Epidemiology:

Pulmonary contusion is found in 30–75% of severe cases of chest injury, making it the most common serious injury to occur in association with thoracic trauma. Of people who have multiple injuries with an injury severity score of over 15, pulmonary contusion occurs in about 17%. It is difficult to determine the death rate (mortality) because pulmonary contusion rarely occurs by itself. Usually, deaths of people with pulmonary contusion result from other injuries, commonly traumatic brain injury. It is controversial whether pulmonary contusion with flail chest is a major factor in mortality on its own or whether it merely contributes to mortality in people with multiple injuries.

The mortality rate of pulmonary contusion is estimated to range from 14–40%, depending on the severity of the contusion itself and on associated injuries. When the contusions are small, they do not normally increase the chance of death or poor outcome for people with blunt chest trauma; however, these chances increase with the size of the contusion. One study found that 35% of people with multiple significant injuries including pulmonary contusion die. In another study, 11% of people with pulmonary contusion alone died, while the number rose to 22% in those with additional injuries. An accompanying flail chest increases the morbidity and mortality to more than twice that of pulmonary contusion alone. Pulmonary contusion is thought to be the direct cause of death in a quarter to a half of people with polytrauma who die.

Pulmonary contusion is the most common cause of death among vehicle occupants involved in accidents, and it is thought to contribute significantly in about a quarter of deaths resulting from vehicle collisions. As vehicle use has increased, so has the number of auto accidents, and with it the number of chest injuries. However an increase in the number of airbags installed in modern cars may be decreasing the incidence of pulmonary contusion. Use of child restraint systems has brought the approximate incidence of pulmonary contusion in children in vehicle accidents from 22% to 10%.

Since their chest walls are more flexible, children are more vulnerable to pulmonary contusion than adults are, and it is more common in children than in adults for that reason. Children in forceful impacts suffer twice as many pulmonary contusions as adults with similar injury mechanisms, yet have proportionately fewer rib fractures. Pulmonary contusion has been found in 53% of children with significant chest injuries (those requiring hospitalization). The rates of certain types of injury mechanisms differ between children and adults; for example, children are more often hit by cars when they are pedestrians.

Differences in the bodies of children and adults also lead to different manifestations of pulmonary contusion and associated injuries; for example, children have less body mass, so the same force is more likely to lead to trauma to multiple body systems. Some differences in children's physiology might be advantageous (for example they are less likely to have other medical conditions), and thus they have been predicted to have a better outcome. However, despite these differences, children with pulmonary contusion have similar mortality rates to adults.

Associated injuries:

Severe pulmonary contusion with pneumothorax and hemothorax following severe chest traumaA large amount of force is required to cause pulmonary contusion; a person injured with such force is likely to have other types of injuries as well, and pulmonary contusion can be used to gauge the severity of trauma. Up to three quarters of cases are accompanied by other chest injuries, the most common of these being hemothorax and pneumothorax. Flail chest is usually associated with pulmonary contusion, and the contusion, rather than the chest wall injury, is often the main cause of respiratory failure in people with these injuries.

Other indications of thoracic trauma may be associated, including fracture of the sternum and bruising of the chest wall. Over half of fractures of the scapula are associated with pulmonary contusion. The contusion is frequently found underlying fracture sites. When accompanied by a fracture, it is usually concentrated into a specific location—the contusion is more diffuse when there is no fracture. Pulmonary lacerations may result from the same blunt or penetrating forces that cause pulmonary contusion. Lacerations can result in pulmonary hematomas; these are reported to develop in 4–11% of pulmonary contusions.

History:

Giovanni Battista Morgagni, credited with having first described lung trauma without chest wall traumaIn 1761, the Italian anatomist Giovanni Battista Morgagni was first to describe a lung injury that was not accompanied by injury to the chest wall overlying it. Nonetheless, it was the French military surgeon Guillaume Dupuytren who is thought to have coined the term pulmonary contusion in the 19th century.

