U.S. patent number 3,893,453 [Application Number 05/441,684] was granted by the patent office on 1975-07-08 for compressed data display system.
This patent grant is currently assigned to American Optical Corporation. Invention is credited to Robert L. Cannon, Herbert E. Goldberg.
United States Patent |
3,893,453 |
Goldberg , et al. |
July 8, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Compressed data display system
Abstract
A compressed data display system. There is disclosed a system
for recording over extended periods of time EKG and other vital
signs of a patient and for automatically displaying the waveforms
in a compressed and readily interpretable manner. The EKG waveform
is recorded on looped paper supported by and/or wrapped around
rotatable drum or drums which may have cylindrical shape. The EKG
is recorded in helical or spiral fashion by simultaneously rotating
the drum and transversely moving a galvanometer pen in the
direction of the axis of rotation of the drum or cylinder. After
the paper is removed, if it is a continuous or closed loop, it can
be slit and opened into a single sheet. The recorded EKG waveforms
are thus displayed compressed in a line-over-line manner and
provide the physician with a clear picture of the patient's heart
activity for extended periods of time.
Inventors: |
Goldberg; Herbert E. (Concord,
MA), Cannon; Robert L. (Waltham, MA) |
Assignee: |
American Optical Corporation
(Southbridge, MA)
|
Family
ID: |
23753877 |
Appl.
No.: |
05/441,684 |
Filed: |
February 11, 1974 |
Current U.S.
Class: |
600/523;
346/33ME; 346/62; 346/138 |
Current CPC
Class: |
A61B
5/333 (20210101); A61B 5/7232 (20130101) |
Current International
Class: |
A61B
5/0432 (20060101); A61b 005/04 () |
Field of
Search: |
;128/2.5Q,2.5R,2.6A,2.6B,2.6F,2.6G,2.6R,2.6V
;346/33ME,63,68,79,101,103,112,138 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Wall; Joel Nealon; Willian C.
Berkenstock, Jr.; H. R.
Claims
What is claimed is:
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 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 2 where said paper includes a
heartbeat rate scale, said system further comprising means for
providing an average heartbeat rate of said patient for a
selectable period of time, means for generating a pen dithering
signal, and means for momentarily disabling said extending means
and for conducting said pen dithering signal to said galvanometer
pen means when said pen is scribing on said paper at a point which
corresponds on said heartbeat rate scale to said average heartbeat
rate.
4. 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.
5. A system as recited in claim 4 further comprising two
electro-optical devices employed in the control of the operation of
at least said rotating means and mounted on the periphery of said
cylinder, said two devices being relatively angularly displaced by
approximately 90.degree., one of 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 electro-optical devices as each of said two electro-optical
devices rotates adjacent said third electro-optical device.
6. A system as recited in claim 5 including means responsive to the
optical communication between said third electro-optical device and
said other of said two electro-optical devices for controlling
speed of said rotating means when said other of said two
electro-optical devices is adjacent said third electro-optical
device.
7. A system as recited in claim 5 including means responsive to the
optical communication between said third electro-optical device and
said one of said two electro-optical devices for inhibiting
operation of said rotating means and said translationally moving
means when said one of said two electro-optical devices is adjacent
said third electro-optical device.
8. A system as recited in claim 4 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.degree., one of said two switching
devices being mounted adjacent said slit, 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.
9. A system as recited in claim 1 and wherein said rotating means
comprises an electrical motor and gear train means for connecting
the rotational output of said motor to said rotatably mounted
cylinder means.
10. A system as recited in claim 9 and wherein said supporting and
translationally moving means comprises a rod fixedly supported by
said chassis and disposed substantially parallel to the
longitudinal axis of said cylinder means, carriage means slidably
mounted to said rod for holding said galvanometer pen means, a lead
screw rotatably mounted parallel to said rod and engaged with said
carriage, and said motor and gear train means including additional
means for connecting said rotational output of said motor to said
lead screw whereby rotational motion of said lead screw causes
translational motion of said carriage.
11. A system as recited in claim 10 comprising a microswitch
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
microswitch for disabling said rotating means and said
translationally moving means.
12. A system as recited in claim 10 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.
13. A system as recited in claim 1 and wherein said sensing means
comprises a plurality of patient-connected sensors, said
galvanometer pen means comprises a plurality of galvanometers, each
of said plurality of galvanometers corresponding respectively to
one of said plurality of sensors, each of said plurality of
galvanometers having a respective pen, and means for extending each
of said plurality of sensors to a respective one of said
galvanometers.
14. A system as recited in claim 1 further comprising means for
generating pen means dithering signals, and manually operated means
for momentarily disabling said extending means and for conducting
said dithering signals to said pen means, whereby a dither mark is
scribed on said paper at will.
15. 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.
