Agent gas analyzer and method of use

Claim 1

A method for simultaneously determining concentrations of N gases in a respiratory gas stream, where N>1, comprising the steps of: (a) irradiating a portion of said respiratory gas stream with radiation; (b) positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; (c) detecting the amount of radiation in each of said N different bands of wavelengths of said radiation; (d) generating N electrical absorption signals representative of said amount of radiation in said N bands; and (e) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream using matrix equations with a dimension of the matrix equal to N, and including said N electrical absorption signals as variables which are at least second order variables in said matrix equations.

Claim 2

A method for simultaneously determining concentrations of N gases in a respiratory gas stream, where N>1, comprising the steps of: (a) irradiating a portion of said respiratory gas stream with radiation; (b) positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; (c) detecting the amount of radiation in each of said N different bands of wavelengths of said radiation; (d) generating N electrical absorption signals representative of said amount of radiation in said N bands; and (e) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream using matrix equations with a dimension of the matrix equal to N, and including said N electrical absorption signals as variables which are at least second order variables in said matrix equations.

Claim 12

A method for simultaneously determining concentrations of N gases in a respiratory gas stream having repeated breath cycles of a patient, comprising the steps of: (a) irradiating a portion of said respiratory gas stream with radiation; (b) positioning each of N different filters and a reference filter to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands and a reference band of wavelengths of said radiation; (c) detecting the amount of radiation in each of said N different bands of wavelengths of said radiation and said reference band for determining a position in said breath cycles; (d) generating electrical absorption signals representative of the amount of absorption detected in step (c) for said N bands; (e) determining portions of each said breath cycle during which the rate of change of said electrical absorption signal for said reference band is within a predetermined range; (f) measuring the absorption of radiation by the respiratory gas stream in as many bands from 1 to N as may e accomplished when the rate of change of said electrical absorption signal for said reference band is within said predetermined range for each said breath cycle; (g) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream using matrix equations with a dimension of the matrix equal to N, and including said N electrical absorption signals as variables which are at least second order variables in said matrix equations, if all said N electrical absorption signals were generated during a breath cycle; and (h) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream using said matrix equations if less than N electrical absorption signals were generated during a breath cycle by interpolating values for the number of electrical absorption signals not generated during such breath cycle based on a time-weighted average for each electrical absorption signal not generated using electrical absorption signals generated during previous and subsequent breath cycles.

Claim 13

A method for simultaneously determining concentrations of N gases in a respiratory gas stream having repeated breath cycles of a patient, comprising the steps of: (a) irradiating a portion of said respiratory gas stream with radiation; (b) positioning each of N different filters and a reference filter to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands and a reference band of wavelengths of said radiation; (c) detecting the amount of radiation in each of said N different bands of wavelengths of said radiation and said reference band for determining a position in said breath cycles; (d) generating electrical absorption signals representative of the amount of absorption detected in step (c) for said N bands; (e) determining portions of each said breath cycle during which the rate of change of said electrical absorption signal for said reference band is within a predetermined range; (f) measuring the absorption of radiation by the respiratory gas stream in as many bands from 1 to N as may e accomplished when the rate of change of said electrical absorption signal for said reference band is within said predetermined range for each said breath cycle; (g) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream using matrix equations with a dimension of the matrix equal to N, and including said N electrical absorption signals as variables which are at least second order variables in said matrix equations, if all said N electrical absorption signals were generated during a breath cycle; and (h) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream using said matrix equations if less than N electrical absorption signals were generated during a breath cycle by interpolating values for the number of electrical absorption signals not generated during such breath cycle based on a time-weighted average for each electrical absorption signal not generated using electrical absorption signals generated during previous and subsequent breath cycles.

Claim 14

A method for simultaneously determining concentrations of N gases in a respiratory gas stream, comprising the steps of: (a) irradiating a portion of said respiratory gas stream with radiation; (b) positioning each of N different filters and a reference filter to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands and a reference band of wavelengths of said radiation; (c) detecting the amount of radiation absorbed in said reference band of radiation; (d) determining an inspired event and expired event of a breath cycle from the amount of detected radiation in said reference band; (e) determining for each of the inspired and expired events the time when the rate of change of radiation absorbed in said reference band has a slope within a predetermined range; (f) detecting an amount of absorption of radiation by the respiratory gas stream at said N discrete bands separately for both the inspired and expired events during the time when said rate of change of absorption in the reference band has a slope within the predetermined range for each event; and (g) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream separately for the inspired and expired events using matrix equations with a dimension of the matrix equal to N, and including said amounts of absorption in said N bands as variables which are at least second order variables in said matrix equations.

Claim 15

A method for simultaneously determining concentrations of N gases in a respiratory gas stream, comprising the steps of: (a) irradiating a portion of said respiratory gas stream with radiation; (b) positioning each of N different filters and a reference filter to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands and a reference band of wavelengths of said radiation; (c) detecting the amount of radiation absorbed in said reference band of radiation; (d) determining an inspired event and expired event of a breath cycle from the amount of detected radiation in said reference band; (e) determining for each of the inspired and expired events the time when the rate of change of radiation absorbed in said reference band has a slope within a predetermined range; (f) detecting an amount of absorption of radiation by the respiratory gas stream at said N discrete bands separately for both the inspired and expired events during the time when said rate of change of absorption in the reference band has a slope within the predetermined range for each event; and (g) computing simultaneously the concentrations of each of said N gases in the respiratory gas stream separately for the inspired and expired events using matrix equations with a dimension of the matrix equal to N, and including said amounts of absorption in said N bands as variables which are at least second order variables in said matrix equations.

