Prostacyclin and right ventricular function in patients with pulmonary hypertension associated with ARDS

Eight patients who developed pulmonary artery hypertension during the adult respiratory distress syndrome (ARDS) were treated with an infusion of prostacyclin (PGI₂, 12.5–35.0 ng·kg^–1·min^–1) for 45 min. We examined whether reducing the right ventricular (RV) outflow pressures by PGI₂ infusion would increase the right ventricular ejection fraction (RVEF) measured by thermodilution. PGI₂ reduced the pulmonary artery pressure (PAP) from 35.6 to 29.1 mmHg (p<0.01). The cardiac index (CI) increased from 4.2 to 5.81·min^–1·m^–2 (p<0.01) partly due to an increased stroke volume. The decreased PAP together with the increased CI resulted in a fall of the calculated pulmonary vascular resistance index (PVRI, from 5.1 to 2.5 mmHg·min·m²·1^–1,p<0.01). In the patients with subnormal baseline RVEF the increased stroke volume was associated with an increased RVEF (from 47.6% to 51.8%,p<0.05) suggesting improved RV function. This result was underscored by a significant relationship between the changes in PVRI and RVEF (r=0.789, % RVEF=–2.11·PVRI-1.45). Despite an increased venous admixture from 27.8% to 36.9% (p<0.05) the arterial PO₂ remained constant resulting in an increased oxygen delivery from 657 to 894 ml·min^–1·m^–2 (p<0.01). We conclude that short term infusions of PGI₂ increased CI concomitant to improved RV function parameters when baseline RVEF was depressed. Since improved oxygen availability should be a major goal in the management of patients with ARDS PGI₂ may be useful to lower pulmonary artery pressure in ARDS.Supported by the Deutsche Forschungsgemeinschaft (grant Fa 139/2-2)