result from nontraumatic conditions Necrotizing pulmonary infections, tuberculosis, pulmonary arteriovenous (AV) malformations, torn pleural adhesions, hemophilia, thrombocytopenia, systemic anticoagulation, and pleural tumors have all been reported to cause hemothoraces Chylothorax, or the accumulation of lymphatic fluid in the pleural space, has increased in frequency as thoracic, especially complex cardiac, surgical operations have become more common in children Clinical Recognition Small, sterile collections, as well as large, chronic collections, may be asymptomatic Symptomatic children often present with nonspecific symptoms such as fever, cough, malaise, and anorexia Additionally, acute collections produce symptoms by compressive effects on the lung, with resultant atelectasis, and right-to-left shunting, with resultant hypoxia and hypercapnia Respiratory distress may follow, marked by dyspnea, tachypnea, increased use of accessory muscles of respiration, and even cyanosis Small to moderate effusions may not be evident on physical examination, with most effusions detected by chest radiograph Larger effusions will cause dullness to percussion and decreased breath sounds Small effusions can be quite subtle and may manifest as slight blunting of the costophrenic angle on chest x-ray Larger effusions may cause significant opacification of a hemithorax and may layer out on an upright view of the chest, creating the so-called “meninscus sign.” Chest radiographs may also demonstrate the likely etiology of the effusion since cardiomegaly, mediastinal masses, and hilar lymphadenopathy may all be appreciated Moderate to large effusions on chest x-ray merit further evaluation by ultrasound to further characterize the effusion and determine whether it is comprised of free fluid or a loculated collection In skilled hands, ultrasound provides more information than either decubitus radiographs or CT and has the obvious advantages of not requiring sedation or exposing the child to radiation Management Children with pleural effusions should have peripheral blood counts and blood cultures obtained since parapneumonic collections are the most likely culprit Many small effusions can be managed conservatively with treatment of the underlying disease For moderate or large effusions, drainage of pleural fluid, or thoracentesis (see Chapter 130 Procedures ), may be necessary Thoracentesis may be therapeutically indicated for significant respiratory distress or diagnostically indicated when there is concern for a noninfectious cause of the collection Gram stain and culture should always be sent when pleural fluid is available Nucleic acid amplification testing through polymerase chain reaction (PCR) or specific antigen testing of pleural fluid may increase the likelihood of pathogen detection, particularly in patients who have been partially treated with antibiotics Fluid should be sent for a cell count with differential since this can help distinguish between various infectious pathogens and malignancy Cytology should be sent as well when malignancy is suspected Analysis of other pleural fluid parameters that have historically been assessed such as pH, LDH, glucose, and protein have been used to predict the need for further interventions, but are not routinely required as they rarely alter management Thin, free-flowing pleural fluid may sometimes be managed by simple thoracentesis (which may be repeated as needed) or the effusion may resolve as the underlying condition is treated Alternatively, a small-diameter tube, such as an 8F to 12F pigtail percutaneous tube, can be placed in the anterior or midaxillary line Early and continued administration of fibrinolytics into the catheter can be helpful in fostering resorption and preventing fibrin and other products from obstructing tube drainage Thick fluid, such as blood, pus, and sometimes chyle, often requires the placement of a larger diameter tube Either tube must be attached to a pleural drainage system When the drainage decreases significantly, to approximately mL/lb of body weight per day, the drain may be removed The drain should not be removed in the presence of an accompanying “air leak” caused by a bronchopleural connection See section below on empyema for discussion of further drainage modalities Disposition Pleural effusions that require drainage or further diagnostic evaluation clearly warrant inpatient admission There is a role for outpatient antibiotic therapy in the setting of very small effusion in the well-appearing child who has close followup Please refer to the pneumonia clinical pathway for suggested empiric antibiotic therapy (https://www.chop.edu/clinical-pathway/pneumoniacommunity-acquired-clinical-pathway ) This should be tailored, however, to local sensitivities for common pathogens Empyema Goals of Treatment The goals of treatment for empyema include the provision of adequate antibiotic treatment for the underlying infection and evacuation of