Pulmonary contusion is the most common intrathoracic injury in children While many contusions cause only mild symptoms such as chest pain, more severe injuries can lead to hypoxemia and respiratory failure Pulmonary contusions may not show up on CXR for to hours after the injury, and in some cases may never be identified on plain films Given the force necessary to cause a pulmonary contusion, a high index of suspicion for other associated injuries is required Current Evidence Pulmonary contusion is the most common thoracic injury in children Pulmonary contusion occurs when a blunt force is applied to the lung parenchyma, though the injury can also be seen in penetrating trauma The pediatric thoracic cage provides less protection from blunt force impact compared to adults, secondary to greater cartilage content and the greater elasticity of the bones Therefore, external kinetic energy applied to the thorax is transferred more readily through the chest wall to the underlying organs Thus, a pediatric patient is more likely than an adult to have an internal injury such as a lung contusion without external evidence of trauma (e.g., rib fracture, laceration, bruising) As in any contusion or bruise, the capillary network becomes damaged, leaking fluid into the surrounding tissues A ventilation:perfusion mismatch will occur because of the extravasation of fluid into injured lung parenchyma, interfering with oxygenation As the edema and swelling worsen, the patient’s respiratory status will deteriorate if the contusion is large Clinical Considerations Clinical Recognition Pulmonary contusion should be suspected in any child with blunt thoracic trauma who presents with chest pain, difficulty breathing, or unexplained hypoxia The contusion may be visualized on radiography or inferred from the absence of another explanation for these symptoms (such as pneumothorax) Due to the pliable nature of the pediatric chest wall, pulmonary contusions can often be seen in the absence of rib fracture When present, however, rib fractures as well as chest wall ecchymosis should further raise suspicion for underlying parenchymal injury Triage