U.S. patent number 3,776,228 [Application Number 05/181,862] was granted by the patent office on 1973-12-04 for portable self-contained electrical cardiometric device with three fixed-position nonuniformly spaced input probes.
Invention is credited to Herbert J. Semler.
United States Patent |
3,776,228 |
Semler |
December 4, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
PORTABLE SELF-CONTAINED ELECTRICAL CARDIOMETRIC DEVICE WITH THREE
FIXED-POSITION NONUNIFORMLY SPACED INPUT PROBES
Abstract
A portable self-contained electrical cardiometric device
employable for the quick monitoring and indicating of a
heart-produced electrical signal in a person's body. The device
includes three specially positioned electrical probes which are for
electrically contacting a person's body to detect such a signal, a
battery-powered electronic amplifier connected to these probes for
amplifying a detected signal, and a suitable display or indicating
unit for following the instantaneous amplitude of an amplified
signal. The probes include fluid passages that communicate with a
pump and a fluid reservoir in the device from which a conductive
fluid may be ejected to enhance the electrical contact between the
probes and a person's skin.
Inventors: |
Semler; Herbert J. (Portland,
OR) |
Family
ID: |
22666116 |
Appl.
No.: |
05/181,862 |
Filed: |
September 20, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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36065 |
May 11, 1970 |
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Current U.S.
Class: |
600/523 |
Current CPC
Class: |
A61B
5/333 (20210101); A61B 5/332 (20210101) |
Current International
Class: |
A61B
5/0404 (20060101); A61B 5/0432 (20060101); A61B
5/0402 (20060101); A61b 005/04 () |
Field of
Search: |
;128/2.5R,2.5T,2.6A,2.6B,2.6E,2.6F,2.6R,2.1E,2.1R,417,DIG.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Kamm; William E.
Parent Case Text
CROSS REFERENCE TO RELATED PRIOR-FILED APPLICATION
This is a continuation of my now abandoned prior-filed copending
application, Ser. No. 36,065, filed May 11, 1970, entitled
"Portable Cardiac Monitor."
Claims
It is claimed and desired to secure by Letters Patent:
1. In a self-contained portable electrical cardiometric device
including a housing, electrical circuit means therein for
processing heart-produced electrical signals including positive,
negative and ground input terminals for said signals, a power
source for said circuit means, and indicator means coupled to said
circuit means for indicating heart activity,
means for electrically contacting a person's body and picking up
heart-produced electrical signals therein, said means consisting of
three electrically conductive probes, including a positive, a
negative and a ground probe each connected to a corresponding one
of said input terminals, mounted in spaced-apart fixed triangularly
disposed positions on said housing,
said positive and negative probes being spaced apart by a distance
of at least seven centimeters, and said ground probe being disposed
closer to the negative probe than to the positive probe.
2. In a self-contained portable electrical cardiometric device
including a housing, electrical circuit means therein for
processing heart-produced electrical signals, a power source for
said circuit means, and indicator means coupled to said circuit
means for indicating heat activity,
means connected to said circuit means for electrically contacting a
person's body and picking up heart-produced electrical signals
therein, said means comprising three electrically conductive probes
mounted in spaced-apart fixed triangularly disposed positions on
said housing,
two of said probes being spaced apart by a distance of at least
seven centimeters, and the third probe being disposed closer to one
of said two probes than to the other probe, with the distance
between said third and one probes being less than 7
centimeters.
3. The device of claim 2, wherein said electrical circuit means
includes positive, negative and ground input terminals, said one
probe is connected to said negative terminal, said other probe is
connected to said positive terminal, and said third probe is
connected to said ground terminal.
4. In a self-contained portable electrical cardiometric device
including a housing, electrical circuit means therein for
processing heart-produced electrical signals, a power source for
said circuit means, and indicator means coupled to said circuit
means for indicating heart activity,
means connected to said circuit means for electrically contacting a
person's body and picking up heart-produced electrical signals
therein, said means consisting of three electrically conductive
probes mounted in spaced-apart fixed triangularly disposed
positions on said housing,
two of said probes being spaced apart by a distance of at least 7
centimeters, and the third probe being disposed closer to one of
said two probes than to the other probe, with the distance between
said third and other probes being less than the distance between
said one and said other probes.
