The aim of this study was to assess the effects of enoximone on the right ventricle and pulmonary hypertension in 10 patients (53 to 84 years) with chronic obstructive airway disease resulting in acute or chronic respiratory failure requiring mechanical ventilation in 9 cases. These effects were compared with those of dobutamine. All patients were in sinus rhythm and 6 had signs of right ventricular failure. Haemodynamic and 2D echocardiographic (study of left and right ventricular function) measurements were made under basal conditions (TB1), with 10 micrograms/kg/mn of dobutamine (TDob), again under basal conditions (TB2) three hours after the end of the dobutamine infusion, and then 30 minutes after an intravenous bolus (1 mg/kg) of enoximone (TE1) relayed by an infusion of 10 micrograms/kg/mn at 3 hours (TE2) and at 12 hours (TE3). The results (x +/- SD) were studied by a 2 factor variance analysis and compared by Student's test with Dunnett's correction. Cardiac index increased similarly by about 45% with enoximone (2.8 +/- 0.8 vs 4.1 +/- 1 l/min/m2; p less than 0.001 at TE2) and dobutamine, although the heart rate did not change significantly. Systemic arterial resistance fell significantly with enoximone (31.3 +/- 11 vs 21.3 +/- 6.8 IU; p less than 0.05 at TE2) but mean arterial pressures were unchanged; mean pulmonary artery pressures decreased from TE1 to TE3 (27.6 +/- 6.9 vs 22.6 +/- 6.3 mmHg; p less than 0.05 at TE2) mainly because pulmonary artery diastolic pressures decreased from TE1 to TE3 (20.1 +/- 4 vs 11.1 +/- 5.2 mmHg; p less than 0.05 at TE3).(ABSTRACT TRUNCATED AT 250 WORDS)