US2202935A - Cardiac recording apparatus - Google Patents

Description

June 4, 1940. H. wExss 2,202,935

CARDIAC RECORDING APPARATUS Filed June 18, 1958 3 Sheets-Sheet l Sauf u B June 4, 1940. H. wElss CARDIAC RECORDING APPARATUS Filed June 18, 1938 3 Sheets-Sheet 2 INVENTOR ATTORNEY Patented June 4, 1940 UNITED STATES 1PrixrlsNT OFFICE 5 Claims.

This invention relates to an automatic and graphic blood pressure recording device intended for use primarily in clinical and experimental cardiac work, or in any situation where a constant and automatic blood pressure record for a predetermined time is of value.

One of the objects of the invention is to provide an automatic and graphic blood pressure recording device which shall be useful in various environments, during sleep, at rest, or during various stages of activities; which shall be capable of automatic blood pressure recording for any desired period of time, or at predetermined intervals of time; which will permit the automatic and graphic dtermination of bloodpressure changes, with changes in psychic, mental or physical state of the person being tested.

A further object of the invention is to provide means whereby the application and release of pressure on the artery of a patient may be recorded in the form of a curve similar to a sine curve on a photographic record strip and sirnultaneously therewith and as a part of the same curve, the arterial sounds occurring and disappearing during the application and release of pressure will also be recorded. The advantages of such an arrangement will be at once apparent to those skilled in this art.

In the accompanying drawings wherein an illustrative embodiment of the invention is shown, Fig. 1 is a side elevation, with parts in section, of a practical structure capable of performing the function desirous of being achieved by the invention; Fig. 2 is a plan view of the same; Fig. 3 is an endview of the structure; Fig. 4 is a diagrammatic view indicating the pump and 'connections thereto; and Fig. 5 shows the'curve produced on a photographic record strip by the device forming the subject matter of the invention,

' The apparatus shown in the accompanying drawings includes a flat base or support I which may be made of metal or of other desired material. Attached to said base, near one end thereof, is an inverted U-shaped supporting bracket 2 having laterally extended feet 3 and 4, which are secured to the base I by means of the screws shown or by any other suitable fastening elements. In the top portion of the bracket 2 ls provided a rectangular slot 5, the sides of the top of bracket 2 adjacent said slot being tapped for the reception ofthe two set-screws 6 and 1. Fitted into the slot 5 is a socket 8 having an upper rectangular end of the same width as the slot 5 into which it fits, but of shorter length than said slot, so that it can be moved back and forth, or tocrystal element I6 cemented in Bakelite at one (c1. 12s-ans) ward the right and left as viewed in Fig. 1, and set in any desired position by means of the setscrews 6 and 1. 'I'he socket 8 is formed with a. rounded lower end and in its center is formed with a recess 9 into which the pivot pin I4 may 5 t and rotate.

Directly below the socket 8 between the vertical legs of the bracket 2 is a similar socket IG secured to the base I, said socket having a central recess II for the reception of the pivot pin I3 on 10 an oscillometer I2. Said oscillometer I2, sometimes known as an oscilloscope, is located within the bracket 2 and has its upper end provided with the pivot pin I4 located in the recess 9 on socket 8, and its lower end formed with the pivot 15 pin 25 located in recess II of socket I0. This arrangement is such that the oscillometer may rotate freely from side to side in its mounting in the two sockets 8 and I0.

The oscillometer shown consists of a sealed casing or chamber I5 in which is xed in oil a crystal element` I 6 such asshown as a Bimorph element, to the upper end of which is attached a filament I8 extending to the top of casing I5. A mirror I'I is attached on said filament. There 25 are two contact members i90. and I9b leading from the crystal element, to which wires 24 may be attached, so that a current may be induced t0 ow through the crystal element to cause it and the attached mirror I'I to twist or rotate. A beam of light reflected from the mirror Il will be projected through a window 20 formed in the upper portion of the casing I5 and will move with the movement of the mirror and will be recorded on a recording camera, The source of light can be directed from any suitable device independent of the apparatus shown, or it may be fixed to the base plate, to the bracket 2, or to the oscilloscope, or to the upper pivot pin thereof, which might be extended through the top of the bracket 2. Its position will mainly depend upon the desired placement of the camera, which will be controlled by factors of convenience and compactness.

