Continuous spectroscopic measurement of total hemoglobin

• US 20070060810A1
• Filed: 09/13/2006
• Published: 03/15/2007
• Est. Priority Date: 09/13/2005
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Higgins, Michael
• Granted Patent: US 7,319,894 B2
• Time in Patent Office: Days
• US Class Current: 600/328
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/417 the bone marrow
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: G01N 33/49 Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80

Abstract

Methods for measuring the total hemoglobin of whole blood include measuring reflective light at multiple wavelengths within the visible spectrum, calculating light absorbance at each of the multiple wavelengths, performing a comparison in a change in like absorbance between the multiple wavelengths, and/or relating the comparison to total hemoglobin. A system for measuring total hemoglobin of whole blood may include at least one light source, a catheter, optical fibers, at least one photodetector, data processing circuitry, and/or a display unit.

Claims

1. A method of determining total hemoglobin of whole blood, comprising:

transmitting light at multiple wavelengths in the visible spectrum into whole blood;

receiving the light from the whole blood;

determining light absorbance of the light at each of the multiple wavelengths;

determining a change in the light absorbance of the light between the multiple wavelengths; and

determining total hemoglobin of the whole blood using the change in the light absorbance of the light between the multiple wavelengths.

2. The method of claim 1, wherein the multiple wavelengths are between about 500 nanometers and about 900 nanometers.

3. The method of claim 1, wherein the multiple wavelengths include a first wavelength between about 500 nanometers and about 600 nanometers and a second wavelength between about 625 nanometers and about 850 nanometers.

4. The method of claim 1, wherein the multiple wavelengths include a first wavelength between about 500 nanometers and about 600 nanometers and a second wavelength between about 700 nanometers and about 720 nanometers.

5. The method of claim 1, wherein the multiple wavelengths include a first wavelength of about 548 nanometers and a second wavelength of about 805 nanometers.

6. The method of claim 1, wherein the first wavelength is between about 700 nanometers and about 720 nanometers.

7. The method of claim 1, wherein the second wavelength is between about 540 nanometers and about 560 nanometers.

8. The method of claim 1, wherein the multiple wavelengths include a first wavelength and a second wavelength where the first wavelength yields less change in the light absorbance than the second wavelength.

9. The method of claim 1, further comprising relating the total hemoglobin of the whole blood to hematocrit.

10. The method of claim 1, further comprising determining the total hemoglobin of whole blood using a change in the multiple wavelengths.

11. A method of determining total hemoglobin of whole blood, comprising:

providing a light source configured to emit light at multiple wavelengths;

measuring a reference signal containing a spectra of the light source;

measuring a dark signal when the light source is off;

measuring a remitted signal from whole blood when the light source is on;

determining light absorbance from the reference signal and the remitted signal; and

determining total hemoglobin of the whole blood based on a change in the light absorbance between the multiple wavelengths.

12. The method of claim 11, further comprising removing noise from the reference signal and the remitted signal prior to determining light absorbance from the reference signal and the remitted signal.

13. The method of claim 11, further comprising:

verifying that the remitted signal is within a preferred range; and

removing dark spectra from the remitted signal.

14. The method of claim 11, further comprising correcting for stray light from the light source.

15. The method of claim 11, further comprising calculating an n-point average about at least one of the multiple wavelengths.

16. The method of claim 15, further comprising correcting for light absorbance error of the at least one of the multiple wavelengths due to the effect of oxygen saturation.