| abstract |
The insufflator is used for introducing limited quantities of carbon dioxide into the human body for operational purposes, particularly for laparoscopy or hysteroscopy, and is of the type comprising two pressure reducers, in series, followed by a gas flow monitoring device through which carbon dioxide is directed from a gas supply to the human body. The two pressure reducers are constantly adjusted to fixed gas supply pressures, and the monitoring device comprises a cylindrical expansion container having a central inlet port and a large diameter, and in whose peripheral zone the gas flow velocity approaches a zero rate. First and second sensing elements for the measured variable are provided in the expansion container, with the first sensing element being located immediately in the area of the inlet port and the second sensing element being located close to the cylindrical side wall at the maximum possible radial spacing from the first sensing element. The two sensing elements are included in a measuring bridge and a measuring amplifier is connected to the bridge output, with an indicator, of the rate of gas flow per unit of time, being connected to the amplifier output. For laparoscopy, the second pressure reducer is adjusted to a gas supply pressure of 15 mm Hg, and the expansion container is followed by a precision needle valve adjustable in the range of zero to 2 liters per minute. For hysteroscopy, the second pressure reducer is constantly adjusted to a supply pressure of 200 mm Hg and the expansion container is followed by a precision aperture limiting the maximum gas flow to 100 ml/min. |