matted States Patent
`
`[191
`
`[111
`
`3,862,636
`
`Bell et al.
`[451 .lan.28, 1975
`
`
`
`[54] COMPUTER CONTROLLED
`DEFIBRIILLATOR
`
`[75]
`
`Inventors: David Bell; William K. Hagan, both
`of Omaha, Nebr.
`
`[73] Assignee: Health Technology Labs, lnc.,
`Omaha, Nebr.
`
`[22]
`
`Filed:
`
`Nov. 29, 1973
`
`[21] Appl. No.: 420,291
`Related U.S. Application Data
`[63] Continuation-in-part of Ser. No. 219,455, Jan. 20,
`1972, Pat. No. 3,782,389.
`
`[52] U.S. Cl............................................ .. 128/419 D
`[51]
`Int. Cl............................................. .. A6ln 1/36
`[58]
`Field of Search .......... .. 128/419 D, 419 R, 421.
`128/422, 423
`
`[56]
`
`References Cited
`UNITED STATES PATENTS
`7/1973
`Cook et al. ................... .. 128/419 D
`3,747,605
`FOREIGN PATENTS OR APPLICATIONS
`1,076,286
`2/I960 Germany
`OTHER PUBLICATIONS
`
`Tacker Jr. et al., “The American Journal of Cardiol-
`ogy,“ vol. 33, Jan. 1974, page 172.
`
`Primary Examiner—William E. Kamm
`Attorney, Agent, or Fz'rm—Zarley, McKee, Thomte &
`Voorhees
`
`ABSTRACT
`[57]
`A computer controlled defibrillator comprising a set
`
`of electrodes which are engageable with a patient and
`which are connected to a source of electrical energy
`by a circuit means. The circuit means comprises stor-
`age capacitors, energy selector, computer, manual and
`reset switches. voltage monitor. current monitor, and
`output meter. The computer responds to certain exter-
`nal
`inputs. automatic and manual. and controls the
`output delivered to the patient. The energy selector
`permits the selection of the energy which is desired to
`be delivered to the patient. The sequence is started by
`closing the manual reset switch which zeroes the out-
`put meter and activates the power supply (electrical
`energy) at a voltage which is dependent on the energy
`selector. The energy derived from the power supply is
`stored in the storage capacitors. The energy selector,
`which is manually set to the energy desired, also feeds
`an input to the computer. When the manual switch is
`activated,
`the computer causes the stored energy
`source to be connected to the patient through the
`electrodes. The current monitor and voltage monitor
`feed instantaneous signals to the computer which
`computes the energy as a continuous integration pro-
`cess. When the computed energy equals the selected
`energy, the computer causes the energy source to be
`disconnected from the patient. The total energy deliv-
`ered to the patient is indicated as a steady reading on
`the output meter. A modified form of. the defibrillator
`is also disclosed wherein the magnitude of current in
`the electrical circuit means may be manually or auto-
`matically selected to enable the defibrillator to com-
`pensate for the patient‘s body weight.
`
`5 Claims, 8 Drawing Figures
`
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`3,862,636
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`I
`COMPUTER CONTROLLED DEFIBRILLATOR
`
`BACKGROUND OF THE INVENTION
`
`This application is a continuation-in-part application
`of the application Ser. No. 219,455 filed Jan. 20, 1972
`which issued as U.S. Pat. No. 3,782,389.
`The use of DC defibrillators in emergency resuscita-
`tion has become well established. Limitations due to
`weight have prevented more widespread use of the de-
`fibrillators. Most clinical defibrillators depend on the
`storage and discharge of energy through a stable RLC
`combination, thus requiring accurate capacitance, in-
`ductance and resistance. The conventional defibrilla-
`tors employ a pair of electrodes or paddles which are
`placed in contact with the patient’s chest. A defibrilla-
`tion or electrical pulse is then applied to the patient,
`through the electrodes, to momentarily stop the heart
`so that fibrillation of the heart is stopped. Since time is
`critical in defibrillation techniques, it is extremely im-
`portant that a sufficiently large impulse be applied to
`the patient during the first attempt. A majority of the
`prior art devices employ some means for selecting the
`energy to be delivered to the patient. However, it has
`been found that
`these devices generally deliver a
`smaller or lower output to the patient than that which
`was selected. A further complication is that the resis-
`tance of the patients vary greatly. Thus, the operator
`could possibly determine that it was necessary to apply
`an impulse of 200 joules to the patient. Quite often, the
`variances in the defibrillator and the variable resistance
`of the patient will result in considerably less than 200
`joules being applied to the patient. If the pulse is insuf-
`ficient to momentarily stop the patient’s heart, the pa-
`tient could possibly die.
