Pleural effusion
Pleural effusion is an abnormal accumulation of fluid between the layers of the pleura, the membranes that line the lungs and chest cavity. This condition can be classified as either malignant or nonmalignant, with the fluid varying in protein content—exudative (rich in protein) or transudative (protein-poor). Common causes include lung cancer, pneumonia, congestive heart failure, and complications from chest surgery or trauma. Symptoms may include shortness of breath, chest pain, and a dry cough, although some individuals may be asymptomatic, with the effusion detected incidentally during imaging studies.
Diagnosis typically involves a thorough medical history, physical examination, imaging tests such as chest X-rays or CT scans, and procedures like thoracentesis, where fluid is extracted for analysis. Treatment strategies are tailored to the underlying cause and may involve fluid drainage, use of sclerosing agents, or surgical interventions in more severe cases. The prognosis of pleural effusion largely depends on the associated medical conditions, with malignant pleural effusions often indicating advanced disease. Management has increasingly transitioned to outpatient care, emphasizing the need for ongoing monitoring and intervention when necessary.
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Subject Terms
Pleural effusion
ALSO KNOWN AS: Parapneumatic effusion, water or fluid in the chest, pleural fluid
RELATED CONDITIONS: Lung cancer
DEFINITION: A pleural effusion is the abnormal collection of excess fluid between the layers of the pleura, the membranes lining the lungs and chest cavity. Pleural effusions are either malignant or nonmalignant.
Depending on the cause of the pleural effusion, the excess fluid is either rich in protein (exudative) or protein-poor (transudative or watery). Congestive heart failure and abnormal lung pressure are often associated with transudative pleural effusions. Certain cancers, kidney disease, pneumonia, or other lung infections are usually associated with exudative pleural effusions.
Risk factors: The risk factors for pleural effusions include chemotherapy or radiation therapy of the chest, a collapsed lung, lung cancer, breast cancer, lymphoma, and leukemia. Pleural effusions may occur as a complication of abdominal or thoracic surgery or because of chest trauma.
Etiology and the disease process: A small amount of fluid is normally present in the pleural cavity to lubricate the pleural surfaces. The abnormal collection of fluid in the pleural space may occur as the result of cancer treatment such as chemotherapy or radiation therapy or in the presence of a collapsed lung or certain cancers. About 15 percent of cancer patients will get malignant pleural effusions. In addition, lung cancer, breast cancer, lymphoma, and account for approximately 75 percent of all malignancy-related pleural effusions. In some cases, the fluid itself is malignant.
Incidence: In the United States, approximately 1.5 million cases of pleural effusions are diagnosed per year, of which between 150,000 and 250,000 are malignant.
Symptoms: Symptoms of pleural effusion include shortness of breath, rapid or labored breathing, chest pain, hiccups, and dry cough. Additional symptoms are often related to the underlying condition, such as fluid retention and swelling. In some cases, there are no symptoms, but the effusion may be discovered during a routine chest X-ray or other diagnostic test.
Screening and diagnosis: The accurate diagnosis of a pleural effusion is essential so that treatment can be targeted for malignant effusions. The first steps in the diagnosis include a medical history and physical exam, lung-function tests, and chest X-ray.
Other diagnostic tests include a computed tomography (CT) scan, chest ultrasound, thoracentesis, and pleural fluid analysis (biopsy). A thoracentesis removes pleural fluid by a needle inserted through the chest wall, between the ribs. The pleural fluid is then analyzed in the laboratory. Thoracoscopy (T-scope) and pleural biopsy are performed in some cases when a thoracentesis cannot be done because of the location of the effusion. A thoracoscopy is a minimally invasive surgical procedure performed with a small videoscope instrument (thoracoscope) and surgical instruments. The scope and instruments are inserted through small incisions to examine the chest cavity and remove a tissue sample or pleural fluid sample (pleural biopsy). The sample is then examined in a laboratory.
Treatment and therapy: In cancer patients, not all pleural effusions are malignant but may result from malnutrition or a comorbid condition, such as congestive heart failure, pulmonary embolism, or pneumonia. Treatment is directed at the underlying medical condition or type of cancer causing the pleural effusion. The goals of treatment include draining excess fluid, treating infection, and fully expanding the lung. When the effusion is transudative and asymptomatic, no treatment may be needed.
Treatment options include thoracentesis, use of sclerosing agents, or surgery. Thoracentesis helps reduce pressure on the lungs by removing excess fluid. It can be used as a palliative treatment to relieve symptoms of advanced cancers. Sclerosing agents such as talc, doxycycline, and bleomycin may be inserted through a chest tube during thoracentesis to prevent a recurring effusion. Sclerosing agents also may be used during pleurodesis, a procedure to close the pleural sac. Pleurodesis is usually performed for cases of recurring malignant effusions in patients with metastatic breast, ovarian, or lung cancer.
Surgical options to drain excess fluid include thoracotomy (open-chest surgery) or minimally invasive video-assisted thoracoscopic surgery. Surgery is recommended for the treatment of infections or when the location of the effusion prohibits the use of thoracentesis for fluid analysis. In some cases, a pleural-peritoneal is implanted to transfer fluid from the pleural cavity to the abdominal cavity, where it can drain more easily. is another surgery performed under general anesthesia to remove the parietal pleura, the outermost lining around the lungs. Video-assisted thoracoscopic surgery and thoracic ultrasound have advanced surgical techniques.
Prognosis, prevention, and outcomes: The outcome of a pleural effusion depends on the underlying condition causing the effusion. Potential complications of a pleural effusion include an empyema (abscess in the pleural space) if the pleural fluid becomes infected and a collapsed lung if the fluid has built up for a long time. In patients with reoccuring pleural effusions, indwelling pleural catheters can reduce the need to drain fluid. Further, management of pleural effusion has become an increasing outpatient issue. Malignant pleural effusions are often associated with advanced disease and increased morbidity and mortality.
Bibliography
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