Plethysmograph cabin breath analyser - has gas analyser and flowmeter connected through switch to graphical display device

摘要

The breath analyser in a plethysmograph cabin (10) to check the quantity of a gas, e.g. N2O absorbed by the lungs, has a line (32) connecting the breather bag (19) and control valve (12) with the gas analyser (34). This line (32) is made suitably long so that the flow of breath through it lasts the same time as that to make the first measurement, this being the exhalation phase. - The inspiration and exhalation phases are indicated on a chart recorder (44). A breath flowmeter (28) and the analyser (34) are both connected by lines (30, 38) to a switch (48) at the recorder input (46) so that they can be connected in sequence to the recorder. The switch can be operated by a programming device.