US2493301A

US2493301A - Electric blood pressure diagnostic device

Info

Publication number: US2493301A
Application number: US587136A
Authority: US
Inventors: Walter J Loria; Suhre Jerome
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-04-07
Filing date: 1945-04-07
Publication date: 1950-01-03
Anticipated expiration: 1967-01-03
Also published as: GB636458A; FR925049A

Description

Jan. 3, 1950 w. J. LoRlA ETAL ELECTRIC BLOOD PRESSURE DIAGNOSTIC DEVICE Filed April 7, 1945 4 Sheets-Sheet 1 N .m me Mx, Y L u No MJA@ u O .E nu N @M r Il l! 1 o T me A wm iA m Jan. 3, 1950 w. J. LoRlA Erm. 2,493,301

ELECTRIC LooD PRESSURE DIAGNOSTIC DEVICE Filed April 7, 1945 4 Sheets-Sheet 2 IN V EN TOR` WALTER .5. L oRmv- EROME UHRE' ATTORNEY I Jan. 3, 1950 w. J. LoRlA r-:rAL

ELECTRIC BLOOD PRESSURE DIAGNOSTIC DEVICE Filed April 7, 1945 4 Sheets-Sheet 3 IN V EN TORS WALTER. I. \-OPJA Y E M WQ.

Jan. 3, 1950 w. J. LoRlA Erm.

ELECTRIG BLOOD PRESSURE DIAGNOSTIC DEVICE Filed April v, 1945 4 Sheets-Sheet 4 RIM! cou. (A)

B Puse INVENTORS WALTERJ. Louw ,ERQME QNHRE BY. ATTQQNEY Patented Jan. 3, 1950 ELECTRIC BLOGD PRESSURE DIAGNOSTIC DEVICE Walter J. Loria, New York, and Jerome Suhre, Richmond, N. Y.

Application April 7, 1945, Serial No. 587,136

This invention generally relates to devices adapted to indicate speciiied characteristics of the flow of a fluid through a conduit and is more particularly concerned with an electronic device of this nature which will indicate the nature, volume, change in volume or the pulsating ow or any combination of these, of a uid through a flexible conduit, for example, for medical diagnosis.

In the diagnosis and treatment lof a great variety of diseases of humans, and also in routine health examinations thereof. the arterial blood pressure of the patient is of vital interest to the examining physician or like technician, and also the rate of pulse beat often is desired.

The arterial pressure in the larger arteries of the patient shows marked variations with the heart beat, the pressure during the beat of the heart, known as systolic pressure, being of a much higher level than the diastolic pressure Heretofore, it has been usual for the examining physician to utilize for the identiiication of the arterial blood pressure of a patient, the application of pressure upon an artery (for example, the brachial artery), by surrounding a limb of the patient with a Vpressure bag which can be inated by air pressure to a measured amount and thereafter the pressure is slowly released by a bleed valve, for example, during which time the physician notes through his stethoscope, the changes in ow of blood through the artery' as it commences to ilow again after it has been cut off by the tourniquet eiect of the pressure bag. By visually noting the pressures as registered for instance on a manometer, at specified points dened by his aural reactions through the stethoscope, the physician is able to identify the specific systolic and diastolic pressures for the patient under examination. Such a device is known as a sphygmomanometer.

It is recognized that such a device, while generally satisfactory, depends much upon the individual skill of the examining physician and also has many obvious disadvantages including the use of cumbersome equipment, the necessity for the physicians hands to be fully occupied in the obtaining of results, and non-sensitivity of the pressure indicating means.

Furthermore, such a device as heretofore used. does not permit the indicating of pulse rate, and

11 Claims. (Cl. 1282.05)

` present invention to improve over existing devices for medical diagnosis relating to conditions of blood pressure in the human system and provide a device, adaptable for the purposes above indicated, as well as for equivalent purposes, which is sensitive, accurate, simple to operate, easy to read,

and can be manipulated by the examining technician with greater freedom.

More specically, the present invention provides a sphygmomanometer which is extremely and accurately sensitive to the changes of arterial blood pressure and which is simple in operation.

A further object of the invention is to provide an oscillometer which is more sensitive, accurate and easy to utilize than the oscillometers heretofore used.

