[FIO2 and SpO2 during cardiac surgery in neonates and infants]

Fractional inspired oxygen (FIO2) applied before and after a repair or palliative procedure for cardiac defects along with SpO2 measured by pulse oximeter were reviewed from anesthetic records of 62 neonates and infants. Fentanyl was used for anesthesia, except in cases without i.v. route in which sevoflurane with nitrous oxide in oxygen was used for induction of anesthesia. FIO2 was adjusted using air and oxygen. The lower FIO2 was applied to the patients for a closure of ventricular septal defect, a reconstruction of coarctation or interrupted aortic arch, and pulmonary artery banding, while the higher FIO2 was used for systemic-to-pulmonary artery shunts and the repair of tetralogy of Fallot. In the congenital heart disease with the intracardiac shunt, the magnitude of the shunt flow and hemodynamics can be altered by changing systemic and pulmonary vascular resistance which could be induced by various ways. Since alveolar oxygen tension is a known determinant of pulmonary vascular resistance, an appropriate FIO2 should be applied to each patient with different pathophysiology. A low FIO2 should be set for the cases with nonrestrictive left-to-right shunting, since a high FIO2 may cause a torrential pulmonary blood flow. A high FIO2 is preferable for the cases with right-to-left shunting and a concomitant decreased pulmonary blood flow.