Subatmospheric oxygen therapy complicating subcutaneous emphysema.

An infant with hypoplastic left heart syndrome, excessive pulmonary blood flow, and tachypnea was placed on subatmospheric oxygen (supplemental nitrogen) to increase pulmonary vascular resistance and decrease pulmonary blood flow. His cardiorespiratory status stabilized without mechanical ventilation, but 2 weeks later he developed spontaneous subcutaneous emphysema. The emphysema worsened over approximately 1 month. During this time his left-to-right shunt gradually decreased, and he was weaned to room air. Even without the use of supplemental oxygen the emphysema resolved without complication, and the patient underwent successful orthotopic heart transplantation at 65 days of age.