Milrinone improves lung compliance in patients receiving mechanical ventilation for cardiogenic pulmonary edema

Background: Decrease in lung compliance is one of the major causes of respiratory failure. We investigated whether amrinone could improve lung compliance. Methods: We selected 20 consecutive patients with respiratory failure due to severe cardiogenic pulmonary edema to receive mechanical ventilation. Patients were administered a bolus injection (1 mg. kg -1 ) over 10 min followed by continuous intravenous infusion (10 μg. kg -1 . min -1 ) of amrinone. Lung compliance, blood gas values, hemodynamic parameters, and sample plasma amrinone levels were assessed over a 120-min period after the onset of the continuous infusion of amrinone. Results: Ten min following amrinone infusion, dynamic compliance (Cdyn) and static compliance (Cst) increased from 30±11 to 36±12 ml/cm H 2 O and from 37±12 to 42±13 ml/cm H 2 O, respectively (P<0.01). Plasma amrinone levels reached a therapeutic level as vasodilator and positive inotropic effects at 10 min after amrinone infusion. The significant change in mean pulmonary artery pressure and pulmonary artery wedge pressure occurred later than the change in compliance of respiratory system. However, there were significant correlations between the mean pulmonary artery pressure and Cdyn (r= 0.36, P<0.01) and Cst (r=0.44, P<0.01), as well as between plasma amrinone levels and Cdyn (r=0.30, P<0.05) and Cst (r=0.41, P<0.01). Conclusions: Amrinone-induced improvement in lung compliance was considered mainly to be due to an increase in the number of functioning lung units by improvement of the hemodynamics and a direct positive effect of amrinone on respiratory muscle contraction.