What is pleura?
Pleura is a membrane that covers the lungs and the inner wall of the chest; visceral and parietal pleura respectively. In normal breathing, they slide over each other without any friction.
What is pleurisy?
It is a condition where the pleurae are inflamed and cause pain due to friction during breathing.
What are the symptoms of pleurisy?
The main symptom is sudden, intense chest pain usually located over the area of inflammation. Although the pain can be constant, it is usually most severe when the lungs move during breathing, coughing, sneezing, or even talking. The pain is usually described as shooting or stabbing but, in minor cases, it resembles a mild cramp. When pleurisy occurs in certain locations, such as near the diaphragm, the pain may be felt in other areas such as the neck, shoulder, or abdomen (referred pain). Another indication is that holding one’s breath or exerting pressure against the chest causes pain relief.
Do patients have breathing difficulty?
Yes. Pleurisy is also characterized by certain respiratory symptoms. In response to the pain, patients commonly have a rapid, shallow breathing pattern. Sometimes fluid accumulation can occur. This is called pleural effusion.
What happens in pleural effusion?
In pleural effusion fluid accumulates between both pleurae. When this occurs pain disappears but respiratory difficulty on exertion occurs. In early stages it is not noticeable while walking on plains but becomes manifest when they climb stairs and run to catch a bus. Disappearance of chest pain should not make one complacent. Be careful enough to observe if they are getting breathless on slight exertion. This should alert them to see a physician.
What kinds of fluid can accumulate in the pleural cavity?
Fluid accumulation can range from simple fluid, pus, blood, lymph and, sometimes, faecal matter and urine if there is an accident and multiple organs are involved.
Pleural effusion is excess fluid that accumulates in the pleural cavity, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during inhalation.
Four types of fluids can accumulate in the pleural space:
Pleural effusion Chest x-ray of a pleural effusion. The arrow A shows fluid layering in the right pleural cavity. The B arrow shows the normal width of the lung in the cavity
Transudate vs. exudate
The third step in the evaluation of pleural fluid is to determine whether the effusion is a transudate or an exudate. Transudative pleural effusions are caused by systemic factors that alter the balance of the formation and absorption of pleural fluid (e.g., left ventricular failure, pulmonary embolism, and cirrhosis), while exudative pleural effusions are caused by alterations in local factors that influence the formation and absorption of pleural fluid (e.g., bacterial pneumonia, cancer, and viral infection).
Transudative and exudative pleural effusions are differentiated by comparing chemistries in the pleural fluid to those in the blood. According to a meta-analysis, exudative pleural effusions meet at least one of the following criteria [1]:
- Pleural fluid protein >2.9 g/dL (29 g/L)
- Pleural fluid cholesterol >45 mg/dL (1.16 mmol/L)
- Pleural fluid LDH >60 percent of upper limit for serum
Previously criteria proposed by Light for an exudative effusion are met if at least one of the following exists (Light’s criteria) [2]:
- The ratio of pleural fluid protein to serum protein is greater than 0.5
- The ratio of pleural fluid LDH and serum LDH is greater than 0.6
- Pleural fluid LDH is more than two-thirds normal upper limit for serum
Twenty-five percent of patients with transudative pleural effusions are mistakenly identified as having exudative pleural effusions by Light’s criteria. Therefore, additional testing is needed if a patient identified as having an exudative pleural effusion appears clinically to have a condition that produces a transudative effusion. In such cases albumin levels in blood and pleural fluid are measured. If the difference between the albumin levels in the blood and the pleural fluid is greater than 1.2 g/dL (12 g/L), it can be assumed that the patient has a transudative pleural effusion.
If the fluid is definitively identified as exudative, additional testing is necessary to determine the local factors causing the exudate.
Exudative pleural effusions
Once identified as exudative, additional evaluation is needed to determine the cause of the excess fluid, and pleural fluid amylase, glucose, pH and cell counts are obtained. The fluid is also sent for Gram staining and culture, and, if suspicious for tuberculosis, examination for TB markers (adenosine deaminase > 45 IU/L, interferon gamma > 140 pg/mL, or positive polymerase chain reaction (PCR) for tuberculous DNA).
