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Noninvasive measurement of hematocrit and hemoglobin content by differential optical analysis

  • US 5,277,181 A
  • Filed: 12/12/1991
  • Issued: 01/11/1994
  • Est. Priority Date: 12/12/1991
  • Status: Expired due to Term
First Claim
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1. A noninvasive method of generating a ratio of signals from which measurement of one or more blood parameters in living tissue may be made, comprising the steps of:

  • a) illuminating the tissue with light of a first wavelength λ

    1 at an incident tissue site, such that the light is scattered and absorbed by the tissue;

    b) while the volume of blood in the tissue is changing, detecting the scattered light at two separate detection tissue sites remote from said incident site and generating first and second electrical signals proportional to the intensity of the detected light;

    c) normalizing the first and second electrical signals to produce first and second normalized signals; and

    d) forming a ratio of the first and second normalized signals.

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