A 40-year-old woman is brought to the emergency department by paramedics after a motor vehicle collision. She was driving and wearing a seatbelt when her car was hit by another vehicle from the opposite direction. Her car went off the road and hit a tree. When paramedics arrived at the scene, the patient was noted to have an open femur fracture but was alert and oriented. Her medical issues include hyperlipidemia and mitral valve prolapse with mild regurgitation. She takes no medications. The patient undergoes open reduction and internal fixation of the femur fracture. She receives intravenous fluids and pain control postoperatively. The next morning she experiences left-sided chest discomfort and shortness of breath. Temperature is 37.6 C (99.7 F), blood pressure is 120/70 mm Hg, pulse is 100/min, and respirations are 30/min. Pulse oximetry shows 84% on room air. Physical examination reveals an area of tenderness over the left chest wall where the seatbelt was placed. On pulmonary examination, the patient has rales over the left upper lung. A 2/6 holosystolic murmur is present over the cardiac apex. Laboratory results are as follows:
ECG shows sinus tachycardia with no ST-segment or T-wave changes. Chest x-ray shows irregular opacification predominantly of the left upper lung.
What is the most likely cause of this patient's respiratory symptoms?

Question

A 40-year-old woman is brought to the emergency department by paramedics after a motor vehicle collision.  She was driving and wearing a seatbelt when her car was hit by another vehicle from the opposite direction.  Her car went off the road and hit a tree.  When paramedics arrived at the scene, the patient was noted to have an open femur fracture but was alert and oriented.  Her medical issues include hyperlipidemia and mitral valve prolapse with mild regurgitation.  She takes no medications.  The patient undergoes open reduction and internal fixation of the femur fracture.  She receives intravenous fluids and pain control postoperatively.  The next morning she experiences left-sided chest discomfort and shortness of breath.  Temperature is 37.6 C (99.7 F), blood pressure is 120/70 mm Hg, pulse is 100/min, and respirations are 30/min.  Pulse oximetry shows 84% on room air.  Physical examination reveals an area of tenderness over the left chest wall where the seatbelt was placed.  On pulmonary examination, the patient has rales over the left upper lung.  A 2/6 holosystolic murmur is present over the cardiac apex.  Laboratory results are as follows:
 ECG shows sinus tachycardia with no ST-segment or T-wave changes.  Chest x-ray shows irregular opacification predominantly of the left upper lung.
What is the most likely cause of this patient's respiratory symptoms?

Quizplus · Accepted Answer

Explanation: This patient's respiratory symptoms are most likely due to a pulmonary contusion. Blunt trauma to the lungs results in accumulation of edema and blood in a localized area of the lung parenchyma. Patients typically have chest pain and may develop accompanying shortness of breath and hemoptysis, and chest x-ray characteristically shows an irregular, localized opacification at the site of injury. The onset of respiratory symptoms may be delayed for approximately 24 hours from the time of injury, and initial chest x-ray sometimes demonstrates no airspace disease. CT scan is more diagnostically sensitive; however, contusions that are apparent on CT scan but not on chest x-ray are often minor and may be of low clinical significance. Depending on the size of the contusion, respiratory distress and significant hypoxemia can develop. (Choice A) Acute respiratory distress syndrome describes noncardiogenic pulmonary edema that typically results from a systemic disease process (eg, sepsis, pancreatitis) or lung injury (eg, toxic inhalation). The pulmonary edema is typically diffuse and bilateral rather than localized as in this patient. (Choice B) Cardiogenic pulmonary edema most often results from left ventricular systolic dysfunction. Trauma patients may experience cardiac contusion resulting in impaired left ventricular contraction and resulting pulmonary edema; however, as in acute respiratory distress syndrome, the pulmonary edema is typically diffuse and bilateral. (Choice C) Fat embolism syndrome is a potential complication of long-bone (eg, femur) fracture and can result in respiratory distress with hypoxemia. However, accompanying neurologic symptoms (eg, confusion) and a petechial rash are often present, and chest x-ray typically shows no airspace disease. (Choice E) Femur fracture increases the risk of acute pulmonary embolism, and the typical presentation is with chest pain and shortness of breath. However, the irregular opacification in the left lung and corresponding chest tenderness at the site of seatbelt contact make pulmonary contusion more likely. Educational objective: Pulmonary contusion is a common injury resulting from blunt chest trauma. Patients typically have chest pain and may develop respiratory distress and hypoxemia that is delayed up to 24 hours from the time of injury. Chest x-ray characteristically shows an irregular, localized lung opacification. References: Pulmonary contusion in the pan-scan era. (http://www.ncbi.nlm.nih.gov/pubmed/26708426)

A 40-Year-Old Woman Is Brought to the Emergency Department by Paramedics