Europaisches Patentamt
`
`European Patent Office
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`Office europeen des brevets
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`@ Publication number:
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`0 330 463
`A1
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`@
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`EUROPEAN PATENT APPLICATION
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`@ Application number: 89301758.2
`
`@ Date of filing: 23.02.89
`
`@ Int. Cl.4: A 61 B 5/02
`A 61 B 8/06
`
`@> Priority: 24.02.88 JP 41678/88
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`@ Date of publication of application:
`30.08.89 Bulletin 89/35
`
`@ Designated Contracting States:
`DE FR GB IT NL SE
`
`@ Applicant: COLIN ELECTRONICS CO., LTD.
`2007-1, Hayashi
`Komaki-shi Aichi-ken (JP)
`
`@ Inventor: Ogletree, William A.
`3421 Saw Mill Road
`Newtown Square PA 19073 (US)
`
`Kawamura, Norio
`c/o Colin Electronics Company Ltd. 2007-1, Hayashi
`Komaki-shi Aichi-ken (JP)
`
`Yokoe, Hifumi
`c/o Colin Electronics Company Ltd. 2007-1, Hayashi
`Komaki-shi Aichi-ken (JP)
`
`@ Representative: Senior, Alan Murray et al
`J.A. KEMP & CO 14 South Square Gray's Inn
`London WC1R SEU (GB)
`
`@ Blood flow resistance measuring apparatus.
`@ An apparatus for detecting a peripheral resistance oppos(cid:173)
`ing blood flow through a peripheral portion (20) of the subject,
`including a first determining device (12, 36) for determining
`blood pressure of the subject, a second determining means
`(38, 40, 44, 36) for determining at least one of a flow rate and a
`flow amount of blood which flows through an arterial vessel (22)
`extending through the peripheral portion (20) of the subject;
`and a calculating device (36) for calculating the peripheral
`resistance of the subject, based on the blood pressure and the
`at least one of the blood flow rate and the blood flow amount.
`
`FIG. I
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`Description
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`EP 0 330 463 A1
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`BLOOD FLOW RESISTANCE MEASURING APPARATUS
`The present invention relates to an apparatus for
`measuring the resistance opposing blood flowing
`through a pheripheral portion of a subject's body.
`It is widely practiced to continuously measure
`blood pressure of a living body, for example to
`monitor the circulatory organ of the living body
`during, or after, a surgical operation. Blood pressure
`can vary through various causes; for example, it is
`decreased as a result of a decrease in cardiac
`output, a decrease in resistance, a high volume of
`bleeding, etc. Accordingly, in addition to the blood
`pressure measurement,
`it
`is also possible
`to
`measure concurrently cardiac output and/or to
`follow the variation in resistance indirectly through
`measurement of skin
`temperature. However,
`measuring skin temperature can be an inaccurate
`way of measuring the resistance, because it varies
`with room temperature. Thus, it has been difficult to
`reliably monitor dynamic condition of the circulatory
`organ of a subject or rapidly detect a state of shock
`of a subject.
`The present invention, provides an apparatus for
`detecting a resistance opposing blood flow through
`a peripheral portion of a subject's body, comprising:
`first determining means
`for determining blood
`pressure of the subject; a second determining
`means for determining at least one of a flow rate and
`a flow amount of blood which flows through an
`arterial vessel extending through the peripheral
`portion of said body; and calculating means for
`calculating the resistance based on the blood
`pressure and the at least one of the blood flow rate
`and the blood flow amount.
`In
`the resistance measuring apparatus con-
`structed as described above, the calculating means
`calculates the resistance of a peripheral portion of a
`subject based on the blood pressure determined by
`the first determining means, and the flow rate or flow
`amount of the blood flowing through an arterial
`vessel extending through the peripheral portion, the
`flow rate or _flow amount being determined by the
`second determining means. Thus,
`the present
`apparatus is capable of directly measuring the
`resistance of the subject. Consequently, the present
`apparatus permits more reliable monitoring of
`dynamic condition of the circulatory organ of a
`patient and a more rapid detection of a shock of a
`patient.
