NASA engineer Dan Dietrich and a team of scientists at Glenn developed the Portable Unit for Metabolic Analysis (PUMA) to monitor the oxygen consumption and carbon dioxide production rates of astronauts exercising during long missions. The portable unit was designed to give the crew the ability to move around the spacecraft without being tethered to a large immovable unit.
PUMA measures six components to evaluate metabolic function: oxygen and carbon dioxide partial pressure, volume flow rate, heart rate, and gas pressure and temperature. From those measurements, PUMA can compute the oxygen uptake, carbon dioxide output and minute ventilation (average expired gas flow rate). A small, embedded computer takes readings of each sensor and relays the data wirelessly to a remote computer via Bluetooth.