Note: Descriptions are shown in the official language in which they were submitted.
~IIYSIOLOGICAL arc ROD ~YS~l).MS
The present application is a division of Canadian Patent
Application, Serial No. 383,327, filed August 6, 1981.
BACKGROUND OF Tulle INVENTION
S Field of the Invention
_, I
This invention relates generally to physiological
electrodes and their associated systems, and more
specifically, this invention relates to physiological
electrode systems by means of which a multiplicity of
physiological functions may be achieved, either individually
or in combination, through a single disposable electrode
set.
Description of the Prior Art
Development of an understanding of electrical
signals generated in the body and the utility of electrical
signals supplied to the body has led to the necessity of
transferring electrical energy to and from the body of
a patient for medical purposecO This transfer of electL~lcal
energy to and from the body of a patient is achieved by
means of electrodes contacting the skin of the patient
These electrodes may be generally classified as physiological
electrodes.
Instruments or devices that are utilized in
connection with physiological electrodes may be divided
into three broad categories -- monitoring devices, stimulating
devices and therapeutic devices. Employs of monitoring
devices include cardioscopes, electrocardiographs and
electrocardiograms (for ease of reference the term "HOG"
1,
If i
I
will be utili~cd to mean all or any of these devices) row
monitoring operation of the heart and impedance pnucmo-
graphs for monitoring respiration. Therapeutic devices
include electrosurgical units (ESSAY) and various radio
S frequency (RYE) and other relatively high frequency apply-
actors to reduce pain and promote healing. In the Sterno-
feting device category there ore defibrillator (used
to shock a patient from fibrillation, an asynchronous
cardiac ventricular or fluttexin~ made of contractions)
and other direct current (DC) and low frequency applicators.
The line between a therapeutic device and a stimulating
device is not always clear, but for purposes of this
discussion a therapeutic device shall refer to an
instrument involving high frequency signals (approximately
100 Ho. and higher while a stimulating device is hereby
defined as one employing DC or low frequency (approximately
¦ 60 Ho. and lower signals.
Most commonly, HOG electrodes are small (on the
order of 1/2 inch) conducting plates from which an electrical
connection to the patients skin is achieved by means of
a saline gel. Fact electrode has its own individual
electrical lead to the HOG and a total of from three to
seven electrodes (even more in the case of some diagnostic
testing are utilized fox cardiac monitoring. The electrodes
are generally disposable so that they are discarded after
a single use, while the leads are retained. New electrodes
are usually connected -to the leads by a snap-on connection.
There are a number of problems associated with
HOG electrodes of this type. For one thing, the multiplicity
of separate leads means that the leads are continuously
getting twisted together, thus creating storing and handling
problems. With the twisted leads, it is also a problem Jo
.
1 assure that proper connections are effected, even with
color coding or similar attempts to minimize erroneous
connections Also, movement of the leads creates electrical
signals, possibly by a piezoelectric-type effect, which
cause distortion of the HOG signal with what are commonly
known as motion or cable artifacts. Further, voltage
potentials between the electrodes can produce displacement
of the baselines of the HOG signals or traces by an effect
known as DC offset which can, in severe cases, preclude
the obtaining of an HOG trace. Variations of the DC offset
with time produces a drift of the HOG baseline that further
complicates evaluation of the HOG signals. Still another
problem associated with HOG electrodes is the existence
of noise on the HOG trace occurring as a result of too
high of an impedance between the electrode and the patient's
body. The existence of too high an impedance is frequently
compounded by the fact that the electrodes are too rigid
to accurately conform to the portion of the body on which
they are located, so that the area of contact between the
electrode and the body is reduced, thus increasing the
resistance or impedance (contact impedance) of the electrical
circuit at that point. In most HOG electrode arrangements,
the snap for connecting the lead to the electrode is right
over the center of the electrode, so that any tension on
the lead tends to lift the electrode from the body and
0 hence increase the impedance. Fluctuations in the tension
on the lead will also vary the contact impedance at the
electrode-body interface by changing the pressure on the
gel and thereby form another source of artifacts.
Conventional defibrillator utilize a purify pad-
dies -to which handles are attached for an operator to press
the paddles against the patient's body. A saline gel is
placid on the peddles before they are applied to the patient
to provide the desired interface between the peddles and
the skin of the patient. us the paddles are pressed against
the chest of the patient, a high volt pulse of defibril-
feting energy is passed to the patient's body by actuation of discharge control buttons in the paddle handles.
One of the most disadvantageous features of the
conventional defibrillator is that the operator is immediately
, adjacent the point of discharge. Thus, the risk that the
operator will get shocked is no insignificant.
From the standpoint of efficacy, a major disadvan-
tare of the conventional defibrillator paddles is that
both paddles are applied to the chest of the patient.
Testing has shown that for the best results in defibrillation
it is desirable to have one of the defibrillating electrodes
on the front of the body and the other on the back. Not
only does this provide more current to the heart to increase
the chances of a successful conversion (resuscitation by
converting the heart from fibrillation to a life-sustaining
rhythm), but it also reduces localized current densities,
which test results suggest produces less myocardial damage.
It is, of course, very difficult, if not almost impossible,
in an emergency situation to prop a patient up so that
one paddle can be pressed against the chest and the other
against the back of the patient.
Yet another disadvantage of having both paddles
on the chest of the patient is that a conducting path can
be established over the skin ox the patient from one paddle
to the other, thus reducing the energy passed through the body
tissue to the heart and also increasing the chances that a patient
may be burned at the paddles A further negative aspect of con-
ventional paddles is that they are very difficult to apply
,
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- ::,, , . ,;.
I Lo
1 to a patient that is draped for surgery or to whom a keyword-
pulrninary resuscitation Cal device is attached. Still
another problem with convention paddle defibrillator is
that the paddle--to-skin impedance may be too high, thereby
causing energy loss and increasing the risk of skin burns.
A number of factors contribute to this undesirably high
impedance, one of them being the rigidity of the paddles
which prevents them from sufficiently conforming to the
portion of the body to which they are applied. This problem
may be overcome to some degree by pressure applied to the
handles, but other factors such as insufficient area, less
desirable contact metals and the use of low-quality gels
still make the impedance problem one of concern. It may
be noted that an insufficient paddle area also provides
less desirable current density patterns.
Finally, conventional paddle defibrillator have
the disadvantage that when a patient begins fibrillation
the paddles must be golfed before being applied to the
patient. The greater the time between the onset of
fibrillation and the application of a defibrillation
pulse, the greater the possibility that the patient will
not be successfully converted.
Some of these problems with paddle defibrillator
have keen at least partially resolved by a disposable defibril-
later electrode set known as the "BI-PAK" sold by Zonks
Corporation. While this device deals with the basic problem
of a fron~-to-back anterior posterior electrode placement,
the impedance characteristics may be improved upon. In
addition, the '3BI-PAK" does not provide for the connection
I of the electrodes to a separate HOG or to an Essay
In order to return RF energy entering the body from
an electrosurgical knife, an ESSAY return pad is normally placed
under or attached to the patient, with a conducting lead
11
.9
extending back to the ESSAY return terminal. Various silapcs
and sizes of these return pads have been utilized, as well
as a variety of conducting materials.
- Since the RF currents introduced Pinto -the body
during the electrosurgical process are relatively large;
there is a continual problem of extracting this RF energy
from the patient's body without heating the pad and burning
the skin due to current concentrations at the ESSAY pad.
Frequently patients are burned despite the efforts to
lo preclude such a result. Such burns usually occur as a
result of a non-uniform current density at various locations
of the ESSAY return pad, particularly about -the outer perimeter
thereof, which is referred to as an improper dispersion
of the RF current. Another problem of prior art ESSAY return
pads that does not appear to be recognized is the existence
of DC or low frequency shocking that occurs during
electrosurgical operations. Some of this undesired
. shocking is probably due to leakage currents reaching the
body through the ESSAY pad. However, it appears that some
DC or low frequency currents are an inherent aspect of
electrosurgical operations, due to rectification of the
RF signals during tissue cutting. With a continuous DC
or low frequency current path through the ESSAY return pad
and the lead back to the ESSAY, it seems that there exists
an ever-presen~ danger of shocking the patient by us-
desired DC and low frequency signals during an electrosurgical
operation.
