US2020469A - Sphygmomanometer - Google Patents

Description

Nov. 12, 1935. 1 l. LAUFMAN' ET AL 2,020,469

SPI-IYGMOMANOMETER Filed Oct. 18, 1934 2 Sheets-Sheet 1 INVENTORJ'.

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Nov. 1 2, 1935. LAUFMAN Er AL 2, 9

I SPHYGMOMANOMETER Filed Oct. 18, 1934 2 Sheets-Sheet 2 INVBNTORJ .lrz'dor Lari man Patented Nov. 12, I935 SPHYGMOMANOMETER.

Isidor Laufman and Arthur L. Laufman, New York, N. Y.

Application October 18, 1934, Serial No. 748,810

6 Claims.

Our present invention relates generally to measuring instruments, and has particular reference to an improved sphygmomanometer.

The primary object of our invention is to provide a device whereby the blood pressure of a subject at any given moment may be determined with great facility and without requiring the attendance or assistance of any person other than the subject, himself. While it is contemplated that the present invention will lend itself readily to the production of a coin-operable ap'-.

paratus (thereby permitting any personto ascertain his own blood pressure at any given time by proper insertion of a suitable coin and by performance. of certain specified steps), nevertheless it will be understood that the invention is by no means restricted to any such utility. In many instances, for example, it may be found highly desirable. to use the present apparatus in clinics, hospitals, or evenin individual doctors offices. 1

One of the outstanding advantages. of our present device lies in its ability to register, with great reliability, the true blood pressure of a subject at any given instant. Ordinary methods of taking blood pressure, and other devices heretofore devised for such purpose, are subject to a serious disadvantage arising from the possibility of error due to inadvertent and irrelevant move- -ments by the subject. The presentdevice, on the other hand, is so constructed and arranged, and

V is providedwith'special means, that it assures a proper and correct registration of blood pressure at anygiven time, even where the apparatus gauge, in permanent communication with the bladder, a means forinflating the bladder, and,

a slow-leaking vent for the bladder. The blade der is first inflated to a degree which totally'impedes the flow of blood; and as the air. escapes" through the. slow-leaking vent, the pressure recorded. bythe manometer gauge gradually falls. At the instant of time when the pressure has been reduced just sufiiciently "to permit the flow of blood to be reestablished, a fluctuation in pressure takes place, andithe manometer gauge indicates such fluctuation.

One of theieatures 'of our invention lies in providing ameanswholly independent of the slow-leaking vent for preventing escape of air through such vent If the escape of air is prevented at thetime the blood flow has been reestablished, the gauge will continue to'fluctuate indefinitely; but, on the other hand, if the escape 5 of air throughthe vent is prevented at any other time, the gauge will. not fluctuate. This additional means for preventing the escape of air through the slow-leaking vent is thus a reliable means for verifying the results of the determina- 1 tion in question.

A further feature of our invention lies in the provision of av device for automatically producing a. signal, preferably a momentary audible signal, whenever the gauge is registering a rise 15 in pressure. This serves as an additional means. for verifying the. results, because, when the gauge is correctly registering the blood pressure of a subject the. audiblev signal can be caused to operatein timed relation to the pulsations of 20 blood through. the blood vessels of the subject.

A further feature of our invention lies in the provision. of a specially constructed device for automatically sealing the bladder when it is tightened upon the arm of a subject, and for 25 automatically permitting a rapid release of the air in the bladder when the arm of a subject is withdrawn. This serves automatically to place the apparatus, with. great rapidity, into proper condit on for the next test, thereby avoiding any 30 reliance upon the subject orsubjects to restore the parts to their nonnai conditions.

Other features of our invention will be more fully appreciated after this specification has been read, and include the provision of an attractive 35 structural arrangement of parts whereby the device: can be. inexpensively manufactured and as, sembled, and, readily dismantled or disassembled for purposes of inspection or repair; the 40 provision of a pump .which'is readily operable by even an inexperienced person; the provision of a means for preventing too speedy an inflation oi the bladder, thereby safeguarding the device fromiintentional or inadvertent abuse; and the 45 Figure 2' is an enlarged cross-sectional view taken substantially along the line 2-2 of Figure 1;

Figure 3 is an enlarged cross-sectional view taken substantially along the line 33 of Figure 1;

Figure 4 is a fragmentary cross-sectional plan View, taken substantially along the line 44 of Figure 3; and

Figure 5 is a diagrammatic view showing the relationship of the various parts.

