The immediate effects of isosorbide dinitrate on right ventricular function in patients with acute hypoxemic respiratory failure. A combined invasive and radionuclide study.

We administered 20 mg of isosorbide dinitrate sublingually to 16 patients with acute hypoxemic respiratory failure (ARF) complicated by pulmonary artery hypertension (PAH) and evaluated its effects 20 to 30 min later using a combination of invasively measured pressures and flows and ECG-gated cardiac scintigraphy. We measured the right and left ventricular ejection fractions and a simultaneous thermodilution stroke volume index; we then calculated respective end-diastolic (EDVI) and end-systolic (ESVI) volume indexes. An initially depressed mean right ventricular ejection fraction (RVEF) increased modestly after the administration of isosorbide dinitrate (35 +/- 10 to 41 +/- 10%; p less than 0.02), whereas both the mean right ventricular end-diastolic (-27 +/- 50 ml/M2; p less than 0.04) and end-systolic (-27 +/- 44 ml/M2; p less than 0.03) volume indexes fell. The RVEF increased in 11 of 16 patients: within this subgroup, a decrease in the RVEDVI and RVESVI was associated with a decrease in both cardiac index (delta 0.3 L/min/M2) and LVEDVI (delta -15 +/- 21 ml/M2; p less than 0.01); hence, O2 delivery also fell (delta -36 +/- 56 ml/min/M2; p less than 0.05). In some patients with ARF complicated by PAH, sublingually administered nitrates may improve right ventricular systolic function when globally depressed. However, left ventricular "pump" function appears to be depressed when a concurrent depression in right ventricular "pump" function ensues.