| 摘要 |
The invention provides an apparatus for measuring and recording the volume of anaesthetic gas administered to a patient, the apparatus comprising a gas flow sensor (1, see fig 1) for measuring the flow rate of an anaesthetic gas, the gas flow sensor being linked to a data storage and processing device (3, fig 1) for flow data, and means (4, 5, 6, fig 1) for retrieving data from the storage device. The sensor circuit 11 is a thermistor arrangement located in the gas flow across inner sleeve 10, one thermistor (R2, see fig 3) being upstream and exposed, and one R4 being downstream and sheltered from gas flow. A thermal or Wheatstone bridge determines the change in resistance and voltage difference, and thus the gas flow (fig 3). The sensor takes into account the starting gas temperature, and may be calibrated prior to use. The sensor may be fixed to an existing flow tube and fitted to an anaesthetic machine. |
