HYBRID SPECTROPHOTOMETRIC MONITORING OF BIOLOGICAL CONSTITUENTS
First Claim
1. A method for near-infrared spectrophotometric (NIRS) monitoring of at least one chromophore level in a biological volume of a patient, comprising:
- determining a non-pulsatile component of an absorption property of the biological volume for each of at least three distinct wavelengths of near-infrared radiation using a phase modulation spectrophotometry (PMS) based measurement method, said PMS-based measurement method being characterized by a relatively high modulation rate and being further characterized in that both amplitude and phase information detected at the relatively high modulation rate are processed to compute said non-pulsatile component of the absorption property;
processing the measured amplitude and the measured phase information associated with said PMS-based determination of said non-pulsatile component of the absorption property to compute PMS-derived intermediate information that is at least partially representative of a scattering characteristic of the biological volume;
determining a pulsatile component of the absorption property of the biological volume for each of said at least three distinct wavelengths using a continuous wave spectrophotometry (CWS) based measurement method, said CWS-based measurement method being characterized by a relatively low modulation rate, wherein said determining the pulsatile component of the absorption property comprises processing amplitude information detected at the relatively low modulation rate in conjunction with said PMS-derived intermediate information to compute said pulsatile component of the absorption property;
computing at least one metric representative of the at least one chromophore level in the biological volume based on said pulsatile component of the absorption property at said at least three wavelengths; and
displaying said at least one metric on an output display.
2 Assignments
0 Petitions
Accused Products
Abstract
Systems, methods, and related computer program products for non-invasive NIR spectrophotometric (NIRS) monitoring of total blood hemoglobin levels and/or other blood constituent levels based on a hybrid combination of phase modulation spectrophotometry (PMS) and continuous wave spectrophotometry (CWS) are described. PMS-based measurements including both amplitude and phase information used in the determination of a non-pulsatile component of an absorption property for each of at least three distinct wavelengths are processed to compute PMS-derived intermediate information at least partially representative of a scattering characteristic. CWS-based measurements including amplitude information is processed in conjunction with the PMS-derived intermediate information to compute a pulsatile component of the absorption property. A metric representative of at least one chromophore level, such as the total blood hemoglobin level, is computed from the pulsatile component of the absorption property at the at least three wavelengths and displayed on an output display.
36 Citations
20 Claims
-
1. A method for near-infrared spectrophotometric (NIRS) monitoring of at least one chromophore level in a biological volume of a patient, comprising:
-
determining a non-pulsatile component of an absorption property of the biological volume for each of at least three distinct wavelengths of near-infrared radiation using a phase modulation spectrophotometry (PMS) based measurement method, said PMS-based measurement method being characterized by a relatively high modulation rate and being further characterized in that both amplitude and phase information detected at the relatively high modulation rate are processed to compute said non-pulsatile component of the absorption property; processing the measured amplitude and the measured phase information associated with said PMS-based determination of said non-pulsatile component of the absorption property to compute PMS-derived intermediate information that is at least partially representative of a scattering characteristic of the biological volume; determining a pulsatile component of the absorption property of the biological volume for each of said at least three distinct wavelengths using a continuous wave spectrophotometry (CWS) based measurement method, said CWS-based measurement method being characterized by a relatively low modulation rate, wherein said determining the pulsatile component of the absorption property comprises processing amplitude information detected at the relatively low modulation rate in conjunction with said PMS-derived intermediate information to compute said pulsatile component of the absorption property; computing at least one metric representative of the at least one chromophore level in the biological volume based on said pulsatile component of the absorption property at said at least three wavelengths; and displaying said at least one metric on an output display. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. An apparatus for non-invasive near-infrared spectrophotometric (NIRS) monitoring of at least one chromophore level in a biological volume of a patient, comprising:
-
a probe assembly including a plurality of source-detector pairs configured to introduce near-infrared radiation into the biological volume and receive near-infrared radiation from the biological volume; a processing and control device coupled to said plurality of source-detector pairs of said probe assembly, the processing and control device being configured to operate at least one of said source-detector pairs in a phase modulation spectrophotometry (PMS) mode, said PMS mode being characterized by a relatively high modulation rate and being further characterized in that both amplitude and phase information are detected and processed to determine an absorption property, the processing and control device being further configured to operate at least one of said source-detector pairs in a continuous wave spectrophotometry (CWS) mode, said CWS mode being characterized by a relatively low modulation rate and being further characterized in that amplitude information is detected and processed to determine the absorption property without regard to phase information; and an output display coupled to said processing and control device; wherein said processing and control device is programmed and configured in conjunction with said plurality of source-detector pairs and said output display to carry out the steps of; determining a non-pulsatile component of an absorption property of the biological volume for each of at least three distinct wavelengths based on measurements acquired in said PMS mode; processing said measurements acquired in said PMS mode to compute PMS-derived intermediate information that is at least partially representative of a scattering characteristic of the biological volume; determining a pulsatile component of the absorption property of the biological volume for each of said at least three distinct wavelengths based on measurements acquired in said CWS mode, including processing said CWS-mode measurements in conjunction with said PMS-derived intermediate information to compute said pulsatile component of the absorption property; computing at least one metric representative of the at least one chromophore level in the biological volume based on said pulsatile component of the absorption property at said at least three wavelengths; and displaying said at least one metric on said output display. - View Dependent Claims (13, 14, 15, 16, 17)
-
-
18. A method for providing an improved apparatus for near-infrared spectrophotometric (NIRS) monitoring of at least one chromophore level in a biological volume of a patient, comprising:
-
acquiring a pre-existing NIRS monitoring apparatus including a probe assembly, a processing and control device, and an output display, the pre-existing NIRS monitoring apparatus being operable in a pre-existing continuous wave spectrophotometry (CWS) mode characterized in that (i) a relatively low modulation rate is used, (ii) amplitude information is detected and processed according to a pre-existing algorithm to determine an absorption property without regard to phase information, and (iii) the pre-existing algorithm incorporates a pre-existing estimate of a scatter-related characteristic of the biological volume in the determination of a pulsatile absorption property, the pre-existing NIRS monitoring apparatus computing the at least one chromophore level based on the pulsatile absorption property and displaying the at least one chromophore level on the output display; modifying said probe assembly and said processing and control device of the pre-existing NIRS monitoring apparatus to be operable in a phase modulation spectrophotometry (PMS) mode in addition to said pre-existing CWS mode, said PMS mode being characterized by a relatively high modulation rate and being further characterized in that both amplitude and phase information are detected; and further modifying said processing and control device to be operable to; compute an actual version of said scatter-related characteristic for the biological volume based on measurements acquired in said PMS mode; and incorporate said actual version of said scatter-related characteristic in place of said pre-existing estimate thereof in said pre-existing algorithm that determines the pulsatile absorption property; whereby the modified version of the pre-existing NIRS monitoring apparatus provides improved monitoring of the at least one chromophore level by virtue of incorporating an actual, patient-specific, updated version of said scatter-related characteristic in place of the pre-existing estimate thereof in computing the at least one chromophore level. - View Dependent Claims (19, 20)
-
Specification