significant pleural collections to allow for lung reexpansion Patients who develop small parapneumonic effusions will frequently improve clinically with appropriate antibiotic therapy, and small- to moderate-sized simple effusions may resorb as the underlying intraparenchymal infection resolves Large effusions that compress the lung or complex, loculated effusions are best treated with drainage Simple layering effusions may be effectively evacuated with tube thoracostomy alone, while large or complex, loculated effusions and simple effusions not effectively managed with tube thoracostomy may require chemical fibrinolysis or surgical drainage and debridement Surgical drainage and debridement, which can typically be done via a minimally invasive thoracoscopic approach, serves to relieve acute lung compression and to prevent a complex parapneumonic effusion from organizing and establishing a thick pleural peel, which could entrap the lung and result in chronic restriction on the affected side CLINICAL PEARLS AND PITFALLS Utilize ultrasound for moderate to large pleural effusions to better characterize the fluid collection and identify loculations For patients with empyema, early consultation with surgical consultants can facilitate more rapid intervention and resolution in appropriate patients Current Evidence An empyema is the presence of infected fluid within the pleural cavity and is typically a sequela of an underlying pneumonia The incidence of empyema has varied over recent decades, largely due to variation in invasive pneumoccoal disease with widespread vaccination Empyemas seem to have seasonal variation, being more common in the winter and spring months While chronic medical problems predispose children to having more complicated pneumonias and empyemas, they also occur in previously healthy children The predominant organisms implicated in empyemas have varied over time with vaccination and resistance patterns but they generally include Streptococcus pneumoniae , Staphylococcus aureus , group A streptococci, and Haemophilus influenza among others When empyema follows trauma or surgery, other bacterial organisms may be involved Viruses and Mycoplasma pneumoniae infections can also cause parapneumonic effusions but these rarely require intervention and patients are generally less severely ill than with traditional bacterial collections Clinical Considerations Clinical Recognition Empyema is most common in children to years of age, though children under years tend to have the highest mortality The clinical presentation varies based on when in the disease course the child is evaluated Presentation with a pneumonia that fails to improve after about 48 hours of appropriate antibiotic treatment should lead to the consideration of a complication like empyema High fever is common, as are the symptoms of pneumonia: cough, pleuritic chest pain, malaise, and shortness of breath Children are typically ill appearing and may demonstrate tachypnea, respiratory distress, and hypoxia Examination findings may include rales, decreased breath sounds on the affected side, and dullness to percussion Please refer to the Community Acquired Pneumonia Clinical Pathway at https://www.chop.edu/clinical-pathway/pneumonia-community-acquired-clinicalpathway Plain radiographs of the chest should be obtained Different guidelines in the United States and the United Kingdom propose either decubitus films or ultrasound to delineate if the fluid in the pleural space layers Children with a moderate (i.e., opacification of more than ¼ of the thorax) to large (i.e., opacification of more than ½ of the thorax) effusion should undergo ultrasound to better characterize the fluid Ultrasound has several advantages over CT including lack of radiation, no need for sedation, earlier detection of septae and loculations, as well as superior ability to describe the nature of the fluid collection Furthermore, it can be a helpful therapeutic adjunct to help with chest tube placement when necessary Management Unlike in uncomplicated pneumonias, children with empyemas are more likely to be bacteremic and they should all have a blood culture drawn in order to help direct antimicrobial therapy Empyema in healthy children may respond to prolonged IV antibiotic therapy and chest tube drainage, if the fluid is thin and not loculated Initial antibiotics should be broad spectrum and based on local resistance patterns and can be narrowed later if a pathogen is identified Coverage for MRSA is often included in initial antibiotic selection If a patient fails to respond to this management, loculation of thick purulent material should be suspected In such cases, both thoracostomy drainage with the addition of fibrinolytic agents and VATS have been shown to be effective in hastening recovery and reducing morbidity Choice of therapy is often dictated by regional expertise Regardless of treatment modality, early surgical consultation is warranted for significant empyemas