3,782,389
`[111
`[191
`United States Patent
`
`
` Bell ' [45] Jan. 1, 1974
`
`
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`
`
`[54] COMPUTER CONTROLLED
`DEFIBRILLATOR
`‘
`.
`Inventor. Davtd Bell, Omaha, Nebr.
`[75]
`[73] Assignee: Health Technology Labs, Inc.,
`Omaha, Nebr.
`
`.
`.
`Jan. 20’ 1972
`[22] Flled'
`[21] Appl. No.: 219,455
`
`.
`
`"""""""
`
`[52] U S C!
`128/419 D 128/421 128/423
`'
`'
`’
`’ 324/1 11’
`Int Cl
`[51]
`A6ln 1/36
`.
`[58] Field of Search
`......... 128/419 D, 419 P,
`128/419 R, 420, 421, 422, 423; 324/111
`
`
`
`[56]
`
`-
`
`References Cited
`
`UNITED STATES PATENTS
`9/197l
`Jaros et a1 ....................... 128/419 D
`3.605.754
`
`12“957 Albert -----
`324/1“
`23171817
`6/1966 sz """"""""""""""""" 1281419 D
`3'258'013
`12/1959
`Brown ................................. 324/111
`2,919,408
`FOREIGN PATENTS OR APPLICATIONS
`l,076,286
`2/1960 Germany ________________________ 123/419 D
`
`Primary Examiner—William E. Kamm
`Attorney—Zarley, McKee & Thomte
`
`.
`
`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 (electric en—
`ergy) at a voltage which is dependent on the energy
`selector. The energy drlved- from the power supply IS
`stored in the storage capacrtors. 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 computer energy equals the selected
`energy, the computer causes the energy source to be
`disconnected from the patient. The total energy delivc
`ered to the patient is indicated as a steady reading on
`the UMP“t meter.
`'
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`4 Claims, 6 Drawing Figures
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`COMPUTER CONTROLLED DEFIBRILLATOR
`
`1 .
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`3,782,389
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`2
`FIG. 5 is a schematic view of more of the circuitry of
`the invention; and
`FIG. 6 is a schematic view of more of the electrical
`circuitry of the invention.
`The defibrillator of this invention is referred to gen-
`erally by the reference numeral 10' and comprises a
`portable housing 12 having a pair of electrodes or pad—
`dles 14 and 16 connected to the circuitry therein as will
`be described in more detail hereinafter. The electrodes
`or paddles l4 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 fibrilla-
`tion of the heart is stopped.
`The circuitry of the defibrillator is depicted in sche—
`matic form in FIG. 2 wherein the numeral 18 refers to
`a ”0 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 a voltage
`monitor means 26 and current monitor means 28. Man—
`ual switch 30 and reset switch 32 are connected to the
`energy computer and control means 34. Energy selec-
`tor 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.
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`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.
`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 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.
`This invention consists in the construction, arrange-
`ments, and combination of the various parts of the de-
`vice, whereby the objects contemplated are attained as
`hereinafter more fully set forth, specifically pointed out
`in the claims, and illustrated in the accompanying
`drawings, in which:
`FIG. 1 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.
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`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
`to a Time Out Comparator 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 con-
`nected 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 33 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 14 and
`16 are then placed into contact with the patient and the
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`manual switch 30, located on either or both of the pad-
`dles l4 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. TP3 transformer feeds
`a full wave bridge rectifier to generate plus and minus
`DC voltage. The transistor and zener diodes regulate
`the DC to :15 v. and are of conventional design. The
`second set of diodes leading to the coils of K1 and K2
`supply power to operate these relays. Contacts K3 op-
`erates coil K2. K2 operates the contacts on FIG. 5. K3
`is operated off of control circuit 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 l 10 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.
`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
`1 and 3 is proportional to the current in the load. The
`5 ohm, 100 watt resistor serves the dual function of
`current shunt and crowbar 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
`T1 and T2. These pulses turn on SCR 1 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 fires the small 2N5062 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 21, 22 and Z3
`form two DC differential amplifiers. These amplifiers 65
`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 ZS. These signals are fed to 40
`
`40
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`which together with Z4 form an analog multiplier. The
`output of ZS in mathematical terms is v(t) x i(l)/K.
`This signal is proportional to the power being deliv-
`ered to the load at any instant of time. ZS 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 pot 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 al-
`lows the energy delivered to be displayed on the meter.
`Comparator Z9 (46) performs a similar function to
`50 except it compares the pot 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 26, controls the charging of the capaci-
`tor bank. 26 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 K].
`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 comparator 56 and 50 and analog mem-
`ory 44 are turned on.
`The operation described causes the selected energy
`to be delivered regardless of the variable patient load
`resistance. The limits are zero resistance at the patient
`(which will occur if the paddles are touched together)
`or an open or high (over 100 ohm) patient resistance.
`In case of the low limit, all of the energy stored in the
`capacitors would be dissipated within the defibrillator.
`In the case of the high limit, the defibrillator would at-
`tempt to deliver the selected energy but would take too
`long and the time out input will terminate the discharge
`before the selected value is reached. The meter 38 will
`indicate to the operator that the energy that was se-
`lected was not delivered and the load was abnormal.
`Thus it can be seen that a novel defibrillator has been
`provided which insures that the energy delivered to the
`patient will be substantially equal to the selected en-
`ergy regardless of the variable patient load resistance.
`The circuitry of the defibrillator permits a light weight
`and portable defibrillator to be provided so that the de—
`fibrillator can be easily transported to the patient. In
`summary, it can be seen that the defibrillator provides
`the following:
`I. Pro-selection of the energy to be delivered;
`2. Automatic Energy Control to deliver the energy
`selected independently of load; and
`3. Verification by computation of energy delivered
`and indication on an output meter.
`Thus it can be seen that the defibrillator accom-
`plishes at least all of its stated objectives.
`I claim;
`1. A defibrillator comprising in combination,
`an electrical power source,
`a set of electrodes engageable with a patient,
`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 selecting the energy to be delivered to the pa-
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`a set of electrodes engageable with a patient,
`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 selecting the energy desired to be delivered to
`the patient, a switch means for causing the stored
`energy to be connected to the patient, said switch
`means being operatively electrically connected to
`said computer means, a power monitor means for
`feeding signals to said computer means when said
`stored energy is delivered to the patient, said cir-
`cuit means having a viSual output means for indi-
`cating the energy delievered to the patient, said
`computer means computing the energy actually de-
`livered to the patient and causing said visual output
`means to indicate the energy actually delivered to
`the patient.
`
`*
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`3k
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`3,782,389
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`tient, said energy selector also feeding an input to
`said computer means, a switch means for causing
`the stored energy to be connected to the patient,
`said switch means being operatively electrically
`connected to said computer means, a power moni-
`tor means for feeding signals to said computer
`means when said stored energy isdelivered to the
`patient, said computer means computing the en-
`ergy delivered to the patient and causing the deliv-
`ery of energy to the patient to be discontinued
`when the computed energy substantially equals the
`selected energy.
`2. The combination of, claim 1 wherein said power
`monitor means comprises a voltage monitor means and
`a current monitor means.
`3. The combination of claim 1 wherein said circuit
`means has a visual output meter which indicates the en—
`ergy delivered to the patient.
`4. A defibrillator comprising in combination,
`an electrical power source,
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