Furthermore, the invention provides means for visually indicating the pulse rate of a patient without tactile operation by the examining technician.

Objects and advantages of theinvention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

According to the invention there is provided a light-sensitive means which is rendered operative to indicate changes in pressure when the usual pressure bag heretofore described is slowly deflated by a bleed valve or the like, such changes being translated by electronic means to simultaneously indicate the pressure applied by the 3 pressure bag at all times, and the pulse amplitude of the patient. When the device is used as an cscillometer, these are the desired readings, since the pressure bag is placed on various parts of the human body and the amplitudes at these various parts are compared for diagnosis.

In the use of the device as sphygmomanometer, the blood pressure reading is given as first systolic and then diastolic in the conventional and desired order.

Preferably, in each use of the device given above, the pulse rate is simultaneously indicated on a separate indicator such as a suitable meter.

In carrying out the invention, there is provided a first suitable source of constant illumination which is adapted to impinge upon a first photoelectric tube, the amount of light transmitted being varied, and following the indications of a ilrst aneroid capsule which is directly iniluenced through a ilexible conduit by the air pressure exerted on the patient by virtue of the conventional pressure bag which is wrapped around the patients arm, leg or the like and inilated by suitable means such as a conventional bulb. Thus the pressure applied may-be recorded on a suitable meter through an amplifying electronic circuit from the first photiectric tube and as the pressure is released, utilizing for example a bleed valve on the iniiating bulb or the ilexible conduit which is connected with the bladder or like inilatable part of the pressure bag. Any desired amplication of the electric current caused to ilow from the photoelectric tube by virtue of the light variations impinging thereon, may be employed to give a desired sensitivity and, if desired, two or three scale readings may be obtained on the meter by shunts or the like, operable to give varied ranges of indicated pressure, as well as accurate readings. The variations of light may be suitably obtained by an opaque shield on the moving vane mounted to move with the vane of the aneroid capsule past a fixed aperture and weighted or damped to avoid oscillations` due to varied pressures.

The recording of pulse amplitude is obtained by mounting a second apertured shield, to the moving vane of the aneroid capsule, aforesaid, and by mounting it to move past its own nxed aperture and parallel with the moving vane of the second aneroid capsule, upon which is mounted a single opaque shield and undamped, so that light will pass through the opening of the apertured shield and iixed aperture in constant quantities at all times, unless interrupted by the movement of the second undamped shield, which readily responds to the iluctuations of pulse amplitudes which will commence when the applied pressure of the pressure bag has become reduced enough to permit flow of blood through the artery. thus in eiect opening and closing the aperture to a degree proportional to the pulse amplitude thereby permitting light to pass through the aperture, in direct proportion to the puise amplitude. f

A second source of illumination coacts with a second photoelectric tube through the second apertured shield and iixed aperture whereby the iluctuations of the blood pressure may be indicated on a second suitable meter, such as an ammeter, electronic ampliiication being utilized to obtain a sensitive reading thereon.

When used as an oscillometer, the indication read upon the second meter will be comparable with readings taken with respect to other parts `4 ofthebody,andtherelativeonthe first meter will be noted for such readings.

Whenusedasasphygmomanometerthereadingonthesecondmeterwillbefirstasmall indication on the dial showing the systolic beat at whichtimethepressureontheilrstmeterwill be noted, and thereafter a much larger indie tiononthesecondmeterwillshowthediastolic beat at which time the pressure on the ilrst meterwillagainbetakemthisspeciicchange of indication on the iirst meter being equivalent to the aural change noted by the physician when using a stethoscope.

Whenitisdesiredtoincorporateapulserate indicator into this device, an additional electronic amplifying circuit is cut into the circuit controlled by thesecondphotoelectriciaibeandis operated therefrom through a relay to give unidirectional surges of pressure during the systolic and diastolic indications on the second meter, whereby by suitablecalibration, the direct pulse rate may beshown on a third meter such as an ammeter controlled by the relay. Preferably, the operating current to the third meter is damped, as by a resistance-capacitator coupling, to give a noniluctuating reading thereon.

Obviously, the second and third meters meiltioned may have two or more scales with suitable meanstopermitreadingonadesiredscale, deiined with respect to the ilrst meter.

