A six-year-old boy with a medical history of Crohn’s disease and recurrent urinary tract infections, treated with phenazopyridine twice daily for five months, presented after having an extensive workup for hypoxemia. Three years prior, the patient was admitted for hematemesis and hypoxemia, where he was found to have an abnormal hyperoxygenation test . Subsequent cardiac catheterization and echocardiogram showed no evidence of intracardiac shunt or pulmonary hypertension with normal heart size and function. The patient underwent a bronchoscopy that showed a small degree of upper airway obstruction and tracheomalacia .
An overnight oximetry study demonstrated unexplainable borderline-low basal oxygen saturation . Upon reviewing the history, it became evident that his symptoms worsened while standing . He underwent a repeat cardiac catheterization demonstrating a patent foramen ovale…
