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`
`
`
`United States Patent
`[19J
`Diab et al.
`
`US006157850A
`[11]Patent Number:
`6,157,850
`*Dec. 5, 2000
`[45]Date of Patent:
`
`I 1111111111111111 11111 111111111111111 1111111111 1111111111 111111111111111111
`
`
`
`[54] SIGNAL PROCESSING APPARATUS
`
`FOREIGN PATENT DOCUMENTS
`
`341327 11/1989 European Pat. Off . .
`
`
`
`
`Mohamed K. Diab; Massi E. Kiani;
`
`[75]Inventors:
`
`
`3328862 2/1985 Germany.
`
`
`
`Ibrahim M. Elfadel, all of Laguna
`
`
`
`1674798 9/1991 U.S.S.R . .
`
`
`Niguel; Rex J. McCarthy, Mission
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`
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`
`2235288 2/1991 United Kingdom .
`Robert A. Smith, Corona, all of Calif.
`
`
`WO 92/15955 9/1992 WIPO .
`
`
`[73]Assignee:
`
`
`
`Masimo Corporation, Irvine, Calif.
`
`OTHER PUBLICATIONS
`
`[21] Appl. No.: 08/859,837
`
`[22] Filed:May 16, 1997
`
`Related U.S. Application Data
`
`
`
`(List continued on next page.)
`
`Int. Cl.7 ........................................................ A61B 5/00
`[51]
`
`
`[52]
`
`Primary Examiner-Eric F. Winakur
`
`
`
`
`
`U.S. Cl. .......................... 600/323; 600/336; 600/509;
`
`
`
`600/529
`
`Attorney, Agent, or Firm-Knobbe, Martens, Olson & Bear,
`
`U.S. PATENT DOCUMENTS
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`ABSTRACT
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`
`
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`The present invention involves method and apparatus for
`
`
`
`
`
`484,500,508,509,529
`
`
`
`
`
`analyzing two measured signals that are modeled as con­
`
`
`
`
`taining primary and secondary portions. Coefficients relate
`
`
`the two signals according to a model defined in accordance
`
`
`
`
`with the present invention. In one embodiment, the present
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`
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`
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`ates a plurality of possible signal coefficients in order to find
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`
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`
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`
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`
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`
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`
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`
`
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`
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`
`in particular detail with respect to blood oximetry measure­
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`(List continued on next page.)
`
`
`
`52 Claims, 37 Drawing Sheets
`
`··610
`
`1-----------�
`I
`I
`I
`I
`INFRARED FILTER BANK 1
`I
`I
`I
`-FN
`O-F1, F1 -F2 , ... F
`N-1
`618
`I
`SATURATION
`HISTOGRAM TO SA TU RATION
`EQUATION
`CALCULATIONS
`
`604-
`
`620
`
`/600
`
`602
`
`RED
`-FN
`606-_.,/ O-F1 , F1 -F2 , •.. FN-1
`
`FILTER BANK 2
`
`Page 1
`
`Masimo Ex. 2021
`Apple v. Masimo
`IPR2020-01714
`
`

`

`6,157,850
`Page 2
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`
`U.S. PATENT DOCUMENTS
`
`OIBER PUBLICATIONS
`
`Page 2
`
`

`

`U.S. Patent Dec.5,2000
`6,157,850
`
`
`Sheet 1 of 37
`
`I FIG. I
`
`BONE
`MUSCLE
`TISSUE
`
`ARTERIAL BLOOD
`VENOUS BLOOD
`
`I
`
`FIG. 3
`
`FIG. 2
`
`/S=s+n
`
`'---------------------t
`
`Page 3
`
`

`

`U.S. Patent Dec.5,2000 Sheet 2 of
`6,157,850
`37
`
`..
`l. �· .... •.·/].. ·./ ...•.
`
`' .
`··. .
`. .
`. -�---. ,' :.�," .
`
`.
`r---,,
`. :.
`22b 24b
`---··._·�
`SIGNAL
`t--t -i A D
`/
`1--------------1�
`CONDITIONER
`SAD 8Ab+nAb
`
`20
`
`220 240
`SIGNAL
`- A D
`/
`CONDITIONER
`
`25
`
`nAb(t)
`(t) - r8
`n'(t) = nA8
`
`27
`
`28
`
`DISPLAY
`CORRELATION
`CANCELER
`S�a(t)
`
`FIG. 4a
`
`Page 4
`
`

