Classification of parapneumonic pleural effusions. From the pathophysiology to classification and modern treatment

Parapneumonic pleural effusions (PPE) and pleural empyema (PE) are pleural effusions that develop as a consequence of bacterial pneumonia, lung abscess or bronchiectasis1,2.It is estimated that every year 4 million cases of pneumonia occur in USA, 20% require hospitalization, 20% of them have effusions, 20% progress to empyema and 20% is the mortality of empyemas.PPE and PE are clinically challenging conditions, both therapeutically and diagnostically, because of their heterogeneity3. They range from small, uncomplicated, pleural effusions that do not require specific treatment to multiloculated effusions and empyema with pleural fibrosis, trapped lung, systemic sepsis, respiratory failure, and metastatic infection.