US2438875A - Electrical treatment apparatus and method of control - Google Patents

Description

March 30, 1948. OFFNER 2,438,875

ELECTRICAL TREATMENT APPARATUS AND METHOD OF CONTROL Filed Nov. 27, 1941 T0 ALI. HEATER) 3 patient presents to the testing current is the same as that presented to the treatment current. Then it is clear that if E'lest bears a constant functional relationship to Ema, ITest will have the same functional relationship to I'Ireat; that is, the ratio of ITest to ITreat will equal the ratio of EI'est to E'Ireat for all values of voltage and patient resistance.

It is convenient to make the relationship of Emu to ETreat as nearly linear as practicable; that is, so that the variation in the power supplied by control device 2 will vary both ETest treatment of mental diseases that the resistance measured with a low value of current was not the effective resistance during treatment. No explanation of this was given, and, in fact, the opinion of experts in the art was that it was impossible to predict the effective value of patient resistance to the treatment current. Applicant A small deviation from linearity will, ingeneral,

give slight and insignificant changes in' the results. Y

A simple illustration of the above principle is ment voltage is applied apparently 1s due to the change in the polarizable nature of the tissues illustrated in Fig. 2. Here the power is derivedfrom an alternating current supply, and a variable autotransformer is therefore used at 2. 3 and A are replaced by a tapped transformer ll. I-Iere the treatment voltage is supplied by the full secondary of II; thatis, the voltage between points [2 and I3. The testing current, on the other hand, is supplied by the voltage between l2 and the secondary tap l4; thus supplying a smaller alternating current voltage for testing.-- Meter 8 is now an alternating current milliammeter I 5; meter I6 in place of meter I0 is a similar meter, but of higher range. The switches! and 9 are replaced by a double throw switch 11. when this is thrown to contact l8, the' testing circuit is connected to the electrodes 5 andB and when at [9, the treatment circuit is connected to the electrodes.

Adjustable resistors and 2| are introduced respectively into the testing and treatment circuits. The relative values of these are adjustedso thatthe total internal resistance in the two' circuits is as nearly identical as possible. These resistors also have another function; by introducing the resistor 2| intothe treatment circuit, and having said resistor large as compared with the effective patient resistance which will be inserte d between electrodes 5 and 6, the effect of small variations in said patient resistance is minimized. 7

Because of the linear relationship between the test and treat voltages, the treatment current will always bear the same relationship to the test current. The test current meter may, therefore, be calibrated not in terms of the actual test current flowing, but rather in terms of the treatment current which will flow. That is, it will be calibrated to read Treat Tc-t X 1TB Then when the switch I! is turned to point I8 for testing, the variable transformer 2 may be adjusted until meter l5 reads the desired value of treatment current. Throwing switch I? to l9 then will apply this actual treatment current through the electrodes. Thus, it is seen that the. voltage is adjusted to the proper'value as would be determined by application of Ohms law, but no actual calculation is necessary. This is taken care of automatically by the construction of the apparatus.

The use of the apparatus of Fig. 2 assumes that the resistance of the patient to the power line frequency is the same for the testing current as for the treatment current. It was, however, discovered early in the art of electric shockhas, however, discovered a means for predicting the effective rsistance of the patient to the treat ment current before application of said current. This then allows the voltage to be set to the proper value to give the desired value of treat- ;1 nent current. V

-; .;Applicant has discovered that the apparent changein the patients resistance when the treatthrough which the current flows. Referring to Fig. 3, the normal tissue may be considered roughly equivalent to a condenser 22, shunted by a resistor 23, the whole being in series with another resistor 24. The two terminals 25 and 26 represent the points of application of therelectrodes with which these electrical characteristics are measured. For low frequencies such as cycles per second, and for low intensities of current, the effective reactance of 22 is large, as is the resistance 23, as compared with the'resistance 24. Representative values would be 22 equals /2 microfarad, or approximately 5200 ohms reactance. .Resistance 23 equals'approximately 1000 ohms. Resistance 24 equals approximately 120 ohms.