Referring for the moment to Figure 5, the subsubstantially rectangular rubber bladder |5 is of a kind which is adapted to be encircled around the'forearm of a subject. By means of a cloth or similar lining II, the bladder is held in superposed relation to a leather backing l2, the latter being rolled upon itself into the form of a loop through which the arm of the subject is inserted. More particularly, the rear end of the backing |2 is secured by screws l3 to a bracket l4, and the forward end of the backing develops into a leather strap l5 having a series of perforations l6 therein. The strap is preferably provided with the knob l1, and when the apparatus is set up the strap i5 extends through the slot |8,'to complete the loop, and is ultimately disposed in substantially the position shown in Figures 1 and 2.

When the arm of a subject is inserted through the loop, as shown in Figure 1, the bladder is tightened around the arm by pulling upon the strap I5 and by then engaging a selected perforation with the movable complementary fastening element IS. The latter is hingedly mounted, as at 2|), and is normally in the dot-and-dash position of Figure 2. The tightening of the strap automatically swings the element l9 into the full-line position of Figure 2, and this movement fulfills a function which will be presently described.

A conduit composed of the sections 2| and 22 7 establishes a permanent communication between the interior of the bladder I0 and the rear end of a U-tube manometer, which is preferably of glass. One arm 23 of the manometer is enlarged to serve as a sort of reservoir for a supply of mercury or similar liquid. The other arm 25 is mounted in vertical relationship in front of a backing 25 upon which suitable scale markings are provided.

' The conduit between the bladder andgauge is provided with a slow-leaking vent in the form of an adjustable needle valve 21. This .valve is set when the device is initially manufactured and subsequent adjustments are not contemplated, except for purposes of repair. The outlet end of the valve or vent terminates in a resilient, collapsible tube 28 composed, for example, of soft rubber. This tube is caused to have its end mounted in a block 29, and a movable pressure member, such as the pushbutton 30, is mounted so that it may be pressed against the tube 28 to collapse the latter and thereby squeeze it closed. The member 30 thus serves as a means wholly independent of the slow-leaking vent 21 to prevent escape of air through the vent 21.

The conduit between the bladder and gauge is further provided with the pressure-releasing outlet 3| which also terminates in a tube of resilient, collapsible material 32. This tube may be, for example, soft rubber, and itsend is mounted in a block 33 and passes between one wall of this block andthe movable element I9. The normal resilience of the tube 32 causes this outlet tube normally "to be open to the atmosphere, and

causes the element [9 to be normally pressed into the dot-and-dash position of Figure 2. When the bladder is caused to be tightened around the arm of a subject, the engagement of the element l9 presses the latter toward the right, and this pressure collapses the tube 32, as shown most clearly in Figure 2, whereby the outlet is sealed. The inflation of the bladder is accomplished by means of a pump 34, which is similar, in character, to an ordinary bicycle pump and is provided with a piston 35 and a plunger 36. The

latter terminates in the knob 31, and is provided further with the ratchet teeth 38. Engaging with one of these teeth is the releasable latch 39 which is normally urged into engagement with one of the teeth by means of a. spring 40 (see Figure 4). The latch 39 is mounted on the end of a. rod

4| which terminates in a projection 42. The latter is adapted to be encountered by the forward I end of a coin slide 43 whenever the latter is capable of being shifted toward the left, i. e., into the dot-and-dash position of Figures 3 and 4.

The coin slide 43 forms part of a coin-operated mechanism which is designated generally by the reference numeral 44 and which will not be de- 5 scribed in detail since its construction is Well known, per se, and does not enter into the present invention. Suflice it to state that when a. suitable coin 45 is inserted into the coin slide i3 the latter may be advanced toward projection 3 42, otherwise not; and during this advance the coin is caused to fall into a suitable collection box.

Beneath the piston of the pump, a compression spring 46 is arranged, normally tending to 35 urge the piston upwardly.