`Research has indicated that there is a possible corre-
`lation between the body weight of the patient and the
`electrical current (energy doses necessary to defibril-
`late a fibrillating heart). In applicant's previous defi-
`brillator, the amount of energy delivered to the patient
`was measured and used as a control to insure that the
`delivered energy is equal to the energy selected to be
`delivered.
`In applicant’s previous defibrillator,
`the
`amount of current was not controlled but fixed.
`Therefore, it is a principal object of this invention to
`provide an improved defibrillator.
`A further object of this invention is to provide a defi-
`brillator wherein the energy delivered to the patient
`substantially equals the selected energy.
`A further object of this invention is to provide a defi-
`brillator including a circuit means having an energy
`computer and control which computes the energy de-
`livered to the patient and causes the energy source to
`be disconnected from the patient when the computed
`energy substantially equals the selected energy.
`A further object of this invention is to provide a defi-
`brillator which delivers the selected energy to the pa-
`tient regardless of the resistance of the patient.
`A further object of this invention is to provide a defi-
`brillator which is light weight and portable.
`A further object of the invention is to provide a defi-
`brillator wherein itheimagnitude of current can be man-
`ually or automatically selected.
`A further object of the invention is to provide a defi-
`brillator having means for manually or automatically
`selecting the magnitude of current responsive to the pa-
`tient’s body weight.
`
`2
`A further object of the invention is to provide a
`method of defibrillating a fibrillating heart.
`A further object of this invention is to provide a defi-
`brillator which is economical of manufacture, durable
`in use and refined in appearance.
`These and other objects will be apparent to those
`skilled in the art.
`
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`BRIEF DESCRIPTION OF THE DRQWINGS
`
`FIG. I is a perspective view of the defibrillator of this
`invention:
`FIG. 2 is a block diagram of the electrical circuitry
`of the defibrillator:
`FIG. 3 is a block diagram illustrating the components
`of the energy computer and control and its relationship
`with other components of the device:
`FIG. 4 is a schematic view of a portion of the cir-
`cuitry of the invention:
`FIG. 5 is a schematic View of more of the circuitry of
`the invention:
`FIG. 6 is a schematic view of more of the electrical
`circuitry of the invention:
`FIG. 7 is a block diagram similar to FIG. 3 except
`that the means for manually controlling the magnitude
`of current in the circuit means is illustrated; and
`FIG. 8 is a block diagram similar to FIGS. 3 and 7 ex-
`cept that an automatic means is disclosed for control-
`ling the magnitude of current in the electrical circuit
`means.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`With respect to FIGS. 1-6, the defibrillator of this
`invention is referred to generally by the reference nu-
`meral 10 and comprisesia portable housing 12 having
`a pair of electrodes or paddles 14 and 16 connected to
`the circuitry therein as will be described in more detail
`hereinafter. The electrodes or paddles 14 and 16 are
`engageable with the patient to deliver a predetermined
`energy output to the patient to momentarily stop the
`patient’s heart
`so that
`fibrillation of the heart
`is
`stopped.
`The circuitry of the defbrillator is depicted in sche-
`matic form in FIG. 2 wherein the numeral 18 refers to
`a 1'10 VAC power supply having a switch 20 associated
`therewith. The power supply 18 is electrically con-
`nected to the storage capacitors 22 which are adapted
`to store energy derived from the power supply 18. A
`“switch" mechanism 24 is connected to the storage ca-
`pacitors 22. Mechanism 24 is connected to the elec-
`trodes 14 and 16 as seen in FIG. 2 and to voltage moni-
`tor means 26 and current monitor means 28. Manual
`switch 30 and reset switch 32 are connected to the en-
`ergy computer and control means 34. Energy selector
`36 is also connected to the computer and control
`means 34 as is the output meter 38. Energy selector 36
`may be comprised of a conventional rotatable dial or
`the like for setting the energy to be delivered to the pa-
`tient.