5. The device of claim 4, wherein said electrical circuit means
includes positive, negative and ground input terminals, said one
probe is connected to said negative terminal, said other probe is
connected to said positive terminal, and said third probe is
connected to said ground terminal.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This invention pertains to a portable self-contained electrical
cardiometric device. More particularly, it pertains to such a
device which features three specially fixed-position electrical
input probes that are for contacting a person's body in a manner
ensuring extremely accurate detection of electrical signals
produced therein by the heart.
There is an urgent need for a portable device of the type just
generally indicated. Emergency situations arise constantly where it
is desired, and necessary, to obtain immediate, on-the-spot,
accurate information regarding a person's heart activity if prompt
and proper treatment is to be given. Often, quickly obtained
information of this type is what makes the difference between
saving and losing a life.
Obviously, conventional, cumbersome cardiac monitoring equipment,
which is relatively nonportable, and which may require considerable
warmup and setup time, does not meet this need.
A general object of the present invention, therefore, is to provide
a novel, portable self-contained electrical cardiometric device
which takes care of the need expressed above in a practical and
satisfactory manner.
Another object of the invention is to provide such a device which
can easily be carried in a person's pocket or in a small travel
case, readily held and operated by one hand, and which permits a
substantially immediate reading, or monitoring, of a person's heart
activity.
More specifically, an object of the invention is to provide such a
device which reliably monitors an electrical signal produced by
heart activity in a person's body, and which affords an accurate,
and easily readable and interpretable, indication of such a
signal.
A further object of the present invention is to provide a device of
the type so far generally described which features three novel
fixed-position, nonuniformly spaced input probes that are specially
oriented in the device to promote accurate detection of electrical
signals of the kind mentioned above.
According to a preferred embodiment of the invention, the proposed
cardiometric device comprises a small elongated housing containing
an electronic amplifier, and a battery power source therefor. The
housing is easily held in one hand. Connected to the amplifier are
three fixed-position input probes, oriented as contemplated by the
invention, and a suitable indicating device, such as a lamp, or a
meter. The three input probes are arranged with two of them, which
are designated herein as positive and negative probes, no less than
seven centimeters apart, and with the third probe, which is
designated a ground probe, disposed closer to the negative probe
than to the positive probe. Preferably, the ground probe is offset
from a straight line extending between the positive and negative
probes.
DESCRIPTION OF THE DRAWINGS
These and other objects and advantages attained by the invention
will become more fully apparent as the description which follows is
read in conjunction with the accompanying drawings, wherein:
FIG. 1 is a full scale top perspective view of a device constructed
according to the present invention;
FIG. 2, on essentially the same scale as FIG. 1, is a top plan
view, partially in section, of the device of FIG. 1, with a portion
of a housing in the device removed;
FIG. 3, on essentially the same scale as FIGS. 1 and 2, is a
sectional side elevation of the device of FIG. 1;
FIG. 4 is an enlarged vertical section of a probe employed in the
device of FIGS. 1, 2 and 3;
FIG. 5 is an enlarged vertical section illustrating one type of a
removable foot which may be attached to a probe in the device;
FIG. 6 is a bottom view of the foot of FIG. 5;
FIG. 7 is an enlarged vertical section view illustrating another
type of removable foot which may be attached to a probe; and
FIG. 8 is a time-base graph illustrating a typical "PQRST" voltage
display of a normally healthy person's heart activity.
DETAILED DESCRIPTION OF THE INVENTION
Turning now to the drawings, and referring first to FIGS. 1-3,
indicated generally at 10 in FIG. 1 is a cardiometric device
constructed according to the present invention. Device 10 includes
an elongated two-part case, including a base 11 and a cover 12. The
base has a somewhat U-shaped transverse cross section, and when
fitted together with cover 12 (as shown in FIG. 1), forms a
completely enclosed protective housing for various other parts in
the device. Such a housing is relatively easy and inexpensive to
fabricate. Preferably, its parts are made of a relatively
lightweight metal, such as aluminum.
Although it is appreciated that the precise outside dimensions of
the housing in device 10 may be made to suit different particular
applications, the housing shown herein preferably has a length of
about 6 to 7 inches, a width of about 2 to 21/2 inches, and a depth
of about 11/2 inches. It will be apparent that with dimensions such
as these, the device may easily be held in one hand, and can
readily be carried in a person's pocket or in various forms of
small travel cases, such as a briefcase.
In the embodiment of the invention being described, the cover and
base of the housing are releasably secured together by screws, such
as exposed thumb screw 15, which are screwed into posts, such as
post 13 (see FIGS. 2 and 3). With such an arrangement, components
inside the housing (still to be described) are readily accessible
for service and other purposes.
