Hemodynamic characteristics in chronic obstructive lung disease as related to cardiac size

The hemodynamic adaptation during exercise was evaluated in 19 patients suffering from chronic obstructive lung disease. They were divided into two groups according to cardiac size on the X-ray (group 1, small; group 2, normal). A small cardio-thoracic ratio could be correlated with 'emphysema' assessed on the basis of hyperinflation and a low transfer test for CO. No clear-cut difference could be found between the two groups concerning the hemodynamic data at rest or during exercise. However, for all subjects, the cardiac output was found to be slightly related to the cardiac size (smaller cardiac output for smaller cardiac size). During exercise, a low cardiac output was characterized by a low oxygen transport and a high level of lactate. From this, it is suggested that a small cardiac size, a classical feature of hyperinflation and emphysema, may lead to a low cardiac output. The explanation for these results is speculative, but variable hemodynamic profiles in chronic obstructive lung disease with or without hyperinflation may be related to the morphology of the cardiac chambers and to variable intrathoracic pressure regimes during respiration.