Apart from the problems associated with the HOG,
defibrillator and SUE electrodes individually, significant
problems are encountered when more than one of these instruments
is used at the same time. Thus, while the patient
¦ .
is being monitored by an HOG, fibrillation may comlncnce
and it is necessary to apply a defibrillating pulse of
energy to save the patient. Similarly, during an
electrosurgical operation, the condition of the patient's
heart will frequently be monitored by an HOG. Further,
it may also be necessary to defibrillate durirly the
electrosurgical operation.
Pulses of defibrillation energy while COG
electrodes or an ESSAY return pad are connected to the
patient may produce burns under the electrodes or pad,
as well as damaging the HOG and ESSAY instruments. Isle
voltage protection circuits have been utilized Jo pxev~nt
these occurrences. Louvre, the recovery time for an HOG
trace after application of a defibrillator signal may take
anywhere from a few seconds to over a minute. Loss of
the HOG trace at the time of defibrillation it particularly
crucial since it is imperative to know if the defibrillation
shock was successful in terminating the fibrillation. Also,
while the high voltage protection circuits protect the
patient from burns and the HOG from damage, they also tend
to prolong the recovery time for the HOG trace.
RF signals from the ESSAY create additional problems
for the HOG, as these relatively high energy signals can
create burns under the HOG electrodes, as well as significantly
interfering with the HOG trace (especially by lower harmonic
distortion). Filter circuits have been utilized to protect
the HOG from such RF interference, but such filters frequently
reduce the amplitude of the HOG trace so that it becomes
difficult to analyze
Jo 30 One of the primary problems occurring at the
prosily time is that efforts have been directed to isolate
the ERG the ESSAY and the defibrillator from one another
to prevent the problems referred to above. Ilowever, these
attempts at isolation have precluded the instruments from
having a common reference, so that an additional hazard
is created by potential differences between the instruments
themselves.
Sommelier OF THE invention
With the present invention, a single pair of
electrode elements may be utilized to selectively convey
electrical energy between the body of a patient and a
monitoring device a stimulating device and a therapeutic
device. (While thy definitions set forth above are useful
for purposes of this discussion, it should be realized
that the physiological electrode system described herein
also has applicability to devices that cannot be strictly
classified. For example, in impedance cardiography, signals
in the therapeutic frequency range are used to chart
physiological changes for purposes of monitoring.) Each
of these instruments may be connected to the patient's
body through the electrode elements by itself or in
combination with one or more of the other instruments by
means of an appropriate interrelating arrangement. Protective
features are incorporated into the physiological electrode
system to minimize or eliminate the risks of injury to
a patient and damage to one of the instruments.
For purposes of illustration and ease of
I.......... ....
expulsion the remainder of the summary description will
relate to an HOG (monitoring device), a defibrillator
(stimulating device) and an ESSAY (therapeutic device). A
singly pair of electrode elements are attached to the body
of a patient to provide for COG monitoring and defibrillation
of the patient and to provide a return path for RF energy
inserted into the patient's body during electrosurgery.
Preferably, the electrode elements are part of a
disposable electrode set that includes the electrode elements,
a connecting plug and a pair of conducting lines (the term
"conducting" being used herein in the sense of the capability
of electrical current conduction, not the existence of such
current conduction at any given time), each of the conducting
lines extending from the ply Tony associated one of the
electrode elements. The plug is standardized for connection
to the HOG, the ESSAY or the defibrillator, or any desired
combination thereof. In a preferred embodiment, the
connecting plug has four contacts with two of the contacts
each having a first end of a respective one of the conducting
lines connected thereto. The other two contacts are electrically
connected or jumper Ed to provide a DC cord fault test circuit
for the ESSAY, as described in more detail below Also,
capacitive coupling, such as one or more capacitors, may be
connected from one or both of the conducting lines to the
jumper Ed or short circuited contacts to provide a path for
the return of RF signals to the ESSAY.
The electrode elements must be capable of meeting
eye varying requirements of monitoring electrodes, stimulating
electrodes and therapeutic electrodes. Thus, for HOG
; 30 monitoring r when the electrode elements are attached to
the body the impedance between the electrode elements and
the skin of the patient should be as small as possible
... . .
;
to prevent undesired attenuation of the HOG signals. Since
the most effective approach for minimizing noise on the
HOG trace is to have a high input impedance at the COG
with a low impedance at the electrode element-to-body
S interface, minimizing the element-to-skin impedance also
-aids in the reduction of interference. Another important
aspect of the HOG electrode is that the polarization of
the electrode material by a high energy electrical signal,
such as a defibrillator pulse, should rapidly dissipate
in order to permit recovery of the HOG trace. This recovery
time should he as short as possible to permit as nearly
continuous monitoring of the heart as possible. till
further, DC offset potentials between the electrode elements
should be minimal and should be as stable as possible.
With respect to handling of the ESSAY signals
at least one of the electrode elements should have a size
and shape that yields a desirable current distribution
to reduce heating and minimize the risks of the patient
being burned by an undesired current concentration at a
small area. Since such an area of concentration will
normally occur at the periphery of the electrode, desired
OF dispersion is primarily a factor of -the perimeter of
the electrode element Use of both of the electrode
elements for the RF return aids in dispersion of the RF
currents and further reduces the risk of burns.
Finally, the electrode elements must have a size
and shape, as well as a sufficiently low electrode element ¦
to-skin impedance when attached to the patient, to maximize
the transfer ox a desired pattern of stimulating energy
30 to the extents body while minimizing the risk of skin
- 10 -
burns. In view of the high energies involved in d~lbrillation,
the electrode elements must be capable of conducting such
high energy stimulating signals, as well as high energy
ESSAY brother therapeutic signals, without loss of any of
the desired characteristics of the electrode elements.
In order to be able to achieve all of these
characteristics, the preferred embodiment disclosed herein
utilizes circular electrode elements each having an
electrically conductive plate sufficiently thin to permit
the conductive plate to substantially conform to the area
of the patient's body to which it is attache. This
conductive plate may be formed entirely of a desired
conductive metal, or it may utilize a layer of the desired
conductive metal coated or plate over another conducting
base metal or even a non-conducting or partially conducting
supporting base. In any event, an outer surface of the
conductive plate is formed of the desired conductive metal.
An electrically conductive medium, such as a saline gel,
is located between the outer surface of the desired
conductive metal and the skin of the patient to improve
electrical energy transfer between the patient and the
conductive plate. A chloride of the desired conductive
metal is located between the conductive metal an the skin
of the patient, such as by forming a layer of the chloride
directly on the metal or by locating the chloride in the
conductive medium. An appropriate adhesive, such as an
adhesive layer on a supporting plastic foam structure,
is utilized to attach the electrode element to the patient
While any suitable conductive metal and its chloride
may be utilized, it has been found that tin and storylines
chloride are particularly useful in meeting the variety
of requirements established for these multi-function
.1 , r
to
1 electrode elements. accordingly, in a preferred embodiment
disclosed herein, the conductive plate may be formed entirely
of tin, such as a tin foil, or by a coating of tin over
a conducting base plate such as brass, or by a layer of
tin over a non-conducting substrate such as a plastic
material. Ire stuns chloride may be directly applied
to the tin surface, such as by spraying a thin layer
thereon, or it may be located in the conductive medium.
However structured, the novel use of a metal-metal chloride
for defibrillation and ESSAY return is made particularly
feasible by the discovery of the highly advantageous
features of the tin-stanno~s chloride electrode element.
Not only does thy tin-stannous chloride electrode element
exhibit highly advantageous features for the multi-function
electrode, but it has also exhibited superior characteristics
for single function usage, such as HOG monitoring. In
addition to its extremely desirable operating characteristics,
the tin-stannous chloride electrode element is highly resistant
to disfiguring corrosion that easily occurs in the presence
of a saline gel, and thus this structure provides a much
longer shelf life for disposable electrodes.