`The energy computer and control means 34 is illus-
`trated in schematic form in FIG. 3. In FIG. 3, it can be
`seen that the current monitor 28 and voltage monitor
`26 are electrically connected to the Multiplier 40 and
`that the Multiplier 40 is connected to an Integrator 42.
`Integrator 42 is connected to an Analog Memory 44
`which is connected to the meter 38. The current moni-
`tor 28 and the voltage monitor 26 are also connected
`
`6
`
`

`
`3,862,636
`
`3
`to a Time Out Comparator 46 which is connected to
`the OR gate 48. The energy selector 36 is connected to
`the Time Out Comparator 46, Integral Comparator 50
`and Voltage Comparator 52., The Integral Comparator
`50 is connected to the OR gate 48 and to the Integrator
`42 as depicted in FIG. 3. Voltage Comparator 52 is
`connected to the Voltage Reference 54 and to the
`Charge Logic 56. The Multiplier 40 is also connected
`to the Voltage Comparator 52.
`The reset switch 32 is electrically connected to the
`Analog Memory 44 and to the Charge Logic 56 while
`the manual switch 30 is connected to the Delay-Start
`58 and to the Charge Logic 56.
`The heart of the control mechanism in the defibrilla-
`tor is the energy computer and control 34 which re-
`sponds to certain external inputs, manual and auto-
`matic, and controls the output delivered to the patient.
`In operation, the manual reset 32 starts the sequence
`by zeroing the output meter 38 and activating the
`power supply 18 at a voltage which is dependent on the
`energy selector 36. Thus, if it were desired to deliver an
`impulse of 200 joules to the patient, the energy selector
`36 would be set at 200 joules. The energy derived from
`the power supply 18 is stored in the storage capacitors
`22. The energy selector 36, which is manually set to the
`energy desired, also feeds an input to the energy com-
`puter and control 34. The electrodes or paddles I4 and
`I6 are then placed into contact with the patient and the
`manual switch 30, located on either or both of the pad-
`- dies 14 and 16, is activated.
`.
`When the manual switch 30 is activated, the energy
`computer and control 34 causes the stored energy
`source to be connected to the patient. The current
`monitor 28 and voltage monitor 26 feed instantaneous
`signals to the energy computer and control 34 which
`computes the energy as a continuous integration pro-
`cess. When the computed energy equals the selected
`energy, the energy computer and control 34 causes the
`energy source to be disconnected from the patient. The
`total energy delivered to the patient is indicated as a
`steady reading on the output meter 38.
`More specifically, the circuitry of FIGS. 4, 5 and 6
`operates as follows. The circuit of FIG. 4 is basically
`the power supply for the device. TF3 transformer feeds
`a full wave bridge rectifier to generate plus and minus
`DC voltage. The transistor and zener diodes regulate
`the DC to il5 v. and are of conventional design. The
`second set of diodes leading to the coils of KI and K2
`supply power to operate these relays. Contact K3 oper-
`ates coil K2. K2 operates the contacts on FIG. 5. K3 is
`operated off of the control circuit illustrated in FIG. 6.
`These devices, K2 and K3, control the main discharge
`from the firing circuit to the patient.
`K1 which is controlled by the voltage comparator 52
`and charge logic 56 switches 110 VAC to transformers
`T1 and T2. This circuit supplies power to the capacitor
`bank 22 in FIG. 5 as required to maintain 1,400 VDC.
`The four rectifiers between T1 and T2 in FIG. 4 and
`the four capacitors 22 in FIG. 5 form two full wave
`voltage double circuits in cascade to generate 1,400 v.
`About 500 joules of energy are then stored in the ca-
`pacitor bank. Initially all four silicone controlled recti-
`fiers SCR are not conducting. The 150 K resistors
`around the SCRS are used to balance the off leakage
`current. The 0.05 mfd - 50 ohm networks around each
`SCR are to suppress switching transcients.
`
`4
`Terminals 1, 2 and 3 are the monitor points. The volt-
`age between 1 and 2 is proportional to the stored volt-
`age and the voltage to the load. The voltage between
`I and 3 is proportional to the current in the load. The
`5 ohm, 100 watt resistor serves the dual function of
`current shunt and crow-bar protection.
