Abstract
Drug treatment of pulmonary hypertension may be limited by systemic hypotension. Selective action of a vasodilator drug in pulmonary arteries could be achieved by administering a vasodilator gas into systemic venous blood so that it dilates pulmonary arteries before immediate first-pass elimination via exhalation. This article presents in vivo data to show that a pharmacologically active gas can be delivered safely into systemic venous blood where it has a distribution pattern and physiologic effects similar to those observed when the gas is inhaled into pulmonary venous (systemic arterial) blood. This is a first step toward development of first-pass pulmonary clearance as a mechanism to concentrate drugs in pulmonary arteries.