Comparison of hemodynamic effects of inhaled milrinone and inhaled nitroglycerin in patients with pulmonary hypertension undergoing mitral valve surgery

IntroductionPulmonary hypertension (PH) frequently complicates the perioperative management of patients undergoing mitral valve surgery and has been shown to be a significant independent predictor of postoperative morbidity and mortality. The aim of this work is to compare the effects of inhaled milrinone and inhaled nitroglycerin on pulmonary and systemic hemodynamic responses in patients with PH undergoing mitral valve surgery.Patients and methodsA total of 50 patients with PH were randomly divided into two groups with 25 patients in each group: group I patients received inhaled nitroglycerin (5 mg, 1 mg/ml) over 15 min and group II patients received inhaled milrinone (5 mg, 1 mg/ml) over 15 min through an ultrasonic nebulizer connected to the inspiratory limb of the ventilator circuit near the endotracheal tube immediately after separation from cardiopulmonary bypass. Hemodynamic parameters were measured after induction of anesthesia (T1), immediately after the end of cardiopulmonary bypass (T2), 30 min after the start of treatment, and 90 min after the start of treatment (T4). The hemodynamic variables were as follows: heart rate, mean arterial blood pressure (MAP), mean pulmonary artery blood pressure (MPAP), cardiac index (CI), systemic vascular resistance index (SVRI), pulmonary vascular resistance index (PVRI), and right ventricular stroke work index (RVSWI).ResultsAt 30 min after the start of treatment, both groups showed a significant comparable decrease in MPAP, PVRI, and RVSWI, with no significant changes in MAP, CI, and SVRI. At 90 min after the start of treatment, MPAP, PVRI, and RVSWI returned to their values in the inhaled nitroglycerin group but remained at significantly lower values in the inhaled milrinone group.ConclusionInhalation of nitroglycerin and milrinone produces a comparable decrease in MPAP, PVRI, and RVSWI without significant changes in heart rate, MAP, CI, and SVRI. Inhaled milrinone has a longer duration of action than inhaled nitroglycerin.