The circuit with respect to the second meter, indicating the changes in ilow, may be of variable sensitivity as by a potentiometer control on an amplifying tube whereby the physician may selectadesh'edsensitivityeasilyandreadilyto assist his speciiic -Itwillbereadiiyseentbatthedeviceberein provided has many advantages over prior de vicesforthesamepurpe.andthatthedevioe is not only more accurate, sensitive and my to use,butalsoitreadilyformsaneasytoread, compact instrument.

Furthermore, in practice, the reading on the second meter will vary only with the amplitude ofthepulsebeatandnotwiththeappliedlxessure,andthereadingonthenrstmeterwillbe controlled only by the applied pressure and will notrespondtothepulsebeat. Thereisthus provided an instrument which indicates the instantaneous value of the applied pressure which acts simultaneously with the pulse amplitude, thereby enabling the physician to measure systolicpressurewbichisthepressureatwhichthe pulserstappearsonthesecondmeterandtbe diastolicprsm'ewhichisthepressureatwhich thepulseamplitudeisatitspeakonthesecond meter, whereby to provide the physician with an instrument which may be used with comparative precisiontoascertainthebloodpressureinthe arteries of man.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate embodiments of the invention, and together with thedescriptiomservetoexplaintheprinciples of the invention.

Figure 1 is a plan view of one en. i of the device according to the present invention;

Figlue2isasideelevation,withcertainparts in section, on the line 2 2 of Figure 1;

Iiiglu'e3isasectionontheline3-3of1igure 1;

Figure4isasectionontheline4-4ofFigure3;

Flgure5isaplanviewofadetailof1ligurel comprisingthe light intercepting vanes for the light sensitive means; and

Figure 6 is a diagrammatic wiring diagram of the electric elements used in the apparatus of Figure 1.

Referring now to the drawings, the elements comprising our instrument may be arranged in the portable casing I0. 4Secured in one wall I2 thereof there is provided a conventional electric current meter or ammeter I4 which is calibrated to indicate'pressure, a second electric current meter or ammeter I6 which visually indicates fluctuations and pulse amplitude and which may be calibrated in units corresponding to pressure in centimeters of water or simply in units of arbitrary value, and a third electric current meter or ammeter I8 which is calibrated to indicate pulse rate in beats per second, these meters being hereinafter defined as to their functions. Thus, meter I4 may be termed an applied pressure indicator and meter I6 a pressure pulsation 1ndicator.

Secured to the sidewall I2 as by means of the .brackets and 22, there is provided a high frequency generator 38, to be hereinafter described,

adapted to energize light sources in the form of

light bulbs

24 and 30. Bulb 24 has a condensing lens 25 adapted to converge light on pohtoelectric tube 21 which is of a conventional type, lens 25 being mounted in a housing 26.

As will be described, the light from bulb 24 directed on the photoelectrc tube 21 is varied with the uctuations of pressure of the blood of that portion of the body to which the instrument is applied, and so generates electric impulses which rise and fall to visually indicate the presthrough the branch 50 into the second aneroid capsule 42 causing the vane 62 thereof to deflect.

Interposed between the

vanes

52 and 48 and secured to a supporting bracket 54 aillxed to the housing I0 by the set screws 56 is a stationary opaque curtain member 58 having a curvilinear aperture or opening 66 through which rays of light may be directed on to the photoelectrc tube 21.

Vane 52 is provided with a shield 62 which is of such size that it will completely cover the opening 60 throughout its oscillatory radial travel about the center 63 (Figure 3) under the influence of air pressure in the aneroid capsule 42, from its normal or zero position to its fully deected position, when the capsule 42 is under a predetermined maximum pressure.

The shield 62 is provided with an aperture 64 which permits the passage of light from the lamp 24 through the opening 60 onto the tube 21.

As the vane 52 moves under influence of pressure, at all positions reached by it in its travel, the window or opening 64 permits a, constant quantity of light to pass through the opening 60 which is preferably curved to correspond to the path of travel of the shield 62.

