Method and apparatus for measuring gas partial pressure in living body

Claim 1

An apparatus for measuring a partial pressure of gas in a living body based on the principle of polarography comprising: a gas partial pressure sensor including a biomedical electrode and a counter electrode for producing an output signal indicative of a polargraphic current, at least said biomedical electrode being placed in said living body wherein said biomedical electrode has a tip end surface covered with a membrane comprised of an outer dense, thin layer having fine pores of an average diameter of 20 Å to 0.7 μm and an inner porous layer, contigous to and integral with the outer layer, having fine pores of an average diameter of 0.7 μm or more, a temperature sensor adapted to be placed at a position suitable for producing an output signal indicative of a temperature of said living body, an interface unit having an A/D converter which digitizes the output signals from said partial pressure sensor and said temperature sensor, an operation unit connected to said interface unit to receive the digitized values of the output signals of said gas partial pressure sensor and said temperature sensor, said operation unit correcting the digitized output signal of said gas partial pressure sensor to an output signal value at a reference temperature on the basis of the temperature measured by said temperature sensor, in accordacne with the following equation: I.sub.t =I.sub.ST (k).sup.T-t where I t is the output value of the gas partial pressure sensor at t° C., I ST is the output value of the gas partial pressure sensor at T° C., k is the temperature coefficient of the gas partial pressure sensor, and t is the temperature measured by the temperature sensor, and calculating a gas partial pressure on the basis of a working curve prepared in said operation unit in advance, said working curve representing a relationship between said gas partial pressure and said corrected digitized output signal of said gas partial pressure sensor.

Claim 2

An apparatus for measuring a partial pressure of gas in a living body based on the principle of polarography comprising: a gas partial pressure sensor including a biomedical electrode and a counter electrode for producing an output signal indicative of a polargraphic current, at least said biomedical electrode being placed in said living body wherein said biomedical electrode has a tip end surface covered with a membrane comprised of an outer dense, thin layer having fine pores of an average diameter of 20 Å to 0.7 μm and an inner porous layer, contigous to and integral with the outer layer, having fine pores of an average diameter of 0.7 μm or more, a temperature sensor adapted to be placed at a position suitable for producing an output signal indicative of a temperature of said living body, an interface unit having an A/D converter which digitizes the output signals from said partial pressure sensor and said temperature sensor, an operation unit connected to said interface unit to receive the digitized values of the output signals of said gas partial pressure sensor and said temperature sensor, said operation unit correcting the digitized output signal of said gas partial pressure sensor to an output signal value at a reference temperature on the basis of the temperature measured by said temperature sensor, in accordacne with the following equation: I.sub.t =I.sub.ST (k).sup.T-t where I t is the output value of the gas partial pressure sensor at t° C., I ST is the output value of the gas partial pressure sensor at T° C., k is the temperature coefficient of the gas partial pressure sensor, and t is the temperature measured by the temperature sensor, and calculating a gas partial pressure on the basis of a working curve prepared in said operation unit in advance, said working curve representing a relationship between said gas partial pressure and said corrected digitized output signal of said gas partial pressure sensor.

Claim 5

A method for measuring a partial pressure of gas in a living body on the basis of the principle of polarography comprising the steps of: placing a biomedical electrode, of a gas partial pressure sensor in the living body, a tip end surface of said electrode being covered with a porous membrane comprised of a most outer layer consisting of a thin dense membrane having fine pores of an average diameter of 20Å to 0.7 μm and an inner layer, contigous to and integral with the outer layer, having fine pores of an average diameter of 0.7 μm or more, said gas partial pressure sensor producing an output of a value which is responsive to the gas partial pressure in said living body, placing a temperature sensor at a position suitable to sequentially measure a temperature of said living body, correcting the value of the output signal from said gas partial pressure sensor continously to a value at a reference temperature on the basis of the temperature measured by said temperature sensor, in accordance with the following equation: I.sub.t =I.sub.ST (k).sup.T-t where I t is the output value of the gas partial pressure sensor at t° C., I ST is the output value of the gas partial pressure sensor at T° C., k is the temperature coefficient of the gas partial pressure sensor, and t is the temperature measured by the temperature sensor, and determining a gas partial pressure value of said living body continuously from said corrected output value and a working curve, said working curve being prepared in advance and representing a relationship between the gas partial pressure value and said corrected output value.

Claim 6

A method for measuring a partial pressure of gas in a living body on the basis of the principle of polarography comprising the steps of: placing a biomedical electrode, of a gas partial pressure sensor in the living body, a tip end surface of said electrode being covered with a porous membrane comprised of a most outer layer consisting of a thin dense membrane having fine pores of an average diameter of 20Å to 0.7 μm and an inner layer, contigous to and integral with the outer layer, having fine pores of an average diameter of 0.7 μm or more, said gas partial pressure sensor producing an output of a value which is responsive to the gas partial pressure in said living body, placing a temperature sensor at a position suitable to sequentially measure a temperature of said living body, correcting the value of the output signal from said gas partial pressure sensor continously to a value at a reference temperature on the basis of the temperature measured by said temperature sensor, in accordance with the following equation: I.sub.t =I.sub.ST (k).sup.T-t where I t is the output value of the gas partial pressure sensor at t° C., I ST is the output value of the gas partial pressure sensor at T° C., k is the temperature coefficient of the gas partial pressure sensor, and t is the temperature measured by the temperature sensor, and determining a gas partial pressure value of said living body continuously from said corrected output value and a working curve, said working curve being prepared in advance and representing a relationship between the gas partial pressure value and said corrected output value.