This disclosure concerns improved capabilities for evaluating pulmonary arterial hypertension (PAH). A system and method of evaluating PAH in a subject may include measuring end tidal partial pressure of exhaled carbon dioxide in the subject, wherein the measurement is made orally using described systems or devices. Integrated sensors enable the measurement and characterization of other respiratory gas components, some of which may be indicative of disease. The system and method can be used to monitor a course of treatment for PAH.