`In a preferred embodiment of the resistance
`measuring apparatus of the present invention, the
`second determining means comprises an ultrasonic
`wave generator for generating ultrasonic wave
`toward the arterial vessel extending through the
`peripheral portion of the subject, an ultrasonic wave
`detector for detecting the ultrasonic wave reflected
`by the blood flowing through the arterial vessel, and
`means for determining the blood flow rate based on
`the detected ultrasonic wave.
`In a modified form of the above embodiment of the
`invention, the first determining means comprises a
`pressure sensor for detecting pulse wave produced
`from the arterial vessel extending through the
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`peripheral portion of the subject, the pressure
`sensor being pressed against a body surface of the
`subject just above the arterial vessel so as to detect
`the pulse wave, and means for determining the
`blood pressure based on magnitude of the detected
`pulse wave.
`According to a feature of the above-indicated
`modified form of the apparatus of the invention, the
`pressure sensor comprises an elastic member for
`defining a fluid-tight space, the elastic member
`being pressed against the arterial vessel via the
`body surface when pressure in the fluid-tight space
`is increased, and a pressure transducer disposed in
`the fluid-tight space, for detecting pressure variation
`in the fluid-tight space upon transmission,. of the
`pulse wave to the fluid-tight space from the arterial
`vessel.
`According to another feature of the above-indi(cid:173)
`cated modified form of the invention, the apparatus
`further comprises a wrist band for supporting, on
`one of opposite surfaces thereof, the ultrasonic
`wave generator and detector and the pressure
`sensor, the wrist band pressing, under the one of
`opposite surfaces thereof,
`the ultrasonic wave
`generator and detector and the pressure sensor
`against a radial artery of the subject via the body
`surface when the wrist band is wound around a wrist
`of the subject. In this case, it is recommended that
`the apparatus further comprise third determining
`means for determining oxygen saturation of blood
`which flows through capillaries in skin of the subject,
`the third determining means comprising a first light
`emitter for emitting toward the skin a light beam
`having a first wavelength, a second light emitter for
`emitting toward the skin a light beam having a
`second wavelength different from the first wave(cid:173)
`length, and a light detector for detecting the light
`beams reflected from the skin, the wrist band also
`supporting the first and second light emitters and
`the light detector, the third determining means
`further comprising means
`for determining
`the
`oxygen saturation based on the detected light
`beams.
`In another embodiment of the apparatus of the
`invention, the second determining means deter(cid:173)
`mines at least one of an average flow rate and an
`average flow amount of the blood flowing through
`the arterial vessel.
`In yet another embodiment of the invention, the
`apparatus further comprises a display device for
`displaying at least one value of maximum, minimum
`and average blood pressure; maximum, minimum
`and average blood flow rate; maximum, minimum
`and average resistance; and maximum, minimum
`and average value obtained by respectively multi(cid:173)
`plying the maximum, minimum and average resist(cid:173)
`ance by an average sectional area of the arterial
`vessel.
`In a modifed form of the above embodiment of the
`invention, the display device displays the at least one
`value each time the pressure sensor detects a pulse
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`of the pulse wave from the arterial vessel.
`In a further embodiment of the apparatus of the
`invention, the second determining means deter(cid:173)
`mines the blood flow amount by multiplying the
`blood flow rate by an average sectional area of the
`arterial vessel.
`The invention will be further described by way of
`non-limitative example, with reference to the accom(cid:173)
`panying drawings, in which:-
`Fig. 1 is a diagrammatic view of a peripheral
`resistance measuring apparatus of the present
`invention;
`Fig. 2 is a cross-sectional view of a pressure
`sensor of the apparatus of Fig. 1 supported by a
`wrist band wound around a wrist of a subject;
`Fig. 3 is a flow chart illustrating the operation
`of the apparatus of Fig. 1;
`Fig. 4 is a graph including curves of periphe(cid:173)
`ral resistance and maximum, minimum and
`average blood pressure; and
`Fig. 5 is a view corresponding to Fig. 1,
`showing another embodiment of the apparatus
`of the invention.
