Pleurisy Health Article

Definition

Pleurisy is an inflammation of the membrane that surrounds and protects the lungs (the pleura). Inflammation occurs when an infection or damaging agent irritates the pleural surface. Sharp chest pains are the primary symptom of pleurisy.

Description

Pleurisy, also called pleuritis, is a condition that generally stems from an existing respiratory infection, disease, or injury. In people who have otherwise good health, respiratory infections or pneumonia are the main causes of pleurisy. This condition used to be more common, but with the advent of antibiotics and modern disease therapies, pleurisy has become less prevalent.

The pleura is a double-layered structure made up of an inner membrane, which surrounds the lungs, and an outer membrane, which lines the chest cavity. The pleural membranes are very thin, close together, and have a fluid coating in the narrow space between them. This liquid acts as a lubricant, so that when the lungs inflate and deflate during breathing, the pleural surfaces can easily glide over one another.

Pleurisy occurs when the pleural surfaces rub against one another, due to irritation and inflammation. Infection within the pleural space is the most common irritant, although the abnormal presence of air, blood, or cells can also initiate pleurisy. These disturbances all act to displace the normal pleural fluid, which forces the membranes to rub, rather than glide, against one another. This rubbing irritates nerve endings in the outer membrane and causes pain. Pleurisy also causes a chest noise that ranges from a faint squeak to a loud creak. This characteristic sound is called a "friction rub."

Pleurisy cases are classified either as having pleural effusion or as being "dry." Pleural effusion is more common and refers to an accumulation of fluid within the pleural space; dry pleurisy is inflammation without fluid build-up. Less pain occurs with pleural effusion because the fluid forces the membrane surfaces apart. However, pleural effusion causes additional complications because it places pressure on the lungs. This leads to respiratory distress and possible lung collapse.

Causes & symptoms

A variety of conditions can give rise to pleurisy. The following represent the most common sources of pleural inflammation:

• infections, including pneumonia, tuberculosis, and other bacterial or viral respiratory infections
• immune disorders, including systemic lupus erythematosus, rheumatoid arthritis, and sarcoidosis
• diseases, including cancer, pancreatitis, liver cirrhosis, and heart or kidney failure
• injury, from a rib fracture, collapsed lung, esophagus rupture, blood clot, or material such as asbestos
• drug reactions, from certain drugs used to treat tuberculosis (isoniazid), cancer (methotrexate, procarbazine), or the immune disorders mentioned above (hydralazine, procainamide, phenytoin, quinidine).

The hallmark symptom of pleurisy is sudden, intense chest pain that is 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 of pleurisy is that holding one's breath or exerting pressure against the chest causes pain relief.

Pleurisy is also characterized by certain respiratory symptoms. In response to the pain, pleurisy patients commonly have a rapid, shallow breathing pattern. Pleural effusion can also cause shortness of breath, as excess fluid makes expanding the lungs difficult. If severe breathing difficulties persist, patients may experience a blue-colored complexion (cyanosis).

Diagnosis

The distinctive pain of pleurisy is normally the first clue physicians use for diagnosis. Doctors usually feel the chest to find the site of inflammation. A stethoscope is used to listen for abnormal chest sounds (such as the friction rub) as the patient breathes. Sometimes, a friction rub is masked by the presence of pleural effusion and further examination is needed for an accurate diagnosis.

To diagnose the illness that is causing pleurisy, doctors must evaluate the patient's history, additional symptoms, and laboratory test results. A chest x ray may also be taken to look for signs of accumulated fluid and other abnormalities. Computed tomography (CT) scan and ultrasound scans are more powerful diagnostic tools used to visualize the chest cavity.

The most helpful information in diagnosing the cause of pleurisy is a fluid analysis. Once the doctor knows the precise location of fluid accumulation, a sample is removed using a procedure called thoracentesis. In this technique, a fine needle is inserted into the chest to reach the pleural space and extract fluid. Several laboratory tests are performed to analyze the chemical components of the fluid and determine whether bacteria or viruses are present. Pleurisy associated with rheumatoid arthritis produces a distinctive pattern of tissue cells in the pleural fluid. Cancerous growths also shed cells into the tissue fluid. While most cases of pleurisy associated with cancer are secondary developments from a primary tumor, in some instances the pleurisy is the first indication of a malignancy.

In certain instances a biopsy of the pleura may be needed for microscopic analysis. A sample of pleural tissue can be obtained several ways: with a biopsy needle, by making a small incision in the chest wall, or by using a thoracoscope (a video-assisted instrument for viewing the pleural space and collecting samples).