`The remainder of this circuit can be best explained
`by a typical operating sequence. Initially the capacitors
`are charged and all SCRs are off. The cycle starts with
`the start input going to a positive 15 v. This starts the
`0.030 sec. timer 58. At the same time K2 relay begins
`to close. The timer delay is to allow K2 to close com-
`pletely. When the unijunction transistor in the timer
`fires, a large current pulse is fed to trigger transformers
`TI and T2. These pulses turn on SCR I and 2 applying
`power to the load. The LED is turned on by the applied
`voltage and is optically coupled to the photo transistor
`in FIG. 6. This transistor starts timeout comparator Z9.
`When the comparator circuit determines the required
`energy has been delivered, a positive voltage is applied
`to the stop terminal. This tires the small ZN5062 SCR
`generating a high current pulse in T3 and T4. This
`pulse fires SCR 3 and 4 which crow-bars the remaining
`energy in the capacitor bank.
`With respect to FIG. 6, amplifiers Z1, Z3 and Z3
`form two DC differential amplifiers. These amplifiers
`convert the essentially floating inputs 1, 2 and 3 to
`ground referenced signals. The two outputs are v(t)
`from Z2 and i(t) from Z3. These signals are fed to 40
`which together with Z4 form an analog multiplier. The
`output of Z3 in mathematical terms is [v(t) .r i(t)]/K.
`This signal is proportional to the power being deliv-
`ered to the load at any instant oftime. Z5 is an integra-
`tor which integrates power with time to give energy.
`The AC coupling network on the output of Z3 removes
`the long term DC drift. The output at this point is ap-
`proximately an increasing ramp voltage. This ramp is
`compared to the setting of the potentiometer 36, by
`comparator 50. When these are equal, the comparator
`sends the stop output high. The peak value of the ramp
`is stored on the 0.22 mfd capacitor in analog storage
`circuit 44. The four transistor amplifier has a gain of
`+1. This allows the energy delivered to be displayed on
`the meter.
`Comparator Z9 (46) performs a similar function to
`50 except it compares the potentiometer 36 setting
`with time. In this way the output pulse width is limited
`to a maximum value for any given setting. This circuit
`does not affect operation for loads of less than 150
`ohms.
`‘
`‘Comparator Z6 controls the charging of the capaci-
`tor bank. Z6 compares the output of amplifier Z2
`which is proportional to the bank voltage to a zener di-
`ode. A certain amount of positive feedback is used as
`controlled hysteresis to prevent chatter of relay Kl.
`The remaining transistors are used as switches to turn
`on or off certain functions when the manual switch 30
`is closed. For example, the voltage comparator Z6 is
`turned off and comparators 56 and 50 and analog
`memory 44 are turned on.
`FIGS. 7 and 8 are block diagrams similar to FIG. 3
`except that means for controlling the magnitude of cur-
`rent in the circuit means is illustrated. With respect to
`FIG. 7, the numeral 100 refers to a variable voltage
`control of the manual type which is electrically con-
`nected to the voltage reference 54. The variable volt-
`age control 100 may be a manually controlled adjust-
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`3,862,636
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`5
`able resistor, switch or the like. The circuitry of FIG.
`7 operates in the same manner as the circuitry illus-
`trated in FIG. 3 except that the control 100 is provided
`for manually controlling the amount of current in the
`defibrillator. The operation of the circuitry of FIG. 7 is
`as follows. The operator would initially determine the
`amount of energy to be delivered to the patient and
`would determine the approximate body weight of the
`patient. The variable voltage control 100 would then be
`manually adjusted in response to the approximate body
`weight of the patient. In the circuitry of FIG. 3, it was
`only necessary to determine the energy to be delivered
`to the patient since the current in the circuitry of FIG.
`3 is not variable but is fixed. The manual reset 32 starts
`the sequence by zeroing the output meter 38 and acti-
`vating the power supply 18 at a voltage which is depen-
`dent upon the energy selector 36. Thus, if it had been
`determined that it was desirable to deliver an impulse
`of 200 joules to the patient, the energy selector 36
`would be set at 200 joules. The energy derived from the
`power supply 18 is stored in the storage capacitors 22.
`The energy selector 36, which is manually set to the en-
`ergy desired, also feeds an input to the energy com-
`puter and control 34. the electrodes or paddles 14 and
`16 are then placed into contact with the patient and the
`manual switch 30, located on either or both of the pad-
`dles 14 and 16, is activated.
