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Parapneumonic Effusions and Empyema
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Definition/Natural History
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Pneumonia accounts for up to 60% of pleural effusions. Most of these effusions are sterile, clear exudates that generally resolve with antibiotic treatment and rarely require tube drainage. Some (5%), however, are complicated with loculations and fibrin deposits. The fluid may be infected, as suggested by a low glucose, an elevated LDH, and a low pH. This stage of pneumonia is not thought to resolve with antibiotics alone and predisposes the patient to complications such as continued pleural sepsis and empyema.
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Empyema progresses through three stages: exudative, fibrinopurulent, and organizing. In the exudative stage, the pleural fluid is nonviscous and freely flowing, with minimally inflamed pleural membranes, and the patient is likely to respond to antibiotics. The early fibrinopurulent stage is characterized by increasing viscosity of the fluid, thickening of the pleural membranes, and formations of intrapleural loculations. Patients may respond to antibiotic therapy alone but often require emptying of the pleural space. In the organized stage, more aggressive intervention is indicated, and on many occasions, the patient will require management for the pleural peel that has formed.
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All patients with pleural infections should be treated with antibiotics. Depending on the clinical picture, anaerobic coverage is also included. Published guidelines are followed if the culture comes back negative.4 In designing a specific treatment plan, it is important to recognize that antibiotics penetrate the pleural space to varying degrees. As a rule, aminoglycosides usually are avoided because of their poor pleural space penetration and weak action in an acidic environment.
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In 2000, a consensus statement was published by the American College of Chest Physicians.5 The statement proposed the following recommendations for drainage in the management of parapneumonic effusions:
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Patients with category 1 and 2 effusions are at low risk for poor outcome and do not require drainage.
Drainage is recommended for the management of patients with category 3 and 4 parapneumonic effusions because of the increased risk for mortality and need for a second intervention.
Therapeutic thoracentesis or tube thoracostomy alone is insufficient for the management of patients with category 3 and 4 parapneumonic effusions.
Fibrinolysis and video-assisted thoracic surgery are acceptable approaches for these patients based on mortality and need for a second intervention.
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Recurrent Nonmalignant Pleural Effusions
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Data that would guide the use of pleurodesis in nonmalignant pleural effusions are scarce. There are no controlled trials comparing various agents and methods of pleurodesis in nonmalignant effusions. In two cohorts,6,7 the authors studied the outcome of talc poudrage in patients with nonmalignant pleural effusions. Their success rate was 97% during a follow-up period of 1 to 84 months. Side effects included prolonged drainage (50%), reexpansion pulmonary edema (2%), and empyema (2%). Acute respiratory distress syndrome did not develop in any patient. From these limited data, it would appear that the success of pleurodesis in the management of nonmalignant pleural effusions is higher than one would expect. We do not recommend pleurodesis as a first-line treatment, but only after treatment of the causative disease has been fully maximized, if the patient is still experiencing symptoms attributable to the pleural effusion.
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Immunologic and Connective Tissue Disorders
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The effectiveness of steroid therapy in treating a variety of immunologic and connective tissue disease entities is well established. However, the data used to define the role of steroids in the management of connective tissue disease-related pleural effusions are limited to case reports and small series.
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Pleural involvement in patients with rheumatoid arthritis is clinically evident in up to 5% of patients. These effusions are characterized by low glucose levels that develop within 5 years of articular manifestations. Once steroid treatment is instituted, the pleural effusion usually resolves within 3 to 4 months. Treatment can be systemic or intrapleural, and the response to therapy is independent of the articular inflammation. Half of these patients, unfortunately, will have a protracted course.
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Among the connective tissue disorders, systemic lupus erythematosis is the most common cause of pleuritis. Pleuritis in systemic lupus erythematosis presents more often in women than in men, with pleural effusions occurring in up to 30% of patients. The pleural symptoms may antedate other disease manifestations and can be bilateral, unilateral, or alternate from one side to the other. A 60- to 80-mg dose of prednisone daily produces positive results in patients with lupus-related pleural effusions.
