Definition

Pulmonary contusion is when lung tissue sustains damage, either directly or indirectly, due to chest trauma, characterized by swelling or bruising in the alveoli (air sacs in the lungs). Damage occurs without significant structural harm to the lungs, such as tearing or lacerating lung tissue. However, due to the bruising or swelling, the lung may experience diminished function.

Pulmonary contusion stands as the most common type of lung injury among patients with chest trauma. Often, this condition occurs alongside other traumas, such as cardiac contusion, head trauma, diaphragm rupture, spleen, aorta, heart, and intestinal injuries. Chest injuries may result from encounters with sharp or blunt objects. The most severe complication of contusion is the rupture of the airway or lung.

Causes

Pulmonary contusion typically arises from blunt trauma or shock caused by sharp object trauma to the chest. It often involves high-energy impacts and is commonly encountered in:

• Traffic accidents
• Workplace accidents
• Falls from heights
• Compression of the chest by heavy objects
• Sudden blows to the chest, often in cases of physical violence
• Explosions
• Sports-related injuries

Contusion generally manifests at the site of impact. The speed and compression level of the impact are crucial factors contributing to lung tissue damage. Resultant damage includes tearing of alveoli and small blood vessels (capillaries) in the lung area, leading to blood and fluid accumulation within lung tissue. Initially, blood appears in the affected lung area, followed by swelling in and around the area several hours later.

Additionally, lung tissue loses its elasticity, hindering lung expansion and respiratory function. Accumulated blood, fluid, and swelling disrupt air exchange, resulting in oxygen deficiency. Although the injury occurs on one side of the chest, swelling and inflammatory reactions may extend to the other side as well.

Risk factor

A contusion can affect anyone, but children are more susceptible due to their greater chest wall flexibility at a young age.

The flexibility of the chest wall dictates the amount of energy impacting lung tissue. Adult rib cages, being stiffer, can absorb more energy compared to the more flexible rib cages of children. High-energy impacts on the chest in children, even without rib fractures, can direct more force toward the lungs, increasing their vulnerability to pulmonary contusion.

Symptoms

Pulmonary contusion resulting from chest injury can manifest various symptoms. Typically, this condition may remain unnoticed until severe complications arise, particularly in high-energy accidents involving motor vehicle collisions with stationary objects like trees or poles. Although the chest wall might remain intact, the substantial energy impact can affect tissues beneath the ribs, leading to pulmonary contusion.

Patients with mild contusion may initially be asymptomatic, especially in the first few days. However, symptoms may eventually emerge, including:

• Breathing difficulties such as:
• Shortness of breath
• Pain when breathing
• Increased respiratory rate
• Coughing
• Chest pain or visible bruising
• Increased heart rate

In severe contusion, impaired lung air exchange can result in decreased blood oxygen levels, leading to tissue oxygen deficiency. Symptoms of severe contusion include:

• Wheezing sound when exhaling
• Bluish lips or fingertips
• Noisy breathing in the chest
• Rapid or shallow breaths
• Coughing up blood
• Pale skin and feeling cold to touch
• Low blood pressure

These symptoms often manifest gradually. Severe injuries may prompt immediate symptoms and can lead to death within hours. Conversely, mild contusion may unveil new symptoms 24-48 hours post-trauma.

Diagnosis

Diagnosing pulmonary contusion involves a thorough inquiry into the trauma history, circumstances of the injury, and a physical examination by a doctor. If warranted, imaging tests such as chest X-rays or CT scans, along with laboratory tests, may be conducted. CT scans are more effective than X-rays in detecting pulmonary contusion, albeit at a higher cost. Additionally, early imaging examinations may yield less accurate results due to delayed symptom onset, which can take up to 24 hours post-injury.

Management

Initial therapy for pulmonary contusion focuses on positioning the patient semi-upright to prevent respiratory failure and enhance tissue oxygenation.

As symptoms may not manifest immediately, asymptomatic patients are monitored in healthcare facilities for several days to detect any contusions, complications, or other injuries. This monitoring involves periodic laboratory and imaging examinations.

Therapeutic goals for pulmonary contusion include improving respiratory function, alleviating pain, and averting serious complications. While there's no specific treatment to expedite healing, patients may receive oxygen therapy to aid breathing, intravenous fluids, pain relievers, and antibiotics if signs of infection arise. Upon discharge, patients may engage in deep breathing exercises at home to enhance lung airflow and promote healing.

Complications

Pneumothorax and hemothorax

Complications arising from pulmonary contusion depend on the injury mechanism, severity, and the individual's overall health. High-energy blunt trauma often results in rib fractures, increasing the risk of life-threatening complications like pneumothorax (air leakage into the chest cavity, outside the lung) and hemothorax (blood accumulation in the chest cavity).

Respiratory failure

Damage to alveoli, blood vessels, and lung tissue can lead to severe respiratory disturbances, culminating in respiratory failure. This failure can manifest immediately or up to a week post-trauma, posing a risk of death. The highest complication risk occurs when over 20% of the lung sustains contusion.

Pulmonary infection

Pulmonary contusion can predispose individuals to pneumonia or lung infections, hindering healing and exacerbating existing conditions.

Aspiration pneumonia

Decreased consciousness in patients impairs swallowing reflexes, increasing susceptibility to aspiration—accidental inhalation of foreign objects into the airways. This exacerbates the condition and may lead to pneumonia.

Prevention

Prevention plays a crucial role, as with any disease. Common causes include accidents while driving or at the workplace. Hence, practising careful driving, regular vehicle inspections, and utilizing safety equipment are essential precautions. Additionally, avoiding risky activities minimizes injury risks.

When to see a doctor? 

Encountering someone with pulmonary contusion or a history of chest trauma warrants immediate medical attention or a visit to the emergency room for proper treatment.