Differential Cyanosis in Persistent Pulmonary Hypertension of the Newborn (PPHN)

In PPHN with right-to-left ductal shunting (indicating syprasystemic pulmonary artery pressure), the upper body (preductal) saturation may be normal or decreased. More poorly oxygenated blood, from the right ventricle, flows through the main pulmonary artery and the ductus arteriosus into the descending aorta, causing decreased lower body (postductal) saturations relative to those in the upper body.

Data from Romer AJ, Johng S, Hsia J, Scott S, Reddy A, Gardner MM. Cyanosis in a Newborn Immediately after Birth. NEJM Evid. 2022;1(2):EVIDmr2100060. doi:10.1056/EVIDmr2100060