Community-acquired pneumonia refers to clinical signs and symptoms of pneumonia acquired outside of the hospital setting. Globally, the number of episodes of clinical pneumonia in young children decreased by 22% from 178 million in 2000 to 138 million in 2015. However, pneumonia remains a common serious childhood infection and accounted for more than 900,000 deaths in children in 2015.

In the United States, pediatric pneumonia occurs at an estimated rate of 30–40 per 100,000 with an annual incidence of 15.7–22.5 hospitalizations per 100,000 children. Although overall rates of bacterial pneumonia have been declining in children, the incidence of complications such as PPEs and empyema has increased. Some hypothesize this is a result of pneumococcal serotype replacement and/or antibiotic resistance.

PPEs can complicate pneumonia in up to 30%–50% of children. ^, In children <2 years of age, the incidence of empyema doubled over a 10-year span, increasing from 3.5/100,000 in 1996–98 to 7/100,000 in 2005–2007. Similarly, in patients between 2 and 4 years of age, empyema rates nearly tripled from 3.7/100,000 to 10.3/100,000 during the same time period. A study of the National Kids Inpatient Database found the incidence of empyema with fistula continued to rise between 2000–2009. Another study of the same administrative database reported the annual empyema-associated hospitalization rates for children under 18 years increased almost 70% between 1997 and 2006, despite decreases in the disease rates of pneumococcal pneumonia. The introduction of the pneumococcal conjugate vaccine did not appear to decrease the incidence of empyema.

While PPEs and empyema in children have a lower mortality rate compared with adults, in whom the mortality can approach 20%, they pose a considerable burden on hospitals and families. Complications of pediatric pneumonia continue to account for a significant proportion of healthcare visits and hospitalizations in high-income countries. ^,

The natural progression of parapneumonic pleural disease has been outlined with four stages of increasing complexity. The Precollection stage involves pleuritis and inflammation. This is followed by the Exudative stage, which is a simple PPE, and is characterized by clear, free-flowing pleural fluid with a low white blood cell count. The Fibrinopurulent stage is a complicated PPE (empyema), marked by the deposition of fibrin and purulent material in the pleural space, and an increase in the fluid leukocyte count. Septations and fibrin strands begin to develop. These result from decreased fibrinolytic activity, thereby allowing increased fibrin deposition. The result is a procoagulant environment that leads to the development of solid material in the form of septations followed by loculations of purulent fluid ( Fig. 21.1 ). The most advanced state is termed the Organization stage, during which a thick peel is established. This peel can entrap the lung and result in chronic restrictive lung disease. These stages are described sequentially, but it does not always follow that disease progresses from one stage to the next. Furthermore, the degree of patient illness may not correspond with these stages, depending substantially on the extent of concomitant parenchymal disease and inflammatory response.

(A) The thoracoscopic view shows the inflammatory septations that can develop with empyema. The collapsed lung is marked with an asterisk . (B) Note the thick, solid purulent material that is often found in these patients.

As the stages advance, the chemistry of the parapneumonic fluid changes: glucose decreases, pH decreases, and lactate dehydrogenase (LDH) rises. The diagnosis and stratification of PPE into complicated and uncomplicated are two major roles of biochemical analysis. The original Light criteria for complicated PPE included pH < 7.2, LDH >1000 units, fluid glucose <40 mg/dL or <25% of the blood glucose, Gram stain or culture-positive fluid, and the presence of loculations or septations observed on imaging. ^, The Light criteria are reported to have a high diagnostic sensitivity (99%) and a specificity between 70%–98% for an exudate. Retrospective data suggest that a prolonged fever and a low pleural fluid pH and glucose, along with a high LDH pleural/serum ratio, are associated with more severe disease.

