pleural effusion associated with pneumonia.
Bacterial pneumonia with associated pleural empyema is the most common cause of pleural effusion found in the pediatric population. Parapneumonic effusions are predominately exudative and occur in as many as 50-70% of patients admitted with a complicated pneumonia. The pulmonary infections of these patients extend into the pleural space and require more extensive therapy, with associated increased morbidity and extended hospital stay.
Involvement of the pleural space with pulmonary infections has been recognized since ancient times. Aristotle identified the increased morbidity and mortality associated with empyema and described drainage of empyema fluid with incision. The practice of surgical drainage as part of therapy for empyema has continued into the era of modern medicine. In his 1901 text, The Principles and Practice of Medicine, Sir William Osler, MD, stated that empyema should be treated as an ordinary abscess, “with incision and drainage.” Of note, Osler underwent a rib resection for his own postpneumonic empyema, from which he ultimately expired.
Complicated parapneumonic effusions are appearing more frequently by most accounts, with reported increases in incidence rates in both in Europe and the United States. In England, the rate of admission with a diagnosis of empyema increased over the last decade, most notably in children aged 1-4 years. In addition, the identification of Streptococcus pneumoniae as the primary pathogen has also been reported, both in both the United States and abroad.
(2) Parapneumonic effusion is any pleural effusion secondary to pneumonia (bacterial or viral) or lung abscess. Empyema is, by definition, pus in the pleural space. Pus is thick, viscid fluid that appears to be purulent. A complicated parapneumonic effusion is a parapneumonic pleural effusion for which an invasive procedure, such as tube thoracostomy, is necessary for its resolution, or a parapneumonic effusion on which the bacterial cultures are positive.
See: Pleural effusions