While the electrode elements could be directly
connected to the instruments, as indicated above the desired
approach by applicant is to utilize a disposable electrode
set with conducting lines running from the electrode
elements to the connecting plug. This connecting plug
could ye made to directly engage the desired instrument,
but the preferred approach disclosed herein is to utilize
a separate cable having an appropriate connector to engage
the plug at one end and being electrically joined to the
, . . .: .
desired instrument or instruments at the other end. These
cables may then be relatively pernlanent, with only the
electrode sets being replaced for each usage.
For the HOG cable, an HOG monitor connector at
one end of the cable is utilized to attach the cable to
the HOG device or instrument. An HOG electrode connector
at the other end of the cable is adapted to engage the
connecting plug of the disposable electrode set. pair
of conducting leads extend from the HOG monitor connector
to the HOG electrode connector to connect the electrode
elements directly to appropriate HOG inputs.
Since most HOG instruments require a minimum
of three inputs, the connection of the electrode elements
directly to two of the inputs will not provide a suitable
trace. Accordingly, it is necessary to provide a body
tissue impedance simulating circuit so that the HOG thinks
that it is receiving three inputs from the body This
body tissue impedance simulating circuit may take any
suitable form ranging from a single resistor to a multiple
resistive-capacitive network. Although this body tissue
impedance simulating circuit may be placed at any appropriate
position in the cable, it has been found particularly desirable
to locate it in the HOG electrode connector, with a third
conducting lead running from the circuit to a third input
of the HOG.
In order to prevent high frequency interference,
such as from the RF signals used in electrosurgery, a low
pass filter is located in the cable. Similarly, to protect
the HOG from high energy signals such as a defibrillator
. 30 pulse, a high voltage protection circuit is utilizedin
1 23
the cable. Finally, in order to further minimize the risk
of RF burns occurring at the HOG electrode elements, an
RF choke filter network may be located in the cable. While
all of these circuits may be located at any appropriate
place in -the cable, the low pass filter, the high voltage
protection circuit, and the RF choke filter network are
preferably located in the HOG electrode connector.
By placing all of the signal attenuation
elements at the end of the cable away from the HOG
instrument, an additional benefit is achieved. This
additional benefit is a significant reduction, virtual
elimination, of cable motion artifacts. Presumably, this
very significant reduction of cable motion artifacts occurs
as a result of the piezoelectrically induced signals being
dissipated across the impedance in the HOG electrode
connector, rather than across the impedance of the HOG
itself.
Therefore, with the present invention, HOG
monitoring may be achieved with a single cable that
overcomes the "rats nest" problems of prior art multiple
HOG leads. In addition, the HOG instrument is protected
from high frequency interference and potentially damaging
high energy signals. Further, the possibility of RF burns
occurring at the electrode elements Jay be reduced. By
I using the HOG cable with the electrode elements of this
invention, noise interference may be further reduced, DC
offset potentials and drift may be minimized, and the
recovery time for an HOG trace after application of a
defibrillator pulse may be minimized, all while providing
I a stronger HOG trace signal
With respect to the defibrillator cable, there
':
I are two varicltions. In one of these variations, the convolutional
defibrillator paddles are completely replaced. In the other,
an adopter is provided for permitting use of the defibrillator
paddle with the electrode elements of this invention.
By using the flat disposable electrode elements of
this invention, a desired front-to-back placement of the
defibrillating electrodes may be easily achieved. This permits
the application of more current to the heart -to greatly increase
, the chances ox successful defibrillation. At the same time,
the provision of smaller and more uniform current densities
over the entire heart considerably reduces the risk of myocardial
damage. In addition, by being able to have the electrode element
already in place before fibrillation occurs, the time elapsed
between the onset of fibrillation and -the application of a
defibrillatillg pulse is minimized. This aspect of pro-
application also permits defibrillation of patients draped for
surgery or to whom CUR equipment is attached
A particularly useful placement of the electrodes
is to have the front electrode located at the apex or left leg
position, while the back or posterior electrode is located at
the right arm position No only does this electrode element
positioning yield very desirable defibrillating results, but
the apex positioning of the front electrode element puts this
element in a generally nunnery portion of the body and the
positioning of the posterior electrode removes it from the
uneven spinal area, thus minimizing electrode-to-skin impedance
problems and difficulties in getting proper adherence of the
electrode element to the skin. Further, the apex positioning
of the front electrode keeps this electrode from interfering
with cardiopulmonary resuscitation (CUR) efforts that may have
to be taken with respect to the patient. This means that HOG
monitoring of the heart may be continued without disruption,
and that the electrode elements can remain in position for
;vJ,~ 3
1 immediate defibrillation if the heart should begin to
fibrillate.
In -the first version of the defibrillator cable,
a defibrillator instrument connector is utilized to replace
the connection of the conventional paddles -to the
defibrillator. pair of conducting leads in the
defibrillator cable extends from the defibrillator
instrument connector to a defibrillator electrode
connector through which the defibrillator outputs may
be connected directly to the electrode elements. A discharge
control module is located in the defibrillator cable,
preferably adjacent the defibrillator instrument end of
the cable. The discharge control module has four plunger
actuated switches connected to the defibrillator through
lo another pair of conducting leads. All four plunger actuators
must be depressed in order for a pulse of de~ibrillating
energy to be passed to the patient through the defibrillator
cable. By locating the discharge control module in the
defibrillator cable, defibrillating control is thus spaced
2Q from the patient to protect the operator from electrical
shocks
An HOG output connector is provided on the
discharge control module. This HOG output connector is
¦ adapted to engage the HOG electrode connector on an HOG
cable to permit an HOG instrument to be connected to the
electrode elements through the defibrillator cable. The
HOG output connector it connected to the conducting leads
in the defibrillator cable through a high voltage protection
circuit. An impedance matching Sixty may be connected
between the high voltage protection circuit and the HOG
output connector in order to improve the HOG signal and
minimize interference. This circuit is particularly
important in situations where the HOG signal is not only
. 3
l being displayed on a local instrument but is also being
transmitted to a central unit, such as a base hospital
for a paramedic system.
While the most logical approach for use of the
defibrillator cable is to utilize the multifunction electrode
set described above, so that the electrode elements may
be utilized for COG monitoring and are already in place
if defibrillation is required, electrode elements for just
HOG monitoring ma be made less expensively Accordingly,
lo an option has been provided by which a pair of HOG electrodes
may be utilized to provide monitoring through the defibrillator
cable. separate receptacle for -the HOG electrodes is
located on the defibrillator electrode connector. In order
to prevent the HOG electrodes (which could not handle
defibrillator pulses or ESSAY return signals) from being
accidentally connected to the other receptacle, the HOG
electrode plug it structured so that it will only fit the
HOG only receptacle. In passing it may ye noted that these
HOG electrodes could be used with the HOG cable, if only
HOG monitoring is desired.
An additional pair of conducting leads extends
from the ECG-only receptacle to the HOG output connector
side of the high voltage protection circuit in the discharge
control module. If an impedance matching circuit is utilized,
the connection would be between the high voltage protection
circuit and the impedance matching circuit.
With reference to the paddle adapter version
of the defibrillator cable, an adapter unit is secured
to the end of the defibrillator cable away from the
defibrillator electrode connector The adapter includes
, . :; - . :-
I; - : . ; . . - .,
l -
a pair of conducting plates upon which convcntiorlal
defibrillator paddles may be located. An insulating
divider between these plates prevents accidental shorting
of the defibrillator paddles. The conducting plates are
connected to the defibrillator electrode connector, which
is the same as the defibrillator electrode connector
utilized with the discharge control module version, by
a pair of conducting leads. A button actuator for a witch
extends up through each of the conducting plates, so that
when the paddles are properly positioned on the plates
the button actuators close switches in a battery powered
DC circuit to actuate an audible alarm buzzer. Actuation
of the buzzer indicates to the operator that a proper
conducting circuit is completed to apply a defibrillator
lo pulse to the patient by actuating the discharge controls
on the conventional paddles. The buzzer also serves to
warn any other attendants to move away from the vicinity
of the patient.
