Apparatus for measuring hemoglobin

• US 5,720,284 A
• Filed: 03/29/1996
• Issued: 02/24/1998
• Est. Priority Date: 03/31/1995
• Status: Expired due to Term

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: Xie, Cheng Tai, Fuse, Masayoshi, Aoyagi, Takuo, Kanemoto, Michio
• Primary Examiner(s): Bahr, Jennifer
• Assistant Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US08/623,862
• Time in Patent Office: 697 Days
• Field of Search: 128/633, 128/664, 356/39-41
• US Class Current: 600/322
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: G01N 33/721 Haemoglobin
• CPC Class Codes: G01N 33/726 Devices

Abstract

Light of various wavelengths emitted from light sources and transmitted through vital tissues is converted by light sensors and current/voltage transducers, into electric signals. The signals are converted into digital values by an A/D converter. The light source emits light of a wavelength which can be optically absorbed by water. A computer obtains a ratio of variations of the digital values for each wavelength, and calculates the values of tissue terms and the hemoglobin concentration on the basis of the ratios. In the calculation, since tissue terms of the wavelengths have mutual constant relationships, an equation which is prepared so that there exists only one unknown in the tissue terms is used.

Claims

1. An apparatus for measuring hemoglobin, comprising:

light irradiating means for irradiating vital tissue with light having different wavelengths, at least one of the wavelengths being optically absorbed by water;

photoelectric converting means for converting light which is emitted from said light irradiating means and transmitted through the vital tissues into an electric signal;

optical density variation calculating means for obtaining an optical density variation for each of the wavelengths from pulsation of an output of said photoelectric converting means, the optical density variation corresponding to the difference between pulsation of light transmitted through the tissue due to blood and pulsation of light transmitted through the tissue due to the tissue;

optical density ratio calculating means for obtaining a ratio of optical density variations for the wavelengths which are obtained by said optical density variation calculating means; and

hemoglobin concentration calculating means for obtaining a total hemoglobin concentration from an output of said optical density ratio calculating means.