It will thus be seen that at frequencies of the order of 60 cycles, almost all the voltage drop is a result of the parallel combination of 22 and 23. rent is applied, this excites the tissue under the electrodes, and results in a substantially complete short circuit of condenser 22.. This may be -represented as resistor 23 falling to a ,very low value, approximately 80 ohms'.. Thus resistance-24 is most effective in limiting the value of the treatment current, while resistance 23 also has some effect.

Applicant has also discovered a method of predicting the change. This is accomplished by measuring the resistance not with the low frequency current to be used in treatment, but rather with a relatively high frequency current; If the frequency is high enough, it will evidently go through condenser 22 almost unimpeded, and the effective resistance measured would be that of resistor 24 alone. .If' a somewhat lower frequency is used, condenser 22 will stillpresent some'reactance, and the frequency may beiad- .l'usted so that the'effective impedance is that presented during treatment; that is, the impedance of 22 and 23 in parallel should add approximately ohms to the total impedance presented between terminals 25 and 26. This is accomplished by'using a frequency of approximately 7000'cycles per second for the testing current. The frequency used is, however, not at all critical, especially in the circuit used in which a resistor is placed in series with the patient, similar to resistance 2| of Fig. 2. This is described in greater detail below.

This principle of using a high frequencycurirent for testing the patients resistance could be employed by using ordinary resistance measurements for determination of this high frequency resistance, subsequentlyv adjusting the treatment voltage, as determined byzapplication of Ohms law. However, a more convenient methodisf the- I-Iowever; when the intense treatment curaccuse-u applicatior-r of a-- circuit simi-lan to th-at ofFig; 1.

To employ thisprinciple with thiscircuit thus eliminate the-needlor-calcrflationa devices may consist; of an" oscillator-generating the desired frequency for-testingzas above-stated; ap-

proximately 7000' cycles per second-:- Thevoltage supply of; thisoscillator-is derived fromvoltage control-device Z=-so-- that voltage-at the: test frequency isproportionahtothewoltage supplied Device -4 k may then be a transformer to change the powerinput voltage *to the desired voltage. A-meter capable -of=-respondingta highfrequencytest currents of smal-l amplitude is used at 8, whereas-anordinary A .-C'. ammeter or mil liammeter-may beused-at I 0 As described above; the internal; resistance of; the-test and: treat circuits must be adjusted-to equality. Thismay beaccomplished by having resistors in devices 3 and 4* for makingsuch adjustment; this is-explained in greater: detail below. Meter 'S may again be calibrated to read} thetreatment current directly so that--in-use the electrodes-S and 6* may he placed on the patientandcontrol-2' adjusted so-thatwith- F closed-"8 Willread the desired treatmentcurrent; on opening l" and closing 9,; the treatment current Wi-lPthflnflow ou hthe a en The wiring diagram of a complete instrument A yoltmeten 4t isconnecteditbaiead the volte age existing across th treatmentizelectrodes; it.

maybe used'to register the value of the applied potential;

employing the principles describedaboveis shown in Fig. i. Thisiillustrates aninstrument for providing known current-oi the power line frequency, for known intervals oftim through thepatient. The power line current, as for example 115 volts sixty cycle alternatingcurrent, is suppliedat the terminals 21,18." The control device 2' of Fig. 1 is here a-variableautotransformeriil.

Thissllpplies a, variable voltage to the primaryof transiiormer 31; The secondary 3 2 of i this transformer supplies the power for-thetreatment of the patient. v The power-for the testingcircuit is also derived from thesecondary of this transformer. This is a somewhat different-arrangement than that shown inFig; l, thepowenbein taken fromrthe secondary forthepurposes ofutilizing the electrical isolating-propertiesof transformer 3|. Following thepa-thof the treatment current, it is seen that-saidicurrentnext flows milliarnmeter 38 thence through one set of con tacts 39a, of the test switch 39 which will bein1 the out position; and thence to one treatment. electrode all:

ground to the lower side of the secondaryltz of transformer-3 I.

Overload relay having co-il and contacts .18;

Thereturn circuit is through. ground u passing from= electrode- 41; through.

