Haemodynamic changes during multistage exercise in patients with chronic lung disease.

A group of 20 patients with chronic lung disease (mainly chronic bronchitis) was studied at rest and during continuous exercise with increasing load, i.e. O Watts (loadless pedalling), 30 and 60 Watts. Ventilatory and haemodynamic measurements, as well as blood gas analysis, was performed at the end of a 5-minute steady state at rest and for each level of exercise. There was no progressive deterioration of blood gases with exercise. Haemodynamic values increased with exercise, already during loadless pedalling. Pulmonary vascular resistance, however, did not change, and the relation between cardiac output and pulmonary driving pressure was a straight line passing through the origin, although its slope was three times higher than in normal persons.