Comparison of Nebulized Versus Intravenous Milrinone on Reducing Pulmonary Arterial Pressure in Patients with Pulmonary Hypertension Candidate for Open-cardiac Surgery: A Double-Blind Randomized Clinical Trial

Background: Regardless of the cause, pulmonary hypertension can increase patient complications and mortality. This study compared the effect of nebulized versus intravenous (IV) milrinone on reducing pulmonary arterial pressure in patients with pulmonary hypertension candidates for open-cardiac surgery. Methods: This double-blind, randomized clinical trial was performed on 32 patients undergoing elective on-pump cardiac surgery during January 2021-January 2022 in the Cardiac Operating Room of Golestan Hospital, Ahvaz, Iran. Patients were randomly divided into test groups nebulize milrinone (N = 16) and IV milrinone (N = 16). The medication was administered after the cross-clamp of the aorta opening. The outcome variables included hemodynamic data, cardiac output, cardiac index, stroke volume, mean arterial pressure (MAP), central venous pressure, mean pulmonary artery pressure (mPAP), systemic vascular resistance, pulmonary vascular resistance, MAP/mPAP ratio, time until extubation, duration of hospitalization in the Intensive Care Unit (ICU), and duration of hospital stay. Results: In the nebulized group, MAP and MAP/mPAP were significantly higher than in the IV milrinone group (P = 0.09 and P < 0.0001, respectively). The time of extubation (P = 0.001), duration of hospitalization in the ICU (P = 0.009), and duration of hospital stay (P = 0.026) in the nebulized milrinone group were significantly shorter than in the IV milrinone group. Conclusions: Nebulized milrinone administration before weaning off cardiopulmonary bypass (CPB) can be accelerated and facilitate weaning off CPB. Moreover, despite maintaining MAP, nebulized milrinone significantly reduces mPAP. According to the results of this study, nebulized milrinone is recommended in patients undergoing cardiac surgery with pulmonary hypertension.