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Central hemodynamics were examined in 50 patients with chronic obstructive bronchopulmonary disease at rest and during mild steady-state supine exercise. The cardiac output rose proportionally to increased oxygen uptake in most cases; there was no difference between the patients with and without chronic right heart failure (RHF). The mean pulmonary arterial pressure in exercise increased disproportionally to cardiac output in about half of the compensated patients and in all cases with RHF. The pulmonary vascular resistance did not change significantly. The right ventricular end-diastolic pressure (RVEDP) at rest was significantly higher in the patients with RHF than in the other but the individual variations were large. Thus, the resting RVEDP cannot be considered as a reliable sign of RV functional abnormality in individual cases. Better agreement with clinical classification of the patients was obtained when considering the exercise values of RVEDP and particularly the relation of RVEDP to stroke volume during exercise.

In order to study the relations between maximal oxygen consumption during exercise (VO2max) and the pulmonary circulation when pulmonary artery pressure (PPA) and pulmonary vascular resistance (PVR) are normal or close to normal, we evaluated twenty-three patients with chronic bronchitis, in stable clinical condition. All these patients performed a progressive exercise test on a bicycle ergometer until exhaustion (VO2max); they were also subjected to right heart catheterization at rest and during light exercise at constant load. In these patients with moderate functional impairment, we observed on average a significant, although weak, correlation (r = -0.52, P less than 0.01) between pulmonary vascular resistance at rest and VO2max. When VO2max exceeded 2 1 min-1, PVR was below 210 dyn s cm-5. From the heart rate during maximal exercise we computed the oxygen pulse (O2Pmax). In eight patients O2Pmax was reduced (less than or equal to 11 ml) with maximal heart rate close to its predicted value; in seven of these subjects PVR was abnormal and Ppa at rest was at least 20 mmHg. Thus it seems that in chronic obstructive bronchitis mild disturbances in pulmonary circulation may be a contributory factor in the limitation of exercise performance, and a maximal exercise test may help to detect pulmonary hypertension in these patients.

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