A power supply unit? fi' suppliese directscurrent power for operation ofthe timer circuit: and: or; the test meter circuit; ltrconsistsx 0f='trans0rmer 46 having primary 41 connected acrossathe power:

line, a-center-tapped voltage winding. 48';

a rectifier filament: winding 49; and& a: heater current winding 50 for operating the; heaters of all other vacuum tubesdn the i. apparatus; Therectifier 5| rectifies the high voltageanda condenser 'iz smooths the csci liationsimthis voltage.

Resistor 53 which i is shunted? across the power supply allows theselectionof proper-voltages for a timer tube 54;

Theoperationof the timeeisias-ifollowsz the. coil 34' of the timerrelay isintheepl'ate circuit of vacuum'tube" 54;- Thecathode circuit. is; rea turned to a point onmesistor -53- su fficiently posia tive that no plate current normally flows-.thrOugh coil 34'; Variable resistorqlifi whi-chis constructed of i a switch selecting alnumber or fixedzresistors,

isconnected betweerrthe grid .,of'5.4'sv andiground,

the latter being alsothermostclnegative pointzrloi testing; switch. 359: is

power supply 45: pushed in, and): contact 39b connects; condenser 56 to theglpositive side O r-power; supply 451 When switch 39 is:released',i condensers5fiire mains charged: to this voltage; When treatment switch 36 is closed; condenser-s 55115 connected.

through contacts iifib to the-gridfofri54,bringing the latter to alpositive-glpotential, andzallowing platecurrent to now through coil134l; Thiszrew sults in the contacts-1331 closing; andvthusiclosesl the: treatment tcircuit. Condenser 56'. almostin stantane ously adischarges'througlr thejgridrcircuit of 54 to apointzwhere its; voltage is equalto:

the cathode voltage.- of 54".: It subsequently 'dis charges more slowly throughlresistor 55, andieventually the grid potential .oi"54ibecomessoclow that the plate current is insufficient to energize the.

coil 34 and hold. contactsn33scloseda; They will then open, terminating;the;flowoil-treatment current. It will be seen thata greatrrange Qf'tirnes maybe achievedtbyr varying the resistanceof; 55.

It will also beseen that the opening of switch 36 will terminate the treatment imt-womanners: first, by causing-thetimer relayr to open'pthrough.

the opening ofcontacts, 36b; and secondly, by

opening-" the. treatment currenti directly; by the opening of the contactsof 350;. Thus; dual, con-- trol is had over-the flow ofthe atreatmentccurrent, and if for any: reasonatheitimer did not;

terminate the treatment; at r the desired :time, ,it may be immediately terminated: by release of. switch 36; This prevents an overly'longrtreata ment which might occur if, for. example thecontacts of relay 33should, stick togethen;

Anothersafety feature is that: when icontacts 3611 are in the out position, theoutput o-f-the treatment circuit is short-circuited:v If" thl'lfor any reason the timer circuit "should stay closed, withouthaving the: treatment switchwpushed in; and autotransformer 29 should'b'e advanced to the point where appreciable voltageis developed by transformer 3|, a large current will-flow. through coil 35 of the overload-relay; causing-it m open the circuit. This then-preventsth'e instrument from being-used when the timer-circuit 15511101331'3- tive.

The, testing circuit 51 consistsofi oscillator tube 58, transformer 59'; which has" a: tapped primary 60; and secondary 61*; a plate block conde'nser 6'2;

" oscillatory 'circuitcondenser 63, grid leak 64, and

condenser 65 and shunt feed. resistor 66. It will be seen that this is the familiar Hartley'oscillator circuit, with the frequency approximately determined by the inductance of primary 60; and condenser 63. For the present purposes this is best adjusted to, approximately 7000 cycles per second. The secondary iii of the transformer '59 is loaded by means of resistance 61; the purpose of this is to make this circuit have an almost pure resistive impedance, so that the resistance of the test and treat circuits may be equalized, as mentioned previously. As th plate voltage of 58 is supplied through resistor'66 from the secondary 32 of treatment transformer 3|, said plate voltage will be nearly proportional to said treatment voltage. Likewise, the voltage appearing at the terminals of secondary 9| will alsobe cl sely proportional to the voltage of said treatment transformer- Thus the linear relationship between testing voltag and treatment voltage is preserved, as required.

