A 23-year-old man is brought to the emergency department after a head-on motor vehicle collision in which both vehicles were traveling at moderate speed. The patient was a restrained driver in the collision. He has no significant medical history and takes no medications. Initially he reports pelvic pain only. Blood pressure on arrival is 132/65 mm Hg and pulse is 102/min. He is given bolus intravenous fluids and opioid analgesics for pain. The patient's cervical spine is clinically cleared for acute fractures, and he is diagnosed by plain film with a pelvic fracture. A pelvic binder is applied. One hour after initial presentation, the patient is short of breath and has chest pain. Blood pressure is 122/70 mm Hg and pulse is 84/min. Pulse oximetry shows 95% on room air. Physical examination shows the patient to be in no apparent distress lying supine. Mucous membranes are moist. No jugular venous distension or tracheal deviation is present. The patient is not using accessory respiratory muscles, and no penetrating chest trauma is noted. Breath sounds are diminished on the right upper lung field with hyperresonance to percussion and absent fremitus. The abdomen is soft and nontender. No distension, hepatomegaly, splenomegaly, or free fluid is present. The remainder of the examination is normal. Which of the following is the best initial test to assess for the suspected diagnosis of pneumothorax in this patient?

Question

A 23-year-old man is brought to the emergency department after a head-on motor vehicle collision in which both vehicles were traveling at moderate speed.  The patient was a restrained driver in the collision.  He has no significant medical history and takes no medications.  Initially he reports pelvic pain only.  Blood pressure on arrival is 132/65 mm Hg and pulse is 102/min.  He is given bolus intravenous fluids and opioid analgesics for pain.  The patient's cervical spine is clinically cleared for acute fractures, and he is diagnosed by plain film with a pelvic fracture.  A pelvic binder is applied.  One hour after initial presentation, the patient is short of breath and has chest pain.  Blood pressure is 122/70 mm Hg and pulse is 84/min.  Pulse oximetry shows 95% on room air.  Physical examination shows the patient to be in no apparent distress lying supine.  Mucous membranes are moist.  No jugular venous distension or tracheal deviation is present.  The patient is not using accessory respiratory muscles, and no penetrating chest trauma is noted.  Breath sounds are diminished on the right upper lung field with hyperresonance to percussion and absent fremitus.  The abdomen is soft and nontender.  No distension, hepatomegaly, splenomegaly, or free fluid is present.  The remainder of the examination is normal.  Which of the following is the best initial test to assess for the suspected diagnosis of pneumothorax in this patient?

Quizplus · Accepted Answer

Explanation: Bedside ultrasonography, performed by a trained provider, has become the test of choice for diagnosing pneumothorax in the acute setting (eg, trauma bay, intensive care unit). In addition to high sensitivity and specificity (both >90%) for pneumothorax, bedside ultrasound allows for diagnostic evaluation without transporting a critically ill patient, and can be more rapidly performed than chest x-ray or CT scan. Ultrasonography allows visualization of the parietal and visceral pleura; inability to detect lung sliding, the 2 pleural layers moving against one another during respiration, is consistent with pneumothorax. In patients for whom tension pneumothorax is highly suspected (eg, chest trauma with hypotension, tracheal deviation), diagnostic confirmation is not needed and urgent treatment can be given with needle decompression or chest tube placement. (Choice B) CT scan of the chest has higher sensitivity for pneumothorax than bedside ultrasound; however, due to the time required to obtain a CT scan, it is an inappropriate test in the acute setting. (Choices C and E) Upright posteroanterior chest x-ray has high sensitivity for detecting pneumothorax; it is the initial test of choice when there is suspicion for pneumothorax in the nonacute setting (low risk of tension physiology). However, in the acute setting, where rapid decompensation from tension pneumothorax is possible, upright chest x-ray is not appropriate. In addition, posteroanterior chest x-ray requires standing, which is not possible in a patient with pelvic fracture. Expiratory chest x-rays do not provide additional sensitivity compared to inspiratory chest x-rays; therefore, inspiratory chest x-rays are generally used when evaluating for pneumothorax. (Choice D) A portable supine anteroposterior chest x-ray can be quickly obtained in the acute setting; however, the sensitivity for detecting pneumothorax is estimated at ~50%, far below that for bedside ultrasonography. It is an acceptable alternative when relatively rapid confirmation of pneumothorax is needed and bedside ultrasonography is unavailable. Educational objective: Bedside ultrasonography can be rapidly performed and has high sensitivity and specificity for pneumothorax. It has become the test of choice for evaluation of tension pneumothorax in the acute setting (eg, trauma bay, intensive care unit). References: Sonographic diagnosis of pneumothorax. (http://www.ncbi.nlm.nih.gov/pubmed/22416161) Value of ultrasound in diagnosis of pneumothorax: a prospective study. (http://www.ncbi.nlm.nih.gov/pubmed/23179505)

A 23-Year-Old Man Is Brought to the Emergency Department After