IL46481A - Data display system - Google Patents

Description

Data display system AiffiEIGAI OPTICAL COEPOBATIOI C. 44473 BACKGROUND OF THE INVENTION 1. Field of the Invention.

The present invention relates generally to the field of medical electronics. More specifically, the present invention relates to means for monitoring and displaying vital signs including EKG of a patient in a line-over-line compressed-data manner which facilitates analysis. 2. Description of Prior Art; Over the years, various medical-electronic systems have been developed which aid physicians in diagnosing and providing therapy to patients. Particularly, in the area of cardiology and heart disease, there have been significant advances. For example, heart pacers and EKG monitoring equipment are but two of the types of equipment that have proved to be valuable to physician and patient alike. These devices are now tending to become somewhat familiar to laymen as well.

As is well known in the medical field, EKG strips are taken by a physician by attaching leads or conductors to the body of a patient (generally three leads) . Electrical signal activity generated by the patient's heart is sensed by these conductors or sensors. These electrical signals are extended to EKG amplif i ers and eventually to galvanometer pens for scribing on the surface of a paper. The paper, is generally spool-wound chart paper and advanced in a continuous manner, the direction of It is thus an object of the present invention to provide an improved system for displaying vital signs of a patient.

It is another object of the present invention to provide an improved EKG monitor and display device.

It is a further object of the present invention to provide an improved EKG display system that has means for indicating average heartbeat rate for a selectable period of time and has means for marking occurrences of other events on a chart paper trace.

Other objects and advantages of the present invention will become apparent to one having reasonable skill in the art after referring to the detailed description of the appended drawings in which » i DESCRIPTION OF THE PREFERRED EMBODIMENTS In Fig. 1, patient 101 is connected by EKG leads 102 to EKG (ECG) amplifier electronics 103. (Herein, a conductor ! .. 1 or lead is intended to imply conductors or leads if appropriate.)! I Output from amplifier electronics 103 is extended on conductor 104 to selector switch 105. Likewise, output from ECG amplifier j electronics 103 is extended on conductor 115 to heart rate module 117. output from heart rate module 117 is extended to selector switch 105 on conductor 137. Output from selector switch 105 is provided on conductor 106 to galvanometer drive electronics 107. Output from electronics 107 is extended on conductor 108 to galvanometer pen and carriage assembly 109.

Scribing output from carriage assembly 109 is provided to chart paper on drum 111 via input (pen) 110. This is the basic sensing, amplifying, monitoring, and recording (and/or displaying) functional chain.

Synchronous motor 129 provides rotational mechanical output 128 to gear train 125 which, in turn, provides rotational outputs 126 and 127 to assembly 109 and drum 111, respectively.

Synchronous motor 129 is supplied by AC line power 131 through speed control 150 on conductor 130. AC line power 131 likewise provides power inputs to power supply 119 on conductor 132, and to dither circuitry 134 on conductor 133. Power supply 119 is a DC power supply, and supplies DC voltage to dither circuitry 134 over conductor 124, heart rate module 117 over conductor 123, selector switch 105 over conductor 12 , electronics 107 over conductor 121, amplifier electronics 103 over conductor 120, and speed control 150 over conductor 151.

A rotational position input 112 is provided from cylindrical drum 111 to electro-optics 113. The output from electro-optics 113 is provided to selector switch 105 on conductor 114. A manual input 116, in the form of a pushbutton switch (not shown) or other switch, is provided to selector switch 105.

Referring now to Fig. 2, cylindrical drum 200, which rotates in direction 250, shows axially directed slit 201 at its surface. Electro-optics assembly 113, located in general at the periphery of the cylinder, provides input 114 through selector switch 105. (In Fig. 2, phantom line 105 represents the outline of selector switch 105 as shown in Fig. 1.) Input 114 is provided to reset circuitry 213, output thereof being extended on conductor 210 to digital counter 204. The other input to counter 204 is provided on conductor 203 from clock 202. Counter 204 provides an output on conductor 205 to ramp generator 206. Output from ramp generator 206 is extended on conductor 207 to one input of comparator 208.