16. A system for displaying vital signs of a patient, said system
comprising means for sensing said vital signs and for providing
analogous electrical signals, supporting means, a looped markable
surface supported by said supporting means, means for advancing and
recycling said surface about a first axis, and marking means
responsive to said signals for coating said surface with
representations of said signals in a helical path about said
axis.
17. 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, means for establishing a recording
rotational speed range, means for controlling said rotating means
to operate within said recording rotational speed range,
galvanometer pen means for scribing on said paper in scribing
directions transverse to the direction of motion of said paper,
means for extending said signals to said galvanometer pen means,
means connected to said chassis for supporting said pen means and
for translationally moving said pen means in one of said scribing
directions from an initial position towards a final position, means
for establishing a recording translational speed range as a
function of said recording rotational speed range to permit said
pen means to scribe said looped paper with representations of said
signals in a non-overlapping path, and means for controlling said
supporting and translationally moving means to operate within said
recording translational speed range.
18. A system as recited in claim 17 and wherein said
representations of said signals are scribed on said looped paper in
a compressed manner.
19. A system as recited in claim 17 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.
20. A system as recited in claim 17 further including
manually-activated speed-control means for causing said rotating
means and said translationally moving means to operate outside of
said recording rotational speed range and said recording
translational speed range respectively.
21. A system as recited in claim 20 and wherein said speed control
means further comprises two electro-optical devices employed in the
control of the operation of at least said rotating means and
mounted on the periphery of said cylinder, said two devices being
relatively angularly displaced by approximately 90.degree., one of
said two electro-optical devices being mounted adjacent said slit,
a third electro-optical device mounted on said chassis adjcent said
periphery and in substantial alignment with the scribing point
between said paper and said pen means, and means for controlling
optical communication between each of said two electro-optical
devices as each of said two electro-optical devices rotates
adjacent said third electro-optical device.
22. A system as recited in claim 21 including means responsive to
the optical communication between said third electro-optical device
and said other of said two electro-optical devices for returning
speed of said rotating means within said recording rotational speed
range when said other of said two electro-optical devices is
adjacent said third electro-optical device.
23. A system as recited in claim 21 including means responsive to
the optical communication between said third electro-optical device
and said one of said two electro-optical devices for inhibiting
operation of said rotating means and sand translationally moving
means when said one of said two electro-optical devices is adjacent
said third electro-optical device.
24. A system is recited in claim 20 and wherein said speed control
means further comprises two switching devices mounted on the
periphery of said cylinder, said two devices being relatively
angularly displaced by approximately 90.degree., one of said two
switching devices being mounted adjacent said slit, 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.
25. A system as recited in claim 19 and wherein said rotating means
includes means to provide a plurality of rotations of said writing
surface means to correspond to the translational motion distance of
said pen means in moving from said initial position to said final
position.
26. A system as recited in claim 25 and wherein said recording
rotational speed range establishing means permits said
representations of said signals to be scribed on said paper in a
compressed manner.
27. A system as recited in claim 26 further including
manually-activated speed-control means for causing said rotating
means and said translationally moving means to operate outside of
said recording rotational speed range and said recording
translational speed range respectively.
28. A system as recited in claim 27 and wherein said vital signs
are the electrocardiogram of said patent.
29. A system as recited in claim 28 where said paper includes a
heartbeat rate scale, said system further comprising means for
providing an average heartbeat rate of said patient for a
selectable period of time, means for generating a pen dithering
signal, and means for monentarily disabling said extending means
for conducting said pen dithering signal to said galvanometer pen
means when said pen is scribing on said paper at a point which
corresponds on said heartbeat rate scale to said average heartbeat
rate.
30. A system as recited in claim 29 further comprising means for
generating pen means dithering signals, and manually operated means
for momentarily disabling said extending means and for conducting
said dithering signals to said pen means, whereby a dither mark is
scribed on said paper at will.
31. A system as recited in claim 17 and wherein said vital signs
are the electrocardiogram of said patient.
32. A system as recited in claim 31 where said paper includes a
heartbeat rate scale, said system further comprising means for
providing an average heartbeat rate of said patient for a
selectable period of time, means for generating a pen dithering
signal, and means for momentarily disabling said extending means
for conducting said pen dithering signal to said galvanometer pen
means when said pen is scribing on said paper at a point which
corresponds on said heartbeat rate scale to said average heartbeat
rate.
33. A system as recited in claim 17 and wherein said rotating means
comprises an electrical motor and gear train means for connecting
the rotational output of said motor to said rotatably mounted
cylinder means.
34. A system as recited in claim 33 and wherein said supporting and
translationally moving means comprises a rod fixedly supported by
said chassis and disposed substantially parallel to the
longitudinal axis of said cylinder means, carriage means slidably
mounted to said rod for holding said galvanometer pen means, a lead
screw rotatably mounted parallel to said rod and engaged with said
carriage, and said motor and gear train means including additional
means for connecting said rotational output of said motor to said
lead screw whereby rotational motion of said lead screw causes
translational motion of said carriage.
