In the past, the hyperoxia test was performed to distinguish pulmonary causes from cardiac causes of cyanosis. The patient is first administered 100% oxygen for 10 minutes. A preductal arterial blood gas is then taken from the patient's right arm. In patients with pulmonary disease, this supplemental oxygen significantly augments systemic oxygenation, which is not the case in cyanotic congenital heart defects. However, in some pulmonary conditions, the oxygen tension might not rise significantly. In these patients, a chest radiograph is invaluable for affirming pulmonary pathology. In some congenital heart lesions with mixing (ie, TA), the supplemental oxygen decreases the pulmonary vascular resistance, which results in an increase in oxygen tension but rarely greater than 150 mm Hg. Although useful in differentiating pulmonary and cardiac causes of cyanosis, this test requires arterial blood sampling, which is invasive and difficult in neonates. In 2009, the American Academy of Pediatrics and the American Heart Association recommended pulse oximetry screening for improved critical CHD detection. Current guidelines recommend that infants be screened with pulse oximetry on the right hand and one foot at 24 hours of life, with a saturation of 95% or greater considered negative.

References

• Geggel RL, Fulton DR. History, physical examination, oximetry, chest radiograph, and other baseline testing. In: Walsh EP, Mayer JE, Teele SA et al. Nadas' Pediatric Cardiology. 3rd ed. Elsevier; 2025:75-91.
• Martin GR, Ewer AK, Gaviglio A, et al. Updated strategies for pulse oximetry screening for critical congenital heart disease. Pediatrics. 2020;146:1-10.