A Study of Intrapulmonary Arterio-Venous Shunts in Patients with Liver Cirrhosis

Djordje Aulafia1, Mirjana Perišia1, Predrag Rebia2, Smiljana Pavlovia3

Abstract

Hepatopulmonary syndrome is defined by the existence of chronic liver disease, hypoxemia, the increase of the alveolar-arterial gradient during the breathing of room air and intrapulmonary vascular dilatation. The pathoanatomical substrate of intrapulmonary vascular dilatation includes: dilated pre-capillaries, direct arterio-venous communications and dilated pleural blood vessels resembling spider-like naevi, so called `pleural spiders'. The deterioration of arterial oxygenation in patients with liver diseases is a poor prognostic sign and, for this reason, hepatopulmonary syndrome could be included in indications for liver transplantation. Our prospective study in the period 1998 - 2000 included 50 patients with liver cirrhosis, at the Clinic of Gastroenterology and Hepatology, Institute of Digestive Diseases, Clinical Center of Serbia. Hepatological studies included laboratory liver function tests, Doppler ultrasonography of portal blood flow and histopathological diagnosis. Two groups of pulmonary function tests were applied: the measurement of respiratory gas concentration in the arterial blood and ventilation tests (spirometry, flow-volume curve and body plethysmography). Orthodeoxia (the fall of PaO2 during the position change, from supine to sitting) had been confirmed in all patients with intrapulmonary shunts. Perfusion pulmonary scintigraphy using albumin macro aggregate, labeled with radioactive technetium (99mTc-MAA) was performed for the visualisation of intrapulmonary shunts. The scanning of extrathoracic organs was used for the measurement of the total number of the brain and kidney impulses, to confirm intrapulmonary arterio-venous shunts. The functional and morphological studies established the diagnosis of hepatopulmonary syndrome in 9 (18%) patients with liver cirrhosis. The majority of these patients (6) belonged to the Child C class, while 3 patients were categorized as Child B. The patients with prominent oxygenation disorders caused by intrapulmonary arteriovenous shunts tended to have more severe liver insuf-ficiency. In the case of mild hypoxemia, intrapulmonary shunts are absent and the Va/Q mismatching of multifactorial genesis in such cases primarily causes oxygenation disorders. In patients with liver cirrhosis and prominent hypoxemia, intrapulmonary left-to-right shunts represent a major pathogenetic mechanism in the development of severe respiratory disorders. Perfusion pulmonary scintigraphy using 99mTc-MAA and the method based on the application of 100% oxygen are valid in the diagnosis of intrapulmonary shunts in liver cirrhosis.

Key words

Hepatopulmonary syndrome (HPS) - intrapulmonary shunts - liver cirrhosis - orthodeoxia - pulmonary scintigraphy