Chest Injuries—Pulmonary

Injuries to the lung parenchyma producing a pneumothorax can be managed with tube thoracostomy to relieve tension, drain accumulated blood, and apply suction to the pleural space until the air leak spontaneously resolves. Bleeding from the low-pressure pulmonary circulation

2480

Although double-lumen endotracheal intubation is desirable during urgent thoracotomy, such intubation should not be the initial approach (also see Chapter 49 ). Rapid-sequence intubation with a large-caliber (at least 8.0-mm internal diameter) conventional endotracheal tube will permit diagnostic bronchoscopy and will protect the patient from aspiration until passage of a gastric tube can reduce stomach contents. The change to a double-lumen tube can then be done under controlled conditions, that is, in the presence of adequate oxygenation, anesthesia, and muscle relaxation. Tolerance of single-lung ventilation is variable in the trauma population and will depend in large part on the absence of significant pathology in the ventilated lung. Many patients with blunt thoracic injury have bilateral pulmonary contusions and will require increased FIO₂ and high levels of PEEP to maintain adequate oxygenation, even when both lungs are ventilated.

Although chest trauma requiring pneumonectomy has historically resulted in mortality approaching 100%, a recent multicenter retrospective review reported on a series of survivors of this surgery.^[196] Intraoperative deaths are the result of uncontrollable hemorrhage, acute right ventricular failure, and air embolism. Patients who survive the initial operative procedure are subsequently at risk for early postoperative morbidity and mortality. Fluid management may be complicated by the need to weigh ongoing resuscitation against the treatment of right ventricular failure. Blunt thoracic trauma requiring pneumonectomy is often associated with abdominal and pelvic trauma. Volume replacement must be judicious, and the use of a pulmonary artery catheter (placed with care in a postpneumonectomy patient) or TEE may be beneficial. Echocardiography will also play an important role in assessing right ventricular function and pulmonary hypertension. Treatment of right ventricular failure after traumatic pneumonectomy is difficult.^[197] During hypovolemic shock there is a disproportionate increase in pulmonary vascular resistance with respect to systemic vascular resistance^[198] and frequent mortality with combined hemorrhagic shock and pneumonectomy.^[199] With severe dysfunction of the right side of the heart, it is generally desirable to maintain a higher preload than normal. Several therapeutic approaches have been used to treat right ventricular failure, including close monitoring of pulmonary artery pressure, the use of diuretics for volume overload, and the use of pulmonary vasodilators. Because this injury is fairly rare and the number of patients reported in the literature is small, it is impossible to definitively state which of the treatment options is superior. A recent case report describes the use of nitric oxide to successfully treat pulmonary hypertension after posttraumatic pneumonectomy.^[200]

Tracheobronchial injury can result from either blunt force or penetrating trauma. Penetrating injuries are usually more promptly diagnosed and treated. Blunt trauma most commonly results in an injury to the tracheobronchial tree within 2.5 cm of the carina and may initially be unrecognized. The presence of subcutaneous emphysema, pneumomediastinum, pneumopericardium, or pneumoperitoneum, without apparent cause, should alert the practitioner to possible tracheobronchial injury.^[201] Despite bronchoscopy and helical CT scanning, a small injury may never be delineated. If the resultant injury is an incomplete tear, it may heal with stenosis, subsequent atelectasis, pneumonia, pulmonary destruction, and sepsis. Alternatively, complete transections heal by scarring of the transected ends. When surgery is required for a delayed, incomplete tracheobronchial injury, pulmonary resection may be required if significant tissue destruction has occurred, whereas complete transection may be amenable to reconstruction with preservation of pulmonary tissue. The level of injury dictates the surgical approach. Cervical injuries are approached through a transverse neck incision, left bronchial injuries through a left thoracotomy, and tracheal or right main stem bronchial injuries through a right thoracotomy.