Biventricular function in the adult respiratory distress syndrome

We examined biventricular function in patients with the adult respiratory distress syndrome (ARDS) by a combination of invasively determined pressures and flows and concomitant radionuclide angiography. Right (RVEF) and left (LVEF) ventricular ejection fractions were measured; right and left ventricular end-diastolic (EDVI) and end-systolic (ESVI) volume indices were calculated from the respective ejection fraction and measured thermodilution stroke volume. With an increase in the outflow pressure load on the right ventricle, measured as the mean pulmonary artery pressure (PAP), the RVEF fell (Y = 66.25 -1.01X; r2 = .42; p less than .001) and both the RVEDVI (y = 13.39 + 3.66X; r2 = .33; p less than .001) and RVESVI (Y = 23.9 + 3.57X; r2 = .41; p less than .001) increased. Progressive increases in the PAP also seemed associated with a change in left ventricular end-diastolic pressure-volume relationships: without pulmonary artery hypertension (PAP less than 20 mm Hg) the mean LVEDVI was 87.2 +/- 31.3 ml/m2 (mean +/- SD) and the mean PCWP was 5.0 +/- 2.8 mm Hg; with a mean PAP exceeding 30 mm Hg, the LVEDVI remained constant (90.4 +/- 26.9 ml/m2) although the PCWP was greater than previous (18.5 +/- 5.7 mm Hg; p less than .01). Analysis of right ventricular peak-systolic pressure end-systolic volume ratios implied a concurrent depression in right ventricular contractility at high levels of PAP. However, right ventricular "pump" function to maintain an adequate left ventricular preload remained unaltered regardless of the presence of pulmonary artery hypertension.