Resistance 68 isinserted in series with the testing voltage in order to maketthe resistance of the testing circuit equal to that of the treatment circuit. It thus is similar in function to resistance 31 of the treatment circuit and will usually be of almost the same magnitude. Resistance 68 performs another function: it provides a source of voltage drop proportional to the testing current. Said voltage drop is measured by a Vacuum tube microammeter, to be described below, thus giving the magnitude of the testing current.

The path of the testing current is as follows: when switch 39 is depressed thetesting voltage is induced in secondary 6! of transformer 59 by oscillator 51. The voltage developed across resistance 61 causes a current to flow through the contacts 39a of switch 39; thence to patient electrode 49, through the patient, through electrode Al thence to ground; thence through resistance 68 and thence back to the'secondary 6! of transformer 59.

The Vacuum tube microammeter 69 consists. of vacuum tube 19, a combination diode and triode. The bias voltage for said triode is furnished by cathode resistor H, which is" bypassed by condenser 12, The plate voltage for said triode is supplied through plate coupling resistor 13 from the positive side of power supply 45. It will be seen that the triode unit of IO thus amplifies the voltage appearing across resistor 68, due to the passage of the current, and, said amplified voltage appears across resistor 13, This voltage is coupled into the diode circuit by means of condenser i l, The diode circuit consists of fixed resistor 15 and variable resistor 15 in series with D. C. microammeter '11; all being acrossthe cathode and diode plates of iii. The alternating current voltage induced in this circuit through condenser 14 causes a rectified current to flow through the diode circuit, giving a reading o microammeter i? closely proportional to the amplitude of said alternating current, Vacuum tube microammeter 69 is calibrated so that its reading for a given testing current will correspond to the desired value of treatment current. This is accomplished in thefollowingmanner: electrodes) and ll may be short-circuited, or a resistance of the order of magnitude of the patients resistance may be placed between said electrodes. In either case, the testing switch 39a is momentarily depressed, in order to set the timer. Sufficient resistance is introduced by resistance 55 into the timer circuit so that the timer will remain closed fora considerable length of time; for example, 10 seconds. depressed causing treatment current to flow. Its magnitude is noted on milliammeter 38, and variable transformer 29 is advanced until this current is of some desired value; for example, 500 milliamperes. Test switch 39 is now depressed, and assuming that the scale of microammeter T! has been calibrated to read the treatment current directly, resistance 18 is adjusted until microammeter i1 registers the same current as was registered on milliamrneter39. Now in use it is only necessary to first press the test switch 39; adjust transformer 29 until microammeter 11 reads the desiredcurrent; then depress switch 36, whereupon the desired treatment current will be giventhe patient. Thelength of the treatment is, of course, controlled by the timer; this is started when the treatment switch 36 is depressed, and interrupts the current after the interval pre-set by means of resistance 55.

Resistance 31, which is in the treatment circuit, is variable and is, adjusted in the following manner: electrodes 49 and M are short-circuited, testing switch 39 depressed, and the variable transformer 29 adjusted so that some given reading is registered on microammeter 11. The treatment switch is now depressed, with testing switch having been released, and the treatment current read on milliammeter 39. The treat switch 36 is now released, and a resistance introduced between electrodes 49 and 4|. This resistance may be of the order of magnitude of the patients resistance. The above procedure is again carried out, the microammeter 'l'i being brought to the same reading as before by adjusting 29, and the reading of 38 is again noted. When the adjustment of resistance 37 is correct, this will be the same as before. If it reads more than before, this indicates that resistance-31 is of too high a value, and should be reduced; and vice-versa.

It will be seen that when testing switch 39 is depressed, the treatment circuit is interrupted by the opening of o-ut contacts 39a, This prevents a simultaneous-application of the testing and treatment currents, which might not only be injurious to the patient but to the instrument as well. 7

As before described, it is necessary to press the test switch 39 to charge the condenser 56 in order to make the timer operative. This thus insures that the test reading will be made before the treatment is given, and is a safety feature of the instrument.

