 This is a placebo-controlled, double-blind, parallel, randomized, two-part, dose-confirming clinical study characterizing the pharmacodynamic effects of pulsed iNO using the combination product, inhaled nitric oxideINOpulse DS-C vs. placebo in subjects with World Health Organization WHO Group 3 pulmonary hypertension PH associated with Chronic Obstructive Pulmonary Disease COPD on Long Term Oxygen Therapy LTOT. 