Claim 17

A method for determining a concentration for each of N gases in a respiratory gas stream comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters and a reference filter to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands and a reference band of wavelengths of said radiation; detecting the of radiation in said reference band corresponding to absorption by a reference gas indicative of inspired and expired events in a breath cycle of said respiratory gas stream; determining the occurrence of an inspired or expired event from the amount of radiation detected in said reference band; detecting the amount of radiation absorbed by said respiratory gas stream in said N different bands of wavelengths of said radiation; computing and displaying said concentrations from said amounts of radiation absorbed for a period of time corresponding to one of said inspired and expired events; determining a sample period within one of said inspired and expired periods wherein the rate of change of absorption by said reference gas is within a predetermined range; and performing said computing step on absorptions detected during said sample period of time.

Claim 18

A method for determining a concentration for each of N gases in a respiratory gas stream comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters and a reference filter to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands and a reference band of wavelengths of said radiation; detecting the of radiation in said reference band corresponding to absorption by a reference gas indicative of inspired and expired events in a breath cycle of said respiratory gas stream; determining the occurrence of an inspired or expired event from the amount of radiation detected in said reference band; detecting the amount of radiation absorbed by said respiratory gas stream in said N different bands of wavelengths of said radiation; computing and displaying said concentrations from said amounts of radiation absorbed for a period of time corresponding to one of said inspired and expired events; determining a sample period within one of said inspired and expired periods wherein the rate of change of absorption by said reference gas is within a predetermined range; and performing said computing step on absorptions detected during said sample period of time.

Claim 21

A method for determining a concentration for each of N gases in a respiratory gas stream, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of radiation in as many of said N bands of wavelengths of said radiation as is possible during each of a plurality of measurement periods; interpolating to determine the absorption in any of said N bands when absorption is not detected in one of said measurement periods; and computing the concentrations of each of said N gases using detected and interpolated absorptions with multiple simultaneous equations; wherein said measurement period is one of an inspired and expired event in a breath cycle.

Claim 22

A method for determining a concentration for each of N gases in a respiratory gas stream, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of radiation in as many of said N bands of wavelengths of said radiation as is possible during each of a plurality of measurement periods; interpolating to determine the absorption in any of said N bands when absorption is not detected in one of said measurement periods; and computing the concentrations of each of said N gases using detected and interpolated absorptions with multiple simultaneous equations; wherein said measurement period is one of an inspired and expired event in a breath cycle.

Claim 23

A method for determining a concentration for each of N gases in a respiratory gas stream, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of radiation in as many of said N bands of wavelengths of said radiation as is possible during each of a plurality of measurement periods; interpolating to determine the absorption in any of said N bands when absorption is not detected in one of said measurement periods; and computing the concentrations of each of said N gases using detected and interpolated absorptions with multiple simultaneous equations; wherein said multiple simultaneous equations are matrix equations with said absorptions being variables which are at least second order variables.

Claim 24

A method for determining a concentration for each of N gases in a respiratory gas stream, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of radiation in as many of said N bands of wavelengths of said radiation as is possible during each of a plurality of measurement periods; interpolating to determine the absorption in any of said N bands when absorption is not detected in one of said measurement periods; and computing the concentrations of each of said N gases using detected and interpolated absorptions with multiple simultaneous equations; wherein said multiple simultaneous equations are matrix equations with said absorptions being variables which are at least second order variables.

Claim 25

A method for determining the concentrations of N gases in a respiratory gas stream, where N>1, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of said radiation in one of said N bands of wavelengths of said radiation; comparing a detected absorption in said one band to criteria for an event; determining whether said absorption is within said event; detecting the absorption of radiation in said N bands other than said one in said event; determining whether said absorption for said other bands are within said event; and computing the concentrations of each of said N gases during said event using detected absorptions with multiple simultaneous equations; wherein said criteria include determining whether the absorption levels for a reference gas cross threshold levels for inspired and expired events of a breath cycle.

Claim 26

A method for determining the concentrations of N gases in a respiratory gas stream, where N>1, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of said radiation in one of said N bands of wavelengths of said radiation; comparing a detected absorption in said one band to criteria for an event; determining whether said absorption is within said event; detecting the absorption of radiation in said N bands other than said one in said event; determining whether said absorption for said other bands are within said event; and computing the concentrations of each of said N gases during said event using detected absorptions with multiple simultaneous equations; wherein said criteria include determining whether the absorption levels for a reference gas cross threshold levels for inspired and expired events of a breath cycle.

Claim 27

A method for determining the concentrations of N gases in a respiratory gas stream, where N>1, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of said radiation in one of said N bands of wavelengths of said radiation; comparing a detected absorption in said one band to criteria for an event; determining whether said absorption is within said event; detecting the absorption of radiation in said N bands other than said one in said event; determining whether said absorption for said other bands are within said event; and computing the concentrations of each of said N gases during said event using detected absorptions with multiple simultaneous equations; wherein said criteria includes a predetermined range for a rate of change of said one band.

Claim 28

A method for determining the concentrations of N gases in a respiratory gas stream, where N>1, comprising the steps of: irradiating said respiratory gas stream with radiation; positioning each of N different filters to intercept said radiation after said radiation passes through and is partially absorbed by said portion of said respiratory gas stream to produce N different bands of wavelengths of said radiation; detecting the absorption of said radiation in one of said N bands of wavelengths of said radiation; comparing a detected absorption in said one band to criteria for an event; determining whether said absorption is within said event; detecting the absorption of radiation in said N bands other than said one in said event; determining whether said absorption for said other bands are within said event; and computing the concentrations of each of said N gases during said event using detected absorptions with multiple simultaneous equations; wherein said criteria includes a predetermined range for a rate of change of said one band.