[Relation of pulmonary hemodynamics and ventilation to tissue hypoxia during exercise in patients with tuberculosis...

We examined a relationship between tissue hypoxia and pulmonary hemodynamics or ventilatory capacity during rest and exercise in patients with tuberculosis sequelae. Nine patients performed exercise test until their symptom limit. Mean pulmonary arterial pressure (PPA) during exercise was plotted against cardiac index (C.I.) from rest to maximum exercise in each patient. In most of the patients, the changes of PPA showed linear relation with the C.I., and a slope (P-F slope) was obtained from the regression equation in each patient, and it was used as an index of circulatory disability during exercise. At the same time a coefficient of oxygen delivery (COD) was calculated and mixed venous oxygen tension (PvO2) was measured to evaluate a tissue hypoxia at rest and during exercise. The changes of COD were similar to those of PvO2 during exercise. COD positively correlated with PvO2 (R = 0.873, P < 0.01) from rest to maximal exercise, indicating that the values of PvO2 depended on those of COD. P-F slope negatively correlated with S.I. (R = -0.887, P < 0.01), oxygen transport (R = -0.780, P < 0.01), COD (R = -0.827, P < 0.01) and PvO2 (R = -0.760, P < 0.01) at maximal exercise. Whereas no significant relationship between ventilatory variables and COD or PvO2 was noted at maximal exercise. In conclusion, the patients with pulmonary tuberculosis sequelae who had a step P-F slope showed low mixed venous oxygen tension during exercise as a result of limited oxygen transport in consequence of low stroke volume.