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Pleural effusion is a rare complication of sarcoidosis. The natural history of sarcoidosis-related pleural effusions is variable; some resolve spontaneously, whereas others resolve with treatment within the same time frame. The approach to a sarcoidosis-related pleural effusion is individualized, and treatment is reserved for symptomatic patients. The dose of prednisone used is variable, ranging between 20 and 40 mg/day with a taper over 3 to 4 weeks.
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Postcardiac Injury Syndrome
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Postcardiac injury syndrome is an immunologic entity associated with a wide array of manifestations, including pericarditis, fever, leukocytosis, elevated sedimentation rate, pulmonary infiltrates, and pleural effusion. The syndrome can occur days, weeks, and even months after myocardial infarction, cardiac surgery, pacemaker placement, and angioplasty. It is seen more commonly after cardiac surgery, occurring in up to 30% of patients.8 The effusion is usually treated with antiinflammatory medication and exhibits a variable time course for adequate response. Nonresponders require steroids tapered over 3 to 4 weeks.
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Hepatic hydrothorax is the term for a pleural effusion arising in a patient with cirrhosis. It is usually the result of fluid transfer from the abdomen to the pleural space via defects in the diaphragm. Most often it is right-sided, and ascitic fluid can be absent in many patients. The first-line treatment is the administration of diuretics and sodium restriction. This treatment is given to counteract ascites caused by sodium retention in the kidney. An inappropriate increase in the dose of diuretics can precipitate hepatic encephalopathy in some of these patients, a severe and life-threatening complication. Common diuretics used include spironolactone and furosemide. If these treatment regimens fail, patients may benefit from a transjugular intrahepatic portosystemic shunt procedure. Thoracentesis is reserved for symptomatic patients and patients with fever, to rule out a spontaneous bacterial empyema. Tube thoracostomy with talc pleurodesis attempts have largely been unsuccessful. This therapy can result in prolonged chest tube drainage, excessive protein loss, renal failure, infection, and severe leak at the chest tube site. Treatment failures using this approach are probably secondary to the rapid formation of fluid in the pleural space, which prevents the formation of adhesions between the visceral and parietal pleura. Pleurodesis generally is not recommended for the medical management of hepatic hydrothorax. We have used indwelling drainage catheters in patients with needs for multiple thoracenteses with an overall good success rate. Patients with hepatic hydrothorax nonresponsive to diuretic treatment constitute a difficult population, and the treatment approach must be individualized.
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A hemothorax is defined as bleeding in the pleural space sufficient to raise the pleural space hematocrit to 50%. Independent of cause, large-tube drainage is the primary therapy because large volumes of blood in the pleural space rapidly form intrapleural loculations and increase the risk for empyema and fibrothorax. In some patients with retained intrapleural blood, fibrinolytic agents are instilled with good results.9 If performed early in the course of the injury, before pleural adhesions form, thoracoscopy can play an important role in the management of patients who sustain traumatic hemothorax complicated by major intrathoracic vessel injury and air leaks.
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Chylothorax, defined as the appearance of lymph and emulsified fat in the pleural effusion, is a rare cause of pleural effusion and is mostly owing to malignancy, thoracic surgical procedures, and chest trauma. A number of cases are associated with diseases such as lymphangioleiomyomatosis and lymphangiectasis. After the underlying cause is determined, specific treatment may be effective for managing the resulting chylothorax. The cornerstone of treatment involves nutritional intervention to prevent protein, vitamin, and lymphocyte loss. Success with a medium-chain triglyceride diet has been variable. Conservative management in a symptomatic patient involves drainage of the chylous effusion by thoracentesis or chest tube placement. Somatostatin has been used successfully in a few cases of chylous effusions refractory to chest tube drainage. Pleurodesis can be successful in the management of chylothoraces, especially if the rate of chyle flow is not high. In refractory cases, embolization and surgical interventions such as ligation, pleuroperitoneal shunting, and fibrin glue application are used.