`

`U.S. Patent
`6,157,850
`
`
`Dec.5,2000 Sheet 3 of 37
`
`22b 24b
`
`SIGNAL /
`...--i A D
`CONDITIONER
`
`220 240
`
`SIGNAL /
`-A D
`CONDITIONER
`
`s'(t) = s Aa(t) - rVsAb(t)
`
`27
`DISPLAY
`CORRELATION
`CANCELER
`n'�a(t)
`
`28
`
`FIG. 4b
`
`Page 5
`
`

`

`U.S. Patent
`6,157,850
`Dec.5,2000
`Sheet 4 of
`37
`
`JO\
`SAJt)= s A Jt) + nAa(t)
`OR
`SA�t)= s A St)+ n Ab(t)
`
`J2
`
`n'(t)- -
`
`FIG. 5a
`
`JO\
`SAJt)= s AJt) + n Aa(t)
`OR
`SA�t)= s A St)+ nAb(t) cAa<t)
`OR
`J2 CA.Ht)
`
`+
`
`s'( t 1-------1
`
`FIG. 5b
`
`Page 6
`
`

`

`6,157,850
`U.S. Patent
`
`
`Dec.5,2000 Sheet 5 of 37
`
`FREQUENCY ( f)
`
`FIG.Sc
`
`z
`0 I----.
`
`t­ u
`
`
`z
`:::>
`LL
`
`Ck:
`w
`LL
`(/)
`z
`<(
`Ck:
`t-
`
`Page 7
`
`

`

`6,157,850
`U.S. Patent Dec.5,2000 Sheet 6 of
`37
`
`r
`A, A, A1 A1 A, A1 A,
`I A2 A2 A2 A2 A2 A2 A2
`1
`.•
`An An An A n An An An
`
`.
`
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`
`FIG. 6a
`
`FIG. 6b D·
`D
`
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`42
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`A2 A2 A2 A2 A2
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`FIG. 6c
`
`Page 8
`
`

`

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`
`t c27
`
`Page 9
`
`

`

`U.S. Patent
`6,157,850
`
`
`Dec.5,2000 Sheet 8 of 37
`
`H •
`
`•
`
`>- �co
`
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`RELATIVE CORRELATION CANCELER
`
`
`ENERGY OUTPUT
`
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`
`Page 10
`
`

`

`U.S. Patent Dec.5,2000 Sheet 9 of 37
`6,157,850
`
`
`
`•
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`
`Page 11
`
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`Page 13
`
`

`

`U.S. Patent Dec. 5, 2000 Sheet 12 of 37
`
`6,157,850
`
`..------�.......___,
`
`1200
`
`INITIALIZE NOISE
`CANCELLER
`�-----
`
`IJOo
`TIME UPDATE
`OF [f 1] ELEMENTS
`
`INPUT NEW SAMPLES
`[SA8(t) AND SAb(t)]
`
`REFERENCE [n' (t) or s' (t)]
`
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`FOR TWO MEASURED SIGNAL
`SAMPLES
`
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`
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`ZERO-STAGE
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`
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`m
`m + 1
`
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`
`NO
`
`2000
`CALCULATE
`OUTPUT
`
`TO DISPLAY
`
`FIG.9a
`
`Page 14
`
`

`

`U.S. Patent Dec. 5, 2000
`Sheet 13 of 37
`
`6,157,850
`
`,-120
`INITIALIZE NOISE
`CANCELLER
`.___ _____ INPUT NEW SAMPLES
`[SAa(t) AND s]!.b(t)]
`
`/30
`TIME UPDATE
`OF (i1] ELEMENTS
`
`/40
`CALCULATE REFERENCE [n' (t) or s' (t)]
`
`FOR TWO MEASURED SIGNAL
`SAMPLES
`
`ZERO-STAGE
`UPDATE
`
`/60
`m = 0
`
`______._
`
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`
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`REGRESSION
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`m = m + 1
`
`__
`
`_
`
`--------'---'---,
`
`190
`NO
`
`,-200
`-----'--�--, CALCULATE
`OUTPUT
`
`,-210
`TO DISPLAY
`
`FIG.9
`
`Page 15
`
`