Thus, when the light impinging on the tube 21 from lamp 24 is not intercepted, the meter I6 to whichit is connected, as hereinafter described, will indicate the presence of an electric current which does not vary by reason of any effect of ence of the pulse beat. The tube 21, as will be 1 described, is connected through a suitably amplifying circuit to the meter I6 which therefore will indicate even the slightest changes in pulse amplitude and greatly magnify it.

Secured to the condensing lens housing 26 as by the bracket 28 is the second lamp 30 arranged in the shaded compartment 32, the light from lamp 3|! being directed against a photoelectrc tube 34, which, as will hereinafter be brought out, generates electric impulses which are proportional to the applied pressure. The photoelectric tube 34 is connected through a suitable circuit to the meter I4 to indicate pressure applied as by means of a pressure bag.

The light focused on the tube 34 is varied in direct proportion to the change in applied pressure so that the impulse generated by the tube 34 willbe varied by a very slight change in applied pressure and said generated impulse can be greatly amplified, so that the meter I4 will disclose even a very minute change in pressure.

Suitably mounted within the casing' I0 are a pair of

aneroid capsules

40 and 42 which are connected to a flexible tube 44.

When the device is used either as a sphygmomanometer or an oscillometer, this tube 44 is connected to the conventional inflation system utilized for such purposes, comprising a bulb, valve, bladder and cloth sleeve (all not shown).

To ascertain the blood pressure at the systole and diastole of the heart, the cloth sleeve, containing the bladder, is wound around a limb, for example the upper arm at the brachial artery, and the bladder iniiated with air by means of the bulb to a level beyond the patients systolic pressure, which is determined as described hereinafter. This air pressure is transmitted through the branch 46 into the first aneroid capsule 40 causing the vane 48 thereof lto deflect, and

the tube 21. When the air pressure of the pressure means is reduced however, and thus the pres.. sure in

conduits

46 and 50 is reduced, vane 48 and its appended opaque shield 65 will periodically intecept the light rays by, in effect, partially closing and opening the aperture 64 to a degree varying with the amplitude of the pulse beat at the systolic and diastolic pressure, and at blood pressures between systolic and diastolic and above and below systolic and diastolic, to produce corresponding variations in current flow through tube 21 and thereby indicate by such variations on meter I6, pulse amplitude at diilerent values of applied pressure.

In order to indicate concurrently the applied pressure, there is secured to the vane 52, a second shield 66 which intercepts light from the lamp 30 directed at the photoelectrc tube 34. This tube 34 is connected to the meter I4 by means of an amplifying circuit, to be described hereinafter. To damp out the variations in blood pressure that would be imparted to the vane 52 in the same manner as they are imparted to vane- 48 by the pulse of the blood, a weight is applied to the end of vane 52 so that it will be too heavy to respond to the fluctuation of the pulse but will be deflected by applied pressure to assume the position that is dependent on and corresponds to the applied pressure.

As indicated in Fig-3, normally, that is, in the absence of applied pressure, the shield 66 intercepts all of the light from the lamp 30 so that the photocell 34 is de-energized. As pressure is applied to the capsule 42, vane 52 rotates in a counterclockwise direction gradually to uncover photocell 34v and permit passage thereto of a beam of light of an area proportional to the applied pressure, so that readings on the meter I4 may be calibrated into pressure readings (such as mm. of mercury).

Since vane 48 is unweighted and comparatively Y light, it will respond not only to the applied pressure, namely it will move parallel to movements 76 of vane 52, but it will also fluctuate with the pulse pressure and thus beats.

I'he capsules

48 and 42 are initially ad- Justed so that, for any given mean positions oi'

vanes

48 and 62, the shield 66 attached to the undamped vane 48 uncovers a minimum area of aperture 64 in shield 62 at the point in its cycle of oscillation at which the blood pressure is the lowest and uncovers a maximum area of aperture 64 at the point in the cycle at which the blood pressure is highest. Thus, the light that is directed on the tube 21 will vary from substantially zero when the window is covered, to a higher value when the window is uncovered.

Since the vane 52 is weighted to damp its oscillation, it will not follow the iluctuations of blood pressure but its position will vary with variations of the applied pressure over the range including the systolic and diastolic pressures. The vane 48 also assumes a mean position varying with applied its major movement follows that/.of vane 52.: 'However, vane' 48, being unwei'ghted; osillatesvbout such mean position and the only variationl'n light reaching the photocell 21 is that due to oscillation of the. shield 66 on vane 48 with respect to aperture 64 in shield 62 mounted on vane 52.