`Referring to Figs. 1 and 2, there is shown a
`peripheral resistance measuring apparatus of the
`present invention.
`In Fig. 1 reference numeral 10 designates a wrist
`band supporting on an inner surface 11 thereof a
`pressure sensor 12. When the wrist band 10 is set
`around a wrist 20 (Fig. 2) of a subject, the inner
`surface 11 of the band 10 is opposed to a body
`surface 19 of the wrist 20. The pressure sensor 20
`includes an elstic hat-like member 14 formed of a
`thin rubber sheet, and a pressure transducer 18. The
`hat-like member 14 has an outer flange at which the
`hat-like member 14 is secured to the inner surface
`11 of the wrist band 10 so as to define an air-tight
`space 16 in which the pressure transducer 18 is
`disposed. The wrist band 10 is wound around the
`wrist 20 such that the hat-like member 14 is aligned
`with a radial artery 22 extending through the wrist 20.
`The radial artery 22 is an arterial vessel extending
`near a radius of the subject.
`The air-tight space 16 communicates with a fluid
`supplying device 28 via a piping 24 and a pressure(cid:173)
`regulating valve 26, and is supplied with pressurized
`air or other sorts of pressurized fluid from the fluid
`supplyin,g device 28. When pressure in the air-tight
`space 16 is increased by the pressurized air supplied
`thereto, the hat-like member 14 is pressed against
`the radial artery 22 via the body surface 19 of the
`wrist 20. The pressure transducer 18 detects, as
`pulse wave, pressure variation produced in the
`air-tight space 16 synchronously with pulsation of
`the radial artery 22 (i.e., heartbeat of the subject),
`and generates pulse wave signal SM whose magni(cid:173)
`tude corresponds to magnitude of the detected
`pulse wave, to a CPU (central processing unit) 36 via
`an amplifier 30 and an AID (analog-to-digital)
`converter 34.
`As shown in Fig. 1, the inner surface 11 of the
`wrist band 10 also supports an ultrasonic wave
`generator 38 and an ultrasonic wave detector 40
`such that the generator 38 and the detector 40 each
`are located adjacent to the hat-like member 14 of the
`
`pressure sensor 12 and spaced apart by a predeter(cid:173)
`mined distance from each other, and that the
`generator 38 is located upstream of the detector 40
`along the radial artery 22 when the wrist band 10 is
`wound around the wrist 20. Thus, the generator and
`detector 38, 40 are positioned right above the radial
`artery 22 with the wrist band 10 set around the wrist
`20. The ultrasonic wave generator 38 continuously
`generates ultrasonic wave having a predetermined
`. frequency toward the radial artery 22, according to
`drive signal SD1 supplied thereto from an output
`interface 52 via a transmitting circuit 42. Meanwhile,
`the ultrasonic wave detector 40 detects the ultra(cid:173)
`sonic wave reflected by blood flowing through the
`radial artery 22, and generates frequency signal SF
`representing the frequency of the reflected ultra(cid:173)
`sonic wave, to a receiving circuit 44. The receiving
`circuit 44 includes an arithmetic circuit for detecting
`a frequency shift of the reflected wave, or a phase
`difference between the non-reflected wave gener(cid:173)
`ated by the generator 38 and the reflected wave
`detected by the detector 40, based on frequency
`signal SF received, determining a flow. rate of the
`blood flowing through the radial artery 22 based on
`the detected frequency shift or phase difference,
`and generating flow rate signal SL representing the
`determined blood flow rate, to the CPU 36.
