End-stage liver disease (ESLD) is associated with a variety of pulmonary changes. According to the degree of liver failure, patients with cirrhosis exhibit progressive abnormalities of the systemic and pulmonary hemodynamics which reflect a complex interaction between intrapulmonary and extrapulmonary factors.1,2 This explains the frequent occurrence of arterial oxygenation and pulmonary function tests (PFT) abnormalities in ESLD. Intrapulmonary shunt (IPS) is another cause of significant arterial oxygenation abnormalities in ESLD. It occurs uncommonly in ESLD and can be diagnosed reliably by contrast trans-thoracic echocardiography.3,4 These changes mandate careful pre-transplantation evaluation to avoid intra-operative or post-operative complications. Most of the studies that evaluated cardiopulmonary changes in chronic liver disease were conducted on a group of patients with different etiologies. Therefore, we evaluated the pulmonary changes in a homogenous cohort of liver transplant (LT) candidates with ESLD due to hepatitis C virus infection (HCV) with special emphasis on the prevalence and features of intra-pulmonary shunt.

Methods. Study population. King Fahad National Guard Hospital (KFNGH) is a tertiary care center in the Kingdom of Saudi Arabia where approximately 25-30 LTs are performed each year. From January 1994 to October 1997, 263 patients with ESLD were evaluated for possible LT. Of these, the study group consisted of 81 patients (31%) with advanced ESLD due to HCV. All patients had biopsy-proven liver cirrhosis consistent with HCV. All patients were anti-HCV positive using a 2nd generation enzyme linked immunosorbent assay (ELISA) test and the HCV infection was confirmed by the presence of hepatitis C ribonucleic acid. Comprehensive investigations were carried out to exclude other etiologies.

Pulmonary function tests. The majority of patients had pulmonary function tests (Jaeger Master lab, Germany) that included spirometry, lung volumes by either body box or helium dilution methods, and diffusion capacity. Spirometric values were calculated from the best of at least 3 trials as recommended by the American Thoracic Society criteria.5 All PFT values were reported as a percentage of the predicted values. Forced expiratory volume in 1 second (FEV1) to forced expiratory capacity (FVC) ratio of less than 70% was considered an obstructive impairment and total lung capacity (TLC) of less than 80% of predicted was considered a restrictive lung impairment.6 A reduced lung diffusion capacity (DLco) of less than 80% of predicted was considered abnormal when corrected DLco to alveolar volume was less than predicted.6

Arterial blood gases. Sixty-seven arterial blood gases (ABG) were performed on room air. The Alveolar-arterial oxygen gradient (A—a) PO2, was calculated by the simplified version of the alveolar air equation.6 Partial arterial tension of oxygen (PAO2)=149-partial arterial tension of carbon dioxide (PaCO2)/0.8 The (A—a) PO2 was then obtained by calculating the difference between calculated PAO2 and measured PaO2. Orthodeoxia was defined as drop in PaO2 by 10% upon standing up from lying position.4

Echocardiographic measurements. As part of the LT work up, all patients had a contrast trans-thoracic echocardiography (TTE) with micro-bubble study to assess cardiac structure and function and to exclude the presence of shunt. All the echocardiographs were carried out by one operator

Received 27th March 2001. Accepted for publication in final form 21st July 2001.

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