`

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`

`

`U.S. Patent
`Dec. 5, 2000 Sheet 29 of 37
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`6,157,850
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`

`

`U.S. Patent Dec. 5, 2000 Sheet 31 of 37
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`6,157,850
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`Page 34
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`Page 35
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`

`

`U.S. Patent Dec. 5, 2000
`Sheet 34 of 37
`
`6,157,850
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`

`U.S. Patent Dec. 5, 2000 Sheet 35 of 37
`
`6,157,850
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`Page 37
`
`

`

`U.S. Patent Dec. 5, 2000 Sheet 36 of 37
`
`6,157,850
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`Page 38
`
`

`

`U.S. Patent
`Dec. 5, 2000
`Sheet 37 of 37
`
`6,157,850
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`

`

`1
`
`6,157,850
`
`SIGNAL PROCESSING APPARATUS
`
`
`
`2
`correlation canceler if a noise reference is available. This is
`
`
`
`
`
`often the case. Although the amplitude of the reference
`REFERENCE TO PRIOR RELATED
`
`
`
`
`signals are not necessarily the same as the amplitude of the
`APPLICATION
`
`
`
`
`
`corresponding primary or secondary signal portions, they
`
`
`
`5 have a frequency spectrum which is similar to that of the
`
`
`
`This application is a continuation of U.S. patent applica­
`
`
`
`primary or secondary signal portions.
`
`
`tion Ser. No. 08/320,154, filed Oct. 7, 1994, now U.S. Pat.
`
`
`
`In many cases, nothing or very little is known about the
`
`No. 5,632,272 which was a continuation-in-part of U.S.
`
`
`
`
`
`secondary and/or primary signal portions. One area where
`
`
`
`
`patent application Ser. No. 08/132,812, filed Oct. 6, 1993,
`
`
`
`
`
`
`measured signals comprising a primary signal portion and a
`
`
`
`now U.S. Pat. No. 5,490,505, issued Feb. 13, 1996, and a
`
`
`
`
`
`10 secondary signal portion about which no information can
`
`continuation-in-part of U.S. patent application Ser. No.
`
`
`easily be determined is physiological monitoring. Physi­
`
`
`08/249,690, filed May 26, 1994, now U.S. Pat. No. 5,482,
`
`
`
`
`ological monitoring generally involves measured signals
`
`
`
`036, issued Jan. 9, 1996, which was a continuation of U.S.
`
`
`derived from a physiological system, such as the human
`
`
`
`
`patent application Ser. No. 07/666,060, filed Mar. 7, 1991,
`
`
`body. Measurements which are typically taken with physi-
`now abandoned.
`
`
`
`
`15 ological monitoring systems include electrocardiographs,
`
`
`
`blood pressure, blood gas saturation (such as oxygen
`BACKGROUND OF THE INVENTION
`
`
`
`saturation), capnographs, other blood constituent
`1. Field of the Invention
`
`
`monitoring, heart rate, respiration rate, electro­
`
`
`encephalograph (EEG) and depth of anesthesia, for example.
`
`
`
`
`
`The present invention relates to the field of signal pro­
`
`
`
`20 Other types of measurements include those which measure
`
`
`
`
`cessing. More specifically, the present invention relates to
`
`
`
`
`the pressure and quantity of a substance within the body
`
`
`
`
`the processing of measured signals, containing a primary
`
`
`such as cardiac output, venous oxygen saturation, arterial
`
`
`
`signal portion and a secondary signal portion, for the
`
`
`
`oxygen saturation, bilirubin, total hemoglobin, breathalyzer
`
`
`
`
`removal or derivation of either the primary or secondary
`
`
`
`
`
`testing, drug testing, cholesterol testing, glucose testing,
`
`
`
`
`signal portion when little is known about either of these
`
`
`
`
`25 extra vasation, and carbon dioxide testing, protein testing,
`
`
`
`components. More particularly, the present invention relates
