A 26-year-old man with an unknown past medical history arrives to the emergency department (ED) by ambulance. He had been driving his car while unrestrained and was involved in a high-speed motor vehicle collision. There was airbag deployment and significant front-end damage to the vehicle, with intrusion into the passenger compartment of the car. The patient was extricated from the vehicle and placed on a backboard, and a cervical collar was placed by EMS. A non-rebreather facemask and 1 peripheral intravenous (IV) line were placed in the field.
On arrival to the hospital, the patient is ill-appearing and combative. His initial vital signs are a heart rate of 117 bpm, a blood pressure of 85/50 mm Hg, a respiratory rate of 32 breaths/min, and an oxygen saturation of 91% on the non-rebreather mask. On primary survey, his oropharynx is clear, his airway is patent, and his trachea appears to be shifted to the right of midline. On auscultation, the patient’s breath sounds are decreased over the left chest. Percussion of the left chest demonstrates hyperresonance. His carotid pulse is weakly palpable, and his jugular venous pulse is elevated. The patient receives a Glasgow Coma Scale score of 12. The patient’s clothing is removed, revealing no obvious deformities or areas of bleeding. The patient’s abdomen is soft, without any tenderness to palpation. His pelvis is stable. Standard trauma x-rays, including an anteroposterior (AP) chest and pelvis scan, are performed after the primary survey. A complete secondary survey is postponed because of the patient’s poor clinical condition.
A second large-bore peripheral intravenous line is placed, and the patient begins to receive a bolus of 1000 cc of normal saline under pressure. A decision to perform an emergent procedure is made. Immediately after the procedure is performed, the patient is noted to have a dramatic clinical improvement. Subsequent to the procedure, the patient has a pulse of 105 bpm, a blood pressure of 95/60 mm Hg, a respiratory rate of 22 breaths/min, and an oxygen saturation of 98% on the non-rebreather mask. The secondary survey is completed, revealing no major injuries. Additionally, the chest radiograph (see Figure 1) confirms the suspected clinical diagnosis that prompted the emergent procedure.
stepowl said,
March 29, 2008 @ 2:31 am
Pneumothorax occurs when air enters the potential space between the visceral and parietal pleura, leading to lung collapse on the affected side. Pneumothoraces may occur spontaneously, especially in the setting of lung disease, or they may result from accidental or iatrogenic trauma. A tension pneumothorax is a life-threatening condition that occurs when the air in the pleural space is under pressure, displacing mediastinal structures and compromising cardiopulmonary function. Tension pneumothoraces result from injuries to the lung parenchyma or bronchial tree that can act as one-way valves so that air enters the pleural space but cannot escape. The trapped air in a tension pneumothorax causes increased intrathoracic pressure, pushing mediastinal structures contralaterally and reducing venous return and cardiac output. These patients are hypoxic and become difficult to ventilate, with potentially rapid progress to cardiorespiratory collapse and death. Hemothorax is defined by blood in the pleural space, and it occurs when the lung parenchyma and the intercostal or mammary vessels are injured. Massive hemothoraces arise with hilar injuries, aortic ruptures, or myocardial ruptures. A tension hemopneumothorax develops when there is both blood and air under tension in the pleural space.
A pneumothorax in any patient who has sustained thoracic trauma should arouse suspicion. The patient may complain of an acute onset of sharp pleuritic chest pain, with radiation to the ipsilateral shoulder and associated dyspnea and anxiety. Typical physical findings in pneumothorax include unilaterally decreased breath sounds, hyperresonance to percussion over the affected lung, and asymmetric chest rise. In tension pneumothorax, the patient displays respiratory distress, tachypnea, and tachycardia, and the patient may also experience cyanosis, jugular venous distention, tracheal deviation away from the affected lung, and a pulsus paradoxus.