'An oscilloscope of the character described is available in the open market, one example of which is that known as the Brush piezo-electric oscilloscope unit, manufactured by the Brush Development Co. of New York city. Such an oscilloscope unit consists of a thin, narrow, twister 50 end and having its other end free to vibrate torsionally and attached to a small plane mirror I1 about one-eighth inch square, the leads being brought out through the pins or posts I9a and ISb inserted in the Bakelite base. This element 55 I6 is located in a housing I5 consisting of a length of tube having its upper end terminating in a square head. A window 20 in the head, sealed by a lens, affords access to the mirror I1. Light from the mirror I1 is brought to a focus by the lens without any additional optical part. The lens or window 20 is tilted slightly downward s0 that any light reflected from its surface will not interfere with light reflected from the mirror.

The housing is iilled with oil which serves as a damping agent and also protects the crystal from physical shocks due to rough handling. While a crystal oscilloscope is herein described, it will be apparent that any other known type of oscillometer including electrically motivated oscillometers can function in the same way.

The current serving to actuate the oscillometer element and mirror to cause them to move within the casing I5 is obtained through the leads 24 connecting to the binding posts Isa and I9b. Leads 24 connect to microphone 2Ia or other source of current which is adapted to be applied to the arm of a patient in the antibrachial space below the blood pressure cuil. The current from this microphone induced by the sound produced at the antibrachial space of the arm, then passes through appropriate apparatus including a variable induction coil 22 and variable resistance 23 through the leads 24 to binding posts I9a and lsb. As the sound is produced at the microphone, the mirror within the oscilloscope will twist and the beam of light therefrom will be reflected into a camera which will thus -record the movement of the mirror.

Rigidly attached to the lower pivot pin I3 or to the lower end of the oscilloscope casing I5 or at any other suitable location therein, is a segmental gear 26. This gear meshes with a second gear or pinion 21 secured to a pivotal shaft 28 at point 29. Said shaft 26 is part of an anaeroid 30. An aneroid suitable for the purpose is that known as the Tycos although other makes may be used. The body of the aneroid 30 is rigidly Ysecured to a supporting saddle 3| fastened to the base plate I by means o1 appropriate screws, rivets or welding. To stabilize the mounting of the aneroid, the pivotal shaft 28 thereof is mounted in a socket 32 secured on the upper face of the base I. The air entrance and outlet of the aneroid comprises the nipple 33 to which is attacheda tube 34 extending to a T-shaped connection 35 leading to an air pump 36 diagrammatically illustrated in Fig. 4. 'I'he piston 31 of this pump is pivotally attached to connecting rod 38 which in turn extends to the crank shaft or to the eccentric of a motor not shown, but of conventional structure, which acts to reciprocate the piston 31 in cylinder 36 in the usual way. The other leg of the T-shaped connection 35 attaches. to a tube 39 which extends to a three-way valve 40. By means of this three-way valve, two other connections are made, one through a tube 4I to a hand bulb not shown, but of the type commonly used in the ordinary blood pressure apparatus, and to which is attached a by-pass to the outside air which can be closed; the other to a tube 42 v which extends to an arm cuil not shown but of the conventional kind known as a blood pressure cuff, adapted to be attached to the arm tok encircle it just above the point of application or attachment of a microphone at the antibrachial space.-

The hand bulb connected to' tube 4I can be used during manual ination and deiiation of the apparatus and can.be used for purposes 'of adjustment. During the automatic operation of the apparatus. the hand bulb is closed oli at the three-way valve 40 and the arm cuil is open to the pump 36.

In operation the apparatus functions as fol lows: 'Ihe piston 31 is slowly reciprocated in cylinder 36 by slow operation ot the motor to which the piston is connected. The movement of piston 36 in cylinder 31 causes the movement oi air into and out of the aneroid 30 through tube 34 and in and out of the arm cuil connected to the tube 42. With this rise and fall of air pressure in the system there is a corresponding oscillating movement of the shaft 28 of the aneroid clockwise and c0unter-clockwise through a predetermined arc. As this movement occurs, the gear 21 is moved and through its mesh with the segmental gear 26, the latter gear is caused to oscillate, causing the oscilloscope to which it is attached, to rotate counter-clockwise and then clockwise with the rise and fall of the air pressure.

If a beam of light is reflected from the mirror I1 onto the moving sensitized lm or paper of a camera, a line is obtained thereon resembling a sine curve, which is smooth and unbroken and represents the baseline upon which the subsequent blood-pressure readings are to be represented. This base line is calibrated to extend between any desired blood pressure levels by means of the amount of displacement allowed the piston 31 within the cylinder 36. This can be regulated in numerous Ways, such as by changing the position of the pump cylinder on its base or by adjusting the degree of eccentricity of the piston on its attachment to the driving motor. This will adjust the amplitude of the curve and the height to which it is desired to carry the curve peak in order to cover the expected blood-pressure range. The lower point of this basic curve is adjusted through the hand bulb. The resultant smooth basiccurve is shown at a in Fig. 5.