An HOG cable may be permanently affixed to the
adapter, with an appropriate body tissue impedance simulating
circuit for this HOG circuit located in the adapter. An
HOG monitor connector is on the other end of the HOG cable.
Alternatively, plug or connector for engaging an HOG
electrode connector could be provided. A high voltage
protection circuit is located between the body tissue impedance
simulating circuit and the conducting leads extending to the
defibrillator electrode connector. A supplemental HOG output
connector is also located in the adapter and connected between
the high voltage protection circuit and the body tissue
Jo 30 impedance simulating sixty The conducting leads from
the ECG-only receptacle in the defibrillator electrode
.~......... . .. . . .
. '
1 connector are also connected between the Howe voltage
protection circuit and the body tissue impedance simulating
circuit.
With either of the defibrillator cable variations,
S defibrillator discharge control is achieved at a distance
removed from the patient for optimum safety of the operator.
on addition, the electrode element structure of relatively
large size, flexibility and a metal-metal chloride,
specifically tin-stannous chloride, conducting plate
results in reduced electrode element to skin impedance
and a better current density distribution. Further, the
fact that the electrodes aye propelled saves valuable
time in applying a defibrillating pulse to the patient
if fibrillation should occur. Additionally, the use of
disposable electrodes permits accurate control of the type
ox gel utilized as gels not specifically manufactured
for defibrillation use can affect defibrillating operation.
An ESSAY cable has a pair of conducting leads extending
from an ESSAY instrument connector -to an ESSAY electrode connector.
These conducting leads extend to the jumper Ed or short-
circuited contacts in the plug of the disposable electrode
set to form a DC cord fault test circuit. A source of
DC potential, such as a battery, in the ESSAY passes a signal
over the conducting leads to actuate the ESSAY for operation.
Thus, the cord fault tester assures that the ESSAY electrode
connector and the connecting plug ox the disposable electrode
set have been properly joined to provide a return path
for the ESSAY I energy before the ESSAY may be operated
Capacitive coupling between the conducting leads
I; 30 and the contacts of the ESSAY electrode connector thatengage
1 the other two contact of the connecting plug provides a
path for OF signals from the electrode elements to the
conducting leads This capacitive coupling preferably takes
the form of a first capacitor connected from one of the
S contacts to one ox the conducting leads, a second capacitor
connected from the other contact to the other conducting
lead and a third capacitor connected between the two
conducting leads This capacitive coupling essentially
provides a high pass filter that prevents DC and low
frequency current from passing to or from the ESSAY instruments.
Thus by using high power capacitors, the SUE may be fully
protected from high energy~DC signals, such as defibrillator
pulses. In addition, the capacitive coupling protects the
patient from low frequency and DC currents that are potentially
capable of causing fibrillation. These low frequency and
DC currents may either be leakage currents from the ESSAY or
currents resulting from rectification of the RF current
during the electrosurgical operation.
Rather than utilizing the disposable electrode
set with its two electrode elements, the FLU cable may be
utilized just for ESSAY return. For this purpose, a single
RF return pad constructed in the same fashion as the electrode
elements described above may be utilized, although a less
expensive return pad using a suitable conducting material
I such as aluminum, instead of the metal-metal chloride structure
that is particularly adapted for defibrillating and HOG usage.
A conducting line extends prom the pad or electrode clement
to a contact of a connecting plug, which has two other
contacts jumper Ed or short circuited for the cord fault test
i 30 circuit. Capacitive coupling is provided in the ESU-electrode
connector to capacitively connect the conducting line to
the conducting leads in the ESSAY cable Alternatively, or
supplemental, this capacitive coupling may be achieved
I-
1 l¦ in the connecting plug by a capacitor connected bison
the conducting line and the jampacked contacts. While a
single conducting line as described provides an operative
system, in the preferred embodiment disclosed herein a
second conducting line is utilized between the return pad
and the connecting plug, so that the ESSAY cable has the
form described in connection with the two electrode elements.
However, the connecting plug and the ESSAY electrode connector
are designed 50 that this connecting plug cannot be engaged
with a connector through which defibrillator pulses or
HOG signals are intended to pass, since the single ESSAY
return pad could not function for defibrillation or HOG
monitoring.
Returning to the ESSAY cable adapted to utilize
the disposable electrode set having a pair of electrode
elements, an ESSAY cable connector is provided in the ESSAY
cable intermediate the SO instrument connector and the
ESSAY electrode connector. This ESSAY cable connector has
a prong arrangement the same as the connecting plug, so
that an HOG electrode connector or a defibrillator electrode
connector may be engaged therewith. A second pair of
conducting leads extend from this plug portion of the ESSAY
cable connector to the two non-jumpered contacts in the
ESSAY electrode connector low pass filter, preferably
located in the ESSAY cable connector, is connected in this
second pair of conducting leads to prevent the RF signals
from passing to an COG or defibrillator connected to the
ESSAY cable connector. In order to provide fox the use of
all three types of instruments in connection with the
jingle pair of electrodes, a defibrillator may be
I I
. , of
Canada to the SUE cable connector, all an HOG may be
connected to the discharge control module or adapter of
the defibrillator cable.
- With the interconnections provided by this
invention, a common reference is established for all of
the instruments connected -to the electrode elements. This
common reference minimizes the problems of dangerous leakage
between the instruments and also provides the basis for
minimizing interference at one instrument resulting from
the output of another instrument. Therefore, this invention
provides physiological electrode systems in which a single
pair of disposable electrode elements may be simultaneously
connected to a plurality of instruments for performing
a variety of functions. Not only does the invention provide
for a multiplicity of functions, but it produces improvements
in each of those junctions whether achieved through the
multi-function arrangement or whether connected for separate
operation.
These and other objects, advantages and features
of this invention will hereinafter appear, and for purposes
of illustration, but not ox limitation, exemplary embodiments
of the subject invention are shown in the appended drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIGURE 1 is a schematic diagram of a preferred
embodiment of the present invention showing three instruments
simultaneously connected to provide multiple functions
Jo
.. . .
through a single pair of electrode elements.
FIGURE 2 is a more detailed view of the electrode
elements connected in a preferred embodiment of a disposable
electrode set.
FIGURE 3 is a schematic diagram of the pin
arrangement of the connecting plug in the disposable
electrode set of FIGURE ED
FIGURE 4 is an enlarged exploded view of one
of the electrode elements of FIGURE 2.
FIGURE 5 is a schematic diagram of a preferred
embodiment of an HOG cable.
FIGURE 6 is a schematic illustration of the HOG
cable of FORE 5 depicting in greater detail certain
features thereof.
FIGURE 7 is a schematic circuit diagram of the
HOG cable of FIGURES 5 and 6.
FIGURE 8 is a schematic diagram illustrating
another embodiment of the HOG cable of FIGURE 5.
FIGURE 9 is a schematic circuit diagram of the
HOG cable of FIGURE 8.
FIGURE 10 is a schematic diagram of a preferred
embodiment of a defibrillator cable.
FIGURE 11 is a more detailed schematic diagram
of the defibrillator cable of FIGURE 10.
FIGURE I is a schematic circuit diagram of the
defibrillator cable of FIGURES 10 and 11.
FIGURE 13 is a schematic diagram of the pin
arrangement in the connecting plug for the HOG electrodes
illustrated in FIGURE 12.
ox 30 FIGURE I is a schematic diagram of another
- 23 -
.~,
I
. .
1 embodiment of the defibrillator cable.
¦ FIGURE 15 it a more detailed schematic diagram
of the defibrillator cable of Figure 14.
FIGURE 16 is a schematic circuit diagram ox the
5 defibrillator cable of FIGURES I and 15.
. FIGURE 17 is a four part schematic diagram
illustrating conventional and a new defibrillator
electrode placement.
