Inhaled Milrinone and Epoprostenol for the Prevention of Difficult Cardiac Pulmonary Bypass Separation

In cardiac surgery, the presence of pulmonary hypertension (PH) is a prognostic factor associated with increased mortality and morbidity. In this context, one of the main causes of PH is related to reperfusion ischemia during weaning from extracorporeal circulation (CPB). One of the consequences of PH is right ventricular dysfunction. During weaning from CPB, the development of a right ventricular dysfunction is associated with increased requirements for vasopressor and inotropic agents, duration of mechanical ventilation, prolonged intensive care and hospital stay, and increased mortality compared with patients with left ventricular (LV) dysfunction. The management of patients with PH with or without right ventricular (RV) dysfunction relies on several strategies such as the administration of intravenous and inhaled agents, or mechanical ventricular support. Among those agents, the administration of inotropes or pulmonary vasodilators such as epoprostenol, milrinone and nitric oxide are among the most widely used treatments recommended by the Canadian Cardiovascular Society. At the Montreal Heart Institute, inhaled epoprostenol and milrinone are routinely administered to patients with PH or LV dysfunction in the perioperative setting. Despite the frequent use of inhaled epoprostenol and milrinone, Health Canada has not yet approved the use of these molecules. The primary objective of this multicenter, double-blind, randomized clinical trial is to evaluate the clinical efficacy of the combined administration of inhaled epoprostenol and milrinone in a cardiac surgery setting. This trial will compare the clinical outcome of 71 patients who will receive inhaled epoprostenol and milrinone before the start of bypass surgery to 71 patients who will receive a placebo before the start of the CPB. The primary clinical outcome is the proportion of patients with an "unsuccessful" CPB weaning defined by the use of an inotrope +/- vasopressor agent or the use of mechanical circulatory support or a return to bypass grafting for hemodynamic reasons. This clinical trial will evaluate the clinical efficacy of the combination of inhaled agents in a cardiac surgery setting. Therefore, if the results of this study are positive, the combination of inhaled epoprostenol and milrinone will optimize the management of patients with pulmonary hypertension with or without a right ventricular dysfunction.