If it is desired to work up to a higher level, as just explained, and ,the displacement of the piston is Aaltered to secure that result, the resultant curve will resemble that shown at b in Fig. 5.

As the apparatus is being alternately inflated and deflated by the pump and the basic line is being produced as just described, the pressure in the arm cuff, received through tube 42, rises and falls in corresponding manner. As the pressure rises from zero to the diastolic pressure, no sound is produced in the antibrachial space, or only a very slight sound up to the point of diastole where the sound changes due to the fact that the artery is now being compressed. This sound is detected by the microphone 2l secured over the artery in this space. As the pressure continues to rise these sounds persist with each heart beat until the pressure rises to the point of systole when the sounds disappear due to the fact that the artery is now completely occluded. As the pressure falls, the same thing occurs except that the sequence of events is now reversed.

The sounds produced in the antibrachial space of the arm are picked up by the microphone 2i and result in the electrical impulses which are transmitted to the crystal I6 of the oscilloscope causing said crystal to distort or twist and simultaneously to twist the mirror I1 through the suspension filament I8. 'I'his distortion or twisting movement of the mirror I1 causes a deviation from the form of base line produced, and as previously described and shown at a and b, resulting in the production of irreguu larities in the line which represent at their beginning and ending the points of systole and diastole. Such a line with the distortions pressent is shown at c in Fig. 5.

Automatic control of the apparatus is readily attained by means of a simple time switch which will simultaneously switch on the pump motor, the camera motor, the source of light, the microphone and any other electrically operated elements of the apparatus, and after a given time, switch these elements oiI. Various other changes and additions may be readily made without departing from the spirit of the invention as expressed in the annexed claims.

What I claim is:

1. In an apparatus oi the character described, an oscillometer mounted for oscillatory movement and provided with an oscillating mirror, means for mechanically oscillating the oscillometer, a pump having its output connected to a blood-pressure cuff and to the oscillometeroscillating means whereby the application and release of pressure in the cuff by operation of the pump will cause the oscillometer to be oscillated, means for recording 'on a line such movements of the oscillometer and means for recording vibratory movements of the mirror on the same single recording line while the oscillometer is being moved under action of the pump.

2. In an apparatus of the character described, an oscillometer including a light-transferring element, means for oscillating the oscillometer through a predetermined path, said means including an air pressure device for automatically supplying to and releasing pressure on the oscillating means, means for recording on a record line the oscillatory movements of the oscillometer, and means for recording on the same record line arterial sounds by movements of the light-transferring element while the oscillometer is being moved.

3. In an apparatus of the character described, a supporting base, a crystal oscillometer mounted ior oscillatory movement thereon, said oscillometer including a lament-supported mirror for directing a light beam, gearing connected to said oscillometer for bodily oscillating the same, an aneroid having an oscillating shaft for driving said gearing, a pump for alternately applying and releasing air pressure on the aneroid, a blood pressure cuil', a connection between the pump and cui, a microphone and connections between the same and the crystal of the oscillometer whereby sounds picked up by the microphone will be electrically transmitted to the crystal to cause the mirror to be oscillated while the oscillometer is being oscillated by pump impulses.

4. In an apparatus of the character described, a supporting base, a crystal oscillometer mounted for oscillatory movement thereon, said oscillometer including a filament-supported mirror for directing a light beam, gearing connected to said oscillometer for bodily oscillating the same through a predetermined path, an aneroid having an oscillating shaft for driving said gearing, a pump for alternately applying and releasing air pressure on the aneroid, a blood pressure cuff, a connection between the pump and cuff by which air pressure will be supplied and relieved by the pump to the cuir simultaneously with the application and release of pressure to the aneroid, a microphone and connections between the same and the crystal of the oscillometer whereby sounds picked up by the microphone will be electrically transmitted to the crystal to cause the mirror to be oscillated while the oscillometer is being oscillated by pump impulses.

5. In an apparatus of the character described,

a crystal oscillometer including a mirror, a pivotal mounting for said oscillometer whereby the same may have oscillatory movements, means for imparting a uniform oscillatory movement to the oscillometer, and means connected to a patients arm and to the oscillometer for causing sounds occurring between the points of systole and diastole to be imparted as vibrations to the mirror of the oscillometer during the uniform oscillatory movement of the oscillometer, and means for recording the oscillatory movements of the oscillometer and the vibratory movements of the mirror on a single line.

HARRY WEISS.

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