The other input of comparator 208 is provided by heart rate module 117 on conductor 137. Output from comparator 208 is extended on conductor 209 as an input to mono-stable circuitry 214. Another input to mono-stable circuitry 214 is manual input 116. Output from mono-stable circuitry 214 is provided to solid state switch 212 on conductor 211. Other inputs to solid state switch 212 include inputs on conductors 135, and 104. Output from solid state switch 212 is extended on conductor 106 , .

I to describing operation of the preferred embodiment, Fig. 3 j / i depicts cylinder or writing surface 200 with slit 201, the writing^ surface rotatably mounted about a substantia I 350. Writing surface 200 can have cylindrical, conical, or other j shape. Writing surface 200 is intended to be adapted for magneticj drum recording as well as paper displays. This axis need not be j vertical; however, for purposes of clarity of illustration it is herein thus depicted. Axis 350 is shown rotatably mounted to base or chassis 400 in Fig. 4. Galvanometer pen 300 is arranged to scribe on the surface of cylinder or drum 200, there being chart- paper or paper 351 (partially indicated for purposes of clarity of illustration) wrapped around and fastened in slit 201. It is j I to be understood that paper 351 extends the entire substantial length of cylinder or drum 200 and essentially wraps around and covers the surface area of the drum. Pen 300 scribes or writes on paper 351.

Lead screw 302 is shown substantially parallel to axis 350 and is likewise rotatably mounted to chassis 400. Rod 303 is fixedly mounted parallel to lead screw 302. Sliding on rod 303 is slidably mounted carriage 304 which, in turn, supports galvano¬ meter 301. Galvanometer 301 receives an electrical signal input on conductor wires (not shown in Figs. 3,4) which signals are transduced into mechanical motion of pen 300. Motor 305 (depicted in Fig. 1 as 129) provides rotational output to.gear train 307 (depicted in Fig. 1 as 125). The gear train provides rotational motion 250 to cylinder 200 about axis 350, and provides rotational motion to lead screw 302 about its longitudinal axis. Carriage 304 is threadingly engaged with threads of lead screw 302. Thus, of carriage 304 in a direction substantially parallel to axis 350J Gears of gear train 307 are designed to provide a plurality rotations of drum 200 corresponding to a single motion in a translational manner from the top of drum 350 (an initial position to the bottom of drum 350 (a final position). Thus, gear train 307 need not have the specific arrangement depicted in Fig. 3.

When chassis 304 reaches final position, it makes physical contacti • ■ i I I and operates micro-switch 306. The micro-switch is electrically j connected between power 131 and motor 305, and operation of the j microswitch disconnects power to the motor thereby stopping the rotational and translational motions of the system. There is provided carriage disengagement means (not shown) for rapid returrl of the galvanometer to the initial position, hot causing the drum to rotate.

In Fig. 1, electro-optics 113 was depicted as being functionally connected between the drum and the selector switch 105. In Figs. 3 and 4, the electro-optics, which is comprised of phototransistors and photodiodes, commercially available, are mounted as shown. Electro-optic elements 113a and 113b are approximately 90° displaced on the periphery of one end of drum 200. These electro-optical elements rotate with the rotating drum. Mounted on base or chassis 400 is a fixed electro-optic sensor 113c. As the rotatable electro-optical elements 113a and 113b in turn pass adjacent electro-optical element 113c, optical communication is achieved there between. The purposes of these optical elements will be discussed more fully below.

Slit 201 is shown in Figs. 2,3, and 4. Chart paper having fixed length and having substantially parallel edges ma be wra ed around drum 200. Ed es of a er 351 are inserted of paper 500 when mounted on drum 200 would be a helix or spiral. When the paper is removed from slit 201 and opened flat, strWght lines with a slightly downward slope are observed. Thus, data line 2 identified by numeral 2 at the left-hand edge of the useable display paper, corresponds in time to the end of data line 1 identified as 2' at the right-hand data edge of the paper.