`The CPU 36 is connected to a ROM (read only
`memory) 46, a RAM (random access memory) 48, a
`display 50 and the output interface 52. The CPU 36
`processes the received signals according to pro(cid:173)
`grams pre-stored in the ROM 46 and by utilizing
`temporary-storage function of the RAM 48. The CPU
`36 generates drive signal SD2 via the output
`interface 52 to the pressure-regulating valve 26 to
`regulate the pressure in the air-tight space 16 of the
`pressure sensor 12. The CPU 36 determines maxi(cid:173)
`mum, minimum and average blood pressure of the
`subject based on magnitude of pulse wave signal
`SM supplied from the pressure sensor 12, and
`commands the display 50 to display the determined
`blood pressure as shown in a lower portion of the
`graph of Fig. 4. Further, the CPU 36 generates drive
`signal SD1 via the output interface 52 to the
`transmitting circuit 42 to activate the ultrasonic wave
`generator 38 to generate the ultrasonic wave toward
`the radial artery 22. Moreover, the CPU 36 calculates
`an averate blood flow rate during a time period
`corresponding to each pulse of the pulse wave
`represented by pulse wave signal SM, based on flow
`rate signal SF received, determines a peripheral
`resistance of the subject regarding each pulse of the
`pulse wave based on the determined average blood
`pressure and the determined average blood flow
`rate, and commands the display 50 to time-wise
`display the determined peripheral resistance as
`shown in an upper portion of the graph of Fig. 4.
`Referring next to the flow chart of Fig. 3, there will
`be described the operation of the present peripheral
`resistance measuring apparatus.
`At a step (not shown) the CPU 36 commands the
`pressure-regulating valve 26 to regulate the press(cid:173)
`urized fluid supplied from the fluid supplying device
`28 to the air-tight space 16, so that the amplitude of
`pulse wave signal SM representing the pulse wave
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`produced from the radial artery 22, is increased to a
`maximum. Next, the control of the CPU 36 goes to
`step S1 at which the CPU 36 reads in pulse wave
`signal SM. Step S1 is followed by step S2 at which
`the CPU 36 reads in flow rate signal SF. At the
`following step S3 it is judged whether or not signals
`SM and SL corresponding to one pulse of the pulse
`wave have been read in. If the judgement at step S3
`is negative (NO), steps S1 through S3 are repeated
`to continue to read in signals SM and SF until the
`judgement at step S3 is turned to be affirmative
`(YES). Once the judgement at step S3 is affirmative,
`step S3 is followed by step S4 at which the CPU 36
`determines maximum blood pressure BPmax, mini(cid:173)
`mum blood pressure BPm;n and average blood
`pressure BPav based on the magnitude of the read
`pulse wave signal SM and according to a predeter(cid:173)
`mined relationship between blood pressure and
`magnitude of pulse wave signal SM. In the present
`embodiment, the pressure sensor 12, step S4 stored
`in the form of program in the ROM 46, the CPU 36
`and the RAM 48 for effecting step S4, and others
`cooperate with each other to serve as the means for
`determining the blood pressure of the subject.
`Step 84 is followed by step SS at which the CPU
`36 calculates an average blood flow rate Vav based
`on the read flow rate signal SL corresponding to one
`pulse of the pulse wave, and at the following step S6
`the CPU 36 determines a peripheral resistance
`based on the average blood pressure BPav and the
`average blood flow rate Vav.
`Peripheral resistance R is expressed by the
`following equation ( 1):
`R = BPav f ( Vav·Sav )
`... (1)
`... (2)
`R' = R. Sav = BP av I Vav
`In the above equations, Sav represents an average
`cross-sectional area of the radial artery 22, and is
`treated as a constant. In the present embodiment,
`value R' obtained by the equation (2), namely, by
`multiplying value R by value Sav is handled as the
`peripheral resistance to be displayed by the display
`SO (see the graph of Fig. 4). The denominator of the
`right side of the equation (1), namely, Vav·Sav
`represents a_n average flow amount of the blood
`flowing through the radial aretery 22. Since the
`average cross-sectional area of the arterial vessel is
`treated as a constant as indicated above, the
`peripheral resistance can be determined based on
`the blood flow amount in combination with the blood
`pressure. In the present invention, the ultrasonic
`wave generator and detector 38, 40, receiving circuit
`44, step SS stored in the ROM 46, the CPU 36 and
`the RAM 48 for effecting step SS, and others
`cooperate with each other to serve as the means for
`determining the blood flow rate regarding the arterial
`vessel extending through the peripheral portion of
`the subject, while step S6 stored in the ROM 46 and
`the CPU 36 and the RAM 48 for effecting step S6
`serve as the means for calculating the peripheral
`resistance of the subject.
