Cardiovascular effects of prolonged milrinone inhalation in patients with pulmonary hypertension undergoing mitral valve replacement

Context Inhaled milrinone has short-acting selective pulmonary vasodilator effect. Aims The aim of the study was to investigate the cardiovascular effects of prolonged inhalation of nebulized milrinone on patients with pulmonary hypertension undergoing mitral valve replacement. Settings and design This is a controlled, randomized, double-blinded study. Patients and methods Forty patients were divided into two groups: the milrinone group and the control group. The milrinone group received milrinone nebulization before cardiopulmonary bypass (CPB) as the loading dose at 50 mg/kg, followed by a maintenance dose of 0.5 mg/kg/min, which was continued for 2 h after tracheal extubation. The control group received an equivalent volume of 0.9% sodium chloride. The measured and calculated variables included heart rate, mean arterial blood pressure, central venous pressure, mean pulmonary artery pressure (mPAP), pulmonary capillary wedge pressure, cardiac index (CI), pulmonary vascular resistance (PVR), and systemic vascular resistance. The time points of measurements and calculations were as follows: at T 0 - after anesthesia induction and before sternotomy; at T 1 - 20 min after CPB cessation; at T 2 - 1 h after CPB cessation; at T 3 - 3 h after CPB cessation; at T 4 - 1 h after tracheal extubation; and at T 5 - 1 h after milrinone discontinuation. The duration of CPB and time of tracheal extubation were recorded. Results The milrinone group showed significant reduction in mPAP (T 2 to T 4 readings), pulmonary capillary wedge pressure (T 3 reading), and PVR (T 2 to T 4 readings), increase in CI (T 3 and T 4 readings), and shorter CPB duration and tracheal extubation time. Conclusion Prolonged inhalation of nebulized milrinone proved to be feasible in patients with pulmonary hypertension (PAH) undergoing mitral valve replacement. It decreased PVR and mPAP while increasing CI. This helped shorter CPB duration and earlier tracheal extubation.