US 5,471,058 AGranted

Anesthesia monitor

AssigneeNikkiso Co., Ltd.

InventorsKazuo Nakagawa, Yuichi Iritani, Hiromi Yamazaki, Yasushi Takakuwa

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Abstract

The invention provides an anesthesia monitor being able to directly make a separation and a determination in real time all components of a gas in which components having the same integer molecular weight exists, more particularly an expiration gas and an inspiration gas as the object of analysis. The monitor has a small size, a low price and a operational facility. A microscopic quantity of the expiration gas is introduced from a circular route of an anesthesia circuit for an inhalation anesthesia to the anesthesia monitor through a material pipe-line. A gas portion is transmitted by a rotary pump through valves and opening and closing valves to a measurement cell within a vacuum chamber arranged in a gap of between magnetic poles of permanent magnets in a Fourier transformation mass analyzer so that the expiration gas is subjected to a high speed sampling. An ionization of the ions is carried out within the measurement cell. A cyclotron resonance is caused thereby causing a high frequency voltage which is received by receiving electrodes of the cell. After a digiterzation of the signals, a computer executes a Fourier transformation mass analyzing process.

Claims12

Dependent claims

An anesthesia monitor comprising:

a pair of permanent magnets having a gap therebetween and a steady state magnetic field in said gap;
a measurement cell having pair of receiving electrodes, a pair of irradiation electrodes and a vacuum chamber exposed to said pairs of receiving and irradiation electrodes, the measurement cell being disposed in said gap and exposed to said steady state magnetic field;
a temperature bath associated with said pair permanent magnets to keep constant the temperature of the permanent magnets and maintain constant the steady state magnetic field;
means for introducing a gas sample including a first component and an anesthetic component into the measurement cell vacuum chamber;
an ion source to ionize said introduced gas sample components in said measurement cell;
means for applying a high frequency voltage to the irradiation electrodes after ionization of said introduced gas components to cause a cyclotron resonance of said ions in said vacuum chamber;
means for making a detection and amplification of a high frequency signal voltage caused by said resonance at said receiving electrodes;
means for converting said detected and amplified signal into a digital signal;
means for storing said digital signals in a memory;
means for executing a Fourier transformation process on said stored digital signals to obtain a mass spectrum of said introduced gas sample to perform a separation and a determination of each component of said introduced gas sample.

7 more elements

A method for determining the components of a mixed gas including a first component and an anesthetic component comprising:

providing a vacuum chamber containing a measurement cell arranged in a gap between a first permanent magnet and a second permanent magnet having a steady state magnetic field therebetween;
maintaining said first and second permanent magnets at a constant termperature to minimize variations of said steady state magnetic field due to temperature changes;
providing the cell with irradiation electrodes and receiving electrodes;
introducing a mixed gas sample including the first and anesthetic components into the measurement cell and causing ionization of the introduced gas sample;
applying a high frequency voltage to the irradiation electrodes to cause a cyclotron resonance of said ions;
sensing a high frequency signal voltage caused by said resonance at the receiving electrodes;
converting said sensed signals into digital signals;
storing said digital signals;
executing a Fourier transformation process on said stored digital signals to obtain a mass spectrum of said introduced gas sample;
and
performing a separation and a determination of each of said first and anesthetic components of said introduced gas sample based on the mass spectrum.

8 more elements

Dependencies are inferred from the claim text.