Pulmonary contusion

intended for medical students and other medical practitioners

1. PULMONARY CONTUSION

2. Outline Introduction Epidemiology Etiology Types Pathophysiology Clinical presentation Investigations Management Complications Prognosis

3. Introduction A  pulmonary contusion  (or  lung contusion ) is injury to the lung parenchyma leading to edema and blood accumulating in the alveolar spaces and loss of normal lung structure and function. A pulmonary contusion is usually caused by  blunt trauma  but can also result from explosion injuries or a shock wave associated with penetrating trauma . The forces associated with blunt thoracic trauma can be transmitted to the lung parenchyma. This results in pulmonary contusion, characterized by development of pulmonary infiltrates with hemorrhage into the lung tissue

4. Epidemiology Globally, 10% of all trauma admissions result from chest injuries and 25% of trauma-related deaths are attributable to chest injuries . In Tanzania, trauma including chest injuries continues to be one of the leading causes of morbidity among the young and old with an estimated mortality of 40 %. In Bugando Medical Centre, chest trauma has been commonest cause of surgical admission and contributes significantly to high morbidly and mortality  . In a study done at MNH, out of 119 patients with chest injuries, lung contusion was found in 25 (21%) of the cases. The causes and pattern of chest injuries have been reported in literature to vary from one part of the world to another partly because of variations in infrastructure, civil violence, wars and crime. Motor traffic accidents are the commonest cause accounting for up to 70% in some cases.

5. Etiology In b lunt trauma , pulmonary contusion is usually caused by the rapid deceleration that results when the moving chest strikes a fixed object . About 70% are due to MVAs, other causes include; falls, sport injuries and assaults. P enetrating trauma can cause pulmonary contusion. It usually surrounds the path along which the projectile traveled through the tissue. The  pressure wave forces tissue out of the way, creating a temporary cavity; the tissue readily moves back into place, but it is damaged. 

6. Pathophysiology Bleeding and edema Consolidation and collapse Ventilation and perfusion mismatch Pulmonary hypoxic vasoconstriction with increased vascular resistance If it is severe enough, the hypoxemia resulting from fluid in the alveoli cannot be corrected just by giving supplemental oxygen; this problem is the cause of a large portion of the fatalities that result from trauma.

7. Clinical presentation Clinical findings in pulmonary contusion depend on the extent of the injury. Patients present with varying degrees of respiratory difficulty . Symptoms include: respiratory distress, coughing up blood or bloody sputum, bronchorrhea (production of watery sputum), wheezing Signs include: dyspnea, tachypnea, tachycardia, hypotension, ecchymosis Respiratory system examination demonstrates decreased breath sounds over the affected area or crackles may be appreciated and tenderness may be elicited if there is associated chest wall injury.

8. Investigations Chest x – ray – Patch irregular infiltrates to frank consolidation which often does not localize in a lobar or segmental pattern However it will often under-estimate the size of the contusion and the true extent of injury is not apparent on plain films until 24-48 hours following injury General imaging differential considerations include: aspiration pneumonia, segmental / focal atelectasis, pulmonary hemorrhage.

9. Computed tomography (CT) More sensitive Unlike X-ray, CT scanning can detect the contusion almost immediately after the injury. Helps determine the size of the contusion which often tend to correlated with the overall prognosis Wagner and Miller have determined that the pulmonary contusion can be divided into mild, moderate and severe based on the size of the contused portion of the lung. Mild (<18%), Moderate (18 – 28%) and severe (>28%)

10. A CT scan showing a pulmonary contusion (red arrow) accompanied by a rib fracture (blue arrow)

11. Management The primary treatment is supportive and efforts should be directed in diagnosing critical concordant chest injuries and providing supplemental oxygen to treat hypoxia. The ATLS course manual states: “Patients with significant hypoxia i.e. paO 2 < 65mmHg SpO 2 < 90% should be intubated and ventilated within the first hour of injury” Intubation should be provided with the goal of reducing the edema, improving the functional residual capacity and decreasing hypoxemia. Positive end expiratory pressure via mechanical ventilation (PEEP) or non – invasive positive pressure ventilation remains controversial as the optimal treatment and therefore should be use with caution on case by case basis.

12. Fluid resuscitation Controversy – hypervolemia vs. hypovolemia Current standard of care – maintenance of euvolemia

13. Other Supportive care: Pain control Pulmonary toilet – suctioning, deep breathing, coughing Chest physiotherapy – breathing exercises, percussion Optimal positioning – placing the good lung in a dependent position

14. Complications Adult respiratory distress syndrome – in up to 38% of patients Pneumonia – inability to clear bacteria and secretions; intubation and mechanical ventilation further increases the risk. Up to 50% of patients tend to develop a bacterial respiratory infection.

15. Prognosis Most resolve 5 to 7 days after injury Signs detectable by radiography are usually gone within 10 days after injury Lung fibrosis with decreased functional residual capacity can occur up to 6 years after injury Contusion can also permanently reduce the compliance of the lungs A larger contusion is associated with an increased risk.

16. References East and Central African Journal of Surgery, Vol. 15, No. 1, Mar-Apr, 2010, pp. 124-129 The Pattern and Management of Chest Trauma at Muhimbili National Hospital, Dar es Salaam. F.A . Massaga , M. Mchembe http :// www.cardiothoracicsurgery.org/content/6/1/7 http :// en.wikipedia.org/wiki/Pulmonary_contusion Pattern and outcome of chest injuries at Bugando Medical Centre in Northwestern Tanzania. Monafisha K Lema ,   Phillipo L Chalya ,  Joseph B Mabula  and William Mahalu