ObjectiveTo evaluate the effects of high-dose almitrine infusion on gas exchange and right ventricular function in patients with severe hypoxemia related to acute respiratory distress syndrome (ARDS).DesignProspective study.SettingMedicosurgical intensive care department (ten beds).PatientsNine patients with ARDS and severe hypoxemia (Pao2/Fio2ratio, <150 torr [20 kPa]).InterventionHigh-dose almitrine infusion (16 &mgr;g/kg/min for 30 mins).Measurements and Main ResultsGas exchange and hemodynamic parameters were recorded before and after almitrine infusion. Right ventricular function was evaluated by using a fast response thermistor pulmonary artery catheter that allowed measurement of right ventricular ejection fraction and calculation of right ventricular end-diastolic and end-systolic volumes. Almitrine did not significantly alter arterial oxygenation and intrapulmonary shunt. Almitrine increased mean pulmonary arterial pressure (MPAP) from 31 ± 4 to 33 ± 4 mm Hg (p< .05), pulmonary vascular resistance index from 353 ± 63 to 397 ± 100 dyne·sec/cm5·m2(p< .05), and right ventricular end-systolic volume index from 71 ± 22 to 77 ± 21 mL/m2(p< .05); almitrine decreased right ventricular ejection fraction from 36% ± 7% to 34% ± 8% (p< .05). Stroke volume index and cardiac index did not change. The almitrine-induced changes in right ventricular ejection fraction were closely correlated with the baseline MPAP (r2= .71,p< .01).ConclusionIn patients with severe hypoxemia related to ARDS, high-dose almitrine infusion did not improve arterial oxygenation and impaired the loading conditions of the right ventricle. The decrease in right ventricular ejection fraction induced by almitrine was correlated with the baseline MPAP. Thus, high-dose almitrine infusion may be harmful in ARDS patients with severe hypoxemia and pulmonary hypertension.