`Step S6 is followed by step S7 at which the CPU
`36 commands the display SO to display the maxi(cid:173)
`mum. minimum and average blood pressure BPmax,
`BPm1n, BPav and the peripheral resistance R' in the
`two dimensional graph as shown in Fig. 4. Steps S1
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`through step S7 are repeated to display a time-wise
`varying trend of the blood pressure BPmax, BPm;n,
`BP av and the peripheral resistance R', on the display
`so.
`As is apparent from the foregoing, the present
`apparatus directly measures the peripheral resist(cid:173)
`ance R' based on the average blood pressure BPav
`and the average blood flow rate Vav and displays the
`resistance R', in contrast to the conventional indirect
`manner in which peripheral resistance is deduced
`indirectly through measurement of skin temperature.
`Thus, the present apparatus permits more reliable
`monitoring of dynamic condition of the circulatory
`organ of a subject, and more rapid detection of a
`state of shock of a subject, since the apparatus is
`capable of concurrently informing the operator or
`medical staff of the blood pressure and the directly
`measured, reliable peripheral resistance.
`In the present apparatus, the ultrasonic wave
`generator and detector 38, 40 together with the
`pressure sensor 12 are disposed on the wrist band
`10. Thus, both the blood pressure and the peripheral
`resistance are concurrently measured simply by
`applying the wrist band 10 to the wrist 20.
`While in the illustrated embodiment the peripheral
`resistance R' is calculated based on the average
`blood pressure BP av and the average blood flow rate
`Vav,
`it is possible to determine maximum and
`minimum blood flow rate Vmax, Vm;n, and calculate
`30 maximum and minimum peripheral resistance R' max
`and R' min based on the maximum and minimum
`blood pressure BPmax, BPm;n and the determined
`maximum and minim blood flow rate Vmax, Vm;n,
`respectively. In this case, it is possible to time-wise
`display all the maximum, minimum and average
`peripheral resistance Rmax, Rmin, R' on the display
`so.
`The illustrated arrangement in which the pressure
`sensor 12 and the ultrasonic generator and detector
`38, 40 are disposed on the wrist band 10, may be
`replaced with another arrangement in that the pair of
`ultrasonic wave generator and detector (38, 40) are
`disposed on the wrist band (20) and the pressure
`sensor (12) is disposed on an upper-arm band to be
`set around an upper arm of the subject so as to
`measure blood pressure based on pulse wave
`produced from a brachia! artery extending through
`the upper arm. Since substantially the same blood
`pressure is measured at any location throughout a
`subject, the above-indicated another arrangement is
`permitted.
`The means for determining blood pressure may be
`of a well-known type including an inflatable cuff to be
`wound around an upper arm of a subject.
`While in the illustrated embodiment blood press-
`ure and peripheral resistance are measured regard(cid:173)
`ing a radial artery extending in the wrist 20, it is
`possible to make those measurements regarding an
`arterial vessel extending in a finger located more
`peripheral than the wrist, or regarding a dorsal pedal
`artery extending near an ankle of a foot.
`As previously described, it is possible to deter(cid:173)
`mine peripheral resistance based on blood flow
`amount in combination with blood pressure, other
`than based on blood flow rate in combination with
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`blood pressure. For example, blood flow amount is
`measured by an electromagnetic flow meter.
`Although in the illustrated embodiment the blood
`flow rate is calculated by the receiving circuit 44, it is
`possible to adapt the CPU 36 to directly process
`signal SF supplied from the ultrasonic wave detector
`40, according to software pre-stored in the ROM 46.
`In this case, the receiving circuit 44 is omitted.
`While in the illustrated embodiment maximum,
`minimum and average blood pressure and peripheral
`resistance are determined based on pulse wave
`signal SM and flow rate signal SL each correspond(cid:173)
`ing to one pulse of the puse wave, it is possble to
`determine a plurality of blood pressures· and periph(cid:173)
`eral resistances based on signals SM and SL
`correspoding to a plurality of the lastly read pulses of
`the pulse wave, and calculate and display moving
`averages of the plurality of blood pressures and
`peripheral resistances. In this case, it is preferred
`that the apparatus employ a ring buffer for storing
`signals SM, SL corresponding to the lastly read
`pulses. For example, the CPU 36 or RAM 48 may be
`adapted to serve as the ring buffer.