In other words, lines of EKG data are identified by numerals 1,2,3, and 4 ....n, and the end of each line corresponds in time to the beginning of the next successive line. Thus, the point marked 2' corresponds in time to the end of line 1 and the beginning of line 2. The designation "n" indicates that there ar an extensive plurality of data lines obtained and limited only by size of paper and drum. The preferred embodiments are design© to provide 60 seconds of data per line with 30 lines per sheet thereby displaying a half hour of electrical heart activity and to provide four minutes per line with 30 lines per sheet thus providing a two hour display.

Reference numeral 510 depicts a selectable period of time during which heart rate is averaged in heart rate module 117 comprised of standard circuitry. Module 117 is triggered by each EKG wave to provide a constant width and constant amplitude pulse output in response thereto. This pulse train is then averaged on capacitor circuitry or other means to provide a DC level corresponding to average heart rate.

Turning to Fig. 2, heart rate module 117 provides this DC voltage to comparator 208. Digital counter 204 is reset by a signal coming from optics 113 when pen 300 is positioned at slit 201 as will be fully explained below. This is the counter 204 is stepped by clock generator 202 once each second. Clock generator 202 is synced to 60 hertz power 131. At a predetermined count, which according to Pig. 5 is equal to about 56 counts (or 56 seconds), ramp generator 206 is energized. Counter 204 is constructed from standard digital circuitry and may be a ring counter. Ramp generator 206 is likewise constructed from standard circuitry for charging a capacitor in a linear fashion. Thus, ramp generator 206 is energized after about 56 seconds and this energization takes place at line 520 on Fig. 5. Comparator 208 compares the two inputs and at coincidence between ramp^generator voltage and DC voltage on conductor 137, the comparator output is extended on conductor 209 to monostable 214. Comparator 208 is likewise standard operational amplifier circuitry. Omission of detailed discussion of the circuit elements in these standard circuits does not inhibit full understanding of the present invention .

In Fig. 1, dither generator 134 is powered by AC line power 131 and is a conduit for 60 hertz power at a substantially reduced power value. This 60 cycle/second signal is provided on conductor 135 in Fig. 2, to solid state switch 212. Operation of monostable 214 causes connection of the dithering signal on conductor 135 to output conductor 106.

Solid state switch 212 is comprised of standard transistor switching circuitry and omission of detailed description does not detract from complete understanding of the present invention. The average DC voltage generated by heart rate module 117 corresponds to rate scale 506 in Fig. 5 and thus, per minute. After a predetermined period of time determined J by time constants of monostable 214, solid state switch 212 returns to its prior connection of conductors 104 and 106, thereby reconnecting the EKG signal to pen 300. Mark 505 indicates average heartbeat rate for time period 510 of line 1. Accordingly, a dithering rate mark is provided in the other lines of data. This is very useful information since it provides at a glance a histogram effect of heartbeat rate change of the j patient over a long period of time.

Numeral 503a and 503b refer to ectopic beats, which are clearly visible in this display. Another module which detects ventricular premature beats (a form of ectopic beats) can be connected between conductor 115 and selector switch 105 in a manner similar to connection of module 117. A premature ventri-1 cular contraction detector is disclosed in Patent 3,616,790 ii entitled MULTIFORM VENTRICULAR PREMATURE BEAT DETECTOR issued on November 2, 1971 in the name of G.J. Harris and assigned to Americal Optical Corporation, the Assignee of the present j invention. Background information disclosed in this patent is j incorporated herein by reference. Portions of circuitry disclosecj I in this patent can be used with other circuitry to provide a DC j voltage corresponding to the number of PVC's per data line.

