Definition

Humans breathe using their lungs, of which there are two: the right lung and the left lung. Both lungs are covered by a membrane known as the pleura, which separates them from the chest cavity they occupy. This membrane functions to protect the lungs and the chest cavity.

The pleural layer is divided into two based on the part it covers: the visceral pleura covers the lung organ, and the parietal pleura covers the inner part of the chest cavity. The pleural cavity or space is formed between these two types of pleural membranes. This space contains pleural fluid, which lubricates and helps maximize lung contraction during breathing. Under normal conditions, the fluid in the pleural space is only a small amount, ranging from 0.1 to 0.2 mL per kilogram of body weight.

The pleural membrane can become inflamed, a condition known as pleuritis. Inflammation of the pleura causes typical pain symptoms (pleuritic pain), described as a stabbing chest pain that worsens, especially when coughing or breathing deeply.

There are many causes of pleuritis. When a doctor suspects pleuritis, they will investigate the underlying cause. In some cases, pleuritis may also involve pleural effusion, which occurs when the amount of fluid in the pleural cavity increases abnormally.

When inflammation accompanies pleural effusion, fluid accumulation can compress the lungs and impair their function. As the amount of fluid in the pleural cavity increases, shallow breathing may result. When fluid accumulation is accompanied by infection or pus in the pleural cavity, the condition is empyema.

Causes

Several diseases can cause pleuritis. Some of the most common medical conditions that often cause pleuritis are tuberculosis and pneumonia. Below are medical conditions that can cause inflammation of the pleura:

• Cancer or malignancy, which can affect the lung organ, pleural membrane, or adjacent areas
• Chest trauma
• Endometriosis of the chest, where tissue from the uterine wall grows abnormally in the chest
• Rheumatoid arthritis, an autoimmune disease causing joint inflammation
• Pneumothorax, or the entry of air into the pleural cavity, leading to lung collapse
• Aortic dissection, or tearing of the large aorta blood vessel
• Pneumonia (infection causing lung inflammation)
• Pericarditis, or inflammation of the heart membrane
• Viral infections such as influenza or shingles
• Embolism, or blood clots in the pulmonary arteries

Pleuritis can affect people of all ages. However, individuals over the age of 65 are at higher risk due to chest infections, making them susceptible to pleuritis.

Risk factor

Several conditions can increase a person's risk of developing pleuritis, including:

• Respiratory tract diseases
• Asbestosis, or lung disease due to inhaling asbestos
• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Cancer or malignancy
• Autoimmune diseases such as lupus and rheumatoid arthritis
• History of chest surgery or chest trauma
• Inflammatory bowel disease
• Certain medications such as hydralazine (for high blood pressure), isoniazid (tuberculosis antibiotic), and procainamide (for irregular heartbeat)

Symptoms

Symptoms of pleuritis include pleuritic pain, described as a sharp stabbing pain felt during breathing. This pain may subside when breathing or applying pressure to the painful area but worsens with sneezing, coughing, or changing positions. Other symptoms may include:

• Pain on one side of the chest, radiating to the shoulder and back
• Shallow and rapid breathing to avoid pain
• Fever
• Chills
• Loss of appetite

Diagnosis

Interview and physical examination

The doctor will interview the patient to inquire about symptoms, other lung diseases, and medical history. If symptoms suggestive of pleuritis are present, the doctor will physically examine the lungs using a stethoscope. In pleuritis, a distinctive sound caused by the movement of the inflamed pleural membrane can be heard when the chest wall moves (during breathing, coughing, sneezing, etc.).

Diagnostic test

The doctor may perform several tests to confirm the diagnosis of pleuritis, including blood tests and imaging studies. Blood tests can reveal signs of infection or inflammation in the body. If the patient experiences shortness of breath, blood gas analysis may be performed to assess blood acidity, oxygen, and carbon dioxide levels.

As symptoms are localized to the chest, the doctor may conduct an electrocardiogram (EKG) to evaluate heart function and determine if symptoms originate from the heart.

Various imaging studies may be used to assess the chest cavity, including:

• Chest X-ray
• CT (Computerized Tomography) scan or MRI (Magnetic Resonance Imaging)
• Ultrasound

Management

Patients may find relief by lying on the painful side of the chest. Pain relief medications are typically prescribed for pleuritic pain. Additionally, treatment is provided based on the underlying cause of pleuritis.

Antibiotics may be prescribed for infections or pus in the pleural cavity. If pleuritis is caused by autoimmune diseases, anti-inflammatory drugs or steroids may be used. Depending on the tumor's stage, treatment options for pleuritis caused by tumors may include surgery, radiation therapy, or chemotherapy.

The outcome of treatment depends on the severity of the underlying disease. Early diagnosis and treatment can lead to complete recovery.

Complications

Complications of pleuritis depend on the progression of the underlying disease and may include:

• Hemithorax, or blood filling in the pleural cavity
• Pleural effusion, leading to difficulty breathing
• Recurrent pneumonia infections
• Thickening of the pleural membrane and formation of scar tissue

Prevention

Pleuritis cannot be prevented entirely, but steps can be taken to reduce the risk by treating underlying diseases and quitting smoking.

When to see a doctor?

Seek medical attention immediately if experiencing stabbing chest pain during breathing or other symptoms of pleuritis.