A pulmonary hematoma is a collection of blood within the tissue of the lung. It may result when a pulmonary laceration fills with blood. A lung laceration filled with air is called a pneumatocele. In some cases, both pneumatoceles and hematomas exist in the same injured lung. Pulmonary hematomas take longer to heal than simple pneumatoceles and commonly leave the lungs scarred. A pulmonary contusion is another cause of bleeding within the lung tissue, but these result from microhemorrhages, multiple small bleeds, and the bleeding is not a discrete mass but rather occurs within the lung tissue. An indication of more severe damage to the lung than pulmonary contusion, a hematoma also takes longer to clear. Unlike contusions, hematomas do not usually interfere with gas exchange in the lung, but they do increase the risk of infection and abscess formation.
A pulmonary contusion, also known as lung contusion, is a bruise of the lung, caused by chest trauma. As a result of damage to capillaries, blood and other fluids accumulate in the lung tissue. The excess fluid interferes with gas exchange, potentially leading to inadequate oxygen levels (hypoxia). Unlike pulmonary laceration, another type of lung injury, pulmonary contusion does not involve a cut or tear of the lung tissue.
A pulmonary contusion is usually caused directly by blunt trauma but can also result from explosion injuries or a shock wave associated with penetrating trauma. With the use of explosives during World Wars I and II, pulmonary contusion resulting from blasts gained recognition. In the 1960s its occurrence in civilians began to receive wider recognition, in which cases it is usually caused by traffic accidents. The use of seat belts and airbags reduces the risk to vehicle occupants.
Diagnosis is made by studying the cause of the injury, physical examination and chest radiography. Typical signs and symptoms include direct effects of the physical trauma, such as chest pain and coughing up blood, as well as signs that the body is not receiving enough oxygen, such as cyanosis. The contusion frequently heals on its own with supportive care. Often nothing more than supplemental oxygen and close monitoring is needed; however, intensive care may be required. For example, if breathing is severely compromised, mechanical ventilation may be necessary. Fluid replacement may be required to ensure adequate blood volume, but fluids are given carefully since fluid overload can worsen pulmonary edema, which may be lethal.
The severity ranges from mild to severe: small contusions may have little or no impact on health, yet pulmonary contusion is the most common type of potentially lethal chest trauma. It occurs in 30–75% of severe chest injuries. The risk of death following a pulmonary contusion is between 14–40%. Pulmonary contusion is usually accompanied by other injuries. Although associated injuries are often the cause of death, pulmonary contusion is thought to cause death directly in a quarter to half of cases. Children are at especially high risk for the injury because the relative flexibility of their bones prevents the chest wall from absorbing force from an impact, causing it to be transmitted instead to the lung. Pulmonary contusion is associated with complications including pneumonia and acute respiratory distress syndrome, and it can cause long-term respiratory disability.
circulatory system injuries
lower respiratory tract injuries
Disorders of blood flow