Pulmonary Contusion (Lung Contusion)
A pulmonary contusion occurs more frequently following blunt trauma, which is commonly associated with a flail segment or broken ribs. This is a very common, potentially fatal injury that is the leading cause of hypoxemia causes after blunt trauma. Following gunshot wounds/injury, there is a region of contusion caused by the bullet’s shock wave.
For the very first 24–48 hours, the normal development of pulmonary contusion is worsening hypoxemia. Chest radiographic results are often overdue. Contrast CT scanning can be used to validate a diagnosis. A pulmonary contusion is indicated by hemoptysis, or blood in the endotracheal channel.
The cure for a minor contusion is oxygen administration, pulmonary toilet, and appropriate analgesia. Mechanical ventilation is needed in more serious cases. Fluid restriction is not recommended since normovolaemia is critical for sufficient tissue perfusion.
Read Pulmonary Vascular Resistance
Pathophysiology of Pulmonary Contusion
Direct and indirect effects of blunt chest injury can result in respiratory failure. Respiratory failure can occur immediately after a trauma, or it can take up to a week. However, after a longer period, determining the primary, the underlying cause becomes more challenging. As a result, the mechanical causes and pathophysiology of the injury will be addressed concurrently.
Tear or penetration of the visceral pleura, which results in a life-threatening haemo- or pneumothorax, is a common result of a direct injury caused by blunt or penetrating injury. The force of the injury transferred to the lung parenchyma causes atelectasis, which leads to respiratory failure.
Aspiration of gastric acid was one variable that may have led to the formation of a contusion with extreme respiratory failure and subsequent ARDS. As a result, the authors concluded that concomitant gastric acid aspiration, increased lung permeability, and enhanced inflammatory processes may all lead to the development of more severe lung contusions.
Pulmonary contusion happens as a result of an external force causing damage to the compressed lung tissue. Three additional processes are thought to be at work in the background: inertial effect, spalling effect, and implosion effect.
- The Inertial effect: This results in similar axonal injury. The shearing force of hilar structures injures the weaker alveolar tissue. This is due to the fact that tissues with different densities decelerate and accelerate at different rates.
- The Spalling Effect: Where the pressure wave meets various bordering surfaces, such as the alveolar wall, a tear forms in the lung tissue.
- The Implosion Effect: It happens when there is a sudden rise in airway pressure. Shock waves compress the gas inside tissues containing air bubbles, and the gas then expands to several times its original volume, resulting in micro explosions inside the aerated tissue.
Pulmonary Contusions usually form at the site of the impact. In rare cases, similar to brain trauma patients, it can manifest in the lung tissue contralateral to the direct trauma through a contrecoup mechanism. The extent of the energy impulse affecting lung tissue is determined by the flexibility/elasticity of the chest wall. Children’s rib cages are more versatile and can transfer more energy without causing rib fractures. Adults, on the other hand, have a more rigid rib cage that can absorb more energy. Children account for 62% of patients with fractures and lung contusions, while adults account for the remaining 80%. Fractures are more common in elderly patients than contusions.
Alveoli and capillaries are torn as a consequence of the contusion, and blood and interstitial fluid spill into the alveoli and tissues. A hematoma forms in the region of the trauma first, followed by edema in or around the affected area several hours later. The emerging inflammatory response and the proteins appearing in the alveoli further hinder ventilation. The volume of surfactant decreases and the alveoli eventually collapse. The pathological fluid that appears in the alveoli thickens, and the lung tissue loses its elasticity. When only either side of the chest is injured, the resulting inflammatory response can cause edema and an inflammatory reaction on the other, intact side as well.
In serious cases, the injury may result in the onset of ARDS.
Ventilation of the contused areas deteriorates progressively as oxygenated air is unable to reach the alveoli during inspiration; perfusion is also hampered as the portion of the lung affected by hypoventilation is excluded from circulation by reflex vasoconstriction. This is the pathway that leads to systemic hypoxia and hypercapnia. Several studies have shown that after a pulmonary contusion, the immune system activates, causing an acutely developing inflammation within the lung. As a result, immune system activation triggers the local accumulation of significant quantities of various cytokines and chemokines in the lung of patients who have suffered a chest contusion injury, accompanied by the invasion of neutrophils granulocytes. Changes in cytokine synthesis and apoptosis have been identified in immune-competent cells in the lung and other distant organs. It has also been stated that there is a lack of bacterial clearance and an increased vulnerability to sepsis.
