US4807631A
Expired / Lapsed
US
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Pulse oximetry system
Assignee: Ethicon Inc
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Filing: 1987-10-09
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Granted: 1989-02-28
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Expires: 2007-10-09
Abstract
Abstract A pulse oximetry system is provided in which LEDs (12, 14) of two different wavelengths illuminate tissue containing arterial blood flow. A photodiode (16) receives light from the LEDs and produces electrical signals (IR(t) RED(t)) containing pulsatile components. The components of the two wavelengths are separated and the pulsatile waveforms are monitored until signal peaks (IRmax) are detected at the end of diastole. The waveforms are then integrated over the systolic interval, and the integrals are combined with the signal peak values to determine an index value. The index value is used to select a value representative of oxygen saturation from a look-up table (36).
Inventors
- 👤 Lawrence T. Hersh
- 👤 Richard Medero
- 👤 Rush W. Hood, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:20
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/1455; A61B5/14551; A61B5/72; A61B5/7235; A61B5/7242
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
104 words
An oximetry system for measuring blood oxygen saturation comprising: means for illuminating tissue containing arterial blood with light of two different wavelengths; means for receiving light from said illuminating means and producing corresponding electrical signals of said two wavelengths of light; means for measuring the peaks of said signals at the transition of the illuminated blood from diastole to systole; means for integrating said signal waveforms during systole to produce integral values; means for combining said integral values and signal peaks to determine an index value; and means responsive to said index value for producing an indication of oxygen saturation of the arterial blood.
Claim 2
Dependent Claim
104 words
An oximetry system for measuring blood oxygen saturation comprising: means for illuminating tissue containing arterial blood with light of two different wavelengths; means for receiving light from said illuminating means and producing corresponding electrical signals of said two wavelengths of light; means for measuring the peaks of said signals at the transition of the illuminated blood from diastole to systole; means for integrating said signal waveforms during systole to produce integral values; means for combining said integral values and signal peaks to determine an index value; and means responsive to said index value for producing an indication of oxygen saturation of the arterial blood.
Claim 3
Dependent Claim
29 words
The oximetry system of claim 1, wherein said receiving means includes means, responsive to said received light, for producing separated signal components representative of light of two different wavelengths.
Claim 4
Dependent Claim
29 words
The oximetry system of claim 2, wherein said receiving means further includes demodulator means responsive to said separated signal components for producing electrical signals of two wavelengths of light.
Claim 5
Dependent Claim
14 words
The oximetry system of claim 3, wherein said demodulator means comprises an amplitude demodulator.
Claim 6
Dependent Claim
73 words
The oximetry system of claim 1, further comprising: means for converting analog signals to digital signals, said converting means exhibiting a defined input dynamic range; and means, having an input responsive to electrical signals corresponding to said two wavelengths of light and an output coupled to the input of said converting means, for shifting the levels of said received signals to a significant portion of said input dynamic range of said converting means.
Claim 7
Dependent Claim
32 words
The oximetry system of claim 5, wherein said shifting means includes an offset voltage source and a capacitor which is selectively charged by said offset voltage source to shift said electrical signals.
Claim 8
Dependent Claim
30 words
The oximetry system of claim 5, wherein said converting means is further coupled to receive said electrical signals corresponding to said two wavelengths of light which have not been level-shifted.
Claim 9
Dependent Claim
27 words
The oximetry system of claim 1, wherein said measuring means is responsive to successive signals for detecting the signal peak at the transition from diastole to systole.
Claim 10
Dependent Claim
27 words
The oximetry system of claim 8, wherein said measuring means is further responsive to successive signals for detecting the minimum signal level at the end of systole.
Claim 11
Dependent Claim
43 words
The oximetry system of claim 9, wherein said integrating means is initialized in response to the detection of said signal peak by said measuring means, and integration of said signal waveform ends upon detection of said minimum signal level by said measuring means.
Claim 12
Dependent Claim
23 words
The oximetry system of claim 10, further including means, responsive to said measuring means, for storing the values of said detected signal peaks.
Claim 13
Dependent Claim
23 words
The oximetry system of claim 11, wherein said combining means produces a quotient by dividing said integral values by said signal peak values.
Claim 14
Dependent Claim
35 words
The oximetry system of claim 12, wherein said combining means produces a first quotient corresponding to one of said wavelengths of light and a second quotient corresponding to the other of said wavelengths of light.
Claim 15
Dependent Claim
23 words
The oximetry system of claim 13, wherein said combining means produces an index value by dividing said first quotient by said second quotient.
Claim 16
Dependent Claim
48 words
The oximetry system of claim 14, wherein one of said wavelengths of light is in the infrared region and the other of said wavelengths of light is in the red region, said first quotient corresponds to infrared light signals and said second quotient corresponds to red light signals.
Claim 17
Dependent Claim
18 words
The oximetry system of claim 14, wherein said means responsive to said index values comprises a look-up table.
Claim 18
Dependent Claim
74 words
The oximetry system of claim 10, wherein said electrical signal producing means includes means for shifting the levels of said electrical signals corresponding to said two wavelengths of light; and means for producing digitized samples of said shifted received signals and of received signals which have not been shifted; wherein said measuring means is responsive to received signals which have not been shifted and said integrating means is responsive to said shifted received signals.
Claim 19
Dependent Claim
17 words
The oximetry system of claim 5, wherein said shifting means is selectively operable during the diastolic interval.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |