Wheezing child.

This case discussion is part of the Integrating Basic Science into Clinical Teaching Initiative. It is intended to examine wheezing as a symptom and to describe the underlying physiology that explains the physical findings and blood gas features in an attempt to localize the site of obstruction. The information contained in this case is a compilation and derived from 2 similar patients. This case discussion describes a 13-month-old girl who presents with wheezing and respiratory distress. A close examination of her physical findings and blood gas analysis indicate that she is experiencing overall alveolar hypoventilation without significant hypoxemia, suggesting her airway obstruction is located above the carina. Subsequent investigations reveal a right aortic arch and vascular ring as the cause of her symptoms. An understanding of the physiology of airway obstruction and pulmonary gas exchange allows for better localization of sites of airway obstruction and the institution of appropriate diagnostic tests and therapy.