35. A system as recited in claim 34 comprising a microswitch
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
microswitch for disabling said rotating means and said
translationally moving means.
36. A system as recited in claim 34 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.
37. A system as recited in claim 17 and wherein said sensing means
comprises a plurality of patient-connected sensors, said
galvanometer pen means comprises a plurality of galvanometers, each
of said plurality of galvanometers corresponding respectively to
one of said plurality of sensors, each of said plurality of
galvanometers having a respective pen, and means for extending each
of said plurality of sensors to a respective one of said
galvanometers.
38. A system as recited in claim 17 further comprising means for
generating pen means dithering signals, and manually operated means
for monentarily disabling said extending means and for conducting
said dithering signals to said pen means, whereby a dither mark is
scribed on said paper at will.
39. A system as recited in claim 17 and wherein said rotating means
includes means to provide a plurality of rotations of said writing
surface means to correspond to the translational motion distance of
said pen means in moving from said initial position to said final
position.
40. A system as recited in claim 17 and wherein said recording
rotational speed range establishing means permits said
representations of said signals to be scribed on said paper in a
compressed manner.
Description
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 and amplifiers 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 advance of paper being the
direction of a time axis. Deflections of the galvanometer pen are
generally perpendicular or transverse to direction of motion of the
paper. The resultant trace, if the EKG is taken for any appreciable
length of time, is very long. Anyone with experience in this field
knows that the accumulated chart paper is unwieldly and cumbersome.
It is thus difficult to accurately compare a patient's heart
activity over periods of an hour or more when the EKG is left
running continuously. Simply, too much paper exists for facile
manual control and analysis. This is a severe problem of the prior
art.
The present invention is a solution to the prior art problem of
recording and displaying large quantities of vital sign data and
particularly the EKG of a patient. It provides an automatic
line-over-line compression of data in a compact and easily usable
form and thus facilitates analysis.
SUMMARY OF THE INVENTION
The present invention relates to recording of vital sign data on a
paper or chart paper wrapped around a cylindrical drum or drums.
The galvanometer pen is translated in a direction transverse to
direction of movement of the chart paper. The chart paper direction
is one time axis, and the direction of motion of the galvanometer
pen is a second quantized time axis. Continuous transverse motion
of the galvanometer pen permits scribing a helix on the surface of
the cylinder's chart paper. Deflections due to the EKG signal are
in directions also transverse to direction of chart paper motion.
The display system includes EKG sensing and amplifying means, a
rotatably mounted cylinder, closed loop chart paper fitted to the
cylinder, and a transversely movable galvanometer pen assembly for
scribing on the paper in the manner described above. Another
feature of the present invention includes circuitry for providing a
dithering mark at selected portions of the recorded data either
upon manual command or automatically to indicate the average rate
of heartbeat for a given portion of EKG data.
An advantage of the present invention is that it compresses vital
sign data, from a long paper trace readout into a single sheet
line-over-line vital sign "picture" thereby facilitating analysis.
It is thus advantageous to patient and physician alike.
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:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a block diagram of an illustrative embodiment of the
present invention;
FIG. 2 depicts certain detail of the block diagram of FIG. 1;
FIG. 3 depicts a perspective view of certain mechanical detail of
the illustrative embodiment of the present invention;
FIG. 4 depicts another perspective view of other certain mechanical
aspects of the illustrative embodiment of the present invention;
and
FIG. 5 depicts the resultant chart paper compressed data display
generated by the present invention.
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 or lead is intended
to imply conductors or leads if appropriate.) Output from amplifier
electronics 103 is extended on conductor 104 to selector switch
105. Likewise, output from ECG amplifier 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
122, 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 to galvanometer drive electronics
107 as indicated in FIG. 1.
Next, proceeding with description of FIGS. 3 and 4 prior to
describing operation of the preferred embodiment, FIG. 3 depicts
cylinder or writing surface 200 with slit 201, the writing surface
rotatably mounted about a substantially vertical axis 350. Writing
surface 200 can have cylindrical, conical, or other shape. Writing
surface 200 is intended to be adapted for magnetic drum recording
as well as paper displays. This axis need not be 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 chartpaper or paper 351
(partially indicated for purposes of clarity of illustration)
wrapped around and fastened in slit 201. It is 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 galvanometer 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, rotational motion of lead
screw 302 provides translational motion of carriage 304 in a
direction substantially parallel to axis 350. Gears of gear train
307 are designed to provide a plurality of 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 contact and operates micro-switch 306.
The micro-switch is electrically connected between power 131 and
motor 305, and operation of the 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 return of the galvanometer to the initial
position, not 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.degree.
