Hyperoxia test results in neonates with cyanosis

The hyperoxia test can be used to help distinguish between cardiac and pulmonary causes of cyanosis in newborns. The newborn's oxygen level is measured before and after administration of 100% inspired oxygen for 10 minutes. Oxygen levels can be measured with PaO₂ and/or SpO₂ and should be performed in the right arm (preductal). The typical PaO₂ and SpO₂ values in room air (FiO₂ = 0.21) or 100% oxygen (FiO₂ = 1) for neonates with different causes of cyanosis are summarized here. Hyperoxia testing is not definitive. An abnormal or equivocal response should generally prompt further evaluation with echocardiography. While a rise in PaO₂ and SpO₂ during the challenge suggests a pulmonary cause of cyanosis, it does not exclude CHD, and echocardiography should still be performed if clinical suspicion for CHD remains high based upon other findings.