`The pressure sensor for detecting pulse wave
`from an arterial vessel extending through a periphe(cid:173)
`ral portion of a subject, may be of a type having a
`pressing surface to be pressed against the arterial
`vessel via a body surface of the peripheral portion,
`and supporting at the pressing surface a pressure
`detector for detecting the pulse wave produced
`from the arterial vessel.
`While in the illustrated embodiment the pressure
`transducer 18 is disposed in the air-tight space 16, it
`is possible to dispose the transducer 18 in the piping
`24.
`Although in the illustrated embodiment the ultra(cid:173)
`sonic wave generator 38 continuously generates
`ultrasonic wave with a predetermined frequency,
`toward the radial artery 22, it is possible to replace
`the generator 38 with a genertor of a type adapted to
`generate pulses of ultrasonic wave toward the artery
`so that the reflected pulses are utilized to determine
`blood flow rate regarding the artery.
`While in the illustrated embodiment the display 50
`timewise displays the peripheral resistance of the
`subject, it is possible to trasnmit signal representing
`the peripheral resistance, to an external monitoring
`device adapted to obtain from the same subject
`information other than the peripheral resistance.
`Referring next to Fig. 5, there is shown a modified
`from of the peripheral resistance measuring appara(cid:173)
`tus of the invention. The same reference numerals as
`used in the embodiment of Figs. 1 and 2 are used to
`designate corresponding elements or parts of the
`embodiment of Fig. 5, and repetitive description
`thereabout will be omitted.
`The present apparatus further serves as an
`oxymeter for measuring oxygen saturation of a
`subject. The apparatus includes a first and a second
`light emitter 54, 56 and a light detector 58. The first
`light emitter 54 emits a red light beam having a
`wavelength of about 660 mµ, while the second light
`-emitter 56 emits an infrared light beam having a
`wavelength of about 804 mµ. The first and second
`light emitter 54, 56 alternately emit the red and
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`infrared light beams toward capillaries in skin (body
`surface) 19 of the subject as a result of being
`activated by drive signals SD3 and SD4, respectively,
`supplied thereto from the output interface 52. The
`light beams reflected from the skin are detected by
`the light detector 58. The light detector 58 generates
`electric signal SV representing intensity of the
`detected light beams, to a pulse wave detecting
`circuit 60. The pulse wave detecting circuit 60
`separates, from signal SV, pulse wave singnal SMR
`when the red light beam is detected and pulse wave
`signal SMrR when the infrared light beam is detected,
`each of signals SMR, SMrR representing pulse wave
`produced from the radial artery 22 synchronously
`heartbeat of the subject. Signals SMR, SMrR are
`supplied to the CPU 36 via an AID converter 62. The
`CPU 36 determines oxygen saturation of the blood
`flowing through the capillaries in the skin of the
`subject, based on signals SMR, SMrR received, and
`commands the display 50 to display the determined
`oxygen saturation. More specifically described,
`oxygen saturation is determined based on a ratio of
`an absorption coefficient of the red light beam
`regarding blood flowing through capillaries, to an
`absorption coefficient of the infrared light beam
`regarding the blood, according to a predetermined
`relationship between the oxygen saturation and that
`ratio, and the ratio in question is determined based
`on a ratio of an amplitude of signal SMR to an
`amplitude of signal SMrR, according to a predeter(cid:173)
`mined relationship between the two ratios.
`While the present invention has been described in
`its presently preferred embodiment and one modi(cid:173)
`fied form thereof with detailed particularities, it is to
`be understood that the invention may be embodied
`with other changes, modifications and improve(cid:173)
`ments that may occur to those skilled in the art
`without departing from the scope and spirit of the
`invention defined in the appended claims.
