Relations of pulmonary diffusing capacity to ventilation and haemodynamics in healthy subjects.

The pulmonary diffusing capacity (DLCO) was measured in 13 healthy subjects during heart catheterization by the steady-state method (according to Bates and his coworkers). The DLCO shows the closest correlation to the tidal volume at rest, and to the central blood volume during exercise. Further, the DLCO correlates with the cardiac index both at rest and during exercise and with the stroke index at rest only. The DLCO did not show any relationship to the pressures in central circulation, pulmonary vascular resistance, total and alveolar ventilation. Statistical analysis shows that DLCO is most consistently related to the tidal volume at rest, whereas relation to central blood volume is much more stable during exercise.