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Title: Reliable noninvasive measurement of blood gases

Methods and apparatus for, preferably, determining noninvasively and in vivo at least two of the five blood gas parameters (i.e., pH, PCO.sub.2, [HCO.sub.3.sup.- ], PO.sub.2, and O.sub.2 sat.) in a human. The non-invasive method includes the steps of: generating light at three or more different wavelengths in the range of 500 nm to 2500 nm; irradiating blood containing tissue; measuring the intensities of the wavelengths emerging from the blood containing tissue to obtain a set of at least three spectral intensities v. wavelengths; and determining the unknown values of at least two of pH, [HCO.sub.3.sup.- ], PCO.sub.2 and a measure of oxygen concentration. The determined values are within the physiological ranges observed in blood containing tissue. The method also includes the steps of providing calibration samples, determining if the spectral intensities v. wavelengths from the tissue represents an outlier, and determining if any of the calibration samples represents an outlier. The determination of the unknown values is performed by at least one multivariate algorithm using two or more variables and at least one calibration model. Preferably, there is a separate calibration for each blood gas parameter being determined. The method can be utilized in a pulse mode and can alsomore » be used invasively. The apparatus includes a tissue positioning device, a source, at least one detector, electronics, a microprocessor, memory, and apparatus for indicating the determined values.« less
Inventors:
 [1];  [1];  [1];  [1]
  1. (Albuquerque, NM)
Issue Date:
OSTI Identifier:
869557
Assignee:
Sandia Corporation (Albuquerque, NM) SNL
Patent Number(s):
US 5355880
Contract Number:
AC04-76
Research Org:
Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA
Country of Publication:
United States
Language:
English
Subject:
reliable; noninvasive; measurement; blood; gases; methods; apparatus; preferably; determining; noninvasively; vivo; five; gas; parameters; ph; pco; hco; sat; human; non-invasive; method; steps; generating; light; wavelengths; range; 500; nm; 2500; irradiating; containing; tissue; measuring; intensities; emerging; obtain; set; spectral; values; measure; oxygen; concentration; determined; physiological; ranges; observed; providing; calibration; samples; represents; outlier; determination; performed; multivariate; algorithm; variables; model; separate; parameter; utilized; pulse; mode; invasively; positioning; device; source; detector; electronics; microprocessor; memory; indicating; blood containing; containing tissue; oxygen concentration; positioning device; noninvasive measurement; multivariate algorithm; generating light; blood gas; reliable noninvasive; pulse mode; non-invasive method; determining noninvasively; determined values; gas parameters; five blood; calibration mode; blood gases; /600/128/