Pleural effusion due to pneumonia is usually not very large, and parapneumonic pleural effusion is a small to moderate amount. Pneumonia can lead to increased local exudation due to inflammation stimulating the pleura, thus forming parapneumonic pleural effusion. Most of these pleural effusions can be relieved relatively quickly through early anti-infective treatment and, if necessary, thoracentesis and drainage of the pleural fluid. For example, severe pneumonia can lead to heart failure and renal failure, which can result in a significant increase in the amount of pleural fluid and a large amount of pleural effusion. Some severe patients can also develop hypoproteinemia, which can also increase the growth rate and amount of pleural fluid, and sometimes combined with Mycobacterium tuberculosis infection to form tuberculous pleural effusion, which can also appear as a large pleural effusion.