Role of Antihistamines in Preventing Haemodynamic Deterioration Caused by Protamine Sulphate in Cardiac Surgery: A Randomized Control Study

Introduction: Heparin is being used universally for anticoagulation in open heart surgery before commencement of cardiopulmonary bypass. Haemostasis is usually secured by neutralizing heparin with protamine sulphate at the end of surgery. Adverse reactions like hypotension, pulmonary hypertension, anaphylactoid reactions, decreased cardiac out put and platelet dysfunction are very common after use of protamine. These adverse reactions are thought to be due to release of histamine or direct toxic effect on myocardium. We used antihistamine, chlorpheniramine and slow rate of administration of protamine to compare the haemodynamic variables between the two groups. Objective: To compare the effects of protamine alone and after pre-treatment with chlorpheniramine while neutralizing heparin in open heart surgery. Design: A randomized controlled trial Place and duration of Study: This study was conducted in cardiac surgery unit, Pakistan Institute of Medical Sciences, Islamabad from January 2009 till May 2009. Subjects and Methods: A total of sixty patients were included in this study, thirty in each group. Patients were randomly assigned groups by lottery method. In antihistamine group chlorpheniramine was given ten minutes before giving protamine. Other group received protamine alone. Haemodynamics were studied till thirty minute and analyzed. Results: There was statistically significant benefit in systolic and diastolic pressure, mean arterial pressure, heart rate, time of extubation and oxygen saturation in the group which was pre-treated with chlorpheniramine but central venous pressure did not change significantly. The PA pressure was significantly lower as well as airway pressure. The need for inotropic support reduced markedly with lower incidence of arrhythmias in this group. No significant change in the incidence of pulmonary oedema was observed. Conclusion: Antihistamine given ten minutes before protamine keeps patient haemodynamically stable, avoids complications attributed to protamine without causing arrhythmias and excessive sedation leading to early recovery and discharge of patients