In the specification, the principles of the invention have been described as applied to a medical therapeutic device, and it has been especially used in the production of convulsive shock in the treatment of mental disorders. It has been particularly useful in this field because of the very close control of the treatment current which it provides. However, these principles can beapplied in other fields, and especially wherever it is necessary to set a current to the desired Value before the application of the full strength of current; and 7 also wherever the electrical characteristics of the medium through which the current isto .be appliedapproaches those described above as being the characteristics of living tissue The invention is, therefore, not limited to the particular uses and embodiments described for the purpose of illustration, but is of broad scope as defined by the following claims. 1

The term circuitfas used'herein is intended Treatment switch 39 is now 9 to denote a conductive part or a system of conducting parts through which current is intended to flow.

I claim: 1. The method of preselecting the magnitude of a low frequency treatment current which comprises passing through a subject to be treated a test current having a frequency of the order of 7000 cycles, measuring the effective impedance of the subject to the test current and ad-' justing the test circuit and treatment circuit simultaneously and proportionately to a value of the test current having a predetermined relationship to the desired value of the treating current.

2. The method of preselecting the magnitude of a low frequency treatment current which comprises passing through a subject to be treated a test current having a frequency not materially less than about 7000 cycles, measuring the effective impedance of the subject to the test current and adjusting the test circuit and treatment circuit simultaneously and proportionately to a value of the test current having a predetermined relationship to the desired value of the treating current.

3. In electrical treatment apparatus, a low frequency current source, current supply adjusting means connected to said low frequency current source, current applying electrodes, means including a current measuring device and a timing means connecting said current supply adjusting means to said electrodes, means connected to said current supply adjusting means for converting the low frequency current to high frequency current, means including a second current measuring device for connecting said current converting means to said electrodes independently of the low frequency current connecting means, and variable impedance elements for calibrating said second current measuring device in terms of the low frequency current indication of said first current measuring device.

4. In an electrical treatment apparatus as defined in claim 3, means in one of said (low frequency and high frequency) current connecting means for adjustment of the internal impedance of said low frequency and high frequency current connecting means to the same value.

5. In an electrical treatment apparatus as defined in claim 3, an impedance in said low frequency current connecting means having a higher value than the value of the impedance of the subject under treatment, whereby the effect of small changes in the resistance of the subject is decreased.

6. In an electrical treatment apparatus as defined in claim 3, said means for converting the low frequency current to high frequency current including a vacuum tube oscillator circuit.

7. In an electrical treatment apparatus as defined in claim 3, said second current measuring device including an impedance in said high frequency current connecting means, an electron tube amplifier for amplifying the voltage developed across said impedance, and means for measuring the intensity of said amplified voltage.

FRANKLIN OFFNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,761,476 Hathaway June 3, 1930 Re. 15,469 Heising Oct. 17, 1922 1,667,451 Arnberg Apr. 24, 1928 1,820,242 Neimann et al. Aug. 25, 1931 2,111,135 Bagno 'Mar. 15, 1938 2,184,511 Bagno Dec. 26, 1939 2,311,935 Dobert Feb. 23, 1943 FOREIGN PATENTS Number Country Date 574,433 France Mar. 29, 1924 554,559 Germany July 11, 1932 157,009 Austria Sept. 25, 1939 158,595 Austria Apr. 25, 1940 239,085 Germany Oct. 7, 1911 OTHER REFERENCES An Electronic Interrupter, by I James H. Hanly, published in Electronics for November 1935.

Marton, superfluous Hair, from Medical Record for February 19, 1936, page 153.

Kovacs, Electrotherapy and Light Therapy, 2nd edition, 1935, pages 149 and 150.

Electric-Convulsion Therapy in Schizophrenia, by Lothar Kalinowsky, M. D., pp. 3-8 (reprinted from Dec. 9, 1939, issue of The Lancet, p. 1232).

Cerletti et al., Bull, Acad. Med. Rome, May 1938, pp. 266-68.

Cole 8: Curtis, J. Gen. Physiol (1939), vol. 22; pages 37-64.

Images