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Method and apparatus for calculating arterial oxygen saturation based plethysmographs including transients

DC CAFC
  • US 5,078,136 A
  • Filed: 08/04/1989
  • Issued: 01/07/1992
  • Est. Priority Date: 03/30/1988
  • Status: Expired due to Term
First Claim
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1. Apparatus for compensating distortion in transmittance caused by transient conditions in a patient'"'"'s plethysmograph waveform having periodic changes related to the patient'"'"'s beating heart, aperiodic changes unrelated to the beating heart, background transmittance, and transient background transmittance changes at frequencies below the heart rate for use in an oximeter device, comprising:

  • means for receiving a detected optical signal corresponding to the transmittance of a first and second light frequency passing through the patient'"'"'s tissue;

    filter means for eliminating frequency components of the detected optical signal other than those that have a frequency below the frequency of the fundamental heart rate, thereby providing a filtered signal; and

    dividing means for dividing the detected optical signal by the filtered signal in phase, thereby providing a compensated optical signal.

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