A conduit 41 extends from the pump to the conduit 2|, and in accordance with our invention we arrange in this'conduit a check valve 48 and an adjustable constricting valve 49. The valve 48 is obviously for the purpose of preventing air from flowing in the return direction after it has passed into the conduits 2| and 22. The valve 49 is for the purposeof constricting the speed with which air may be caused to flow from the pump into the bladder.

At its upper end, the tube 25 of the gauge terminates in the enlarged chamber 50 which serves as a reservoid for accommodating excess liquid in the event that thejliquid in the tube 25 is 50 caused to, rise too high. Communicating with the interior of the chamber 50 is a tube 5| which terminates in a tubular fitting 52 tilted upwardly by a very slight degree toward its open end.

Within this fitting the steel ball 53 is mounted. 55 2 Gravity causes this ball ordinarily to be positioned at the inner end of the fitting 52, but the smoothness of the ball and the snug fit of the ball within the fitting 52 permits the ball to be advanced to the left whenever there is an increase of pressure within the tube 5|. Immediately to the left of the fitting 52 we mount a bell or gong 54, so that whenever the ball is urged to the left it encounters the gong and causes an audible signal to be produced.

Beneath the fitting 52 is a chamber 55 which serves as a convenient overflow receptacle in the event that any of the liquid 24 should, by accident, be forced into the tube 5|.

All of the mechanism is suitably supported and assembled within a framework which is preferably accommodated within acabinet 56, as shown inFigure 1. Many of the various parts that have been hereinbefore 'described'will be recognized in Figure 1. While the arrangement of parts is a matter of preference-and design, we prefer to have the coin slide 4'3 in the front wall of the cabinet; to mount the leather backing Won the top of the cabinet; toarrange the button: 30 in an" accessible position on the top of the cabinet; and: to mount the manometer: gauge within a casing 5! so that it will be approximately on a: level with the eyes of the average person. The pump handle 31 is also arranged in an accessible position on top of the cabinet, and it will be understood that this handle is normally in the full line position of Figure 1.

The mode of operation of the apparatus is as follows. The person whose blood; pressure issought first inserts: his forearm into the looped backing l2, as indicatedin dot-and-dashlines in Figure 1; and the knob I1 is then grasped andpulled to the left, thereby tightening the bladder around the arm. During this procedure, the lining H may wrinkle somewhat, as indicated in Figure 2, but this wrinkling is purposely provided for, so as to keep the bladder l concealed and protectedat all times. The bladder is secured in tightened relationship around the arm by engaging a selected perforation l6 over the movable element [9. This automatically causes the element I?! to swing toward the right and seal the pressure-release outlet 3 I.

The subject then places a proper coin in the slide 43, and when the slide is pushed in the latch 39 releases the pump rod 36, causing it to jump upwardly, under the action of the spring 46, into the dot-and-dash position of Figure 1.

The handle 31 is then pressed downwardly, whereby the bladder becomes inflated. The speed of inflation is limited by the constricting valve 49 which prevents the operator from either intentionally or inadvertently forcing the piston of the pump downwardly at too great a speed. During the inflation of the bladder, the liquid 24 rises in the gauge glass 25, and suitable directions attached to the machine will instruct the user to inflate the bladder until a certain predetermined gauge reading is reached. The pressure thus specified will be one which is well above any conceivable blood pressure, as a result of which the flow of blood through the arm of the subject will be completely impeded.

After the pump handle has been pushed downwardly to inflate the bladder, it remains in its downward position by 'Virtue of the locking latch 39.

Since the slow-leaking vent 21 is constantly open, the inflation of the bladder gradually lessens and the observer will be able to note a gradual falling of the liquid in the gauge glass 25. At the instant when the pressure has fallen just sufliciently to permit the flow of blood to be reestablished, the pressure in the bladder will momentarily increase because of the expansion of the blood vessel in the arm. This will cause the liquid in the column 25 to bob up and down rhythmically. The level at which this occurs can be read upon the scale 26, and is a measure of the blood pressure of the subject.

During the up-and-down movement of the liquid, the ball or member 53 will be caused to oscillate back and forth in the fitting 52, thereby causing an audible signal to be produced. With the device herein illustrated, each pulsation of the blood in the subjects arm will cause a momentary ringing the the bell 54.

