| 摘要 |
A device for admixing liquid anesthetics into the respiratory gas to be supplied to a patient makes it possible to monitor the concentration, the flow of respiratory gas, the mixture ratio, and the flow of anesthetic. Errors may thus be indicated and safety is increased in medical practice. The device utilizes the phenomonen that during the evaporation of an anesthetic admixed with the respiratory gas, the temperature in the thermally insulated ambience of the mixing chamber drops by an amount depending on the ratio of the vaporized anesthetic to the respiratory gas, thus on the concentration. The temperatures are measured at the inlet of the mixing chamber by an inlet sensor and an intermediate sensor, and at the outlet of the mixing chamber by an outlet sensor. Upon heating the stream of respiratory gas by means of a heating element in the inlet portion, the breathing gas flow, its mixing ratio, and the flow of anesthetic can be measured, and thus the concentration can be determined from the necessary heating power input and the heating temperature. The measurement is effected by a heater control and evaluating circuit connected to the sensors and the heater, by which heater controlling measures are effected upon deviations from desired values.
|