FIGURE 18 is a schematic diagram of-a single
pair of electrode elements simultaneously connected to
a defibrillator and an HOG.
FIGURE 19 is a more detailed schematic diagram
of the system of FIGURE 18.
FIGURE 20 is a schematic diagram of -the pin
placement in the connections plug for the electrode set
illustrated in FIGURES 18 and lo
FIGURE 21 is a schematic diagram of a preferred
embodiment of an ESSAY cable.
FIGURE 22 is a more detailed schematic diagram
of the ESSAY cable of FIGURE 21.
FIGURE 23 is a schematic diagram of a, preferred
embodiment of a disposable ESSAY return pad swept
FIGURE 24 is a schematic circuit diagram of the
disposable ESSAY return pad set of FIGURE 23 and the ESSAY
cable of PHARAOH 21 and 22.
FIGURE 25 is a schematic diagram of the pin
placement in the connecting plug for the ESSAY return pad
set of FIGURES 22 and 23.
FIGURE 26 is a schematic diagram of an ESV and
. 30 an HOG simultaneously connected to a pair of electrode
so
elemellts .
FIGURE 27 is a more detailed schematic diagram
of the system of FIGURE 26.
FIGURE 28 is a more detailed schematic diagram
of the system of FIGURE 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment of a physiological electrode
system constructed in accordance with this invention is
illustrated in FIGURE 1. A single pair of electrode
elements 31 and 33 are simultaneously connected to an HOG
instrument or device 35, a defibrillator instrument or device
37, and an ESSAY instrument or device 39. Of course, -these
instruments could be any type of monitoring, stimulating
and therapeutic devices/ as defined above.
Electrode elements 31 and 33 could be any type
of suitable electrode placed on the body of a patient, but
in this preferred embodiment these electrode elements are
single use elements arranged in a disposable electrode set.
In this preferred embodiment, electrode element 31 is
approximately 8 centimeters in diameter and electrode
element 33 is approximately 12 centimeters in diameter,
although any appropriately sized electrodes may be utilized.
An interrelating arrangement includes conducting lines I
and 43, a connecting plug 45, an ESSAY cable 47~ a defibrillator
cable 49 and an HOG cable 51. Details of this interrelating
arrangement and of the protective circuits and approaches
that permit the simultaneous connection of a plurality of
instruments -to a single pair of electrode elements to achieve
a multiplicity of functions are set forth hereinafter.
A disposable electrode set 53 is shown in more
1 detail in FIGURE 2. This disposable electrode set includes
the electrode elements 31 and 33, conducting lines 41 and
43 and the connecting plug 45. Connecting plug 45 is a
standardized plug that may be connected to the ESSAY cable
47, or the defibrillator cable 49, or the HOG cable 51.
Although the connecting plug 45 may be constructed with
two or three contacts for certain applications, in order
to achieve the desired multifunction capabilities, plug
if 45 should have four contacts.
While plug 45 could be any appropriate type of
connecting plug, in this preferred embodiment connecting
plug 45 has the structure illustrated with projecting
insulating sheathes 55, in which are located conducting
prongs or contacts 57. Conducting prongs or pros 57 may
either be solid male prongs, or hollow, female prongs.
These prongs may be arranged in appropriate patterns to
preclude undesired engagements of the connector ply with
other connectors. For example, as illustrated in FIGURE
3, the outer two prongs 59 and 61 are female, while the
inner two prongs 63 and 65 are male. In order for this
plug to engage a connector, the connector must have male
prongs at the outer contacts and female prongs at the inner
contacts. Electrode set 53 is for use with all types of
functions, so the HOG, the defibrillator or the ESSAY, may
be connected to electrode elements 31 and 33 separately
or in various combinations, so long as the connector on
the cable utilized has the appropriate pin arrangement
Referring back to FIGURE 2, it may be seen that
connecting plus 45 has an easily assembled structure
consisting of two casing components 66 and 67. Although
1 ¦ any appropriate structure could be utilized, of course,
-this structure provides a complete and yet easily assembled
connecting plug
A preferred assembly or structure of the elcc~rode
elements 31 and 33 is depicted in FIGURE 4. Although various
shapes of electrodes might be utilized, it has been found
that the circular or round shape disclosed herein has
certain advantages, as discussed in more detail hereinafter.
Also, it may be noted that the description of the circular
electrode element shown in FIGURE 4, which has been
identified as electrode element 33 for purposes of
illustration, relates to the preferred structure of all
of the electrode elements discussed in this application.
A circular foam base 67 having a layer of adhering
material (adhesive) 69 on one side thereof provides the
bottom or basic layer of the electrode element. While
base 67 is preferably formed from a plastic foam, it may
be made of any suitable insulating material that is
relatively rigid but with some degree of flexibility.
Labeling may be affixed to the side of base 67 away from
the adhesive layer 69, although this labeling should no
be sized or located in a way that will not significantly
restrict the flexibility of the electrode element.
An electrically conductive plate 71 is then
secured to the adhesive layer 6g of base 67. Conductive
plate 71 preferably has a circular shape with a desired
electrically conductive petal forming at least one surface
thereof. A chloride ox the conductive metal is located
to be between the conductive metal and the spin of the
patient, such as by spraying a layer 72 thereof on the
conductive metal Sirius
Although it is possible that other metal-metal
' ' bsj '
1 ¦ chloride combinations could be successfully utilized
(silver-silver chloride has been utilized for HOG
electrodes), an important aspect of -the present invention
is the discovery that a tin-stannous chloride combination
provides unexpected highly significant advantages over
other types of materials. (I-t is possible that alloys
formed primarily of tin would also provide some or all
of the desired characteristics when used with stuns
chloride.) Thus, measurements have revealed that the -tin-
stuns chloride electrode element can be utilized to
produce a very low impedance between the electrode element
and the skin of the patient. This result is especially
significant in the case of HOG monitoring and defibrillation
In addition, the tin-stannous chloride electrode element
conducts the high energy currents produced by defibrillation
without apparent deterioration, while at the same time
recovering very rapidly from the polarization caused by
these high energy levels. In fact, the recovery ox an
HOG trace after the application of a defibrillating pulse
is almost instantaneous, showing a significant improvement
over prior art HOG recovery times. Measurements to date
have indicated that the DC offset produced by utilizing
tin-stannous chloride electrode elements is well within
thy accepted range and comparable or superior to existing
devices. Very significantly, however, these measurements
also show that the DC offset potential resulting from the
utilization of tin-stannous chloride electrode elements
was very stable, so that only a very small amount of drift
of the HOG trace occurred.
The structure of electrically conductive plate
71 can take any of a variety of acceptable forms For
.
. . . .
l example, plate 71 could be formed completely of tin, such as
a tin foil, or it could be a tin coating over a substrate.
Lois substrate could be another conducting metal, such
as brass, or it could be a non-conducting material, such
as a plastic In the preferred embodiment disclosed herein,
a tin foil has been utilized
In order to achieve electrical conduction between
the conductive plate 71 and the conducting line 43, an
electrical connection must be made between the conductive
lo plate 71 and conductors 73 of line 43, from which the
insulation has been stripped. Any suitable approach could
be utilized, but in this preferred embodiment it has been
found that the end of line 43 and the conductors 73 may
be secured to the adhesive layer 69 before the tin plate
71 is adhered, so that when plate 71 is secured to the
adhesive layer 69 a good electrical connection is established
and maintained between the conductors 73 and the tin plate
71.
A porous foam disc 75 is then placed over the
tin conductive plate 71. The porous foam disc 75 has been
provided with lugs or ears 77 extending outwardly from
the perimeter thereof to aid in securing disc 75 in the
structure. The porous foam of disc 75 is adapted to receive
and maintain an electrically conductive medium, such as
a saline gel, to provide a good conductive path between
the tin plate 71 and the skin of the patient. Any suitable
type of conductive medium or gel may be utilized that meets
the requirements for the various functions to be performed
thrush the electrode elements. Particular attention
however, must be directed to the selection of a conductive
medium or gel that provides the desired results during
application of the high energy defibrillating pulses.
