I am going to answer the sample USMLE Step 1 Questions with Explanation. These questions are available at USMLE.org
Q- A 19-year-old man who is in the US Army is brought to the emergency department 45 minutes after he sustained a knife wound to the right side of his chest during an altercation. He has no history of major medical illness and takes no medications. His temperature is 36.9°C (98.4°F), pulse is 110/min, respirations are 24/min, and blood pressure is 114/76 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 94%. On physical examination, the trachea appears to be shifted to the left. Pulmonary examination of the right chest is most likely to show which of the following findings?
| Fremitus | Percussion | Breath Sounds | |||
| (A) | Decreased | dull | decreased | ||
| (B) | Decreased | hyperresonant | decreased | ||
| (C) | Decreased | hyperresonant | dull | ||
| (D) | Increased | dull | bronchial | ||
| (E) | Increased | dull | decreased | ||
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Answer
This patient presents with respiratory distress, decreased oxygen saturation and tracheal shift to the left after an open wound to the right side of the chest. This is a typical presentation of tension pneumothorax. This condition leads to compression of the left lung and tracheal shift to the left. Air on the right side causes decreased fremitus, hyperresonance in percussion and decreased breath sounds on the affected side.
The correct answer is B