Pulmonary vascular resistance (PVR; dyn/s/cm) at baseline and after exposure to inhaled nitric oxide (INO; 20 ppm) for 10 min, inhaled epoprostenol (EPO; 50 μg/min) for 10 min, and the combination (Combo). * P < .05 versus baseline. Pulmonary vascular resistance (PVR; dyn/s/cm) at baseline and after exposure to inhaled nitric oxide (INO; 20 ppm) for 10 min, inhaled epoprostenol (EPO; 50 μg/min) for 10 min, and the combination (Combo). * P < .05 versus baseline. From Reference 7, with permission. Nicholas S Hill et al. Respir Care 2015;60:794-805 (c) 2012 by Daedalus Enterprises, Inc.