STAND-ALONE CIRCLE CIRCUIT WITH CO2 ABSORPTION AND SENSITIVE SPIROMETRY FOR MEASUREMENT OF PULMONARY UPTAKE

摘要

A system that determines the volume of oxygen taken by the lungs comprises a ventilation that is connected to a spirometric device (44) that contains oxygen. The oxygen absorbed by the lungs from the circuit is replaced by an equivalent amount of oxygen from the device. The volume of oxygen that leaves the device is measured to indicate the volume of oxygen taken by the lungs. A source of make-up oxygen (16) is connected to the circuit and the flow of make-up oxygen is adjusted as necessary to maintain a constant volume of oxygen in the device. The volume of make-up oxygen is measured and serves as an indication of the amount of oxygen taken by the lungs. A valve (28) is used to isolate the device from the circuit during all but a part of the ventilation cycle to prevent substantial pressure or movement excursions within the device.