`
`Claims
`
`1. An apparatus for detecting a resistance
`opposing blood flow through a peripheral
`portion (20) of a subject's body, comprising:
`first determining means (12, 36) for determining
`blood pressure of said subject;
`second determining means (38, 40, 44, 36) for
`determining at least one of a flow rate and a flow
`amount of blood which flows through an arterial
`vessel (22) extending through said peripheral
`portion (20) of said body; and
`calculating means (36)
`for calculating said
`resistance based on said blood pressure and
`said at least one of the blood flow rate and the
`blood flow amount.
`2. The apparatus as set forth in claim 1,
`wherein said second determining means com-
`prises
`an ultrasonic wave generator (38) for genera(cid:173)
`ting and transmitting ultrasonic wave toward
`said arterial vessel (22) extending through said
`peripheral portion (20) of said . body, an ultra-
`sonic wave detector (40) for detecting the
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`a display device (50) for displaying at least one
`value of maximum, minimum and average blood
`pressure; maximum, minimum and average
`blood flow rate; maximum, minimum and aver(cid:173)
`age resistance; and maximum, minimum and
`average value obtained by respectively multi(cid:173)
`plying said maximum, minimum and average
`resistance by an average sectional area of said
`arterial vessel (22).
`9. The apparatus as set forth in claim 8,
`wherein said display device (50) displays said at
`least one value each time said pressure sensor
`(12) detects a pulse of said pulse wave from
`said arterial vessel (22).
`10. The apparatus as set forth in any one of
`claims 1-9, wherein said second determining
`means (38, 40, 44, 36) determines said blood
`flow amount by multiplying said blood flow rate
`by an average sectional area of said .arterial
`vessel (22).
`
`ultrasonic wave reflected by said blood flowing
`through said arterial vessel, and
`means (44, 36) for determining said blood flow
`rate based on the detected ultrasonic wave.
`3. The apparatus as set forth in claim 2,
`wherein said first determining means comprises
`a pressure sensor (12) for detecting a pulse
`wave produced from said arterial vessel (22),
`said pressure
`sensor being pressed against a body surface
`(19) of said subject just above said arterial
`vessel so as to detect said pulse wave, and
`means (36) for determining said blood pressure
`based on magnitude of the detected pulse
`wave.
`4. The apparatus as set forth in claim 3,
`further comprising
`a wrist band (10) for supporting, on one (11) of
`opposite surfaces thereof, said ultrasonic wave
`generator and detector (38, 40) and said
`pressure sensor (12), said wrist band pressing,
`under said one of opposite surfaces thereof,
`said ultrasonic wave generator and detector
`and said pressure sensor against a radial artery
`(22) of said subject via said body surface (19)
`when said wrist band is placed around a wrist
`(20) of said subject.
`5. The apparatus as set forth in claim 3 or
`claim 4, wherein said pressure sensor (12)
`comprises an elastic member (14) for defining a
`fluid-tight space (16), said elastic member
`being pressed against said arterial vessel (22)
`via said body surface (19) when pressure in said
`fluid-tight space is increased, and
`a pressure transducer (18) disposed in said
`fluid-tight space, for detecting pressure vari(cid:173)
`ation in said fluid-tight space upon transmission
`of said pulse wave to said fluid-tight space from
`said arterial vessel.
`6. The apparatus as set forth in claim 4 or
`claim 5, further comprising
`third determining means (54, 56, 58, 60, 36) for
`determining oxygen saturation of blood which
`flows th_rough capillaries in skin (19) of said
`subject, said third determining means compris(cid:173)
`ing a first light emitter (54) for emitting toward
`said skin a light beam having a first wavelength,
`a second light emitter (56) for emitting toward
`said skin a
`light beam having a second
`wavelength different from said first wavelength,
`and a light detector (58) for detecting the light
`beams reflected from said skin, said wrist band
`(10) also supporting said first and second light
`emitters and said light detector, said third
`determining means further comprising means
`(60, 36) for determining said oxygen saturation
`based on the detected light beams.