The Light criteria have been modified to confirm complicated parapneumonic effusion with the addition of pleural fluid cholesterol measurements. The combination of pleural fluid cholesterol greater than 1.04 mmol/L (40 mg/dL), and pleural fluid LDH greater than 0.6 of the upper limit of normal serum LDH concentration, were validated to confirm an exudative effusion with the same sensitivity and accuracy as the original Light criteria, while simultaneously avoiding blood sampling. Another study, using multivariate logistic analysis of a retrospective dataset, found that a pleural fluid pH < 7.27 was the only significant factor for the formation of fibrin with or without septations. A third study suggested that a tumor necrosis factor level >13 ng/dL in the pleural fluid suggests a complicated effusion.

In his 1995 review, Light proposed a detailed classification that defines seven different stages ranging from nonsignificant PPEs to a complex empyema. Also, recommendations on appropriate therapy were described that ranged from observation to thoracoscopic debridement or decortication ( Table 21.1 ). A retrospective study that evaluated the American College of Chest Physicians and the British Thoracic Society guidelines to distinguish complicated from uncomplicated PPE reported a high specificity (from 78% for LDH to 94% for glucose <40 mg/dL), but low to moderate sensitivity (from 25% for culture to 73% for LDH) in predicting the need for chest tube placement in nonpurulent PPE. Larger effusions were more likely to undergo thoracostomy. The need for a chest tube in each case was determined by the treating surgeon. In contrast, one retrospective study found many children with empyema can be treated with IV antibiotics alone and have a reasonably short hospitalization. The specific function of thoracostomy placement in complicated PPE was clarified in that tube placement may impact and improve outcomes if the patient has clinical deterioration and respiratory distress in the setting of a large PPE, or mediastinal shift that impacts the cardiopulmonary status.

In another retrospective study, a pleural fluid pH < 7.1 was found to result in a sixfold increase in the likelihood of an operative intervention. Although all these criteria may document disease progression, the clinical relevance of pleural fluid analysis may be less important once symptoms develop and fluid with or without septations is found, because intervention is now required to resolve the illness. One prospective study of pediatric pneumonia found hypoxemia and chest retractions were independent clinical predictors of the need for medical interventions.

PPE typically progresses from pneumonia. Patients with a significant PPE or empyema almost always demonstrate some degree of respiratory distress, malaise, cough, persistent fever, or pleuritic chest pain. ^, Diminished breath sounds with dullness to percussion on the affected side are found on examination. An ileus is common, as is a lack of appetite. ^,

Initial imaging is a chest radiograph that shows poor penetration on the affected side. However, it is often difficult to distinguish between parenchymal consolidation and pleural fluid on a plain film. In a retrospective review of over 300 adult patients, the chest radiograph missed all effusions that were significant enough to warrant drainage when compared with subsequent computed tomography (CT) scans ( Fig. 21.2B ). Decubitus films may be helpful to distinguish between nonloculated and loculated effusions.

Ultrasonography and/or CT of the chest are helpful during the initial evaluation of children with a pleural effusion and possible empyema. (A) In the ultrasound study, note the loculations identified in the pleural fluid. (B) On the CT scan, a large pleural effusion ( asterisk ) is noted. Also, there is collapse of the underlying lung parenchyma as well as septations ( arrow ).

Ultrasonography (US) is portable, relatively inexpensive, and does not involve radiation ( Fig. 21.2A ). It is sensitive to diagnose loculated fluid and can be used to guide percutaneous drainage and catheter placement. Some suggest US is superior to chest radiographs to determine lung consolidation in children. Others suggest that US is superior to CT in the identification of pleural debris or loculations. US can reliably differentiate between parenchymal and pleural-based processes. A post hoc review of a prospective trial in children found that in 31 patients in whom both CT and US were performed, there was no advantage of CT over US in most cases. Two independent series reviewed the implementation of an algorithm using initial US in children with complicated pneumonia. ^, Both demonstrated a significant reduction in hospitalization and a decrease in the use of CT without an increase in the rate of operative management or pleural drainage. The use of contrast-enhanced US may further expand the role and accuracy of US to determine diagnosis and therapy for pediatric pneumonia and empyema.