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 may be wrapped
around drum 200. Edges of paper 351 are inserted into slit 201 and
are fastened therein by rotatable clamping control 352.
In operation, the preferred embodiment as described in FIGS. 1-4,
and the obtained display of FIG. 5 to be described, provides a
compressed EKG (or other vital sign) data display. The EKG signal
of patient 101 is amplified in electronics 103, extended to
selector switch 105, extended to galvanometer driver electronics
107 which drives galvanometer pen means 301 which in turn causes
pen 300 to scribe on paper 351 supported on cylinder 200. While
this signal is being applied to pen 300 and while scribing motion
is taking place, cylinder or drum 200 rotates in direction 250.
Simultaneously carriage 304 translated in a downward vertical
direction. This combined rotational and translational motion
creates a helical base line on paper 351. (It is intended herein
that the words "helix," "spiral" and "coil" can be used
interchangeably.) The result can be seen in FIG. 5.
In FIG. 5, paper 500 (which is shown partially as paper 351 in FIG.
3) is depicted as having usable display length 511 which
corresponds to the circumference of drum 200. Dotted lines 501
indicate where folds of the paper are made for insertion of these
folds into slit 201 as described earlier. Paper 500 is shown in a
broken diagrammatic fashion for purposes of clarity of
illustration. A time scale of zero through sixty seconds is
provided and break 504 in the paper takes place at approximately
between 23 seconds and 53 seconds.
The scribing of pen 300 on paper 500 provides EKG wave forms 502.
As intended to be depicted by lines 508, 509, 512, and 513, the
entire surface of the page can be scribed with EKG signals. As
noted earlier, the base line scribed on the surface 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, straight 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 are an extensive
plurality of data lines obtained and limited only by size of paper
and drum. The preferred embodiments are designed 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 zero or reset setting for the
scribing motion. Digital 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 FIG. 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,
dithering mark 505 is indicated to be approximately 60 beats per
minute. After a predetermined period of time determined 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 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 ventricular contraction
detector is disclosed in U.S. Pat. No. 3,616,790 entitled MULTIFORM
VENTRICULAR PREMATURE BEAT DETECTOR issued on Nov. 2, 1971 in the
name of G. J. Harris and assigned to Americal Optical Corporation,
the Assignee of the present invention. Background information
disclosed in this patent is incorporated herein by reference.
Portions of circuitry disclosed in this patent can be used with
other circuitry to provide a DC voltage corresponding to the number
of PVC's per data line. Similarly to the histogram display of
average heartbeat rate for a patient on a line by line basis, a
separate histogram can be displayed at a different location on the
paper having a different scale for indicating the number of
occurrences of premature ventricular beats.
In FIG. 5, direction 522 represents direction of translational
motion of carriage 304. Numerical designation 507 represents cross
hatching which may be spread throughout the page in a uniform
manner as depicted. It is illustrated only in a portion of sheet
500 for the purpose of clarity of illustration.
FIG. 1 and FIG. 2 indicate manual input 116 to selector switch 105
and more specifically to monostable circuitry 214. This utilizes a
push-button or other manual switch arrangement whereby the
physician or operator of the system can mark at will on sheet 500,
a dither signal such as mark 521. As before, output 211 from
monostable 214 causes solid state switch to make a connection
between conductors 135 and 106. Dither generator 134 provides a 60
cycle dithering signal to conductor 106 and thus to pen 300 which
scribes in a dithering or vibrating manner on chart paper 500.
Dither mark 521 is displayed at this point in FIG. 5 for a special
reason. It marks the occurrence of a significant event such as
patient complaints of discomfort, or infusion of a drug, or the
beginning of exercise testing, etc.
After one minute and 21 seconds of EKG recording, the patient is
subjected to exercise testing (not shown, but can be treadmill
walking with EKG leads attached to the patient). A feature of the
present invention is a speed-up switch 150 as shown in FIG. 1. This
speed-up push-button switch, which is designated on the chassis of
the preferred embodiments as "reset," increases the speed of the
synchronous motor 129 thereby operating gear train 125 more
rapidly. As depicted in FIg. 5, line 2, after 22 seconds of
recorded data, the galvanometer pen 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 slit 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 screw 302 must be altered to accommodate this
feature. In order for this to work properly, the end of line 1
would have 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 translational motion and rotational motions of the
invention. Rather than providing continuous translational motion of
carriage 304 transverse to direction of paper motion, one could
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 attachment 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).
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 paper 351
on drum 200 remains smooth. Accordingly, even more data can be
recorded and displayed. And, another cylinder (not shown) can be
installed at a remote distance, to provide pulley support means for
this extended circumference endless paper loop. However, these are
alternative embodiments and the preferred embodiment is that which
is shown in the Figures.
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's 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.
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