"In Figure 6 is shown the wiring diagram with respect to the device. Photoelectrie tube 21 is suitably connected to meter I6 through an ampliIying circuit of conventional form comprising an amplifier pentode tube 66 and a triode amplifier tube 16. A voltage divider resistor 1I is utilized to couple the plate circuit of tube 68 to the grid of tube 16, the current meter I6 being connected in series in the plate circuit of tube 16 so as to respond to variations in the plate current thereof.

`Photeelectrie tube 34 is connected through a single triode amplifier tube 66' to its meter I4, which is connected in series in the plate circuit of tube 68 to respond to the plate current thereof,v the required degree of amplification not being as great due to the meter I4 being of less sensitivity than meter I6 since it serves only to indicate relatively large increments of applied pressure, whereas meter I6 responds to relatively small applied increments of fluctuation.

The power supply 36 is in the form preferably of a voltage regulated supply of conventional form and the high frequency oscillator 88 is also of usual construction. Oscillator 38 is employed primarily to energize the

lamps

24 and 36, since low frequency supply does not yield as constant and sensitive results.

In Figure 6, the circuit is also shown with respect to the energizing of the pulse rate meter I8. Where such indication is also desired incorporated in the one device, a relay 14 is incorporated in the circuit of meter I6, as shown, with its operating coil 12 actuated in synchronism with the iluctuations of energy supplied to meter I6. Meter I8 is connected to the high-frequency source 38 through the contacts of relay 14, a transformer 11, a diode rectifier 82, and a time constant of integrating circuit comprising a condenser 16 in parallel with the meter I8 and resistor 18 in series. The time constant of the circuit comprising elements I8, 16, and 18 is such that the average charge of the condenser 16 is proportional to the frequency of operation of the relay 14 and independent of the pulse amplitude utilized to actuate the relay 14. That is, the charge on condenser 16 is proportional to the pulse rate.

Thus. by means of the device of the present invention the physician is enabled also to ascertain the pulse rate of the patient by a glance at meter I8, which accurately and quickly indicates changes in pulse rate. The coil 12 of a relay is arranged between one lead of the meter I8 and the plate of the tube 18, and as the tube current iluctuates, the armature 14 of the relay is opened and closed in synchronism with such uctuations to cause flow ot current in the coils of the transformer 11. There is thus induced or generated a current ilow in the secondary coil of the transformer. This induced current is rectiiied by a rectifier tube 62 in the circuit of which the meter I8 is arranged. 'Ihe pulsations ci' the rectied induced current are effective to charge condenser 16. Each pulse adds a substantially constant incremental charge to condenser 16 since the pulses are derived from a constant amplitude source Il. Between successive pulses. the charge of condenser 16 leaks oil at a steady rate, depending on the voltage on the condenser. Thus, the condenser is charged to a voltage varying with the frequency of the pulse. The meter I8 is eilectively energized by the voltage across condenser 18, the deilection of the needle of meter Il corresponding in value with the charge of condenser 16. Thus by Calibrating meter I6 in units corresponding to pulse velocity or rate, the physician is enabled to simultaneously observe the pulse rate at the same time that the meters I4 and I6 indicate applied pressure and blood pressure respectively.

In operation, the physician ilrst inflates the sleeve or cui above the patients systolic pressure, which causes substantial stoppage of the ilow of blood through the arteries. Nevertheless there will be a weak pulsation at the sleeve due to the pulsations of blood pressure from the heart which are transmitted weakly to the intake tube 44 of the apparatus due to the vane action of the blood in the portion of the limb above the sleeve in striking the sleeve. These weak pulsations cause a small amplitude oscillation of the undamped lightweight vane 48 and shield 65 operated by the aneroid capsule 40. 'I'he oscillation of the shield 65 causes the light falling on the photocell 21 from the lamp 24 to undergo low-amplitude pulsations. As shown in Fig. 6, pulsations of light on the photocell 21 results in amplified current pulsations in the plate circuits of the amplifier tubes 68 and 10 and these pulsations are indicated by the meter I6. At the same time, the high supersystolic pressure applied through the intake tube 44 to the aneroid capsule 42 Acauses a large deflection of its vane 52 and its connected shield 66 to a mean position proportional to the value of this supersystolic pressure. The deilection of the vane 52 causes the shield 66 to expose a substantial portion of the photocell 34 to light from the lamp 30 so that the illumination of the photocell results in an ampliiled current in the plate circuit of the tube 68 (Fig. 6) which includes the applied pressure meter I4. As explained above, the undamped vane 48 of the capsule 46 also assumes a mean position corresponding to that of the vane 52, since both the

