Pleural Effusion in Children : A Review

Introduction Pediatrics pleural effusion is an abnormality frequently develops from the collection of fluids in the pleural space commonly caused by a primary phenomenon or secondary to variety of disorders such as an infection. This accumulated fluid can be originated from excessive filtration or defective absorption. Despite asymptomatic feature in mild effusion, it may be accompanied with complications such as respiratory failure due massive fluid accumulation, septicemia, bronchopleural fistula, pneumothorax, and pleural thickening (1). Pathophysiology Any conditions that may lead to fluid effusion increase into the pleural space can cause pleural effusion. In this regard, different baseline mechanisms suggested for pleural effusion include empyema, abnormal capillary permeability leading, increased hydrostatic or decreased oncotic pressure in the setting of normal capillaries, abnormal lymphatic clearance, and also hemothorax (2). Etiology The etiological mechanisms of pleural effusion is considerably different in childhood and adulthood that the effusion secondary to pleural infections is the most common cause of this abnormality in children, while the most common causes in adults have been shown to be congestive heart failure and malignancies (3). Some population-based studies have shown that about half of pediatrics pleural effusion can be caused by pneumonia, followed by malignancies, renal disorders, trauma, and heart failure (4). In infectious pleural effusion, bacterial infections are the most common sources may led to serious complications such as empyema; however effusion can be less commonly occurred by viral infections that are usually asymptomatic. Among bacterial causes of pleural effusion, Streptococcus pneumoniae is the most common germ for this abnormality (5-6-7). In this context, among different serotypes of this pathogen, serotype 1 is dominant in children with empyema (8-12). Although Streptococcus pneumoniae is the most infectious etiology for pediatrics pleural effusion, but other less common causes for this defect include communityacquired methicillin-resistant Staphylococcus aureus, Haemophilus influenzae type B, coagulase-negative staphylococcus, and other streptococcal species as viridans streptococcus, Group A streptococcus, alpha-hemolytic streptococcus (13-15). Another cause of pleural effusion in children is pulmonary tuberculosis that was widely reported in 2 to 38% (16). This infection is frequently unilateral that may be occurred primarily as from direct hematogenous invasion of the pleural space or secondary to a reactivation disease such as pulmonary parenchymal disease (17). Disseminated Mycobacterium bovis also reported with complicated pneumonia (18). Pediatrics pleural effusion is an abnormality that frequently develops from collection of fluids in the pleural space and commonly caused by a primary phenomenon or secondary to variety of disorders such as infections. This accumulated fluid can be originated from excessive filtration or defective absorption caused by different infectious agents such as Streptococcus pneumoniae, which is the most common, or non-infectious factors like lymphoma or congestive heart failure. It may present a various range of complications from a self-limited one to respiratory failure. Pediatrics pleural effusion is most commonly seen in boys and younger children. The incidence and distribution of pleural effusion is increasing in most industrial countries according to the population studies. The prognosis is highly related to the underlying disorder as well as treatment approach. early drainage of fluid may dramatically reduce the rate of mortality and morbidity. Clinical manifestations are variable depended on the underlying disease, size, and location of the effusion. They range from persistent fever, cough, anorexia, malaise, tachypnea, dyspnea, and chest pain, like in infectious pneumonia, to abdominal pain, distension and vomiting. In physical examinations a pleural rub may be the only initial manifestation during the early stage of pleurisy. A large amount of fluid diminishes the chest excursion on the affected side and may shift the mediastinum and displace the trachea and cardiac apex to the contralateral side, unilaterally. Initial diagnostic test for ruling out the different causes of pleural effusion is analyzing the pleural fluid apparently and biochemically. Also imaging tests could be used such as chest radiography so as to ensure the existence of pleural effusion. Ultrasonography and computed tomography (CT) scanning are also beneficial for a more accurate assessment. In most affected cases removing underlying etiologies and also applying supportive care are sufficient to heal effusion, which can range from antibiotic therapy and using fibrinolytics to chest tube drainage. Surgical therapy in patients with pleural effusion with the failed medical management has remained controversial, though. Thus, selection of the best management approach can result in favorable outcomes and significantly reduces morbidity and mortality rates.