Point of care lung US can facilitate early diagnosis of pulmonary pathology such as consolidation, abscess, and pleural effusion. Children are amenable to the modality due to their thinner chest wall and smaller thoracic width. Ultrasonography can be performed at the bedside and all exposure to ionizing radiation is avoided. The modality of US has been shown to be more sensitive than radiographs, and comparable to chest CT, in many pulmonary pathologies.

A small retrospective review comparing US against CT found that CT had no advantage in most cases. It suggested that CT should be used in complex cases only, such as patients undergoing operation or thought to have parenchymal abscesses or a broncho-pleural fistula. In addition, CT has been found to be inferior to US at demonstrating fibrin strands or septations within the pleural fluid. The main limitations of US appear to be a lack of 24-hour availability in many centers, a steep learning curve, and the fact that the technique is not well standardized. ^,

Although CT with intravenous contrast can differentiate between parenchymal and pleural processes, the resulting radiation exposure has raised the concern for a long-term cancer risk. CT scans are the largest contributor of medical radiation in the United States, with approximately five to nine million CT studies performed annually. ^, Even low levels of radiation exposure are associated with elevation in cancer risks and more data are emerging. ^, One multicenter European study reported a significant dose–response relationship between CT-related radiation exposure in childhood and brain cancer. Radiation exposure is magnified in young children because of their smaller size compared with adults. Pediatric CTs require careful justification and use of radiation doses as low as reasonably possible. ^,

Most pneumatoceles involute over time and do not require any specific therapy other than supportive care and appropriate antibiotic coverage. In ventilated patients, reduction in mean airway pressure through alternative ventilatory modes, selective bronchial intubation of the contralateral lung, or balloon occlusion of affected bronchi can resolve pneumatoceles, particularly in premature neonates. ^, In the case of respiratory compromise from a rapidly enlarging cyst, cyst rupture with bronchopleural fistula, or tension pneumatocele, urgent decompression may be needed. Various methods have been shown to be effective, including tube thoracostomy or cystostomy and image-guided percutaneous catheter drainage, ^, with surgical treatment reserved for refractory cases. Cyst or lung resection as well as cyst unroofing with oversewing of bronchial defects have been described. ^,

The majority of pneumatoceles decrease in size and resolve over a period of several weeks to months with supportive care and treatment of the underlying cause, and no residual pulmonary compromise or radiologic sequelae are likely in most cases.

Patients typically present with nonspecific symptoms such as chronic or recurrent productive cough, exertional dyspnea, and lethargy. Patients with more advanced disease can present with hemoptysis, chest pain, pulmonary hypertension, and growth failure. Physical examination usually reveals coarse inspiratory crackles and expiratory wheezes, and in more severe cases patients can have digital clubbing or a chest wall hyperinflation deformity. The diagnosis is often delayed due to the lack of specific signs and the low incidence of this disease.

Initial evaluation for children with a chronic productive cough consists of a thorough history and physical examination as well as a chest radiograph. While a chest x-ray typically does not allow for a diagnosis of bronchiectasis, it may show a focal crowding of interstitial markings or honeycombing ( Fig. 21.7 ). Many children with a chronic productive cough but without a clear diagnosis will receive an empiric course of antibiotics, and children who fail to improve or those in whom there is an initial high suspicion for bronchiectasis should receive further investigation, which may include bronchoscopy, genetic or immunologic evaluations, and advanced imaging. High-resolution CT is the preferred imaging modality for the diagnosis of bronchiectasis ( Fig. 21.8 ). ^{, ,} Once diagnosed, all patients with bronchiectasis should receive pulmonary function testing, a sweat chloride test for CF, an immune deficiency screening panel, and sputum microbiology to direct antibiotic therapy.