It still was not until the early 20th century that pulmonary contusion and its clinical significance began to receive wide recognition. With the use of explosives during World War I came many casualties with no external signs of chest injury but with significant bleeding in the lungs. Studies of World War I injuries by D.R. Hooker showed that pulmonary contusion was an important part of the concussive injury that results from explosions.

Pulmonary contusion received further attention during World War II, when the bombings of Britain caused blast injuries and associated respiratory problems in both soldiers and civilians. Also during this time, studies with animals placed at varying distances from a blast showed that protective gear could prevent lung injuries.These findings suggested that an impact to the outside of the chest wall was responsible for the internal lesions. In 1945, Buford and Burbank described what they called "wet lung", in which the lungs accumulated fluid and were simultaneously less able to remove it. They attributed the respiratory failure often seen in blunt chest trauma in part to excessive fluid resuscitation, and the question of whether and how much to administer fluids has remained controversial ever since.

During the Vietnam War, combat again provided the opportunity for study of pulmonary contusion; research during this conflict played an important role in the development of the modern understanding of its treatment. The condition also began to be more widely recognized in a non-combat context in the 1960s, and symptoms and typical findings with imaging techniques such as X-ray were described. Before the 1960s, it was believed that the respiratory insufficiency seen in flail chest was due to "paradoxical motion" of the flail segment of the chest wall (the flail segment moves in the opposite direction as the chest wall during respiration), so treatment was aimed at managing the chest wall injury, not the pulmonary contusion.

For example, positive pressure ventilation was used to stabilize the flail segment from within the chest. It was first proposed in 1965 that this respiratory insufficiency is most often due to injury of the lung rather than to the chest wall, and a group led by J.K. Trinkle confirmed this hypothesis in 1975. Hence the modern treatment prioritizes the management of pulmonary contusion.Animal studies performed in the late 1960s and 1970s shed light on the pathophysiological processes involved in pulmonary contusion.

Epidemiology:

Pulmonary contusion is found in 30–75% of severe cases of chest injury, making it the most common serious injury to occur in association with thoracic trauma. Of people who have multiple injuries with an injury severity score of over 15, pulmonary contusion occurs in about 17%. It is difficult to determine the death rate (mortality) because pulmonary contusion rarely occurs by itself. Usually, deaths of people with pulmonary contusion result from other injuries, commonly traumatic brain injury. It is controversial whether pulmonary contusion with flail chest is a major factor in mortality on its own or whether it merely contributes to mortality in people with multiple injuries. The mortality rate of pulmonary contusion is estimated to range from 14–40%, depending on the severity of the contusion itself and on associated injuries.

When the contusions are small, they do not normally increase the chance of death or poor outcome for people with blunt chest trauma; however, these chances increase with the size of the contusion. One study found that 35% of people with multiple significant injuries including pulmonary contusion die. In another study, 11% of people with pulmonary contusion alone died, while the number rose to 22% in those with additional injuries. An accompanying flail chest increases the morbidity and mortality to more than twice that of pulmonary contusion alone. Pulmonary contusion is thought to be the direct cause of death in a quarter to a half of people with polytrauma who die.

Pulmonary contusion is the most common cause of death among vehicle occupants involved in accidents, and it is thought to contribute significantly in about a quarter of deaths resulting from vehicle collisions. As vehicle use has increased, so has the number of auto accidents, and with it the number of chest injuries. However an increase in the number of airbags installed in modern cars may be decreasing the incidence of pulmonary contusion. Use of child restraint systems has brought the approximate incidence of pulmonary contusion in children in vehicle accidents from 22% to 10%.

Since their chest walls are more flexible, children are more vulnerable to pulmonary contusion than adults are, and it is more common in children than in adults for that reason. Children in forceful impacts suffer twice as many pulmonary contusions as adults with similar injury mechanisms, yet have proportionately fewer rib fractures. Pulmonary contusion has been found in 53% of children with significant chest injuries (those requiring hospitalization). The rates of certain types of injury mechanisms differ between children and adults; for example, children are more often hit by cars when they are pedestrians.

