On January 13, 1931, the United States Patent Office granted a patent (No. 1,788,434) for an “Apparatus for Recording Arterial Blood Pressure” to Leonarde Keeler of Berkeley, California. This invention, often referred to as the first lie detector, marked a significant milestone in forensic science and psychological testing.
Table of Contents
Invention and Functionality
Leonarde Keeler’s device aimed to record both the cardiac cycles and other oscillations in arterial pressure simultaneously. Traditional sphygmographs, which recorded sphygmograms or connected curves of cardiac cycles, could only indicate the systole (upstroke) and diastole (downstroke) phases of the heart. Keeler’s invention went further by capturing slower oscillations superimposed on these cycles. These slower oscillations could be attributed to factors such as respiratory movements and variations in vasoconstrictor or cardiac activity.
The key advancement of Keeler’s apparatus was its ability to graphically record a curve that combined both the cardiac cycle and these slower oscillations. This provided a more comprehensive understanding of the arterial pressure dynamics and their variations under different physiological and psychological conditions.
Design and Mechanism
The apparatus consisted of several key components:
- Kymograph: A motor-driven device that moved paper through a system of gears, enabling the recording of data via multiple styli.
- Stylus and Tambour Units: The stylus, connected to a series of metal tambours, would trace the oscillations onto the paper. The tambours were interconnected and communicated with each other to transmit vibrations and movements accurately.
- Adjustable Mechanism: The tambour unit could be adjusted to maintain a desired pressure level, allowing for accurate recording of both high-frequency cardiac cycles and slower oscillations.
The device also included a brachial cuff and inflator for measuring blood pressure from different parts of the body, such as the arms or legs. This versatility made it possible to record multiple physiological responses simultaneously.
Applications and Impact
Keeler’s invention found significant application in psychological testing, particularly in criminal investigations. By recording variations in arterial pressure in response to questions, the device could indicate psychological stress or deception. This principle laid the foundation for modern polygraph testing, where multiple physiological indicators (such as respiration, heart rate, and galvanic skin response) are monitored to detect lies.
In practical use, the apparatus could produce distinct graphical records that showed the cardiac cycles superimposed on waves influenced by emotional or physical changes. These records provided valuable insights into the physiological responses associated with stress or deception.
Conclusion
The patenting of Leonarde Keeler’s “Apparatus for Recording Arterial Blood Pressure” in 1931 was a groundbreaking development in forensic and psychological testing. By providing a means to record detailed and comprehensive physiological data, Keeler’s invention paved the way for the modern lie detector and advanced the field of investigative science. Despite the controversies surrounding polygraph tests, this invention remains a testament to the innovative efforts to understand and utilize human physiological responses for truth verification and psychological assessment.
Patented Jan. 13t 1931 1 197889434
Classifications
IPC
A61B5/021;
CPC
A61B5/021 (EP,US); Y10S128/90 (EP,US);
Priorities
US4698625A·1925-07-30
Application
US4698625A·1925-07-30
Publication
US1788434A·1931-01-13
Patented Jan. 13t 1931 1 197889434
UNITED STATES PATENT OFFICE,
LEONARDE KEELER, OF BERKELEY, CALIFORNIA
APPARATUS FOR RECORDING ARTERIAL BLOOD PRESSURE
Application Illed July 30, This invention relates to means for recording cardiac cycles and other oscillations in arterial pressure simultaneously. Sphygmographs are well known in the art. Sphygmograms, or the series of connected curves recorded by a sphygmograph, indicate cardiac cycles only, in which the up stroke is the systole curve and the down stroke-the diastole curve. In addition to the pressure oscillalotion’s of the cardiac cycle, there are slower oscillations, which are more or less irregular and which may be superimposed on a considerable number of cardiac cycles. The slower oscillations in the arterial pressure may be due to various factors such as for example, respiratory movements, rhythmic variations in the activity. of the vasoconstrictor center or in the cardiac activity. Heretofore, it has not been possible to record graphically 2o a curve combining the cardiac cycle, which showed the systolic and diastolic pressures and dicrotic notch and the slower oscillations, and it is an object of this invention to provide means for accomplishing this purpose.
