Method and apparatus for monitoring metabolism in body organs
Blood diagnostic spectrophotometer
Pulse oximeter monitor
Spectrophotometric method and apparatus for the non-invasive
Method and apparatus for noninvasive monitoring of arterial blood oxygen saturation
Method and apparatus for monitoring blood components
Non-invasive near infrared measurement of blood analyte concentrations
Non-invasive measuring method and apparatus of blood constituents
Blood constituent measuring device and method
Method and an apparatus for determining blood components
ApplicationNo. 152913 filed on 11/12/1993
US Classes:600/322, Determining blood constituent356/39, BLOOD ANALYSIS600/330Separation of ac/dc components in signal
ExaminersPrimary: Sykes, Angela D.
Attorney, Agent or Firm
International ClassA61B 005/00
AbstractAn improved spectrophotometer which noninvasively and qualitatively or quantitatively determines the concentration of light and other radiation absorbing substances in the bloodstream inside a radiation scattering body by assessing, at one or more wavelengths, the pulsatile changes which occur with each heartbeat in the absorbance of radiation passing through the medium, whereby the measurement is confined to the blood-stream and the absorbance of material outside of the bloodstream is cancels out. A light emitter (11), consisting of one or more radiation sources (11a, 11b, . . . 11n), emits light into a tissue sample (14) in vivo. Radiation returning to a detector (17) is filtered (21) to remove any nonpulsatile component, amplified (27), demodulated (31) to separate the component of absorbance due to each radiation source. Peak signal intensity is determined (33), and these peak signal values are stored in an absorbance register (37). Solving a matrix of n equations with n unknowns (42) yields the relative absorbance of up to n components in the bloodstream, which are stored in qualitative register (47). Correcting relative concentration (49) using the numbers stored as conversion factors (53) yields the concentration of up to n chromophores, which are stored in quantitative register (51) and displayed on an output device (55).