Pulmonary hemodynamics and gas exchange during exercise in liver cirrhosis

We have recently shown that ventilation-perfusion (VA/Q) mismatching at rest in cirrhosis is due to an abnormal pulmonary vascular tone. It has been suggested that in patients with cirrhosis, O2 transfer might become diffusion-limited during exercise. This study examined pulmonary hemodynamics and mechanisms modulating gas exchange during exercise (60 to 70% VO2max) in six patients (41 +/- 5 yr, mean +/- SEM) with cirrhosis but with normal lung function tests. At rest, QT was high (8.4 +/- 0.5 L/min), pulmonary vascular resistance (PVR) was low (0.61 +/- 0.17 mm Hg/L/min), and there was mild to moderate VA/Q mismatching (LogSD Q, 0.79 +/- 0.09; normal range, 0.3 to 0.6). However, hyperventilation (PaCO2, 29 +/- 2 mm Hg) and high QT (thus, high PVO2, 41 +/- 2 mm Hg) contributed to the maintenance of PaO2 within normal values (99 +/- 7 mm Hg). Exercise VO2 (1,278 +/- 122 ml/min) was normal relative to work load, but, contrary to that in normal subjects, QT was higher and PVR did not fall. During exercise, PaO2 showed a trend to decrease (to 90 +/- 5 mm Hg) and PaCO2 to rise (to 35 +/- 2 mm Hg), but the differences failed to reach statistical significance (p = 0.07 each). PVO2 fell significantly with exercise (41 +/- 2 to 33 +/- 0.3 mm Hg, p less than 0.05), but neither AaPO2 (15 +/- 7 to 21 +/- 6 mm Hg) nor VA/Q inequality (LogSD Q, 0.82 +/- 0.11) changed. No systemic difference was noticed between predicted and measured PaO2 values, suggesting no O2 diffusion impairment during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)