The curves referred to will be better understood from the detailed description hereinafter in connection with the drawings in which such curves are illustrated.
Mv invention also has been found of great 3o value in connection with making certain psychological tests based on arterial blood pressure’ variations.. In such cases I have simultaneously recorded with means embodying my invention two curves taken from different parts of the body, such for example, as the two arms, two legs, one arm and.one leg, etc. My invention may also record a respiration curve, which curve is recorded simulfaneouisly with the two aforesaid curves.
4o An apparatus of this character will be more fully described hereinafter.
It is an object of the invention to provide means whereby the sphygrnogram or cardiac cycle raay be recorded simultaneously with and be superimposed on the slower oscillations in the arterial pressure, whereby the characteristics of each as well as their relation to each other at any moment may be readily ascertained.
The invention possesses other advantage1925. Serial No. 46,986.
ous features, some of which with the foregoing will be set forth at length in the following description where I shall outline in full that form of the invention which I have selected for illustration in the drawings ac- as companyin,g and forming part of the present specifickion. In said drawings I have shown one form of device embodying my invention, but it is to be understood that I do not limit myself to such form, since the eo invention as sei forth in the claims may be embodied in a plurality of other forms.
Referring to the drawings:
Figure 1 is a top plan view of apparatus embodying my inv. ention.
Fig. 2 is a side elevation of the apparatus shown in Fig. 1. Fig. 3 is an end view illustrating the mechanism of the Irymograph.
Fig. 4 is an enlarged detail view illustra. TO ting “ilie mechanism connecting a, tambour unit with a stylus of the kymograph.
Fig. 5 is a cross-sectional view of a brachial cuff with the inflator and tubes shown in elevation, and Fig. 6 illustrates an enlarged specimen of a graphic record obtained by my invention. a atus embodying m invention is i T. rpa br ly mounted on a suitable base 1 and includes a kymo(yraph 2, which comprises a so motor 3 which drives a roller 4, having a plurality of teeth 5 on its. periphery, through a suitable gear train indicated as a whole by the numeral 6. The kymograph is provided with a suitable supply roll 7, which carries smoked ppTr 8 or any other suitable medium for receiving records. The paper 8 is provided with holes 9 adapted to be engaged by the teeth so as to draw the paper throuili the kym?graph in a well understood manner. This go apparatus is well known and does not of itself form a part of m invention as any standard type of apparatus for accomplishina the same result may be employed.
Records or graphs are ttaced on the paper 8 by a stylus of which three are shown, designated 9′, 10 and 11, although it is to be understood that I do not limit myself to any particular number. Since each of the styli is actuated by similar mechanism embodying as 100 2 1,788,434 my invention, a description, of one will be sufficient, and will best be understood by referring to Figs. 1 and 4. The stylus 9′ is secured at right angles to a small shaft 12, 5(Fig. 4 preferably at a point midway be tween tL ends thereof, 4nd the shaft is rotatably supported by two adjustable screws 13 and 14., Preferably the ends of the shaft are provided with conical depressions to receive the ends of said screws which are suitably pointed. The screws 13 and 14 are supported on a fixed vertical member 15 by two arm 16 and 17 and the axis of shaft 12 as it appears in Figure 1 is in a plane at right angles to the plane of paper 8, which is preferably horizontal as shown. The shaft 12 is provided with a small. lever 18, positioned preferably At a point midway between the ends of the shaft. The lever18 is provided with a hole 19 to receive,a hook or L-shaped member 20.
