United States Patent
`Herczfeld et al.
`
`[72)
`
`[541 HEART RATE AND RESPIRATORY
`MONITOR
`Inventors: Bonita Falkner Herczfeld; Peter R.
`Herczfeld, both of Philadelphia, Pa.;
`Richard D. Klafter, Willingboro,
`N.J.
`(73) Assignee: Drexel 'Universlty, Philadelphia, Pa.
`[22) Filed:
`Oct. 23, 1969
`I 21 I Appl. No.: 868,823
`
`(52) U.S. Cl . .......... l28/2 R, 128/2.05 T , 128/2.05 P,
`356/4 1
`Int. Cl . ............................................... A6lb 5/02
`[51)
`[58) Field of Search .... 128/2, 2.05 T, 2.05 V, 2.05 P,
`128/2.05 F; 356/39-42
`
`[56)
`
`References Cited
`
`UNITED STATES PATENTS
`
`2,640,389
`3,103,214
`3,123,066
`3,139,086
`3,152,587
`3,167,658
`
`6/1953
`9/1963
`3/1964
`6/1964
`10/1964
`1(1965
`
`Liston ................................... 128/2 R
`Smith ............................... 128/2.05 P
`Brumley ............................... 128/2 R
`Botsch et a1.. .................... 128/2 .OS P
`Ullrich et at. ......................... 128/2 R
`Richter ............................ 128/2.05 P
`
`[15)
`
`[4 5)
`
`3,704,706
`Dec. 5, 1972
`
`3,228,39 1
`3,230,95 I
`3,511,227
`
`1/1966 Fitter et at. ...................... 128/2.05 T
`1/1966 Teschner .......................... 128/2.05 P
`5/1970
`Johnson ........................... 128/2.05 F
`
`FOREIGN PATENTS OR APPLICATIONS
`
`987,504
`
`3/1965 Great Britain ................... 128/2.05 P
`
`Primary Examiner-Richard A. Gaudet
`Assistant Examiner-Kyle L . Howell
`Attorney-Paul and Paul
`
`ABSTRACT
`[57)
`Apparatus for detection of pulse repetition rate and
`oxygenation of blood flow, comprising a solid state
`probe having a narrow bandwidth light source housed
`to direct light upon a patient's fmger and a photode(cid:173)
`tector housed for receiving reflected light from such
`finger, the output of the detector being connected to
`electronic circuitry for detecting pulse repetition rate
`of blood flow and for detecting signal level representa(cid:173)
`tive of the degree of oxygenation of the patient's
`blood. The use of a low power narrow bandwidth light
`source with a red emission characteristic permits
`precise detection of the degree of oxygenation of the
`blood.
`
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`MONITORING
`DEVICE
`
`Apple Inc.
`APL1016
`U.S. Patent No. 9,289,135
`
`001
`
`

`

`PATENTED DEC 5 1972
`
`3 . 7 0 4. 706
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`SHEEI 1 OF 2
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`MONITORING
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`
`INVENTORS.
`BONITA FALKNER HERCZFELD
`PETER R. HERCZFELD
`RICHARD 0 . KLAFTER
`
`BY t?a.-«1.¥-~.-
`
`ATTORNEYS.
`
`002
`
`

`

`PATENTED OEC 5 1972
`
`3. 704,706
`
`SHEET 2 OF 2
`
`__fig. 4(o)
`
`NORMAL PROBE
`OUTPUT VOLTAGE
`
`£i.g . 4(b)
`RESPIRATORY
`DISTRESS
`
`Pig . 4(c)
`SCH MITT
`TRIGGER
`
`Fig . 4(d)
`
`MUL TIVIBRATOR ID
`
`D D D
`
`INVENTORS.
`BONITA FALKNER HERCZFELD
`PETER R. HERCZFELD
`RICHARD 0. KLAFTER
`
`BY f?au!J~
`
`ATIORNEYS.
`
`003
`
`