`When the manual switch 30 is activated, the energy
`computer and control 34 causes the stored energy
`source to be connected to the patient. The current
`monitor 28 and voltage monitor 26 feed instantaneous
`signals to the energy computer and control 34 which
`computes the energy as a continuous integration pro-
`cess. When the computer energy equals the selected
`energy, the energy computer and control 34 causes the
`energy source to be disconnected from the patient. The
`total energy delivered to the patient is indicated as a
`steady reading on the output meter 38.
`As previously stated, the voltage reference 54 is vari-
`able which results in the output of the voltage compara-
`tor 52 and charge logic 56 to result in a variable charge
`voltage on the energy storage capacitors 22 in FIG. 2.
`Since the amount of current is proportional to the volt-
`age. the desired current can be selected by manually
`selecting the reference voltage 54 by means of a suit-
`able variable voltage control which may be a switch or
`variable resistor.
`It
`is also possible to control the reference voltage
`with the energy selector 36 through a proper scaler
`such as seen in FIG. 8 so that as higher energy levels are
`selected, corresponding higher values of current are
`supplied automatically. FIG. 8 is identical to FIG. 7 ex-
`cept that a scaler 102 has been substituted for the vari-
`able voltage control and is electrically connected to the
`energy selector 36 in conventional fashion as seen in
`FIG. 8. Scaler 102 may comprise an amplifier having a
`gain of A which may be greater than or less than 1.
`Thus, the reference voltage 54 is controlled with the
`energy selector 36 through an amplifier or proper sca-
`ler so that as higher energy levels are selected, corre-
`sponding higher values of current are supplied auto-
`matically to the system.
`The circuitry illustrated in FIGS. 7 and 8 may be sub-
`stituted for the circuitry of FIG. 3 in the defibrillator so
`that the magnitude of current therein can be manually
`or automatically selected since there appears to be a
`correlation between the patient’s body weight and the
`
`6
`current—energy doses necessary to defibrillate a defi-
`brillating heart.
`Thus it can be seen that the defibrillator accom-
`plishes at least all of its stated objectives.
`We claim:
`I. A defibrillator comprising in combination,
`an electrical power source,
`a set of electrodes engageable with a patient.
`electrical circuit means connecting said power
`source to said set of electrodes
`comprising, a computer means, a storage capacitor
`means for storing energy derived from said
`power source, an energy selector means for se-
`lecting the energy to be delivered to the patient.
`said energy selector means also feeding an input
`to said computer means, a switch means for caus-
`ing the stored energy to be connected to the pa-
`tient, said switch means being operatively electri-
`cally connected to said computer means, a power
`monitor means for feeding signals to said com-
`puter means when said stored energy is delivered
`to the patient, said computer means computing
`the energy delivered to the patient and causing
`the delivery of energy to the patient to be discon-
`tinued when the computed energy substantially
`equals the selected energy,
`said electrical circuit means also comprising means
`for selecting the magnitube of current delivered to
`the patient in accordance with the body weight of
`the patient.
`2. The defibrillator of claim 1 wherein said electrical
`circuit means includes a variable reference voltage
`means electrically connected to said storage capacitor
`means for variably charging said storage capacitor
`means and wherein said means for selecting the magni-
`tude of current delivered to the patient comprises a
`second switch means electrically connected to said ref-
`erence voltage means, said second switch means com-
`prising a variable voltage control.
`3. The device of claim 1 wherein said electrical cir-
`cuit means includes a variable reference voltage means
`electrically connected to said storage capacitor means
`for variably charging said storage capacitor means and
`wherein said means for selecting the magnitude of cur-
`rent delivered to the patient comprises a variable resis-
`tor electrically connected to said reference voltage
`means for varying the voltage in said reference voltage
`means.
`4. The defibrillator of claim I wherein said electrical
`circuit means includes a variable reference voltage
`means electrically connected to said storage capacitor
`means for variably charging said storage capacitor
`means and wherein said means for selecting the magni-
`tude of current delivered to the patient comprises an
`automatic scaler means electrically connected to said
`energy selector means and said reference voltage
`means, said automatic scaler means automatically sup-
`plying higher values of current to said variable voltage
`reference means as higher energy levels are selected for
`delivery to the patient.
`5. The defibrillator of claim 4 wherein said scaler
`means comprises an amplifier having a predetermined
`gain so that higher values of current are supplied to said
`variable voltage reference means as higher energy val-
`ues are selected for delivery to the patient.
`=l<
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