A plurality of holes 19 may be provided so that. the member 20 may be placed in different ones for the purpose of adjusting the amount of leverage. The member 20 is connected in a Manner hereinafter described to the eifd of a tambour unit 21, which comprises a series of metal tambours 22, whereby vibrations or motion transmitted to the tambours 22 may be transmitted to the stylus 9″, the amplification of such motion or vibrations of course being determined by the lengths of the lever 18 and stylus 9′. The tambour unit 21 is supported, at. one end by an L-shaped member 23 and at its oposite end by a vertical member 24, as best shown in Fig. 2. -The interiors of the tambours.22 are all in communication with each other. The tambour 22 adjacent the member 20. is closed, as indicated at 25 and the tambour 22 at the opposite end of the unit is open and connected with a pipe 26. For the purpose of Maintaining the tambour unit 21 n any desired distended position, such for example as to correspond- to a given pressure, adjusting means have been provided. These 4; comprise the provision of a screw 27 whi6h is swiveled on the end of member 20 and adapted to engage threads in the end 25 of the tambour unit 21, and a. shoulder 28 (Fig. 4) bearing against the support 23. Thus when the screw 27 is rotat;ed, the tambour unit 21 may be fixed in a given distended position with respect to the member 3. The L-shaped member is supported on a fixed vertical element 29 as shown in Fig. 2, and may extend through In ompenin in the member 24, – nOt shown. he eml! er 24 is pivotally connected to the base 1 at 30 and normally urged toward the fixed element 29 by a spring 31. The distance between the m em&rs 94 and 29 is regulated by a screw 32 in a manner readily unde – – -:)d.
In this manner the end of the tambour unit adi icent the pipe 26 may also be held in a disieided position. I preferably – employ both the screws 27 and 32 for adjusting the tambour unit. The purpose of the aajustment will be better understood froni’the following description. In Fig. 5, an arm of a person is indicated in cross-section at 33 which is partially surrounded by a rubber bag 34 held in position by a leather cuff 35. The rubber bag is connected by means of a suitable tu e 36 with a pump 37 and with the pipe 26 which communicates with the interior of trie tambour unit 21. The bag.34 is inflated by means of the pump 37 to a pressure at which pulsations impart a free motion to the stylus. As the stylus would now travel through a. wide arc, and be likely to jump from the paper 8, the tambour unit 21 is adjusted in the manner described to a dist,nded position corresponding to the pressure at this time. Thereafter the travel -of the stylus is limited in a manner readily understood.
By means described, I secured a graphic record of -the character shown in Fig. 6. 81 Heretofore. sphvgmographs have been obtained showing the cardiac cycle which was similar to the first five cycles shown in Fig. 6’designated a to e inclusive in whi&,the upward line d’ to the peak!Icates the systolic – pressure, the downward line a” ihe diastolic pressure and a… the dicrotic notch.
These cycles were uniform with respect to a given line.. The applicant’s invention, however, -produces a new and additional result. While maintaining the individual charact6ristieso’f each cardiac cycle, the same are imposed upon a wave, which may rise or fall irregularly as shown in. Fig. 6. It has been found that this wave may -be varied 101) by physical, psychological or emotional changes; however, the applicant does not undertake to analyze -at this time the properties of the curve obtained. The same is the subject matter of study by the medical pro- 11,3 fession, and it is now known that the curve is different from, any other curve heretofore obtained. While my invention. probably has its greatest pplication in the field of the medical to profession, for purposes of illustration 11 have shown the same embodied in apparatus for making certain psychological tests.
This apparatus is provided with two styli, 9′ and 10, with associated mechanism similar to that above described; however, in one case the impulse transmitting means is connected, with an arm and in the other case to the other arm. or a leg, or in each case said means are con-, nected with a1eg, whereby. parallel records’ are obtained from different portions of the body. The stylus 11 is connected with means for recording a respiration curve. This apparat. us m also cdmprise a clock-mechaI Mich controls the circuit of -an nism 38 w electromagnet 39 for indicating time intervals on the paper 8, said magnet actuating a stylus 39′. In carrying out the tests, the person under ex –nation i subjected to questioning and his various reactions are -iso 1,788,434 indicated in the graphs recorded. In order to indicate on the record the time when certain questions are asked, a time markina device is provided which comprises an electromagnetically actuated stylus 40, which may be controlled by a,push button 41. Four other push buttons, 42, 43, 44 and 45 are also shown which control signal lamps 46, 47, 48 and 49 respectively so that a signal may be flashed to a remote point to indicate what the recorded graphs show. This arrangement is provided as the person conducting the examination may be at a distance from the device and not be able to read the indications, and thus avoid any conversation which may be heard by the person under examination.
The particular construction shown is designed for use by the police in making criminal investigations.