`

`1
`HEART RATE AND RESPIRATORY MONITOR
`
`3,704,706
`
`2
`of the radiated energy being outside of the red. Only by
`inclusion of a prohibitively expensive optical filter
`could such a light and ftlter combination produce a nar(cid:173)
`row band width on the order of that provided by a laser.
`5 In addition to being more cumbersome, the device
`necessarily has a heating problem, which makes it par(cid:173)
`ticularly undesirable for use with infants. Further, the
`device detects only volume of blood flow, and cannot
`10 disting~ish between blood volume and degree of ox(cid:173)
`ygenation.
`
`BACKGROUND OF THE INVENTION
`A. Field ofthe Invention
`This invention lies in the field of heart rate monitors
`and, more particularly, solid state monitors for detec(cid:173)
`tion of peripheral flow and oxygenation of blood in a
`newborn infant patient.
`B. Description of the Prior Art
`The problem of accurately monitoring the heartbeat
`and of obtaining information regarding the flow of ox-
`SUMMARY OF THE INVENTION
`ygenated blood in a newborn infant has long resisted
`The primary object of this invention is to provide ap-
`the development of an economical instrument. The
`severity of the problem is based on the medical con- 15 paratus for the detection of oxygenated blood flow
`sideration that an infant, and particularly a premature
`which is simple, efficient, lightweight, inexpensive and
`infant, when undergoing an exchange blood transfu-
`sion, sometimes suffers cardiac arrest which, if unde-
`effective for the purpose and which overcomes the dis(cid:173)
`advantages of the prior art.
`tected for a relatively short period of time, may cause
`It is a further object of this invention to provide a
`permanent brain damage or death. Further, physicians 20
`heart rate monitor comprising a solid state optical
`are vitally interested in obtaining information relating
`to respiratory arrest and the degree of oxygenation of
`probe which is suitable for use on premature infants,
`the blood being circulated throughout the body during
`and which senses peripheral pulsations of the heart.
`and after an exchange transfusion. It is of particular im-
`It is a further object of this invention to provide ap-
`paratus which monitors both heart pulse rate and ox-
`portance to have information which discloses a partial
`cardiac arrest or a partial respiratory arrest, so that the
`ygenation of blood flow.
`:"-.ccordin~y, this invention provides ap~arat~s com-
`physician can take swift action to alleviate and correct
`p~1s1~g a s~hd stat~ laser as a source of hght t~ com-
`the situation. There is thus a requirement for continu-
`bm~t1on wtth a .sohd state ph~todet~ctor, formm~ an
`ous monitoring of both pulse repetition rate, a change
`in which often precedes cardiac arrest, and the level of 30 opttcal probe suttab~e for sensmg. penpheral pulsations
`of th.e heart. The sohd state laser ts a very small and ex-
`oxygen in the blood, which is an indication of respirato-
`ry distress.
`tremt':ly efficient light source emitting microwatts of
`The prior art shows a number of heart monitoring
`power in a narrow band width having peak emission oc-
`devices. However, most of these devices are designed
`curring in the red range of the optical spectrum. The
`for clinical use on adults and are generally not suitable 35 laser directs a low energy beam of light at the capilla-
`rics of a finger, the blood flowing within reflecting in-
`for use with newborn infants. Particularly, devices
`cident red light which is detected by a photodetector
`utilizing electrodes generally require that the elec-
`trodes be of a sufficient size to pick up the extremely
`housed adjacent to the laser and having a response
`small biopotential signals which are monitored, such
`curve suitable for detection throughout the emission
`large electrode sizes being unworkable for newborn in- 40 spectrum of the laser. The electrical output of the
`probe is transmitted to processing apparatus having
`fants. Furthermore, commercially available heart
`monitoring devices are extremely expensive, and pro-
`pulse detection circuitry to determine the pulse repeti-
`vide no information about the flow of oxygenated
`tion rate, as well as DC level detection circuitry to
`determine the relative oxygen content of the blood.
`blood.
`Apparatus for the measurement of peripheral pulsa- 45
`BRIEF DESCRIPTION OF THE ORA WINGS
`tions has a number of distinct advantages over the elec-
`FIG. 1 shows a schematic diagram of the probe hous-
`trocardiogram and other similar devices. First, it is
`ing and its elements in relation to a patient's finger.
`known that it is possible for electrical activity of the
`FIG. 2 shows a schematic diagram of an alternate
`heart to persist after the heart has actually stopped
`beating. Thus, a monitor designed to detect biopoten- 50 construction of the probe housing.
`tials could be late in detecting any cardiac arrest.
`FIG. 3 shows a block diagram of electronic
`Further, it is extremely difficult to place electrodes on
`processing circuitry which is connected to the probe.
`infants in such a way as to avoid extraneous noise pick-
`FIG. 4 shows a representation of waveforms
`up. And, perhaps most importantly, a monitor that only
`senses biopotentials cannot detect respiratory distress. 55 produced by the probe and electronic processing cir-
`Digital monitors, or transducers, for detecting
`cuitry.
`peripheral pulsations, and utilizing a light source in
`combination with a detector, have been shown in the
`art. More particularly, the prior art discloses a digital
`transducer comprising a light source in combination 60
`with a photoelectric cell, with a red filter placed over
`the photoelectric cell. Since the photocell is responsive
`to light in the red region of the spectrum, arterial pulsa(cid:173)
`tions which drive blood into the digit result in an in-
`creased redness and increased photocell response, thus
`giving an indication of the pulse repetition rate. How(cid:173)
`ever, a bulb and filter combination is inefficient, most
`
`25
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Referring now to the drawings, FIG. I shows a sche(cid:173)
`matic diagram of the probe and its elements. The probe
`20 is placed on the patient's finger by conventional
`strapping or tape and aligned such that the light source
`21 directs incident light, indicated by arrows marked
`"1," at the patient's finger. The detector 22 is placed
`adjacent to light source 21 and disposed in order to col(cid:173)
`lect reflected light, indicated by arrows marked "R,"
`
`65
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`llll
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`106009
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`