Suitably mounted on the underside of base 11 and protruding
outwardly from the base, are three signal input probes constructed
and arranged as contemplated herein. These three probes are
designated by reference numerals 16, 17, 18. For reasons which will
be more fully explained herein, probe 16 constitutes a positive
probe, probe 17 constitutes a ground probe, and probe 18
constitutes a negative probe. As will also be more fully explained
later on, these three probes are employed to make electrical
contact with a person's skin, for the purpose of picking up the
usual electrical signal produced in the person's body by heart
activity.
The relative positioning and spacing of the probes has been found
to constitute an important and critical factor in the device's
ability to provide accurate and easily interpretable information
regarding heart activity. More specifically, it has been discovered
that for the highest possible accuracy, the negative and positive
probes should be spaced apart no less than seven centimeters, with
the ground probe positioned more closely to the negative probe than
to the positive probe. Probe positionings and spacings differing
from these criteria have been found to produce inaccurate and
poorly interpretable information. Particularly satisfactory
performance has been found to result with the probes spaced apart
and oriented essentially as indicated in FIG. 2, which (as
indicated above) is approximately a full scale view of a device 10.
In this specific probe arrangement, it will be noted that ground
probe 17 is offset from a straight line extending between probes
16, 18. Further, it will be observed that the distance between
probes 16, 17 is somewhat less than the distance between probes 16,
18.
Preferably, probes 16, 17, 18 are fabricated of, or plated with, a
suitable highly electrically conductive material, such as silver or
nickel. The probes have essentially the same constructions -- their
lower end portions being tapered as indicated. As can be seen
clearly in FIG. 4, which illustrates positive probe 16, the probes
include axially disposed central, double-open-ended bores 22, the
purpose for which will be explained shortly. In their respective
mountings on base 11, the probes are insulated from electrical
contact with the base by means of insulators 19 (see FIG. 4).
Referring for a moment to FIGS. 5 and 6, illustrated therein is
what might be thought of as a detachable contact foot 64 which is
shown detachably mounted on probe 16. Similar feet may be provided
for and mounted on probes 17, 18. A foot 64 has the axial
cross-sectional configuration clearly illustrated in FIG. 5, and
includes a knurled bottom surface 65, and a central, axial, tapered
bore 66 which joins axially with a considerably smaller bore 69
that opens to the base of the foot. Eact foot 64 is adapted to be
easily twisted onto and off of a probe, with the tapered outside
surface of the probe fitting snugly against the tapered inside wall
of the bore 66 inside the foot. Preferably, feet 64 are constructed
from the same type material used in the probes.
Feet 64 may be used advantageously in various circumstances where
it is desired to maximize the contact area with a person's skin. It
will be apparent that the knurled bottom surfaces of these feet
facilitate relatively large-area contact with skin.
Considering FIG. 7, this illustrates at 67 another type of foot
which may be fitted (in a manner similar to that described for feet
64) onto a probe. A foot 67 includes a substantially flat bottom
face 70 from which projects a short central needle 68. This kind of
a foot may be used on the probes under circumstances where it is
desired to make electrical contact with a person through puncturing
of his skin.
It will be noted that the two different types of feet which have
just been described, do not appreciably change the relative
positions and spacings of the points at which electrical contact is
made with a person's skin. This is an important feature.
Considering now other components employed in device 10, and
referring again particularly to FIGS. 1-3, suitably mounted inside
the housing are a fluid supply system 25, and an electronic
amplifier, or electrical circuit means, 24. The fluid supply system
is adapted to be used in conjunction with the central axial bores
mentioned previously in the probes, for the purpose of ejecting
through these bores, and onto a person's skin, a suitable
conductive fluid, such as alcohol or water, to enhance the
electrical contact between the probes and the skin. Accordingly,
the fluid supply system includes a reservoir 27, a digitally
operable pump 34, and three flexible tubes 32 which connect outlets
31 in the reservoir with the interiors of the bores in the probes.
Access for filling and draining the reservoir is had through an
inlet 29 which is exposed through housing cover 12.
Reservoir 27 preferably is made of a relatively thin flexible
material, such as a pliable plastic material. Pump 34, which is
used to eject fluid from the reservoir, comprises an elongated arm
35 which is pivoted at 37 on housing base 11. An end portion 36 of
the arm contacts a side of the reservoir (as can be seen clearly in
FIG. 2), and the arm carries a push button 39 which extends freely
through a bore 40 in base 11, outwardly of the housing.
