Asthma USMLE Step 1 Practice Question
A 1-day-old female presents with severe respiratory distress, cyanosis, and a scaphoid abdomen. Vital signs show HR 165/min, RR 68/min, BP 58/38 mmHg, and SpO2 78% on room air. Physical examination reveals markedly decreased breath sounds over the left hemithorax with bowel sounds audible in the chest. Chest radiograph demonstrates bowel loops in the left thoracic cavity with rightward mediastinal shift. No meconium passage has occurred. Which of the following is the most likely underlying defect?
Answer choices
- AAbnormal regression of the right fourth aortic arch
- BProximal esophageal atresia with distal fistula
- CFailure of closure of the ductus arteriosus
- DFailure of fusion of the pleuroperitoneal membraneCorrect answer
- EDeficiency of surfactant production by type II pneumocytes
- FIncomplete separation of the foregut into respiratory and digestive components
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