Final answer:
Cirrhotic patients present with pleural effusions due to portal hypertension and the flow of excess fluid from the abdominal cavity to the pleural space.
Step-by-step explanation:
Due to the presence of scarring within the liver, cirrhosis leads to obstruction of the passage of blood through the liver causing portal hypertension. This means it is difficult for blood from the intestines to go through the liver to get back to the heart. Portal systemic anastomoses (shunts') develop, and portal blood (from the intestinal veins) will bypass the liver and return to the heart via another route without undergoing first-pass detoxification by the liver.
Because of the increased pressure in the portal vein, fluids can accumulate in different areas of the body, including the abdomen (resulting in ascites) as well as the pleural space around the lungs (resulting in pleural effusions). Pleural effusions in cirrhotic patients are mainly transudative, meaning they have a similar composition to the fluid that is filtered from the blood.
Overall, the pleural effusions in cirrhotic patients are a consequence of portal hypertension and the flow of excess fluid from the abdominal cavity to the pleural space due to the increased pressure.