| 摘要 |
An exhalation monitoring apparatus measures and then instantly displays the volume of expired air from a patient. The instrument includes a manifold having a central chamber with an inlet opening for receiving exhaled gas from a patient. The manifold also has attached a flaccid bag so as to allow for the collection of all the exhaled gases without increasing the pressure in the manifold above the ambient air pressure. A venturi is provided in the chamber with an inlet port for connection to a source of driving gas outside the manifold and an outlet port for venting the driving gas outside the manifold. Also provided is an induction port in the throat of the venturi within the chamber for drawing in exhaled gas received in the chamber and flaccid bag. A pressure responsive electrical switch and timing circuit generate a signal constituting a function of the time it takes for the venturi to exhaust all of the exhaled air from the chamber and flaccid bag. This time interval in turn is directly proportional to the volume of exhaled air and thus can be converted to a digital signal indicating such volume in volumetric units.
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