NIRS Blood Hemoglobin Measurement with Hemodynamic Correction
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Solution Overview
Problem
Existing non-invasive methods for determining blood circulatory hemoglobin values are affected by hemodynamic parameters, which are not present in invasive blood samples, leading to inaccurate measurements due to the lack of accounting for these factors in tissue-based hemoglobin analysis.
Innovation Solution
A system combining near-infrared spectrophotometric (NIRS) sensing devices with hemodynamic measuring devices to non-invasively sense tissue hemoglobin, identify confounding factors, and calculate circulatory hemoglobin values by accounting for hemodynamic effects using empirical data and calibration parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-invasive tissue hemoglobin sensing is used, then continuous real-time measurement is achieved, but measurement precision deteriorates due to hemodynamic confounders
Solution Approach 1:
The patent introduces hemodynamic parameter measurements (blood flow, oxygen consumption, cardiac output) as intermediary variables that mediate between the NIRS tissue hemoglobin signal and the actual circulatory hemoglobin concentration. By measuring these intermediary hemodynamic factors and using them to correct the NIRS signal, the system resolves the contradiction between continuous monitoring capability and measurement accuracy affected by hemodynamic confounders.
2Measurement precision
If invasive blood sampling is used, then measurement precision is improved, but ease of operation deteriorates due to invasive procedures
Solution Approach 1:
The patent replaces the mechanical invasive blood sampling system with an optical NIRS-based sensing system. Instead of physically drawing blood samples for analysis, the system uses near-infrared light to non-invasively measure tissue hemoglobin concentrations. This substitution maintains measurement precision by incorporating hemodynamic corrections while dramatically improving ease of operation and enabling continuous monitoring without repeated invasive procedures.
3Ease of operation
If NIRS tissue hemoglobin measurement is used, then ease of operation is improved, but measurement precision deteriorates due to tissue-specific hemodynamic effects
Solution Approach 1:
The patent implements feedback mechanisms where hemodynamic parameter measurements continuously inform and adjust the interpretation of NIRS tissue hemoglobin signals. The system uses measured hemodynamic data (such as blood flow and oxygen consumption rates) to feedback-correct the tissue hemoglobin measurements, thereby accounting for local tissue-specific hemodynamic effects and improving the accuracy of circulatory hemoglobin representation while maintaining non-invasive operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate, non-invasive determination of blood circulatory hemoglobin values by separating tissue hemoglobin components affected by hemodynamic factors, providing continuous and real-time measurements without the need for invasive sampling.
Implementation Method 1
Near-infrared spectroscopy (NIRS) is an optical spectrophotometric method of continually monitoring tissue parameters (e.g., oxygen saturation, hemoglobin levels, etc.) that does not require pulsatile blood volume to calculate parameters of clinical value. NIRS spectroscopy is based on the principle that light in the near-infrared range (700 to 1,000 nm) can pass easily through skin, bone, and other tissues where it encounters hemoglobin located mainly within micro-circulation passages (e.g., capillaries, arterioles, and venules). Hemoglobin exposed to light in the near infra-red range has specific absorption spectra that varies depending on its oxidation state (i.e., oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) each act as a distinct chromophore). By using light sources that transmit near-infrared light at specific different wavelengths, and measuring changes in transmitted or reflected light attenuation, concentration changes of the oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) within tissue can be monitored
Implementation Method 2
Hemoglobin exposed to light in the near infra-red range has specific absorption spectra that varies depending on its oxidation state (i.e., oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) each act as a distinct chromophore)
Data Source
AI summary
A method of and system for non-invasively measuring tissue hemoglobin of a subject is provided. The method includes: a) non-invasively sensing tissue of a subject using a near infrared spectrophotometric (NIRS) sensing device, and determining at least one NIRS tissue THb value based on the non-invasive sensing; b) determining whether at least one Hb confounding factor is present during the non-invasive tissue sensing with the NIRS sensing device; and c) determining a NIRS circulatory THb portion of the NIRS tissue THb value based on the presence of the at least one Hb confounding factor during the non-invasive tissue sensing with the NIRS sensing device.