`

`3,704,706
`
`10
`
`3
`4
`condition, the DC component of the signal, or the
`from the patient's finger. The light source 21 and
`peak-to-peak value, is monitored. Thus, by distinguish-
`photodetector 22, combined with housing 23, form the
`probe 20, which has typical overall dimensions of !AI
`ing pulse repetition rate and DC level, the two cases
`inch X Yt. inch X Yt. inch. The light source 21 is suitably
`can be separately diagnosed.
`a gallium arsenide solid state laser which itself is one- 5
`Referring now to FIG. 3, a block diagram of the heart
`rate and respiratory monitor i.s shown. The signal
`tenth inch in diameter and 0.15 inch in length, having
`developed by the probe 20, as shown in FIG. 4a, is cou-
`typically 25 microwatts of power being emitted in a
`pled into electronic circuitry 40 for information
`narrow band width with the peak emission occurring at
`processing. The signal is first fed through a conven-
`6,700 angstrom, i.e., in the red range of the color spec-
`tiona) solid state DC amplifier 25 which amplifies the
`trum. Such a typical gallium arsenide laser is commer-
`total signal. The output of amplifier 25 is parallel cou-
`cially available. See, for instance, Monsanto model
`pled to a conventional Schmitt Trigger circuit 26 and to
`MV 1 OA. The photodetector 22 is required to have high
`a detector 29. The Schmitt Trigger 26 is a bistable elec-
`sensitivity through the frequencies of the emission
`spectrum of the laser. A suitable photodetector is the 15 tronic device which, when driven by the pulsating
`Motorola MRD210 50 volt NPN silicon photodetector.
`signal, will switch between two stable states, thus
`This detector is approximately 0.06 inch in diameter
`producing a squarewave output as shown in FIG. 4c.
`a!ld a maxi.m~m of 0.11.8 i~ch in heig~t, which ~imen-
`Such squarewave may suitably be differentiated and
`sJO.ns permit mco~poratJOn mto the ',{lmch. X Yt. mch X
`applied to a conventional mono-stable mu1tivibrator
`Yt. mch p~o.be dev1ce: A photodetector hav1.n~ frequen- 20 27, which multivibrator will produce a pulse train out-
`cy sele~tJVIty matchmg t~e .laser charactenstics would
`put having suitable pulse widths, and having a pulse
`further mcrease the. selectiVIty of the pro~e.
`repetition rate equal to that of the probe waveform .
`. The robe hou~mg 23 may b~ fabncated from a
`Such a mono-stable output is shown in FIG. 4d. This
`p1ece o metal! su1ta~ly. br.ass, havmg parallel recesses
`output, then, can be coupled to a conventional driver
`h
`or holes 25 dnlled w1thm 1t to accommodate the laser 25
`·
`h. h ·
`"t 31 C1rcu1 , sue as an em1 er .o ower, w 1c m tum
`
`·tt
`r 11
`
`.
`.
`the holes bemg
`.
`.
`.
`.
`.
`and photodetector respectively,
`·
`d
`h" h .
`d" 1
`dnves a su1table momtonng dev11ce 28, such as a beep
`b , ~
`h
`onente p:rpen 1cu ar to t e pro e s su •• ace V: IC . IS
`tone generator or oscillograph.
`plac~d agamst the finger. B.etween ~ecesse~ 25 IS an m-
`Still referring to FIG. 3, the output of amplifier 25 is
`the
`sulatmg member 26 . which. opt!cally Isolates
`also fed into a detector 29, suitably a conventional DC
`recesses, thereby optically 1solatmg the . laser and 30 detector. The output of detector 29 is coupled,
`bl th
`h b "
`l"fi
`30 t
`"tabl
`photodetector. Alternately, the probe housmg may be
`r
`, o a su1
`e
`roug a uuer amp 1 1er
`d f
`.
`.
`.
`.
`pre.era y
`rna e ro~ an epitaxial plastic, as sh_own 10 ~IG. 2· A
`volt meter 32 which would indicate the magnitude of
`front port1on 27 of a clear nonhardenmg plast1c may be
`th d t
`t d DC
`Ita
`Th
`It
`t
`32
`b
`added, thereby encapsulating the laser and photodetec-
`~ e ec e .