Similarly to the histogram display of average heartbeat rate for I a patient on a line by line basis, a separate histogram can be displayed at a different location on the paper having a operating gear train 125 more rapidly. As depicted in Fig. 5, line 2, after 22 seconds of recorded data, the galvanometer ¾T is translated to position 3' in a time which is equal to or less than the time between the last heartbeat and the next heartbeat. At point 3 ' , the speed control 150 is returned to its standard speed arrangement. A purpose of this feature is to provide the beginning of exercise testing at a beginning point of line 3 for purposes of clarity of presentation for later analysis. Speed control 150 is a device which changes current flow to motor 129 (305).

Likewise, as noted the same display method can be utilized with other tests such as drug testing. If the patient is given certain drugs for medical reasons, the speed control can be operated to "reset" the display, where the heartbeats begin from the left-hand side of the paper as described above.

From Fig. 5, it is seen that approximately 8 seconds elapse after exercise begins before a noticeable change in heart rate occurs. This time value may not be realistic but does not detract from understanding of the present invention. Manual means 116 may also be operated to create designation 521 indicating the beginning of the increased heart rate.

Optical pick-ups 113a, 113b, and 113c are utilized in the operation of speed control 150 as well as in other features of the present invention. Speed control 150 is made to return to its original state when optical pickup 113b is in optical communication with pick-up 113c. At this point, galvanometer pen 300 is positioned at slit 201. A signal from optical pick-up 113c causes the switch in speed control 150 to return to its original state.

The optical pick-ups function in at least two modes.

The first mode was described above. When the "reset button" is depressed speed control 150 is operated and causes drum 200 to move rapidly until optical pick-up 113b is aligned with optical pick-up 113c, (thus causing pen 300 to line up with dit 201). In another feature, when a "load button" is depressed, speed control 150 again increases speed of motor 129, thereby increasing speeds of rotation and translation of the system components. But, when optical pick-up 113a is in optical communication with 113c, all motion of the system is stopped. Control 150 disconnects motor 129 from AC power line 131. This load button is depressed when it is desired to have the slit position to the front of the apparatus for easy access regarding loading and unloading of the paper.

Depressing the "run" button reconnects power to the motor.

The invention may be embodied in yet other specific forms without departing from the spirit or essential characteristics thereof. For example, one can use three galvanometers with three galvanometer pens to monitor EKG leads 102. Leads 102 generally are three in number, and each of these leads may be thus monitored. Thereby, lines 1, 2, and 3 in Fig. 5 could be made to represent the outputs from three leads 102 from patient 101. However, pitch or relative speed of lead or er or t s wor proper y, t e en o ne woul ave to correspond to the beginning of line 4, being sufficiently displaced downward so as to not create interference with other lines corresponding to the other two leads. Furthermore, other sensors may be used to sense other vital signs (eg: blood pressure) simultaneously with EKG. For another example, it is to be understood that speeds other than constant speeds can be utilized in the translat ional motion and rotational motions of the invent-ion. Rather than providing continuous translat ional motion of j carriage 304 transverse to direction of paper motion, one could j provide ratchet means for stepping carriage 304 in transverse manner upon each completion of a revolution of drum 200.

It is to be understood that other means of paper attach- j ment could be made. An assembly cartridge including drum and ! paper could be used where one cylinder with paper is removed and another cylinder with paper is installed (where the paper is not a single sheet but is an endless loop or belt of paper). j Furthermore, if cylinder 200 were held in a horizontal position (rather than vertical as shown for purposes of clarity of illustration only), a paper loop of the endless belt variety (not shown) , can be used which has a circumference in excess of the circumference of drum 200. The system works well if the scribing point of contact between pen 300 and the surface of the S paper 351 on drum 200 remains smooth. Accordingly, even more data can be recorded and displayed. And, another cylinder j It is to be further understood that more than 60 seconds or less than 60 seconds per line can be recorded and that more than or less than 30 lines per page can be recorded.

