Pulse Oximetry Patents

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Pulse Oximetry Patents

• Lilly Cho, Adam College, Dean Dieker, Brendan Doms

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Patent 4,759,369

• Uses red and infra-red light sources
• Senses differences in light after exposure to
  skin
• Returns electrical signal to microprocessor for
  oximetery computation using Lambert-Beers
  relationship
• Self-adapting

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Patent Design
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Lambert-Beers Law

• Implementation
• A x m C
• A is absorption, x is distance wave travels, m is
  coefficient of absorption, and C is concentration
• A is measured
• C is calculated
• Results
• The ratio between 2 different C values is used to
  find oxygen concentration
• The time between 2 different C values determines
  pulse

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Patent 6,564,077

• Another design for the pulse oximeter using light
  distortion to measure oxygen content of blood
• 2 signals, of different wavelengths are used to
  calculate the noise disruption ratio

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Patent 6,564,077

• Uses light distortion of different wavelengths to
  measure blood absorption
• Involves multiple-step calculus operations in
  determining oxygen content
• Arterial blood absorption ratio combined with
  noise ratio to optimize measurement

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Comparison

• No. 4,759,369
• Two light wavelengths
• Calculates Dispersion of Light
• First Modern Pulse Oximeter

• No. 6,564,077
• Two light wavelengths
• Calculates Noise Absorption Ratio
• Increased computational speed
• Best Interval for Pulse to Pulse ratio

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Sources

• Lambert Beers. Technical University of Denmark.
  Accessed 26 January 2004 http//ibt.dtu.dk
• United States PTO. Accessed 26 January 2004.
  http//www.uspto.gov