`
`
`carbon monoxide testing, and other in-vivo measurements,
`
`
`
`
`to modeling the measured signals in a novel way which
`
`
`
`for example. Complications arising in these measurements
`
`
`
`
`facilitates minimizing the correlation between the primary
`
`
`
`are often due to motion of the patient, both external and
`
`
`
`
`
`signal portion and the secondary signal portion in order to
`
`
`
`
`
`internal (muscle movement, vessel movement, and probe
`
`
`
`
`produce a primary and/or secondary signal. The present
`
`
`
`
`30 movement, for example), during the measurement process.
`
`
`
`
`invention is especially useful for physiological monitoring
`
`
`
`systems including blood oxygen saturation systems.
`
`
`Many types of physiological measurements can be made
`
`
`
`by using the known properties of energy attenuation as a
`
`
`
`2. Description of the Related Art
`
`
`
`
`selected form of energy passes through a medium.
`
`
`
`Signal processors are typically employed to remove or
`
`
`A blood gas monitor is one example of a physiological
`
`
`
`
`
`
`derive either the primary or secondary signal portion from a 35
`
`
`monitoring system which is based upon the measurement of
`
`
`
`
`
`
`composite measured signal including a primary signal por­
`
`
`
`
`
`energy attenuated by biological tissues or substances. Blood
`
`
`
`tion and a secondary signal portion. For example, a com­
`
`
`gas monitors transmit light into the test medium and mea­
`
`
`
`
`
`posite signal may contain noise and desirable portions. If the
`
`
`
`sure the attenuation of the light as a function of time. The
`
`
`
`
`secondary signal portion occupies a different frequency
`
`
`
`
`output signal of a blood gas monitor which is sensitive to the
`
`
`
`
`
`spectrum than the primary signal portion, then conventional
`40
`
`
`
`arterial blood flow contains a component which is a wave-
`
`
`
`filtering techniques such as low pass, band pass, and high
`
`
`
`
`form representative of the patient's arterial pulse. This type
`
`
`
`pass filtering are available to remove or derive either the
`
`
`
`
`of signal, which contains a component related to the
`
`
`
`
`
`primary or the secondary signal portion from the total signal.
`
`
`
`patient's pulse, is called a plethysmographic wave, and is
`
`
`
`Fixed single or multiple notch filters could also be employed
`
`
`shown in FIG. 1 as curve s. Plethysmographic waveforms
`
`
`
`
`
`if the primary and/or secondary signal portion(s) exist at a
`45
`
`
`
`are used in blood gas saturation measurements. As the heart
`fixed frequency(s).
`
`
`
`
`beats, the amount of blood in the arteries increases and
`
`
`
`It is often the case that an overlap in frequency spectrum
`
`
`
`
`decreases, causing increases and decreases in energy
`
`
`
`
`
`between the primary and secondary signal portions exists.
`
`
`attenuation, illustrated by the cyclic wave s in FIG. 1.
`
`
`Complicating matters further, the statistical properties of one
`
`
`
`Typically, a digit such as a finger, an ear lobe, or other
`
`
`
`
`
`or both of the primary and secondary signal portions change 50
`
`
`
`portion of the body where blood flows close to the skin, is
`
`
`with time. In such cases, conventional filtering techniques
`
`
`
`
`employed as the medium through which light energy is
`
`
`
`are ineffective in extracting either the primary or secondary
`
`
`
`transmitted for blood gas attenuation measurements. The
`
`
`
`
`
`signal. If, however, a description of either the primary or
`
`
`
`finger comprises skin, fat, bone, muscle, etc., shown sche­
`
`
`
`secondary signal portion can be derived, correlation
`
`
`
`
`matically in FIG. 2, each of which attenuates energy incident
`
`
`
`canceling, such as adaptive noise canceling, can be 5