A particularly advantageous utility of the present invention is in connection with the transcription of EKG cassette tape recorders. Presently, portable tape recorders exist which record a patient's EKG for long periods of time, 24 hours or more. Playback of 24 hours of EKG data at real time would take thus 24 hours. On ordinary EKG chart paper, this would amount to many feet of paper. But, to playback this portable tape recorder data in a transcribing manner utilizing the present invention, both the tape recorder and the present invention fs speed control can be increased by a factor of 20 or more (with respect to real time). Thus, all of this data can be recorded on a large single sheet of paper in an hour or less. The tremendous advantage of being able to analyze 24 hours of EKG activity of a patient within an hour or less after receiving that data on tape from the patient is clear.

Thus, the present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of the equivalency of the claims are therefor intended to be embraced therein.

Claims (6)

1. 46481/2 CLAIMS; 1. A system for displaying vital signs of a patient, said system comprising: means for sensing said vital signs and for providing analogous electrical signals, means for amplifying said electrical signals, a chassis, means axially-rotatably mounted to said chassis for providing a writing surface, looped paper fitted to and supported by said writing surface means, means supported by said chassis for rotating said writing surface means thereby advancing and re-cycling said paper, galvanometer pen means for scribing on said paper in scribing directions transverse to the direction of motion of said paper, means connected to said chassis for supporting said pen means and for continuously translationally moving said pen means in one of said scribing directions from an initial position towards a final position, and means for extending said signals to said galvanometer pen means.

2. A system as recited in claim 1 and wherein said vital signs are the electrocardiogram of said patient.

3. A system as recited in claim 1 and wherein said writing surface means comprises a cylinder having axially directed slit means in the surface of said cylinder and extending the entire length of said cylinder for receiving two substantially parallel edges of said paper and for clamping said edges to create a smooth overlapping of said paper around said cylinder. 1

4. A system as recited in claim 1 and wherein said | 2 rotating means comprises an electrical motor and gear train j 3 means for connecting the rotational output of said motor to 4 said rotatably mounted cylinder means. 1

5. A system as recited in claim 4 and wherein said 2 supporting and translationally mo ing means comprises a rod 3 fixedly supported by said chassis and disposed substantially 4 parallel to the longitudinal axis of said cylinder means, 5 carriage means slidably mounted to said rod for holding said 6 galvanometer pen means, a lead screw rotatably mounted parallel 7 to said rod and engaged with said carriage, and said motor and 8 gear train means including additional means for connecting said 9 rotational output of said motor to said lead screw whereby 1' rotational motion of said lead screw causes translational motion 1. of said carriage. 1

6. A system as recited in claim 1 and wherein said 2 sensing means comprises a plurality of patient-connected sensors, 3 said galvanometer pen means comprises a plurality of galvanometers 4 each of said plurality of galvanometers corresponding respectively 5 to one of said plurality of sensors, each of said plurality of 6, galvanometers having a respective pen, and means for extending 7 each of said plurality of sensors to a respective one of said 8 galvanometers. two electro-optical devices being mounted adjacent said slit, and a third electro-optical device mounted on said chassis adjacent said periphery and in substantial alignment with the scribing point between said paper and said pen means and arranged to be in optical communication with each of said two i electro-optical devices as each of said two electro-optical devices rotates adjacent said third electro-optical device. 46481/2 13. A system as recited in claim 1 and wherein said rotating means includes means to provide a plurality of rotations of said cylinder means to correspond to the translational motion distance of said pen means in moving from said initial position to said final position. 14. A system as recited in claim 5 comprising a switch fixedly attached to said chassis near one end of said rod and arranged to be operated by contact with said carriage means in said final position, and means responsive to operation of said switch for disabling said rotating means and said translationally moving means. 15. A system as recited in claim 3 and wherein said cylinder means further comprises two switching devices mounted on the periphery of said cylinder„ said two devices being relatively angularly displaced by approximately 90°, one of said two switching devices being mounted adjacent said slite and a third switching device mounted on said chassis adjacent said periphery and in substantial alignment with the scribing point between said paper and said pen means and arranged to be in communication with each of said two switching devices as each of said two switching devices rotates adjacent said third switching device. HEsdn