After the desired measurement has been ascertained, it is a relatively simple matter to release the strap i from the element [9, thereby loosening the bladder from. the: arm. The subject then withdraws his arm; and the: release of the."

element ldproduces an instantaneous release of all the pressure the system. The apparatus is then immediately'ready for the succeeding subject or test.

From the. foregoing; it will be understood that the purpose of observing the gauge is'to notev the point at which. the-liquid commences to bob. upv and down. It frequently happens that voluntary or involuntary movements of a digit, hand, or other parts of the subject, occasioned, for ex-' ample, by tremor or ticks, or by a cough or a sneeze, will cause. a. momentary bobbing of the liquid in the gauge. To. prevent such an incident from causing the user of the apparatus to. draw an erroneous conclusion as. to the: blood pressure being measured, it is merely necessary for the user to press down upon the button 3t: whenever the liquid commences. to bob. If' the bobbing of the liquid is due to any cause other than a reestablishment of blood flow in the arm of the subject, pressure upon the button 30 will cause the liquid in the column 25 to halt completely. An erroneous reading can thus be definitely recognized as such, and disregarded. If, on the other hand, the button 30 is pressed down during a fluctuation of the. liquid, which properly measures the blood pressure of the subject, a sealing of the vent will have no effect upon the fluctuations, and the liquid 24 will continue to bob up and down rhythmically, causing the audible signal to function each time there is a rise in pressure registered upon the gauge. The true measurement that is sought can thus be verified.

It will be understood that our invention is not necessarily restricted to the specific detailed construction of parts, as herein illustrated by way of example, nor to the specific arrangement of such parts or mode of assembly, as herein shown.

In general, it will be understood that changes in the details, herein described and illustrated for the purpose of explaining the nature of our invention, may be made by those skilled in the art without departing from the spirit and scope of the invention as expressed in the appended claims. It is, therefore, intended that these details be interpreted as illustrative, and not in a limiting sense.

Having thus described our invention, and illustrated its use, what we claim as new and desire to secure by Letters Patent is 1. In a sphygmomanometer, a manometer,

gauge, a bladder in permanent communication with the gauge, a slow-leaking vent and a normally open, rapid release outlet for the bladder, means for inflating the bladder, means for tightening the bladder around a subject's arm, and a device automatically operable by said tightening means for sealing said outlet.

2. In a sphygmomanometer, a manometer gauge, a bladder in permanent communication with the gauge, a slow-leaking vent and a nor-- mally open, rapid release outlet for the bladder, means for inflating the bladder, means for tightening the bladder around a subject's arm, means for sealing said outlet when the bladder is in position, and means independent of the slow-leaking vent for preventing the escape of air through said vent.

3. In a sphygmomanometer, a manometer gauge, a bladder in permanent communication with the gauge, a slow-leaking vent and a normally open, rapid release outlet for the bladder, means for inflating the bladdenmeans for tightening the bladderaround a subject's arm, a device automatically operable by, said tightening means for sealing said outlet, and means independent ofthe slow-leaking vent for preventing the escape of air through said vent.

4. In a sphygmomanometer, a manometer gauge, a bladder in permanent communication with the gauge, a slow-leaking vent and a nor-- mally open, rapid release outlet for the bladder,

means for inflating the bladder, means for tightening the bladder around .a subjects arm, said means including cooperable fastening elements one of which is necessarily moved when the bladder is tightened, and a device automatically operable by said movable element for sealing said outlet.

5. In a sphygmomanometer, a manometer gauge, a bladder in permanent communication with the gauge, a slow-leaking vent and a normally open, rapid release outlet for the bladder,

means for inflatingth'e bladder, means for tightening the bladder around a subjects arm, said means comprising a perforated strap and a movable element adapted to engage in a selected perforation when the bladder is tightened, and a device automatically operable by said movable element for sealing said outlet.

6. In a sphygmomanometer, a manometer gauge, a. bladder in permanent communication with the gauge, a slow-leaking vent for the bladder, means for inflating the bladder, means for tightening the bladder around a subjects arm, and means independent of the slow-leaking vent for preventing the escape of air through said vent, said last-named means comprising a resilient, collapsible vent tube, and a pressure member mounted for movement against said tube so as to collapse the latter.

ISIDOR LAUFMAN. ARTHUR L. LAUFMAN.

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