capsules

40 and 42 are exposed to the same mean pressure. However, due to the fact that the vane 48 is unweighted or undamped. it oscillates about this mean position, resulting in the ampliiled current oscillations supplied to the meter I6, as described, while the heavier or weighted vane 52 fails to follow these pulsations in pressure.

It will be understood that, while the meters I4 and I6 are conventional electric current meters or ammeters, they may be provided with scales 9 suitably calibrated to'read directly in any convenient unit of pressure, for example, Ain millimeters of mercury, which is the conventional unit of the usual manometer.

The physician then slowly bleeds the pneumatic system by means of a bleed valve generally associated with the sleeve or cuff, allowing the pressure in the system to fall gradually. As the pressure in the sleeve falls, -blood again begins to flow through the artery beneath the cuif and the amplitude of the pressure pulsations rapidly increases, causing an increase in theA amplitude of the oscillation of the vane I8 and its associated shield 65 and a corresponding increase in the amplitude of oscillation of the meter I6 in the manner described above. Simultaneously, the mean pressure of the system, as indicated by the vane 52 of the capsule l2, its associated shield 88, photocell 3|, amplifier 68', and meter Il, falls correspondingly; As is well known in diagnostics, there will be a point reached in the bleeding of the pneumatic system'at which the amplitude of the pressure pulsations increases rapidly. This transition pointis called the systolic pressure of the patient and, by the use of the apparatus of the invention, the physician may note on the meter Il the mean pressure at which this rapid increase takes place and thus quickly obtain the value of a patients systolic pressure.

As the bleeding of the pneumatic system progresses, the amplitude of the pressure pulsations continues to increase and, when these pulsations reach their maximum amplitude, as indicated on the meter I6, corresponding to the unrestricted iiow of blood in the patients arteries, the physician may note the pressure,"termed the diastolic pressure, on the meter I4. Further bleeding of the pneumatic system causes both the amplitude of the pressure pulsations, as indicated on the meter I6, and the amplitude of the mean applied pressure, as indicated on the meter I l, to fail continuously, although the readings have less signicance below the'point at which the diastolic pressure is indicated.

Nevertheless, by the use of the System as described above, it is within the means of the physician to obtain continuous indications of the amplitude of the blood pressure pulsations as the mean blood pressure varies from a supersystolic value through the systolic value and on through the diastolic value to infra-diastolic values.

Simultaneously with the measurement of the blood pressure pulsations as described above, it will be noted that each pulse flowing in the plate circuit of the tube III (Fig. 6) and the meter I6 actuates the relay coilof the relay 'Il causing it to close its contacts momentarily. Upon each closing of the contacts of the relay 14 the transformer I1 is energized from the source 38 and a series of pulses of high-frequency current of constant amplitude are transmitted through the transformer TI 'and rectified by the rectifier tube 82 to charge the 'condenser 16. As explained above, the values of the condenser 15 and of the resistor I8 in parallel therewith are so selected in relation to the resistance of the meter I8 that, within the range of pulse frequencies generally encountered, the condenser I6 will receive an average rectified current through the relay 'Il substantially equal to that which it discharges through the resistor I8 andthe meter I8 in series during the interval between the series of pulses supplied by the relay 14. Under these conditions, a slight increase in the' pulse rate causes the rectified pulses to be supplied to the condenser 'I6 more 1o frequently and the voltage across it will rise to the point at which again the average value of the discharge current through the meter I8 is substantially equal to the average value of the rectified current received. As stated above, the meter I8 responds to the value of the voltage across condenser 'I8 and, by the provision of a suitably calibrated scale, the meter I8 gives a direct indication oi' the pulse rate in pulses per minute. This provides the examining physician with addi# tional diagnostic information useful in his exam# ination of the patient. f l

