Measurement process for blood gas analysis sensors

• US 5,772,589 A
• Filed: 11/19/1996
• Issued: 06/30/1998
• Est. Priority Date: 02/13/1995
• Status: Expired due to Term

• Current Assignee: Bernreuter, Peter
• Original Assignee: Bernreuter, Peter
• Inventors: Bernreuter, Peter
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/716,321
• Time in Patent Office: 588 Days
• Field of Search: 128/632, 128/633
• US Class Current: 600/323
• CPC Class Codes: A61B 2560/0233 Optical standards
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 33/4925 measuring blood gas content, e.g. O2, CO2 , HCO3

Abstract

This is a method for measuring oxygen saturation of arterial blood in tissue using at least two different wavelengths of light directed into the tissue and measuring the amount of radiation retained by the tissue and compensating the measurements for tissue haemoglobin content and skin pigmentation and pilosity and calibrating the equipment by obtaining measurements after the injection of a medical dye into the tissue.

Claims

1. Process for measuring oxygen saturation of arterial blood in tissue by pulse oxymetry, comprising the steps of directing electromagnetic radiation of at least two different wavelengths at the tissue, determining radiation retained by the tissue for each said wavelength, producing an electric signal (I1, I2, . . . ) corresponding to radiation intensity retained for each said wavelength, producing at least one measured oxygen saturation variable (Ω

1, Ω

2 . . . ), and compensation for undesired dependency of each individual measured variable on haemoglobin content in the tissue, pigmentation and pilosity of the skin, wherein for at least one wavelength a level of the measured light attenuation (LA) in the tissue is allocated to pilosity, pigmentation in the skin and haemoglobin content (perfusion p) of the tissue and the level of light attenuation (LA) is used as a correcting factor for one or several measured variables Ω

n, and wherein a value for the oxygen saturation of the arterial blood is obtained by selecting a calibration curve in dependence upon the LA from a number of possible calibration curves assigned by way of Ω

n as an initial signal to one or several measured values for the measured variable Ω

n.

2. Process for measuring oxygen saturation of arterial blood in tissue by pulse oxymetry, comprising the steps of directing electromagnetic radiation of at least two different wavelengths at the tissue, determining the radiation retained by the tissue for each said wavelength, producing an electric signal (I1, I2, . . . ) corresponding to radiation intensity retained for each said wavelength, producing at least one measured oxygen saturation variable (Ω

1, Ω

2, . . . ), and compensating for undesired dependency of each individual measured variable on haemoglobin content in the tissue, pigmentation and pilosity of the skin, wherein a value for oxygen saturation of arterial blood is assigned as an initial signal to several measured variables (Ω

1, Ω

2 . . . ), which demonstrate a different dependency with respect to specific tissue relating characteristics, and wherein in each case the weighting on the measured variable Ω

n is greater in order to form the initial signal, anticipated interference being less at the measured variable.

3. Process for measuring oxygen saturation of arterial blood in tissue pulse oximetry, comprising the steps of infecting a medical dye with which it is possible in the case of predetermined wavelengths to simulate different light absorptions based on levels of blood oxygenation in tissue intravenously into a human being or animal, taking blood samples from tissue of the human or animal during a period in which the dye decomposes and allocating to said blood samples based on absorption characteristics values for oxygen saturation of blood, assigning to a pulse oxymetry sensor initial signals corresponding to values of oxygen saturation of blood whilst simultaneously measuring the tissue with a pulse oxymetry sensor to determine light attenuation LA.