It has been noted that the stuns chloride may
be associated with the tin plate 71 by spraying a layer 72
of the stuns chloride on the plate. This layer need no-t
cover the whole surface of the plate 71, but could be in
a smaller selected area, or in a number of selected areas.
Louvre, another possibility is to locate the stuns
chloride right in the conductive medium, so that it is not
necessary to actually affix the stuns chloride to the
conductive plate 71.
A holding ring 79 is then positioned over the
porous foam that contains or will contain the conductive
medium. Ring 79 may be formed of any suitable material,
lo but for ease of manufacture it is formed of the same foam
material as base 67, in this preferred embodiment. Ring
79 is secured to the adhesive layer 69 on base 67 over the
lugs or ears 77 to fix the foam disc 75 in place. In passing,
it should be noted thaw other methods of securing the foam
disc 75 in place could be utilized and that the extending
lugs 77 are merely exemplary of a fastening approach utilized
in this preferred embodiment. It should also be noted thaw
ring 79 will normally be somewhat thicker than the assay I
as it provides a "pull for the gel absorbed in the porous
foam of disc 75. An adhesive layer 81 is formed on the top
of ring 79.
Finally a sealing cover 83 is secured to the adhesive
layer 81 of the ring 79. The purpose of cover 83 is to provide
a substantially airtight or hermetic seal to prevent the vet in
the disc 75 from drying out. This cover may be formed
.'
.
of any suitable material, but a thin, rigid, transparent
plastic is utilized in the preferred embodiment disclosed
herein. During operation, the cover 83 is removed from
the electrode element and the electrode clement is then
attached to the patient by means of the adhesive layer
81 on ring 79.
Among the advantages of the circular electrode
elemerlt is the uniform flexibility -that is provided, so
that the electrode element and the conductive plate 71
may accurately conform to the shape of the portion of the
body on which the electrode element is placed. By being
able to accurately conform the electrode and the conducting
plate to the shape of the body, the largest possible conducting
area is maintained, which reduces the contact impedance between
the electrode element and the skin of the patient. This
low impedance is espy fly important for HOG monitoring
and defibrillation. With respect to the ESSAY, the circular
nature of the electrode element and the conductive
plate 71 provides the most uniform possible current
distribution for RF dispersion. The flexibility of the
electrode to conform to the shape of the body portion to
which it is attached also contributes to a uniform contact
area to prevent current concentrations that could result
in RF burns.
I A schematic illustration of a preferred embodiment
of the COG cable 51 appears in FIGURE 5. Cable 51 is a
shielded cable having an HOG monitor connector 85 at one
end thereof. This HOG monitor connector 85 is adapted to
engage the input jack of a standard HOG instrument. The
HOG input jack is constructed to receive three or more
...
HOG inputs.
At the other end of HOG cable 51 there its an
HOG electrode connector 87. This HOG electrode connector
87 may be any appropriate arrangement to engage the
connecting plug 45, but preferably this HOG electrode
connector 87 has a standard configuration that may also
be used with the ESSAY and defib.rillating cables 47 and 49.
The preferred form shown herein is that ox a rectangular
box with enough internal space to receive the various
circuits included in the different electrode connectors
of the various cables. A receptacle 89 extends outwardly
from the box of connector 87 to engage the plug 45.
FIVE 6 is a partial circuit diagram of the
cable of FIGURE 5 illustrating the cable in more detail.
As may be seen, there are three conducting leads 91, 93
and 95 extending from the HOG monitor connector 85 to the
HOG electrode connector 87. A body tissue impedance
simulating circuit 97 is included in the connector 87,
together with a high voltage protection circuit 99. Body
tissue impedance simulating circuit 97 provides for the
use ox an HOG, which normally requires three or more inputs,
with only the two electrode elements 31 and 33. High voltage
protection circuit 99 is included to protect the HOG from
high energy signals, such as defibrillator pulses In
addition, a low pass filter 101 is located in connector
87 with the body tissue impedance simulating circuit 97
and the high voltage protection circuit 99. Low pass
filter 101 serves to minimize the interference from RF
signals, such as those produced by an ESV, and other
relet rely high frequency signals that can distort the
- 32 -
I
ERG trace and rewelder analysis difficult.
In the more detailed circuit diagram of FIGURE
7, it may be seen that the conducting leads 91 and 93 are
connected directly from two inputs of the HOG 35 (these
inputs having been designated A and C) to contacts of the
receptacle 89 (FIGURE I that will result in inputs A and
C being connected to the electrode elements 31 and 33.
Body tissue impedance simulating circuit 97, to which the
third HOG input B is connected by a conducting lead 95,
is represented as a single resistance 103. While a single
resistor may be appropriate in some conditions, the body
tissue impedance simulating circuit 97 may also involve
multiple resistor networks or resistive-capacitive networks.
The exact structure of the body tissue impedance simulating
circuit 97 is such that it will produce at the HOG the
appearance of three inputs rather than the two inputs that
are actually received. Either of the inputs B or C may
be the reference or ground lead for the HOG.
Low pass filter 101 is illustratively indicated
as a capacitor 105 and a resistor 107 connected in parallel
between lines 91 and 93. Of course, this circuit is repro-
tentative only end any appropriate low pass filter circuit
may be utilized.
High voltage protection circuit 99 is illustratively
depicted as a pair of series resistances 109 and 111 connected
in lines 91 and 93, respectively. Again, the high voltage
resistance circuit 99 may take any appropriate form,
although a pair of series resistors 109 and 111 will
normally suffice to provide the desired protection.
To further ensure against the establishmellt of
....
. . 'I
any conductive pain for RF signals, such as when only
smaller HOG electrodes are going to be connected to the
cable 51 which thus increases the risk of RF burns at
these electrodes, an RF choke filter 113 may be added to
connector 87, as illustrated in FIGURE 8. With reference
to FIGURE 9, an illustrative choke filter 113 includes
choke coils 115, 117, 119 and 121 and a capacitor 123.
Of course, this particular circuit is only representative
and any appropriate RF choke filter arrangement could be
employed.
Another variation of the circuitry that may be
employed is the addition of oppositely poled diodes 125
and 127 connected between leads 91 and 93 in the low pass
filter 101. Diodes 125 and 127 aid in the filtering of
relatively high frequencies that could distort or interfere
with the HOG trace, such as "shot" noise. While the
circuits 97, 99 and 101 could be located at any place in
cable 51, the placement of these circuits in connector
87 not only sLmplifles manufacture, but also aids in greatly
reducing motion artifacts by having all of the signal
attenuation located at the electrode end of the cable.
Artifacts produced by movement of the cables while HOG
signals are being obtained from a patient are dissipated
to a great extent across the impedances at this end of
the cable, with the result that very little effect therefrom
is experienced at the HOG instrument itself. Diodes 125
and 127 also aid in protecting the HOG from defibrillating
pulses by substantially short circuiting leads 91 and 93
through the high voltage protection circuit 99.
Defibrillator cable 49 is schematically illustrated
- 34 -
in Flyer loo A defibrillator instrument connector 129
is located at one end of cable 49, while a defibrillator
electrode connector 131 is positioned at the other and
thereof. Defibrillator electrode connector 131 his a
receptacle 133 to engage connecting plug 45. Connector
131 is also provided with a second receptacle 135 to engage
a connecting plug for a pair OX HOG electrodes, in the
event that it is desired to use cable 49 only for HOG
monitoring, without a defibrillating capability until a
lo connecting plug 45 is engaged with receptacle 133 and
electrode elements 31 and 33 are attached to the patient.
A defibrillator discharge control module 137
is located in cable 49. Discharge control module 137 has
four plunger actuators 139, 141, 143 and 145, all of which
must be depressed in order to pass a defibrillating pulse
through cable 49 to electrode elements 31 and 33 on the
patient. An HOG output terminal 147 has a plug portion
corresponding to connecting plug 45 to engage an HOG
electrode connector receptacle 89 to provide for HOG
monitoring through cable 49. Separate cable portions 149
and 151 extend from discharge control module 137 to the
instrument connector 129. Cable portion 149 contains the
conducting leads to carry the defibrillating current, while
cable portion 151 contains conducting leads for a discharge
control circuit.
