A 31-year-old man is brought to the emergency department after being involved in a motor vehicle collision as an unrestrained passenger. He was given 3 L of normal saline in the ambulance on the way to the hospital and has been receiving 5 L/min of oxygen by nasal cannula. The patient is agitated and moves all 4 extremities spontaneously. Blood pressure is 82/50 mm Hg, heart rate is 130/min, and respirations are 30/min. On examination, the pupils are symmetric and reactive to light. The neck veins are flat, and the trachea is shifted slightly to the right. Over the left chest, breath sounds are diminished and there is dullness to percussion. Which of the following is the most likely diagnosis?

Question

A 31-year-old man is brought to the emergency department after being involved in a motor vehicle collision as an unrestrained passenger.  He was given 3 L of normal saline in the ambulance on the way to the hospital and has been receiving 5 L/min of oxygen by nasal cannula.  The patient is agitated and moves all 4 extremities spontaneously.  Blood pressure is 82/50 mm Hg, heart rate is 130/min, and respirations are 30/min.  On examination, the pupils are symmetric and reactive to light.  The neck veins are flat, and the trachea is shifted slightly to the right.  Over the left chest, breath sounds are diminished and there is dullness to percussion.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

This patient has hypotension, tachycardia, and flat neck veins despite fluid resuscitation (ie, 3 L normal saline), consistent with hypovolemic shock. In the setting of trauma (eg, unrestrained passenger in a motor vehicle collision), hypovolemic shock is attributed to hemorrhage until proven otherwise. A source of bleeding should be sought, with special attention directed toward compartments that can conceal massive, traumatic hemorrhage: the chest, abdomen/pelvis (including retroperitoneum), and thigh. This patient's examination shows left-sided diminished breath sounds and dullness to percussion, most consistent with hemothorax. Hemothorax may result from injuries to larger intrathoracic structures (eg, aorta, hilar vessels) and/or smaller structures (eg, lung parenchyma, intercostal blood vessels). Each hemithorax can hold up to 40% of the circulating blood volume, and massive hemothorax (>1,500 mL) can present with signs of hemorrhagic shock and tracheal deviation from mass effect (as in this patient). Tube thoracostomy should be performed, with immediate bloody drainage of >20 mL/kg (~1,500 mL) being an indication for emergent surgical thoracotomy. intercostal blood vessels (Choice A) Traumatic diaphragmatic rupture can cause diaphragmatic dysfunction and abdominal content herniation into the thorax, which can present with decreased breath sounds (due to unilateral hypoventilation) and tracheal deviation (due to mass effect). However, because it does not typically cause significant bleeding, diaphragmatic rupture would be very unlikely to cause refractory hypotension and tachycardia, which are more suggestive of hemorrhagic shock in this patient. (Choices C and D) Lung atelectasis (with collapsed alveoli) and lung contusion (with resulting alveolar edema) can cause tachypnea (to compensate for ventilation-perfusion mismatch) and tachycardia (to compensate for hypoxemia). In addition, both may cause decreased breath sounds and dullness to percussion. However, neither typically causes the severity of hypotension and tachycardia seen in this patient. (Choice E) A left-sided tension pneumothorax can produce hypotension, tachycardia, and tachypnea with rightward tracheal deviation. However, because tension pneumothorax requires a large quantity of intrathoracic air, it would typically cause absent (rather than diminished) breath sounds and hyperresonance (rather than dullness) on percussion. (Choice F) Tracheobronchial injury causes respiratory distress due to rapid leakage of air from the tracheobronchial tree into the pleural space and surrounding tissues. Such injuries typically have associated findings of severe pneumothorax, palpable crepitus (from subcutaneous air), and/or audible crunch on cardiac auscultation (ie, Hamman sign, from pneumomediastinum). Educational objective: Hypovolemic shock in the setting of blunt trauma is concerning for hemorrhage. Decreased breath sounds and dullness to percussion, with contralateral tracheal deviation, is most likely due to a massive hemothorax. References: Hemothorax: etiology, diagnosis, and management. (http://www.ncbi.nlm.nih.gov/pubmed/23206720) Practice management guidelines for management of hemothorax and occult pneumothorax. (http://www.ncbi.nlm.nih.gov/pubmed/21307755)

A 31-Year-Old Man Is Brought to the Emergency Department After