A respiratory gas analyzer for measuring the metabolic activity and the cardiac output of a subject includes a bi-directional flow meter and a capnometer sensor interconnected by conduits and valving between a mouthpiece and a source of respiratory gasses which may be a controlled source...http://www.google.com/patents/US5836300?utm_source=gb-gplus-sharePatent US5836300 - Metabolic gas exchange and noninvasive cardiac output monitor