(A) Chest radiograph demonstrating the classic appearance of bronchiectasis in a pediatric patient with cystic fibrosis. (B) Magnified view of the patient demonstrating a honeycombed appearance to the lung parenchyma.

High-resolution CT demonstrates severe bronchiectasis. On the patient’s left side, dilated bronchi ( arrow ) are seen throughout the lung. Apically, they extend to near the pleural surface. On the patient’s right, the dilated bronchi are seen extending into an upper lobe complicated by infection and consolidation, which can be a recurring problem in patients with bronchiectasis.

For patients with non-CF bronchiectasis, optimal management includes identification and specific treatment of the underlying cause, if possible, as well as aggressive management of acute exacerbations with antibiotics, airway clearance, and ongoing maintenance and supportive therapy. Maintenance therapy consists of chest physiotherapy for airway clearance as well as medications that may include chronic antibiotics, mucolytics, bronchodilators, or glucocorticoids. Supportive therapy includes nutrition, immunization to prevent infection, healthcare infection control measures, and avoidance of environmental irritants like cigarette smoke. Patients with CF, in addition to these therapies, are also treated with antiinflammatories and CF transmembrane conductance regulator (CFTR) modulators to correct the underlying CFTR protein deficiency. ^,

With optimal medical therapy, surgery for bronchiectasis is rarely indicated. However, reports of it are much more common in lower-resource settings where severe and undermanaged disease is more prevalent. Severe bleeding is one possible indication. While scant, mild, or moderate bleeding often responds to medical therapy, severe bleeding should prompt immediate intervention. Bronchial artery embolization is first-line therapy in unstable patients with CF, has a high probability of success without rebleeding, and is useful although less well studied in other causes of bronchiectasis. ^, In more stable patients, rigid or flexible bronchoscopy is used to localize and treat the source of bleeding, with direct or balloon tamponade, laser coagulation, and topical vasoconstrictors and hemostatic agents. Surgery for resection of the affected area should be considered only for life-threatening, ongoing focal bleeding refractory to other therapies.

Carefully selected patients with severe localized disease can be considered for focal lung resection, as less-affected areas of the lung can expand to fill the space. Ventilation-perfusion scanning showing absence of perfusion indicates end-stage disease, which is supportive evidence for resection. The principles of operative treatment should be to preserve as much uninvolved pulmonary parenchyma as possible using segmental resections, with either an open or thoracoscopic approach. ^, A large metaanalysis in non-CF patients included five pediatric studies, where 60% of patients had resolution of chronic symptoms and 37% improved.

Finally, lung transplantation for end-stage disease has been used in carefully selected patients, mainly with bronchiectasis due to CF. Median patient survival in children after transplant is around 5 years, similar to adults.

As with any pleural effusion, chylothorax can present with respiratory symptoms. Congenital cases may be suspected during routine prenatal ultrasound. In postoperative patients, it will classically present with milky drainage from the chest drain/tube. It is important to note that the drainage may seem like normal pleural fluid until enteral nutrition is resumed and the drainage becomes chylous. Analysis of the fluid confirms the diagnosis. Chyle typically demonstrates a fluid to serum protein ratio of 0.5 or more, triglycerides >110 mg/dL, and elevated fluid lactic dehydrogenase. In addition, Gram stain demonstrates the presence of >80% lymphocytes, and Sudan red staining may reveal the presence of chylomicrons. In appropriate cases, ultrasound and echocardiogram may be important adjuncts to evaluate venous thromboembolism/hypertension and the hemodynamic profile, respectively, as potential contributing etiologies.

Magnetic resonance lymphangiography is favored over CT scan to diagnose a lymphatic leak. If available, dynamic contrast-enhanced MR lymphangiography may provide superior visualization of lymphatic flow to better localize leaks for planning interventions or surgical procedures. Conventional lymphangiography utilizing fluoroscopy is traditionally accessed through a pedal site. More recently, intranodal lymphangiography may facilitate greater technical success in real-time diagnostic and therapeutic interventions in pediatric patients.