From the partial circuit diagram on FIGURE 11,
more details of the cable 49 may be observed. Thus, it
may be seen that cable portion 151 contains the conducting
leads ]53 and 155, which are series connected through
switches 157, 159, 161 and 163, corresponding, respectively,
.,
I
to plunger actuators 139, 141, 143 and 145, Also, i-t may
be seen that cable portion 149 contains conducting leads
165 and 167 which continue through the discharge control
module 137~ to thus extend from the defibrillator instrwnent
S connector 129 to receptacle 133 in the defibrillator elector
connector 131. A high voltage protection circuit 169 is
connected between the HOG output terminal 147 and the
conducting leads 165 and 167. Another pair of electrically
conducting leads 171 and 173 connects the ECG-only receptacle
135 in connector 131 to the HOG output terminal 147.
Conducting leads 171 and 173 are connected to terminal
147 on the plug side of toe high voltage protection circuit
. 169~ so that this high voltage protection circuit also
protects an instrument connected to leads 171 and 173 from
the defibrillating energy on leads 165 and 167.
In the more detailed circuit diagram of FIGURE
12, further details of the defibrillation cable 49 may
be observed Thus, it may be seen that the high voltage
protection circuit 169 includes a pair of large series --
resistors 175 and 177 and a capacitor 179 connected across
the lines. It should be observed once again that this
is merely an illustrative circuit and that any appropriate
high voltage circuit arrangement could be utilized. It
. may also be seen that an impedance matching circuit including
a resistor 181 and oppositely poled diodes 183 and 185
is connected across the HOG output terminal 147~ While
this impedance matching circuit may be utilized in connection
with any HOG, it it particularly adapted for use in remote
or emergency situations in which the HOG trace is transmitted
I; 30 to a central unit or hospital by telemetry. Conducting
. I
1 toads 171 and 173 from the ~CG-only receptacle 135 irk con-
netted between this impedance matchillg circuit and the high
voltage protection circuit 169.
A disposable set of HOG electrodes 187 and 189
and an HOG electrode connecting plug 191 are schematically
illustrated in FEVER 12. The plug 191 is adapted to engage
the ECG-only receptacle 135 of the defibrillator electrode
, connector 13:1. Plug 191 and receptacle 135 are specially
designed so that the connecting plug 191 could not engage,
for example, the receptacle 133, since the HOG electrodes
lS7 and 18~ could not handle the defibrilla~ing energy from
lines 165 and 167~ To prevent the HOG electrodes 187 and
189 from being connected to lines 165 and 167/ FIGURE 13
shows that although the HOG connecting plug 191 has female
prongs 193 and 195 in the outer insulating sheathes 55 to
permit connection to plug 45, a female prong 194 has been
located in one of the inner sheathes US. Thus, plug 191
could not be engaged with receptacle 133, which would also
have a female prong in the inner contact or sheathe position,
thus preventing any possibility of defibrillation energies
being conveyed to HOG electrodes 187 and 189.
HOG electrodes 187 and 189 could be conventional
HOG electrodes, specially designed HOG electrodes or smaller
versions of the electrode element illustrated in FIGURE I.
For example, the HOG electrodes could be constructed in the
same fashion as the element of FIGURE. 4 but having a dotter
in the vicinity of 4 centimeters. Such a pair of electrode
elements has proved to be very satisfactory for HOG operation.
In addition to the other benefits discussed above, such an
I 30 HOG electrode has the further advantage that the lead 43
comes from out the wide of the electrode element. Since
. ;.~
conventional snap-type HOG electrodes have the snap directly
over the center of -the electrode, -tension on the lead to
the snap varies the gel pressure and produces electrode
motion artifact on the HOG trace. With the lead coming
out the side of the electrode element, most of these
artifacts can be eliminated. this reduction of artifacts
emanating from the electrode elements is also true of
electrode elements 31 and 33,
A final comment with respect to the structure
of def~rillator cable 49 is that a shorting jumper 196 may
be located in the defibrillator instrument connector 129
to adjust for the application of adult defibrillating
energies or child or internal defibrillating energies.
A variation of defibrillator cable 49 is illustrated
in the schematic diagram of FIG UP 14, in which a paddle
adapter 197 it located at one end of cable 49~ with the
defibrillator electrode connector 131 still positioned
at the other end of cable 49. Rather than describe each
of the elements of this variation of cable 49, the same
or similar parts have been identified by the same numerals
for ease of reference
Paddle adapter 197 has a pair of conducting
plates 199 and 201 adapted to receive conventional
defibrillator paddles and form a continuous electrically
conducting path. Conducting plates 199 and 201 are separated
by an insulating divider 203 to prevent accidental shorting
of the defibrillator paddles. Button switch actuators
205 and 207 extend upwardly from conducting plates 1.99
and 201, respectively. When both of the button actuators
205 all 207 are depressed by defibrillator paddles, an
_ 33 _
.
.
audible alarm is produced to lndica~e to the opcra~or thaw
an appropriate defibri.llating connection has been achieved
and to warn other attendants -to move awry Rome the area
surrounding the patient.
on HOG cable 209 is shown as permanently affixed
to the paddle adapter 197 in this preferred embodiment (although
alternatively a plug or connector could be provided for external
connection through an HOG cable 51), and an HOG monitor connector
211 is located at the end of this cable 209. An HOG output
terminal 213 is also provided on the paddle adapter 197 for
connection to another HOG instrument, an for connection to
a telemetry unit for transmittal of the HOG signals to a central
unit or hospital.
Further details of the defibrillator cable 49 with
the paddle adapter 197 are illustrated in FIGURE 15. In this
FIGURE, it may be seen that button actuators 205 and 207 close
corresponding switches 215 and 217, respectively, when the
actuators are depressed. this completes the circuit to a suit-
able energy source, such as a nine jolt DC battery 219~ to
actuate a buzzer 221. COG cable 209 has three conducting leads
that extend from the HOG monitor connector 211 to a body tissue
Impedance simulating circuit 223 located in the paddle adapter
197. Body tissue impedance simulating circuit 223 to connected
to the main conducting leads 165 and 167 through a high volt-
age protection circuit 225.- HOG output terminal 213 is con-
netted between the body tissue impedance simulating circuit
223 and the high voltage protection circuit 225, since this
connector would engage the HOG electrode connector of an HOG
cable in which a body tissue impedance simulating circuit Waldo
, 30 already be present. Conducting leads 171 and ~73 from the HOG=
only receptacle 135 in connector 131 are also connected
- 39 -
1 between the body tissue impedance simulating circuit 223
and the high voltage protection circuit 225.
The more detailed circuit diagram of FOGGIER 16
provides further explanation of -the defibrillating cable
49~ Thus, conventional defibrillator paddles 227 and 229
are schematically illustrated for engagement with conducting
plates 199 and 201. Paddles 2~7 and 229 have respective
associated handles 231 and 233, with corresponding
defibrillating discharge control actuators 235 and 237.
Placement of the paddles Z27 and 229 on the plates 199
and 231 will depress the button actuators 205 and 207 to
sound buzzer 221. Defibrillation may then be achieved
by actuation of the discharge control buttons 235 and 237
to pass a defibrillating pulse through lines 165 and 167
to the electrode elemerlts 31 and 33.
sigh voltage protection circuit 225 is illustrated
as including series resistors 239 and 241~ together with
a spark-gap device 243 connected across the resistors.
However, any appropriate type of high voltage protection
circuit would be acceptable.
Impedance simulating network 223 is represented
by the resistor 245. The permanent HOG cable Z09 is also
provided with a low pass filter network including resistor
Z47, capacitor 249 and oppositely poled diodes 251 and
253.