Clinical Manifestations of Pulmonary Contusion
Clinical manifestations differ greatly on a wide scale. Mild contusions can be asymptomatic for a long time. Disrupted alveolar gas exchange reduces arterial oxygen concentration in extreme lung contusion. The resulting tissue hypoxia causes dyspnea, tachypnea, and, as a result, tachycardia. Clinical symptoms manifesting are unusual and often grow slowly. Auscultation can reveal decreased breathing sounds above the area affected by the contusion, as well as difficulty breathing and coughing. Excessive bronchorrhea and hemoptysis are not typical and can appear only in serious contusions. In addition to tachycardia and hypotension, pain, rib fractures, hematoma, and subcutaneous emphysema can occur in the affected region of the chest.
It takes time for symptoms and signs to appear. A serious injury causes symptoms to occur quickly, within hours, and can even result in death, while milder injuries cause incremental deterioration in the patient’s condition, with the characteristic clinical appearance appearing 24–48 hours after the injury.
To reach an accurate diagnosis, an evaluation of the patient’s general condition and the mechanism of the injury, as well as an evaluation of physical examination results, imaging test results, and targeted laboratory tests, are required.
The development of haemo- and pneumothorax is a normal and immediate consequence of the incident. Higher intensity trauma to the more flexible chest in young patients can result in serious diffuse contusion without actual injury to the chest bones. Rib fracture, on the other hand, is a very common finding in older patients with much more rigid chest structures following blunt chest trauma. ARDS appears in 17% of patients with no more than a lung contusion and 78% of patients with polytrauma. If more than 20% of the pulmonary area is damaged, ARDS develops in 82% of victims; if less than 20% is affected, it develops in just 22% of patients. In 20% of patients, pneumonia grows. This figure could be higher in ventilated patients. There is no distinction between children and adults in terms of the production of ARDS or pneumonia.
Read Tension Pneumothorax
Diagnosis of Lung Contusion
The diagnostic procedure of penetrating, high-energy damages that greatly damage chest tissue and produce clinical signs is well-known and can provide useful guidance. The mechanism of the crash, as well as the existence or absence of the characteristic clinical symptoms, do not provide sufficient evidence to exclude or assume the existence of lung contusion with accuracy.
The availability of clinical diagnostic procedures is inextricably linked to the level of sophistication of a given healthcare system. In the absence of a CT, a traditional X-ray and chest ultrasound might be necessary to diagnose a Pneumothorax or Hemothorax. The regular use of whole-body CT in trauma care altered diagnostic accuracy in individuals suffering from extreme chest trauma. However, in the case of minor chest injuries, diagnostic accuracy improved dramatically. The increased sensitivity and spatial resolution of examination methods result in a decrease in lung parenchyma injuries and an increase in lung contusion injuries. Nonetheless, no increase in survival chances was discovered.
Read Pneumothorax X-ray
Treatment of Lung Contusion
The pulmonary contusion can disappear after 3-7 days without complications.
The wounded should be placed in a reclining position, which is a cardinal rule of early therapy. The primary goal is to prevent respiratory failure and maintain sufficient tissue oxygenation. In cases where mechanical ventilation is not needed, non-invasive ventilation is used to save the first five post-trauma days before the anticipated development of frank lung contusion. This, however, necessitates a proper patient monitoring system, arterial blood gas analysis, and, if necessary, the availability of radiological support. In everyday clinical practice, general and special laboratory diagnostic findings can only implicitly apply to the condition’s rapid development or silent removal. There is currently no medication available that could aid in rehabilitation. The goals of supportive therapy are to avoid respiratory insufficiency, eliminate discomfort, control airway cleaning, and prevent complications from developing.
Inadequate ventilation can lead to non-resolving hypoxia and hypercapnia. Excessive ventilation, on the other hand, can result in hyperoxia and hypocapnia. It can aggravate respiratory insufficiency due to its hemodynamic impact. Excessively high pressures can result in barotrauma, while excessively high volumes result in volume trauma. Early invasive ventilation of trauma patients can worsen lung contusion condition, posing a morbidity and mortality risk factor.
Additional injuries and conditions should be treated also, such as hemothorax, pneumothorax, etc.
Few Last Words About Pulmonary Contusion
A pulmonary contusion can be life-threatening if not treated early properly. It can arise some additional conditions such as pneumothorax, hemothorax. Lung contusion should be treated as e emergency and early diagnosis and treatment are key to success here.
Last Updated on February 23, 2022 by Learn From Doctor Team