Differences in the bodies of children and adults also lead to different manifestations of pulmonary contusion and associated injuries; for example, children have less body mass, so the same force is more likely to lead to trauma to multiple body systems. Some differences in children's physiology might be advantageous (for example they are less likely to have other medical conditions), and thus they have been predicted to have a better outcome. However, despite these differences, children with pulmonary contusion have similar mortality rates to adults.

Associated injuries:

Severe pulmonary contusion with pneumothorax and hemothorax following severe chest traumaA large amount of force is required to cause pulmonary contusion; a person injured with such force is likely to have other types of injuries as well, and pulmonary contusion can be used to gauge the severity of trauma. Up to three quarters of cases are accompanied by other chest injuries, the most common of these being hemothorax and pneumothorax. Flail chest is usually associated with pulmonary contusion, and the contusion, rather than the chest wall injury, is often the main cause of respiratory failure in people with these injuries.

Other indications of thoracic trauma may be associated, including fracture of the sternum and bruising of the chest wall. Over half of fractures of the scapula are associated with pulmonary contusion. The contusion is frequently found underlying fracture sites. When accompanied by a fracture, it is usually concentrated into a specific location—the contusion is more diffuse when there is no fracture. Pulmonary lacerations may result from the same blunt or penetrating forces that cause pulmonary contusion. Lacerations can result in pulmonary hematomas; these are reported to develop in 4–11% of pulmonary contusions.

History:

Giovanni Battista Morgagni, credited with having first described lung trauma without chest wall traumaIn 1761, the Italian anatomist Giovanni Battista Morgagni was first to describe a lung injury that was not accompanied by injury to the chest wall overlying it. Nonetheless, it was the French military surgeon Guillaume Dupuytren who is thought to have coined the term pulmonary contusion in the 19th century. It still was not until the early 20th century that pulmonary contusion and its clinical significance began to receive wide recognition. With the use of explosives during World War I came many casualties with no external signs of chest injury but with significant bleeding in the lungs. Studies of World War I injuries by D.R. Hooker showed that pulmonary contusion was an important part of the concussive injury that results from explosions.

Pulmonary contusion received further attention during World War II, when the bombings of Britain caused blast injuries and associated respiratory problems in both soldiers and civilians. Also during this time, studies with animals placed at varying distances from a blast showed that protective gear could prevent lung injuries.These findings suggested that an impact to the outside of the chest wall was responsible for the internal lesions. In 1945, Buford and Burbank described what they called "wet lung", in which the lungs accumulated fluid and were simultaneously less able to remove it.

They attributed the respiratory failure often seen in blunt chest trauma in part to excessive fluid resuscitation, and the question of whether and how much to administer fluids has remained controversial ever since.

During the Vietnam War, combat again provided the opportunity for study of pulmonary contusion; research during this conflict played an important role in the development of the modern understanding of its treatment. The condition also began to be more widely recognized in a non-combat context in the 1960s, and symptoms and typical findings with imaging techniques such as X-ray were described. Before the 1960s, it was believed that the respiratory insufficiency seen in flail chest was due to "paradoxical motion" of the flail segment of the chest wall (the flail segment moves in the opposite direction as the chest wall during respiration), so treatment was aimed at managing the chest wall injury, not the pulmonary contusion. For example, positive pressure ventilation was used to stabilize the flail segment from within the chest.

It was first proposed in 1965 that this respiratory insufficiency is most often due to injury of the lung rather than to the chest wall, and a group led by J.K. Trinkle confirmed this hypothesis in 1975. Hence the modern treatment prioritizes the management of pulmonary contusion.Animal studies performed in the late 1960s and 1970s shed light on the pathophysiological processes involved in pulmonary contusion.