin. The protocol II evaluates the neutralization of the full dosage of heparin used during cardiopulmonary bypass.The protocol III evaluates the neutrlization of the full dosage of heparin, plus a reinforcement of 30% of this dosage, administered in peripheral vein during four hours. RESULTS: In the protocol I, 60% of the patients had necessity of reinforcement of the dosage of protamine and 20% showed hemorrhagics complications, requiring reoperation. From these 20%, one patient passed away and another had cerebrovascular accident; 53% of the patients of the protocol II had necessity of reinforcement of the dosage of protamine. The patients from protocols II and III didn't have neither hemorrhagics complications nor necessity of reoperation. CONCLUSIONS: 1- The dosage of protamine to neutralize heparin in the proportion less than 1:1, isn't sufficient. The patients that need of doses of reinforcement, have more hemorrhagics complications and greater necessity of blood transfusions. 2 - The neutralization of heparin, with dosage of protamine in the proportion of 1:1 isn't totaly effective; 53% of the pacients needed complementary doses in the frist hours affter surgery. 3 - An additional dose of 30% in the dosage of protame in the proportion of 1:1 in continual infuse in the frist hours after surgery, decreases the loss of blood and the necessity of transfusions.
Protamines; Heparin; Extracorporeal circulation
