Table 1.

Pleural infections staging and recommended drainage [7].

Category	Pleural space anatomy		Pleural fluid chemistry	Risk of poor outcome	Drainage
1	Minimal free-flowing effusion (<10 mm on lateral decubitus)	and	Gram stain and culture results unknown	Very low	No
2	Small to moderate free-flowing effusion (≥10 mm and less than one half hemithorax)	and	Negative Gram stain and culture	Low	No
3	Large, free-flowing effusion (≥ one half hemithorax), loculated effusion, or effusion with thickened parietal pleura	or	Positive Gram stain and/or culture	Moderate	Yes
4	Empyema		pus	High	Yes