Since the inflation of the cuff applies the pressure to the part under examination and the indicating meter I6 indicates the amplitude of the pulse or the volume of the blood in the arteries at the indicated pressure, it will be seen that comparison of the volume of blood in oneA limb with the volume of blood in the other limb. or the comparison of pulse amplitudes, may easily be accomplished by the physician by 'successively applying the inilatable bladder to such limbs. Thus, the physician is provided with an index to the condi-- tion of the circulating system of the limb under investigation and the corresponding limb orany other corresponding part of the extremities. The extreme sensitivity of the device according to the present inventionprovides the physician with a means of studying not only the major portions of the arms and legs, but also hands and lingers as well as the feet and toes, which, in the present state of the art, lthe physician is unable to acf complish because the usual form of sphygmoma-f nometer is not suiiicientlysensitive to investigate the feeble pulse in such extremities.

In the use of applicants electric blood pressure diagnostic device, the physician is relieved of the use of the conventional stethoscope and sphyg-J' momanometer. l

While we have described in detail va modification of the .present invention, and illustrated as embodied in a sphygmomanometer, or an electronic oscillometer, it is to be understood that changes may occur to those skilled in this art but any permissible change must fall within the pur-- view of the claims in this application.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the ln-V vention and without sacrieing its chief advan tages.

What is claimed is:

1. An electric blood-pressure diagnostic device for use with a pressure applying element and sub-` ject to blood-pressure pulsations comprising, 'an aneroid pressure capsule responsive primarilyto pulsations of an applied pressure, a radiant'energy source. a radiant energy responsive device disposed to be excited by said source for deriving an electrical effect varying with the excitation thereof, and means controlled by said pressure capsule for controlling the excitation of said deviceby said source, said electrical effect being representative of said applied pressure pulsations, f 4 y 2. An electric blood-pressure diagnostic device for use with a pressure applying element and subject to blood-pressure pulsations comprising, an aneroid pressure capsule responsive primarily to pulsations of an applied pressure, a radiant energy source, a radiant energy responsive devicev disposed to be excited by said source f or deriving electrical effect varying with the vexcitation there-` of, and a pivoted vane operated by said capsule ll andinterpocedbetweensaidsourceandsaiddevice to control the excitation thereon-said electrical elect being representative of said applied pressure pulsations.

3. An electric blood-pressm'e diagnostic device for use with a pressure applying element and subject to blood-pressure pulsations comprising, meansresponsiveprimarilytopulsatons ofan applicdpressln'e,aradiantencrgysource,ara diantenergyresponsivedevlcedisposedtobe exdted by said soluce for deriving an electrical dect varying with the excitation thereof, means emtrolled by said pressure responsive means for the excitation of said device by said source. and a presume pulsation indicator energiaed by said electrical eii'ect.

4. An electric blood-pressure diagnostic device for use with a pressure applying element comprising, an applied pressure responsive means, means including an element controlled by said pressure respomive means neslwmdve primarily to pulsatimsofanappliedpreasure,aradiantenergy generating means, radiant energy responsive meansdisposedtobeexcitedbysaidgenerating meansforderivingelectricaleil'ectsvaryinswith the excitation thereof, and means controlled by said pressm'e responsive means for controlling the excitation of said energy responsive means by' said generating means, means controlled by said puhation responsive means for controlling the excitation ot said energyrcsponsive means by said generating means, said electrical eiiects being individually rqiresentative of said applied pressure and said applied pressure pulsations.

5. An electric blood-pressure diagnostic device for use with a pressure applying element comprlslng. an applied pressure responsive means, Mnsincluding an elanent controlled by said measure responsive means rponsive primarily to pukationsof an applied presure, a radiant energy gan-ating means, a pair of radiant energy re sponslve devices disposed to be individually excited by said generang means for deriving electril elects varying with the excitations thereof, means controlled by said presure responsive means for controlling the excitaon of one oi said devices by said generating means, means contmlledbysaidpulsatlonresponsive meansior exmtrolling the excitation of the other of said devicesbysaidgeneratingmeanaanappliedpressure indicator energized bythe electrical eii'ect duivedbysaidoneofsaiddevices,andapres sure pulsation indicator energized by the other o! said electrical eiiects.

