The characteristics of respiratory function and pulmonary hemodynamics in patients with portal hypertension.

OBJECTIVE: To investigate the respiratory function and pulmonary hemodynamics in patients with portal hypertension (PHT). METHODS: A total of 148 patients with PHT were divided into three groups according to Child-Pugh classification. Results of blood biochemistry test, lung function test, arterial blood gas analysis, free portal pressure (FPP) and pulmonary hemodynamics measurements of the three Child-Pugh grade groups were compared with those of the control group. RESULTS: The overall incidence of arterial hypoxemia was 27.0% in PHT patients. Arterial oxygen tension (PaO(2) ) had a significant negative correlation with FPP (r=-0.76, P<0.01) and Child-Pugh grade (r=-0.42, P<0.01), as well as a positive correlation with systemic vascular resistance (SVR, r=0.24, P=0.01). Alveolar-arterial oxygen difference (A-aDO(2) ) increased in Child-Pugh grade C group when compared with Child-Pugh grade A and B groups (P<0.05). Restrictive impairment of lung function was seen in Child-Pugh grade C group. Direct measurement of the hemodynamics in PHT patients revealed a hyperdynamic disturbance in both systemic and portal venous systems, and was illustrated in pulmonary circulation as an increase of mean pulmonary arterial pressure (MPAP) and pulmonary arterial wedged pressure (PAWP) as well as a decrease of pulmonary vascular resistance (PVR). CONCLUSIONS: High output and low resistance are the key characteristics of pulmonary circulation in PHT patients and the decrease of PVR can be detected even when liver function is still compensated.