The epidemiology of traumatic pneumothoraces has not been well characterized. In the united States, trauma is the leading cause of death in persons younger than 45 years, and it accounts for approximately 150,000 deaths annually.1 The overall mortality for thoracic trauma is 10%, and chest injuries cause approximately 1 in 4 trauma deaths in North America.2 Pneumothorax is a serious complication of thoracic trauma, and it has been described in 1 in 5 patients that survive major trauma.3 Interestingly, in one study, 12% of patients with asymptomatic chest stab wounds had a delayed pneumothorax or hemothorax.8
While pneumothoraces in stable patients can be confirmed radiographically, a tension pneumothorax causing hemodynamic compromise should be diagnosed clinically, and treatment should never be delayed in favor of diagnostic imaging. A chest x-ray may show a linear shadow of visceral pleura, without lateral lung markings. An upright chest x-ray is more sensitive than a supine radiograph, as air tends to accumulate at the lung apex. In recumbent patients, air often accumulates in the anterior portion of the inferior chest and manifests radiographically as a “deep sulcus.” If a pneumothorax without tension physiology is suspected but not seen on the initial upright chest x-ray, a repeat film during exhalation may reveal it. Increasingly, ultrasound is being used as a rapid bedside modality for diagnosing pneumothoraces; some studies have shown that it is more sensitive than radiography for detecting traumatic pneumothoraces.4,5 Computed tomography (CT) is more sensitive and specific than chest x-rays or ultrasonography for the evaluation of small pneumothoraces and hemothoraces. Occult pneumothoraces may be present in 2-55% of trauma patients, although the clinical significance of occult pneumothoraces in patients who are not mechanically ventilated under positive pressure is unclear.6 Making the diagnosis of hemothorax may be more challenging. A minimum of 200-300 mL of blood is needed in the pleural space for blunting of the costophrenic angle to be visible on an upright chest x-ray. Blood is more difficult to appreciate on a supine x-ray because it will typically layer posteriorly, and ever larger volumes (up to 1000 mL) of blood may produce only a mild diffuse radiodensity. Lateral chest films may help differentiate hemothoraces from pulmonary contusions, and ultrasonography may also be useful for detecting fluid above the diaphragm. As with pneumothoraces, CT scanning is the most sensitive modality for diagnosing hemothoraces, although patients with massive hemothoraces may be too unstable for the scan.
The treatment of traumatic pneumothoraces and hemothoraces depends upon the volume of blood or air that has accumulated and on the condition of the patient. Hemodynamically stable patients who are not intubated and have a relatively small pneumothorax (ie, less than 1 cm wide) can be placed under observation. A repeat film should be obtained after 4-6 hours; if the pneumothorax is unchanged in size, the patient can continue to be observed without the need for decompression or tube thoracostomy. These patients should always be placed on 100% oxygen to increase the rate of reabsorption of the air in the pleural space. In unstable patients who, on clinical grounds, are suspected of having a pneumothorax, a needle thoracostomy may be performed to quickly decompress the pleural space. A 14-gauge Angiocath (18-gauge or 20-gauge in an infant) should be placed immediately superior to the rib in the second intercostal space, midclavicular line on the affected side. Once in place, the needle is removed and the Angiocath is secured. A rush of air may be appreciated as the Angiocath enters the pleural space. Pneumothoraces should preferentially be decompressed either by needle decompression or placement of a tube thoracostomy before the patient is intubated, as positive pressure ventilation will exacerbate a pneumothorax; however, definitive management of the airway should never be delayed when indicated. Needle thoracostomy generally necessitates the subsequent placement of a chest tube; however, stable patients who do not require a chest tube may be observed. In simple spontaneous pneumothoraces, a 20F or 22F chest tube may be used; however, larger-caliber chest tubes (28F to 40F) should be used in most traumatic pneumothoraces and hemothoraces to ensure adequate drainage of any fluid. Chest tubes are placed in the fourth or fifth intercostal space in the anterior axillary or midaxillary line, and they should be directed posteriorly and toward the apex of the lung. After the tube is secured, it should be connected to a water seal and vacuum device, and placement should be confirmed by chest x-rays. In the case of a hemothorax, immediate drainage of more than 1500-2000 mL (or 20 mL/kg) of blood, or ongoing hemorrhage exceeding
600-1200 mL/6 hours (or >3 mL/kg/hr) after the initial drainage, constitute the definition of a massive hemothorax and generally are indications for a thoracotomy. Occasionally, placement of an additional chest tube may be necessary to assist in draining of the hemothorax. Additionally, the possibility of a bronchial injury should be considered if a continuing air leak is observed after several chest tubes and an unexpanded lung. In hemothorax, chest tubes should be directed posteriorly and inferiorly to arrive posterior to the diaphragm (as opposed to the placement for a simple pneumothorax).
In this case, the junior emergency medicine resident placed a 14-gauge Angiocath in the second intercostal space, midclavicular line of the left chest. A rush of air was appreciated, and the patient’s blood pressure (as previously noted in the case presentation) improved to 95/60 mm Hg. The resident then prepared the left chest and placed a 38F chest tube in the fifth intercostal space, midaxillary line. There was immediate drainage of 1600 mL of bloody fluid through the chest tube. Uncrossmatched blood was administered, and the surgical team was consulted for the massive hemothorax. The patient was intubated and transported to the operating room (OR). In the OR, the surgery team performed a thoracotomy, repaired the injured lung parenchyma, and ligated several small arteries that were actively bleeding. The patient was transported to the surgical intensive care unit (ICU) and extubated the following day. The chest tube was removed 48 hours later, and the patient was discharged on hospital day 4 in stable condition.