Cardiac*

Right-to-left shunting or mixing lesions with normal or increased pulmonary flow: Transposition of the great vessels, tetralogy of Fallot with minimal pulmonary outflow tract obstruction, total anomalous venous return, truncus arteriosus, hypoplastic left heart syndrome

Right-to-left shunting with decreased pulmonary flow:† Pulmonary atresia, tetralogy of Fallot with significant pulmonary outflow tract obstruction, critical pulmonic stenosis, tricuspid atresia, single ventricle with pulmonic stenosis, Ebstein anomaly, persistent pulmonary hypertension

Respiratory

Upper tract: Choanal atresia or stenosis, tracheobroncholaryngeal stenosis, compressive obstruction (eg, vascular ring), tracheoesophageal anomalies (eg, cleft, fistula)

Lower tract: Respiratory distress syndrome, transient tachypnea of the newborn, meconium aspiration, pneumonia, pneumothorax, congenital diaphragmatic hernia, pulmonary hypoplasia, cystic malformation of the lung, congenital deficiency of surfactant proteins B or C

Neurologic‡

Intracranial hemorrhage or hypertension, oversedation (infant or maternal), diaphragmatic paralysis, neuromuscular disease, seizure disorder

Hematologic

Methemoglobinemia (methemoglobin levels > 40%), polycythemia, severe anemia

Miscellaneous

Hypoglycemia, metabolic disorders (eg, acid-base disorders, hyperammonemia), hypovolemic shock, sepsis