Pulse oximeter monitor Patent #: 4653498
ApplicationNo. 07/127835 filed on 12/02/1987
US Classes:600/330, Separation of ac/dc components in signal356/41Oximeters
ExaminersPrimary: Chambers, A. Michael
Attorney, Agent or Firm
International ClassesA61B 5/00 (20060101)
G01N 21/31 (20060101)
AbstractApparatus and method for measuring the level of a constituent such as oxygen in the blood of a living subject. Light at a plurality of wavelengths is emitted and directed through the patient's body to a photodetector. The amplitude of the emitted light at each wavelength is varied in accordance with a different carrier frequency, and the photodetector signal thus includes a component at each carrier frequency. Each such component represents transmissivity of the body structure at one wavelength of the emitted light. The photodetector signal is subdivided by frequency so as to separate the components at the different carrier frequencies. The constituent level is determined from these separated components.