Response to Symptom-Limited Exercise in Patients With the Hepatopulmonary Syndrome

¹ From the Pulmonary and Critical Care Division, Department of Medicine, Tupper Research Institute, and Cardiopulmonary Exercise Physiology Lab, New England Medical Center, Tufts University School of Medicine, Boston, MA.

Scott K. Epstein, MD, FCCP, Pulmonary and Critical Care Division, Box 369, New England Medical Center, 750 Washington St. Boston, MA 02166

Objective: To study the response to symptom-limited exercise in patients with the hepatopulmonary syndrome (HPS).

Design: The response to maximal cardiopulmonary exercise (CPX) was studied in 5 patients with HPS and compared with 10 case control (normoxemic, NC) cirrhotics (matched for age, gender, etiology and severity of liver disease, tobacco use, and β-blocker therapy) and 9 hypoxemic control cirrhotics (HC) without clinical evidence of HPS.

Setting: Cardiopulmonary exercise physiology laboratory in a tertiary care referral center.

Patients: Cirrhotics referred for CPX as part of their preliver transplantation evaluation.

Measurements: Standard pulmonary function tests and echocardiography were performed to assess resting pulmonary and cardiac function. Peak oxygen consumption (VO₂), minute ventilation, arterial blood gases, and dead space (VD/VT) were detennined during symptom-limited maximal CPX.

Results: Resting spirometry and lung volumes were similar between HPS and NC subjects, while HC subjects had restrictive physiology. Differences existed in diffusing capacity corrected for hemoglobin and alveolar volume percent predicted (HPS, 45±2 vs NC, 68±3, p<0.05; vs HC, 70±4, p<0.05), PaO₂ (HPS, 70±5 mm Hg; HC, 79±3 mm Hg, vs NC, 102±3 mm Hg, p<0.05) and alveolar-arterial (A-a) O₂ gradient (HPS, 42±8 mm Hg vs HC, 27±2 mm Hg, p<0.05; vs NC, 6±2 mm Hg, p<0.05). During CPX, HPS patients achieved a lower peak VO₂ percent predicted (HPS, 55±6 vs NC, 73±3, p<0.05; vs HC, 71±5, p<0.05) and VO₂ at the ventilatory threshold as percent predicted peak VO₂ (HPS, 36±2 vs NC, 55±4, p<0.05; vs HC 55 ±5, p<0.05). While no differences existed in heart rate and breathing reserve, HPS patients had significantly lower PaO₂ (HPS, 50±5 mm Hg vs NC, 97±4 mm Hg, p<0.05; vs HC, 87±6 mm Hg, p<0.05), wider A-a O₂ gradient (HPS, 73±5 mm Hg vs NC, 13±3 mm Hg, p<0.05; vs HC, 31±5 mm Hg, p<0.05) and higher VD/VT (HPS, 0.36±.03 vs NC, 0.18±.02, p<0.05; vs HC, 0.28±.02, p<0.05) at peak exercise. For HPS patients, VO₂ was negatively correlated with VD/VT (r²=0.9) and positively correlated with PaO₂ (r²=0.41) at peak exercise.

Conclusions: Patients with HPS demonstrate a severe reduction in aerobic capacity, beyond that found in cirrhotics without syndrome. The significant hypoxemia and elevated VD/VT at peak exercise suggest that an abnormal pulmonary circulation contributes to further exercise limitation in patients with HPS.

Key Words: cirrhosis • exercise testing • gas exchange • hepatopulmonary syndrome • pulmonary vascular disease

Submitted on September 24, 1997
Accepted on February 26, 1998

This article has been cited by other articles:

				R. Rodriguez-Roisin, M.J. Krowka, Ph. Herve, M.B. Fallon, and on behalf of the ERS Task Force Pulmonary-Hepatic Pulmonary-Hepatic vascular Disorders (PHD) Eur. Respir. J., November 1, 2004; 24(5): 861 - 880. [Full Text] [PDF]