With fluid stored in the reservoir, digital pressure by an operator
upon button 39 forces end portion 36 of the arm against the
reservoir, distorting the same and causing the ejection of fluid
through the outlets, tubes, and probes. A conventional air inlet
valve 43 admits air to the reservoir to replace ejected fluid.
The ejecting of fluid through the probes to improve electrical
contact with a person's body is especially useful where it is
desired to establish such contact without removing clothing. In
other words, by ejecting fluid, the fluid wets the clothing and
reaches the skin to establish adequate electrical contact between
the skin and the probes.
Amplifier 24 is a conventional three-input, high-gain,
high-frequency-AC-isolation-type amplifier capable of responding to
relatively low frequency electrical signals, such as those produced
by the heart. The amplifier includes the usual positive, negative
and ground input terminals (hidden from view in the drawings), and
is adapted to detect a differential voltage between its positive
and negative terminals. Probes 16, 18, 17 are suitably conductively
connected to the amplifier's positive, negative and ground
terminals, respectively--thus accounting for the reference made
earlier to these probes as positive, negative and ground probes,
respectively. Power for energizing the amplifier is supplied by a
battery 56 which is contained within the housing. A switch 58
mounted on base 11, and interposed electrically between the
amplifier and battery, is provided for turning the amplifier on and
off.
Details of the amplifier form no part of the present invention, and
thus are not illustrated. Preferably, however, the amplifier is
constructed using modern semiconductor devices, thus enabling it to
be relatively compact, whereby it can easily fit into a housing
having dimensions like those described above, and permitting it to
operate at relatively low power levels. In addition, there is
preferably provided in the amplifier, interconnecting the three
input terminals, a conventional diode protective circuit which
protects the amplifier per se from any excess input voltages (such
as might occur during defibrillation of a patient), and which, more
importantly, protects a patient against any possible internal
malfunction of the amplifier that might accidentally place a
harmful voltage between any two of its input terminals.
An output signal from the amplifier takes the form of an
intensity-varying signal which follows intensity variations in the
differential voltage appearing between its positive and negative
input terminals. In device 10, such an output signal is supplied
both to an indicating lamp 51, which is mounted on cover 12, and
also to a conventional output jack 57 mounted on base 11.
Referring now to FIG. 8, the manner in which device 10 may be used
to monitor a person's heart activity is explained. FIG. 8 is a
time-base graph illustrating typical "PQRST" voltage excursions
which occur in a normally healthy person's body due to heart
activity. In this type of display, various points in a single cycle
reflecting heart activity are designated by the letters P, Q, R, S
and T. Medical practitioners skilled in the art are fully familiar
with such a graph.
With device 10 turned on, and with electrical contact established
between probes 16, 17, 18 and a person's skin (typically on the
person's chest), the electrical voltage signal in the person's body
is picked up by the probes, fed to amplifier 24, amplified therein,
and then supplied to lamp 51 and jack 57. Under such circumstances,
the intensity of light coming from lamp 51 follows intensity
changes in the output signal from the amplifier. Through experience
in using the device, one can readily detect in the flickering of
the lamp all of the significant points--P, Q, R, S and T--in a
cycle of heart activity. As a consequence, and with such
experience, a skilled medical practitioner can easily determine the
then condition of the person's heart.
With a device such as device 10 available, it will be obvious that
an immediate on-the-spot emergency diagnosis of a person's heart
condition can be made. If desired, lamp 51 may be replaced by a
suitable meter whose needle tracks or follows the output signal of
the amplifier. Further, and under circumstances permitting such
operation, output jack 57 may be employed to supply a signal to any
desired external indicating device, such as a strip-chart
recorder.
The novel positioning and spacing of the fixed probes employed in
the device facilitate the obtaining of accurate information
regarding heart activity. This is especially important in making
the device practical for use in emergency-type situations, where
time must not be wasted in setting up to take measurements. Under
different kinds of circumstances, and as dictated by user
experience, the different kinds of probe-mounted feet described
above may be used, and/or the fluid system may be employed, to
enhance electrical contact with a person's body.
It is thus apparent that the proposed device adequately fills the
need expressed earlier herein. And, while a preferred embodiment of
the invention has been described, and certain modifications
suggested, it is appreciated that other variations and
modifications may be made without departing from the spirit of the
invention.
* * * * *