Pseudochylothorax (also termed cholesterol pleurisy or chyliform effusion) is a rare condition that is characterized by a cholesterol-rich pleural effusion and is commonly associated with chronic inflammatory disorders such as tuberculosis or rheumatoid arthritis. These are often long-standing effusions that are distinguished from chylothorax by the lack of triglycerides and chylomicrons.

Management should involve drain placement and fluid analysis in symptomatic cases. Management of a chylothorax begins with drainage and consideration of the physiological consequences of chyle loss. Protein and fat losses can result in acute malnutrition. Lymphocyte losses result in immunosuppression. The net fluid losses can cause dehydration. Therefore, it is important to appreciate these losses so vigorous monitoring and replacement can occur concomitant with maneuvers to address the leak. Initially, nonoperative maneuvers should be attempted based on the goals of reducing the amount of chyle produced while still providing adequate nutrition.

The chyle leak can be classified as low or high output based on its relationship to 20 mL/kg/day. ^, This may help guide management, as low output leaks can be maintained on a medium-chain triglyceride (MCT)-based diet, while high output leaks should be made nil per os (NPO) with total parenteral nutrition (TPN) supplementation. As many as 80% of patients respond to this management strategy. ^, While on MCT therapy, the patient should be monitored for essential fatty acid deficiency. When clinical response is observed (output decreasing to < 10 mL/kg/day) in iatrogenic chylothorax, new consensus guidelines suggest a fat-modified diet need only be continued for 2–4 weeks, instead of the traditionally recommended minimum of 6 weeks. ^,

In refractory cases, more aggressive therapies, localization studies, and interventions can be pursued. While there are no accepted standards to define refractory management, the Chylothorax Work Group from the Pediatric Cardiac Critical Care Consortium proposed that a continued chest tube output of >10 mL/kg/day after 7 cumulative days while NPO would qualify.

Octreotide, a somatostatin analog, has emerged as an important adjunct in the management of chylothorax, with numerous series and a Cochrane systematic review demonstrating success in both acquired and congenital settings. ^, Some authors advocate octreotide early in the care process. Octreotide may be administrated at an initial dose of 0.5 μg/kg/h. Most clinical algorithms escalate dosing up to 10 μg/kg/h. ^, Notable side effects include hyperglycemia, necrotizing enterocolitis, pulmonary hypertension, transient hypothyroidism, and gastrointestinal intolerance, but studies have demonstrated safe use of Octreotide up to a maximum dosing of 20 μg/kg/h. ^, Other adjuncts are less described but have included steroids in the postoperative cardiac setting, and propranolol and sirolimus in congenital chylothorax. ^{, ,}

Nonoperative therapy is typically recommended for at least 1–2 weeks prior to considering interventional options, though there is no agreed-upon optimal time for surgical intervention, with variation depending on the underlying etiology, severity of symptoms, and available resources. ^{, , , ,} The goal of the operation begins with stopping the leak. This is straightforward if the leak is visualized and can be closed or obliterated. Thoracic duct ligation proximal to the leak is usually curative. Currently, these cases can be approached with thoracoscopy or laparoscopy ( Fig. 21.9 ). Right thoracoscopy with occlusion of the thoracic duct as it crosses the diaphragm has been shown to be a useful technique in patients with a traumatic leak when a clear chylous leakage point cannot be detected. ^, Others have described direct suture of the area of chylous leak followed by the application of fibrin glue or Vicryl mesh for reinforcement. ^{, ,} Identification of the leak site may be facilitated by the administration of heavy cream, and as more recently described, intraoperative indocyanine green (ICG) lymphangiography.

