Causes of hypotension in infants with PPHN: Sepsis and hypoxia causes intravascular oligemia due to capillary leak or due to systemic vasodilation. Neonates with PPHN often require high mean airway pressure that impedes venous return to the right side of heart. Increased pulmonary vascular resistance results in less blood flow through pulmonary circulation reducing left ventricular preload. The deviation of the interventricular septum towards left ventricle further impedes left ventricular filling. Neonates with PPHN secondary to sepsis, hypoxia and CDH can also experience systemic hypotension secondary to left ventricular dysfunction. (copyright Satyan Lakshminrusimha).