6. An electric blood-'pressure diagnostic device r measure. Y

1. An electric blood-pressure diagnostic device for me with a pressure applying element comprising, means responsive primarily to pulsations of an arpliod pressures-radiant energy source, a radiant energy responsive device disposed to be excited by said source for derivinglan electrical eii'ect varying with the excitation thereof. means controlled by said pressure responsive means for controlling the excitation of said device by said source to derive a pulsating electrical ed'ect, relay means responsive to said pulsating electrical eil'ect for deriving a secondary pulsating electrical eii'ect of constant amplitude, and means tor integrating said secondary pulsating electrical eii'ect to derive an eil'ect varying with the average frequency thereof, said last-named eiiect being representative oi.' the pulse rate of the applied pressure.

8. An electric blood-pressure diagnostic device for use with a pressure applying element and subject to blood-pressure pulsations comprising, electricai means for developing an electrical eii'ect, means responsive to applied pressure for controlling said electrical means to vary said electrical eiiect in accordance with variations in applied pressure, said pressure responsive means having the characteristic of being unresponsive to said blood-pressure pulsations, and an applied pressure representative device energized by said electrical eil'ect.

9. An electric blood-pressure diagnostic device for use with a pressure applying element and subject to blood-pressure pulsations comprising, a radiant energy source, a radiant energy responsive device disposed to be excited by said source for deriving an electrical eiicct varying with the excitation thereoi, means responsive to applied pressure for controlling the excitation of said device by said source to vary said electrical eilect in accordance with variations in applied pressure, said pressure responsive means having the characteristic of being unresponsive to said bloodpressure pulsations, and an applied pressure representative device energized by said electrical eiiect.

10. An electric blood-pressure diagnostic device for use with a pressure applying element and sub.. ject to blood-pressure pulsations comprising, a radiant energy source, a radiant energy responsive device disposed to be excited by said source for deriving an electrical effect varying with the excitation thereof, means responsive to bloodpressure pulsations incident to applied pressure for controlling the excitation of said device by said source to vary said electrical eiiect in accordance with said blood-pressure pulsations, said pressure responsive means having the characteristie of being unresponsive to said applied pressure, and a pressure-pulsation representative device energized by said electrical edect.

11. An electric blood-pressure diagnostic device for use with a pressure applying element comprising two pressure responsive elements, each connected with a movable member and controlling its position, one of said movable members being formed with an aperture and damped so as to assume a mean position when subject to pulsations, a light source and a photocell on opposite sides of said dampedV member and arranged to provide a uniform beam through the aperture to the photocell in any position of the damped member, the other of said movable members being formed to screen said aperture in varying amounts subject to pulsing iiuctuations in pressure above said mean, an electrical circuit including said photocell and an indicator for indicating the magnitude of such ductuations, and means controlled by said damped member for indicating the magnitude of said mean pressure.

WAL'IER J. IQRIA. JEROME SUHRE.

(References on following Ille) 14 REFERENCES CITED FOREIGN PATENTS The following references are of record in the Number Country Date le of this patent: 465,406 Great Britain May 3, 1937 UNITED STATES PATENTS 5 OTHER REFERENCES Number Name Date Page 499 of Continuous Electronic Pulse-Rate 1,759,581 Kwartin May 20, 1930 Indicator, published in Review of Scientific In- 1,794,685 Hayman et al. Mar. 3, 1931 struments, for Nov. 1942. (A copy is available in 1,955,315 Styer Apr. 17. 1934 Div. 55 of the U. S. Patent Omce. This article 2,099,938 Lockhart Nov. 23, 1937 10 is by Schwarzschild et al. and covers pages 496 2,114,578 Strauss -et al. Apr. 19, 1938 to 501, inclusive). 2,121,014 Cameron June 21, 1938 2,193,945 Strauss et al Mar. 19, 1940 2,439,495 Sturm Apr. 13, 1943