This 2-year-old child underwent repair of a recurrent tracheoesophageal fistula (TEF) via thoracotomy and developed a chylothorax that was unresponsive to nonoperative management by using medium-chain fatty acids, which was followed by nothing per os and total parenteral nutrition, and subsequently somatostatin. The leak was found to be in the thoracic duct along its course in the mediastinum at the level of the TEF repair. Laparoscopy was utilized because he also needed a fundoplication due to significant gastroesophageal reflux, and ligation of the thoracic duct was performed at the time of the laparoscopic fundoplication. In (A), the two instruments are being used to initiate a dissecting plane through the right diaphragmatic crus. Further dissection through the right crus is seen in (B). In (C), the thoracic duct has been exposed and is quite large (cream had been given preoperatively). Ligation of the duct was performed with two silk ties. The first ligature is being tied in (D).

Photos courtesy of Dr. Rebecca Rentea.

In adults, a minimally invasive technique of percutaneous injection of the cisterna chyli with platinum coil embolization of the thoracic duct has been shown to be successful in more than two-thirds of patients with high-output chylothorax in whom nonoperative management has failed. Additionally, embolization using N -butyl cyanoacrylate mixed with lipiodol (1:5–1:20) has also been successful. While conventionally a contrast agent, Lipiodol has been found to have embolic properties as it accumulates at the site of leakage inducing a local inflammatory granulomatous reaction causing fibrosis. While adoption of these techniques in infants and children is limited by technical and anatomic challenges, there is growing experience with these strategies. ^, Compared to traditional pedal access, using intranodal access (via the groin lymph nodes) for interventions such as Lipiodol injection may offer an additional minimally invasive therapy and provide increased technical success in the pediatric population.

If all of the above interventions fail to address, pleurodesis can be attempted. ^, Consideration should be given to the potential toxicity profile of the sclerosing agent in the context of the patient’s age. Previously described pleurodesis agents have included talc, minocycline OK-432, bleomycin, and povidone iodine. D50 may be a feasible alternative sclerosant in premature neonates. In cases of severe congenital chylothorax, earlier intervention (<28 days) with pleurectomy and mechanical pleurodesis and thoracic duct ligation may be associated with improved survival and shorter length of stay. Lymphovenous anastomosis has been described as an additional possible therapy in refractory cases of chylothorax. As a final resort, use of a pleural–peritoneal shunt has been described ( Fig. 21.10 ). The chyle in the pleural space is then manually pumped into the peritoneal cavity where it is absorbed, presumably into the venous system. These shunts can remain open for several months until the chylous leak seals. A variation of this strategy includes diaphragmatic fenestration. It is also worth mentioning that in prenatally diagnosed cases of severe congenital chylothorax, fetal interventions such as thoracoamniotic shunting have been used at experienced fetal centers but are beyond the scope of this chapter.

Insertion of a pleuroperitoneal shunt. (A) The affected hemithorax is elevated 30°. The two incisions are planned to allow the pump chamber to rest on the costal margin. (B) A small incision is made over the rib in the anterior axillary line, and a deep subcutaneous pocket is created inferiorly. (C) Insertion of a pleuroperitoneal shunt into the pleural space is done with a large curved clamp. The pleural catheter is tunneled 2–3 cm and bluntly passed through the intercostal space. The catheter must be carefully passed through the intercostal muscle at an angle to avoid kinking. (D) A second small incision is made overlying the rectus muscle, and the peritoneal catheter is tunneled through this incision. The distal end of the shunt device is delivered to the second incision, as shown. The pumping chamber is drawn into the subcutaneous pocket by traction on the peritoneal catheter. (E) The flow of chyle is confirmed before the distal catheter is inserted into the peritoneum. (F, G) A purse-string suture is used to secure the peritoneal catheter at the level of the posterior rectus fascia. (H) Both incisions should be closed with an absorbable suture, leaving a totally implanted system.

Adapted from Murphy M, Newman B, Rodgers B. Pleuroperitoneal shunts in the management of persistent chylothorax. Ann Thorac Surg. 1989;48:195–200.