PDE5A and persistent fetal circulation syndrome: For this reason, PDE4 inhibitors might be of benefit in situations, such as persistent pulmonary hypertension of the newborn (PPHN) or in abnormally constricted pulmonary vasculature in sepsis, RDS, meconium aspiration syndrome etc., as well as in ARDS-induced pulmonary vasoconstriction and pulmonary hypertension, although the PDE5 and PDE3 inhibitors are of a major importance in influencing of these changes [164].