Paradoxical Hypoxemia with Simultaneous Use of Pulmonary Vasodilators in a Case of PPHN

Persistent pulmonary hypertension of the newborn (PPHN) is characterized by the persistence of high pulmonary vascular resistance (PVR) of fetal life, after birth. Inhaled nitric oxide (iNO) has been the mainstay of PPHN treatment. Intravenous (IV) sildenafil and inhaled epoprostenol are newer agents, which are currently not FDA approved. We describe the first reported case of PPHN in which the simultaneous use of iNO, IV sildenafil and inhaled epoprostenol resulted in hypotension and paradoxical hypoxemia. Term infant with PPHN of unknown etiology was treated with iNO with inadequate clinical response. Inhaled epoprostenol was added on day 4 of life to achieve synergism to iNO action. IV sildenafil was added to minimize rebound pulmonary hypertension associated with iNO withdrawal. However, within minutes of its administration a paradoxical response was noticed with significant hypotension and hypoxemia. IV sildenafil was immediately discontinued. We discuss the mechanism of action of each pharmacological agent and the resultant interactions that led to adverse effects in this patient.