Selective pulmonary vasodilatation by inhalation of the vasorelaxant agent is an appealing concept to circumvent some of the hazards inherent in systemic vasodilator therapy in COPD patients with PH. Treatment of these patients with aerosolization of iloprost may reduce pulmonary vascular resistance , increases cardiac output while conserving ventilation-perfusion matching and and shunt preventing worsening of arterial hypoxia and wasting of the small ventilatory reserve of these patients.