`v~ ge.
`e vo me er
`. can e
`tor without significantly impeding light transmission. A 35 su1tably equtpped w1th a r~f~rence needle, wh1ch nee-
`die can be set at a lower h.m•.t, such that when the DC
`power supply 39 provides power for the laser and the
`level drop~ to such t.o~er hm1t, ~~meter would. sound
`photodetector, as well as the electronic circuitry
`described hereinbelow.
`an alarm Signal, not1fymg a physician. By checkmg the
`pulse ~ate output, the phys!cian could immediately
`In operation, the probe is placed upon the patient's
`finger such that blood which is flowing in the capillaries 40 dete~mme whethe~ the drop m DC level was due to a
`respl~atory or cardtac cause.
`of the finger reflects incident red light. The intensity of
`the reflected light is proportional both to the amount of
`It IS to be understood that detector 29 coul~. at-
`blood flowing in the finger and to the freshness of the
`t:ma~ely, be a peak-to-peak detector of conventiOnal
`blood, i.e., the degree to which it is oxygenated. For 45 ctrcu1try,. and be c?n~ected to a pe~k-to-peak volt
`meter wh1ch would md~cate the. magnttude of the de-
`each heartbeat, fresh blood is pumped into the capilla-
`ries, thereby causing a periodic increase and decrease
`tected voltage pulses m the s1gnal from probe 20.
`in the reflected light intensity. Under normal condi-
`Either the DC level or the peak-to- peak information,
`tions then, a periodic waveform such as shown in FIG.
`when compared with the pulse repetition rate, would
`4a will be detected, which waveform represents both 5o be sufficient. to enable the p~ysician . to distinguish
`voli1me and color of the circulating blood. The
`between card1ac arrest and respiratory diStress.
`waveform has an AC component corresponding to the
`From the foregoing, it is seen that this invention pro-
`heart pulsations, and a DC component which will be
`vides an extremely efficient and suitably small device
`directly proportional to the redness, or oxygenation, of
`for monitoring blood flow characteristics of an infant.
`the blood. In the event of partial ca~diac arrest, the pul- 55 The choice of a laser which produces approximately 25
`microwatts makes possible a very cool and efficient
`sations vary in frequency, which condition can be easily
`detected. When a respiratory distress occurs, the heart
`device. Further, by using a narrow beam laser, it is
`possible to produce a device which is very sensitive to
`continues to pump blood, but it is relatively unox-
`changes in blood color. By contrast, apparatus utilizing
`ygenated blood with a characteristic bluish hue. Since
`the probe is relatively insensitive in the blue region of 60 white light in combination with a red filter, in addition
`to being inefficient and generating heat which would be
`the light spectrum, such a respiratory distress is im-
`mediately manifested by a probe signal of diminished
`prohibitive in clinical uses with infants, produces a rela-
`amplitude, as shown in FIG . 4b. By contrast, in the par-
`tively broad range of red light. Consequently, relatively
`tial cardiac arrest condition, the pulse repetition rate 65 large changes in oxygen content must take place before
`will change, while the amplitude and DC level will
`detection by a white light and falter combination,
`remain essentially the same. To distinguish the respira-
`whereas extremely small changes can be detected with
`tory distress condition from the partial cardiac arrest
`the frequency selective laser probe of this invention.
`
`2211
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`106009
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`