`7. The apparatus as set forth in any one of
`claims 1-6, wherein said second determining
`means (38, 40, 44, 36) determines at least one
`of an average flow rate and an average flow
`amount of said blood flowing through said
`arterial vessel (22).
`8. The apparatus as set forth in any one of
`claims 1-7, further comprising
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`
`6
`
`

`

`10\
`
`24
`
`11
`
`----·-··-I-·-·----··-·-·--·····
`
`A/D CoNVEkTER
`36
`
`34
`
`.30
`
`SM
`
`I
`
`I
`
`38
`
`SF
`
`R.FcE/VING C!Rcurr
`44
`
`CPU
`
`SL
`
`('/
`TkA/\JSNI TTING
`CIRCUIT
`
`.
`
`SD2
`
`SD1
`
`\
`
`42
`
`28 fLUID-Su??L'(l/Jq DEVICE
`
`52
`
`fRESSURE-f(E(JUL ATING VALVE
`
`OUTPUT
`
`/IJTERFACE:
`
`FIG. I
`
`46
`
`ROM
`
`-1
`48 y
`
`RAM
`
`I
`
`D/SfLIJYI
`
`50
`
`m ,,
`
`0
`w
`w
`0
`.i:i.
`O> w
`)>
`.....
`
`7
`
`

`

`EP 0 330 463 A1
`
`FIG.2
`
`FIG.3
`
`PuLSE WAVE SIGNAL
`Sl1 READ
`
`FLovv RATE Sl~NAL
`SL READ
`
`NO
`
`53 SJG-NALS CoRR£.S1>oNDINq
`To oNE ?t1LSE REt4l> ?
`
`~---l..---,,.... ---l3LOOJ) 'tRESSuRE (f/LCuLATED
`54
`______ fiVERAGE BLoot> fLow RATE
`5 5 CALCULATE])
`rER.l?HERl!L RES/STANCE
`CALCULATED
`
`57
`
`----- /)/SfLAY
`
`8
`
`

`

`EP 0 330 463 A1
`EP 0 330 463 A1
`
`FIG.4
`
`- - - - - - R'
`
`BP max
`
`BPa?r
`
`BP min
`
`T!f1£
`T/ME
`
`qimigq
`
`32Emama
`
`wasmmmod
`
`Qogm
`
`9
`
`
`

`

`10\
`
`PULSE WAVE DETECTING
`
`60
`
`SMR
`SMIR
`
`30
`
`sv
`
`----11-14
`
`SM
`
`A//) CoNVERTER.
`CIRCUIT
`62 ~
`1/~ 36
`
`19.
`
`34
`
`I CPU
`
`46
`~
`I
`48
`
`ROM
`
`RAM
`
`I
`
`I
`D1sfLAr
`
`--- l
`I
`50
`
`m ,,
`
`0
`(,)
`(,)
`0
`.i:o. en
`....
`
`)>
`
`(,)
`
`38
`
`SF
`
`24
`
`'RECEIVING
`C!RCurr
`
`A/D
`44 CoNVERTEl<.
`
`( c
`
`' ~
`
`SL
`
`501
`
`42
`
`503
`504
`iR.ANSMI TTINCT CIRCUIT
`
`26
`
`502
`
`PRESSVR~-RE6ULATINC! VALVE
`
`28
`fLU(D-SUPF'L YI N<i
`
`52
`OUTPUT /NTERr~CE
`
`FIG.5
`
`10
`
`

`

`European Patent
`Office
`
`EUROPEAN SEARCH REPORT
`
`DOCUMENTS CONSIDERED TO BE RELEVANT
`Citation of document with indication, where appropriate,
`of relevant passages
`US-A-4 703 758
`(Y. OMURA)
`* Abstract; column 3, lines 36-55;
`claims 1,6-9; figures 5-8 *
`
`Relevant
`to claim
`1,7
`
`2,3
`
`Application Number
`
`EP 89 30 1758
`
`CLASSIFICATION OF THE
`APPLICATIOl'i (Int. Cl.4)
`
`A 61 B
`A 61 B
`
`5/02
`8/06
`
`Category
`
`y
`
`A
`
`y
`
`