Pleural fluid amylase is elevated in cases of esophageal rupture, pancreatic pleural effusion, or cancer. Glucose is decreased with cancer, bacterial infections, or rheumatoid pleuritis. Pleural fluid pH is low in empyema (<7.2) and may be low in cancer. If cancer is suspected, the pleural fluid is sent for cytology. If cytology is negative, and cancer is still suspected, either a thoracoscopy, or needle biopsy of the pleura may be performed.
Causes
The most common causes of transudative pleural effusions in the United States are left ventricular failure, pulmonary embolism, and cirrhosis (causing hepatic hydrothorax), while the most common causes of exudative pleural effusions are bacterial pneumonia, cancer (with lung cancer, breast cancer, and lymphoma causing approximately 75% of all malignant pleural effusions), viral infection, and pulmonary embolism. Although pulmonary embolism can produce either transudative or exudative pleural effusions, the latter is more common.
Other causes of pleural effusion include tuberculosis (though pleural fluid smears are rarely positive for AFB, this is the most common cause of pleural effusion in some developing countries), autoimmune disease such as systemic lupus erythematosus, bleeding (often due to chest trauma), chylothorax (most commonly caused by trauma), and accidental infusion of fluids. Less common causes include esophageal rupture or pancreatic disease, intraabdominal abscess, rheumatoid arthritis, asbestos pleural effusion, Meigs syndrome (ascites and pleural effusion due to a benign ovarian tumor), and ovarian hyperstimulation syndrome.
Pleural effusions may also occur through medical/surgical interventions, including the use of medications (pleural fluid is usually eosinophilic), coronary artery bypass surgery, abdominal surgery, endoscopic variceal sclerotherapy, radiation therapy, liver or lung transplantation, and intra- or extravascular insertion of central lines.
Diagnosis
How can pleural effusion be diagnosed?
The symptoms of chest pain and respiratory difficulty are too classic to be missed. A chest x-ray can easily diagnose effusion.
What are the causes of pleural effusion?
It could be due to infections like TB, pneumonia or cancers. Pleural effusion can also occur in heart failure, liver diseases and kidney diseases where improper diet and decrease in protein are the causes. In fact they are bigger causes of pleural effusion.
Are there any tests to diagnose the cause of pleural effusion?
The fluid in the chest can be removed by a procedure called aspiration. In this a needle is introduced through the skin under local anaesthesia, fluid is withdrawn and sent for bacteriological and pathological tests. This test can be done under the guidance of a radiologist, as he can guide the needle exactly to the point where fluid is located. The tests and the markers are to be decided by your physician.
Can effusion occur in people who smoke?
People who smoke are prone to lung cancer and when cancer involves pleura, effusion occurs making the cancer slightly advanced.
Which is the best way to confirm the cause of effusion?
The confirmatory test is pleural biopsy, which can be done by a needle or thoracoscopy.These small pieces of pleural tissue is sent for a pathological examination that will confirm the diagnosis.
What is pleuroscopy?
Some times the needle biopsy may not yield the diagnosis. In such cases pleuroscopy can be used. It is a fibre-optic instrument that is passed into the chest and the whole pleural cavity can be visualised in a monitor, biopsies can be taken under vision. In this procedure the diagnosis can be obtained with greater accuracy.
Can all the fluid be removed?
All the fluid is removed only during respiratory difficulty or when it is accumulating rapidly. This occurs more often in cancers. A tube is then kept in the chest cavity to prevent the rapid expansion of the lung. In cancer after complete expansion a chemical or talc powder is introduced to seal the chest cavity to prevent further accumulation.
The free end of the Chest Drainage Device is usually attached to an underwater seal, below the level of the chest. This allows the air or fluid to escape from the pleural space, and prevents anything returning to the chest.
Treatment depends on the underlying cause of the pleural effusion. Therapeutic aspiration may be sufficient; larger effusions may require insertion of an intercostal drain (either pigtail or surgical). Repeated effusions may require chemical (talc, bleomycin, tetracycline/doxycycline) or surgical pleurodesis, in which the two pleural surfaces are attached to each other so that no fluid can accumulate between them.