`3,704,706
`
`10
`
`5
`It is to be noted that equivalent narrow beam light
`sources including light-emitting diodes, whether the
`light is coherent or not may be utilized in place of lasers
`in the practice of this invention. It is further noted that
`while specific electronic circuitry for processing the 5
`probe signal has been discussed in this specification, a
`wide variety of pulse repetition rate and level detection
`circuits can be used.
`We claim :
`1. Heart rate and respiratory monitor apparatus for
`detecting pulse repetition rate and oxygenation of
`blood flow in a patient, comprising:
`a. a probe housing having first and second light trans(cid:173)
`mitting faces;
`b. a low power solid state laser red light source, hav· 15
`ing narrow bandwidth emission characteristics,
`positioned in said probe housing to emit red light
`through said first face;
`.
`c. semiconductor photodetector means for detecting
`red light reflected thereon, said photodetector 20
`means positioned in said housing to receive light
`through said second face of said housing, such that
`when said faces of said probe housing are posi(cid:173)
`tioned contiguous to a periphery of a patient, in(cid:173)
`cident light from said red light source is reflected 25
`from such periphery and received by said photode(cid:173)
`tector means;
`d. electronic processing means connected to said
`photodetector means having pulse repetition rate
`circuitry and first output means coupled thereto 30
`for monitoring said patient's pulse repetition rate,
`and signal level detection circuitry and second out-
`
`6
`put means coupled thereto for monitoring the
`degree of oxygenation of said patient's blood; and
`e. a power source connected to and supplying energy
`to said red light source, said photodetector means,
`and said electronic processing means.
`l . Heart rate and respiratory apparatus for detecting
`the pulse repetition rate and degree of oxygenation of
`blood flowing in a peripheral portion of a patient, com(cid:173)
`prising:
`a. narrow bandwidth red light means for transmitting
`incident red light upon said peripheral portion and
`detecting red light reflected therefrom;
`b. a probe housing means for housing said red light
`means such that, when positioned contiguous to
`said periphery, some of said incident light is
`reflected from the blood flowing in said periphery
`and received by said reflecting means; and
`c. electronic processing means connected to said de(cid:173)
`tecting means for transforming said reflected red
`light into an electrical signal representing said
`reflected red light, and including pulse repetition
`rate circuitry for monitoring said patient's pulse
`repetition rate, and signal level detection circuitry
`for monitoring the degree of oxygenation of said
`patient's blood, said red light means including a
`narrow bandwidth solid state laser mounted within
`said probe housing means to direct incident red
`light to said periphery, and a semiconductor
`photodetector mounted in said probe housing
`means to receive red light reflected from said
`periphery.
`
`* • * • *
`
`35
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`40
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`45
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`so
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`55
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`106009
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`0187
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`