With either of the defibrillator cable 49
variations of FIGURE 10 and FIGURE 14, improved defibrillator
operation is achieved. Among the improved features are
the production of better current density distributions
due to the provision of sufficient electrode area electrode
f~3
elements 31 and 33 are on tile order of 8 cm. and 12 cm.
in diameter, respectively, sufficient flexibility of the
electrode elements to maximize the amount of available
area tliat is in proximity to -the skin of the patient, and
the reduction of electrode element-to-skin impedance.
Other advantages are -that the electrodes 3] and 33 may
be propelled to the patient and reconnected to the
defibrillator, 50 that a defibrillator pulse can be conveyed
to the patient very shortly after the initiation of
fibrillation. Also, use of disposable electrodes yields
better control over the conductive medium or gel utilized,
and the discharge control apparatus being located at a
distance spaced from the patient provides better protection
for the operator and other personnel.
Perhaps one of the most significant advantages
of the present invention for defibrillation is that it
permits utilization of a novel apex-posterior placement
of the electrodes. The four schematic representations
of FIGURE 17 illustrate the advantages of this placement.
In FIGURE AYE the heart 255 is illustrated in its normal
position nestled between the lungs 257 and 259. It is
immediately obvious from this sketch that there are
difficulties in getting sufficient defibrillating energy
to the heart from the conventional sternum-apex placement
of the defibrillating paddles 261 and 263. From the
schematic diagram of FIGURE 17B, the problem of getting
sufficient defibrillating energy to the heart is dramatically
clear. Not only is there significant energy loss directly
between the paddles 261 and 263, but most of the current
3Q that reaches the heart is directed through only a portion
-thereof. Therefore, no only is it difficult to gal energy
to the heart, but the current that does not reach the heart
is concentrated in a relatively small portion thereof all
thus increases the risk of myocardial damage.
S FIGURE 17C demonstrates -the novel apex-posterior
placement utilized in connection with this invention. Thus,
it may be seen that the smaller electrode element 31 is
located in the apex or left leg position. There are two
immediately obvious advantages of this placement. One
0 it that the electrode is out of the way of any CUR efforts
that may have to be performed on the patient. The other
is that the electrode is located in a generally non-hairy
portion of the body so that adherence and conductive problems
are minimized. With the larger electrode element 33 located
on the back in the right arm position, it is also in a
generally non-hairy portion of the body and does not interfere
with any operations that must be carried on from -the front
of the patient, as well as being spaced from the uneven
spinal area. FIGURE 17D dramatically illustrates how this
positioning of the electrode elements 31 and 33 permits
most of the defibrillating energy to be passed through
the complete volume of the heart, with very minor interference
by the lungs. Not only does this greater energy concentration
in -the heart increase the chances of successful defibrillation,
but due to the distribution of this defibrillating energy
over the entire heart the risk of myocardial damage is
greatly lessened.
FIGURES 18 and 19 illustrate -the combining of
cables 49 and 51 to provide both the HOG monitoring and
., 30 defibrillating functions through the single pair of-electrode
- 42 -
1 elements 31 and 33. When HOG electrode connector 87 is
engaged with the COG output terminal 147 on the defibrillator
discharge control module 137, operation of -the HOG 35 its
lust as if the connector 87 had been directly engaged with
the connecting plug 45. The only difference is that an
additional high voltage protection circuit 169 is provided
to further protect HOG 35 from the high energy discharge
pulses from the defibrillator 37. Further discussion of
the details of these circuits would be repetitious, although
it should be noted that the discharge control switches
157, 159, 161 and 163 are represented schematically in
FIGURE 19 by a single box ~65 that may be termed the
discharge control circuit.
By use of this combination, electrode elements
31 and 33 may be attached to a patient for monitoring by
a separate HOG instrument 35. Of course, if the defibrillator
37 is the type that has an HOG built into the unit for
monitoring through the defibrillating paddles, then the
monitoring can occur without the use of the separate HOG
35 and cable 51. However, even with such a unit, it may
ye necessary to have a separate HOG or to be able to
transmit the HOG signal to a remote location, such as a
central hospital. The latter is particularly true of
emergency situations, such as where a paramedic team is
involved. Thus, the capability for connecting a separate
. HOG or a telemetry unit to the electrodes 31 and 33 through
. the EGG output connector 147 is very significant as well
as being extremely valuable in those cases where the
defibrillator does not have a built-in HOG monitor.
If the HOG trace should indicate that -the -
pa-tierlt has gone into fibrillation, the electrode elements
31 and 33 are already in place for defibrillation and
these electrodes are already connected -to the defibrillator
through the cable 49. thus, a defibril]ating pulse may
be applied to the patient almost as soon as i-t is noted
that fibrillation is occurring, thereby increasing the
chances of a successful conversion of the patient. Further,
the action of the conducting gel on the skin increases
the conductivity (and hence reduces the impedance) between
the electrode element and the patient's body during an
initial period after application of the electrode element.
Therefore, by having the electrode elements propelled
to the patient, the transmittal of defibrillating energy
to the patient is improved. At the same time, nearly
continuous HOG monitoring is achieved through the
electrode elements 31 and 33, with the loss of the HOG
trace for only a very minimal time during application of
a defibrillating pulse Therefore/ this combination has
great utility for paramedic use, for emergency room use,
for operating room use and for intensive care use. Of
course, it also has very significant utility in other types
of situations, such as where a stimulating signal of another
type is being applied to the body and it is desired to
monitor the heart to be sure that the stimulation is not
creating any cardiac problems.
In some situations, it may be desired to have
only the HOG monitoring and defibrillating capacity, in
which case the connecting plug 45 may have the pin arrangement
illustrated in FIGURE 20. From this schematic representation,
it may be seen that the outer sheathes 55 are provided
PA
.
. . I
with felinely prongs 267 and 269, corresponding to the prongs
59 and 61 of -the basic plug 45. However, the two middle
sheathes contain solid non-conducting slugs 271 and 273.
- on ESSAY cable 47' is illustrated in FIGURE 21
5 and 22 primed numeral is utilized to identify this
cable, which does not include a cable connector that is
included in the basic ESSAY cable 47, as discussed in more
detail hereinafter. SUE cable 47' has an ESSAY instrument
connector 275 at one end for connecting the cable to the
ESSAY device At the other end of cable 47' there is located
an ESSAY electrode connector 2770 ESSAY electrode connector
277 employs the same standardized rectangular box employed
in the HOG and defibrillator electrode connectors 87 and
131.
With reference to FIGURE 22, it may be seen that
the ESSAY cable 47' includes a pair of conducting leads 279
and 281 that extend from the ESSAY instrument connector 275
to contacts 283 and 285 in the ESSAY electrode connector
277. Contacts 283 and 285 are capacitively coupled to
another pair of contacts 287 and 289 in connector 277,
such as by capacitors 291, 293 and 2g5. Although this
preferred embodiment utilizes the two contacts 287 and .
289, a single contact 287 could be employed, as discussed
more fully hereinafter. If a single con-tact 28; were
employed, the capacitive coupling would preferably extend
to both of the leads 279 and 281, although only a single
lead 279 could be used in some cases.
In some circumstances, the purchaser may only
need or desire an ESSAY return pad for returning the RF
curve to the 35U instrument. For such a situation, a
,
- I -
I
1 single ESSAY return pad 297 may be provided although any appear-
private type of conductive pad could be employed, in this
preferred embodiment an electrode element constructed in
accordance with the discussion of FIGURE 4, with the exception
that just a conducting plate such as aluminum, rather than
the tin-stannous chloride structure, is employed. For menu-
lecturing simplicity, the ESSAY pad 297 may be identical to
the electrode element 33 in other regards. As discussed
above, there are many advantages to the particular SUE return
pad of this invention, but certain aspects of the invention
could at 50 be utilized with other types of return pads.
ESSAY pad 297 is joined to a connecting plug 299 by
one or more conducting lines. In this preferred embodiment,
two conducting lines 301 and 303 are utilized. Plug 299 is
essentially the same as plug 45, but with different pin
placements (FIGURE 25).
With reference to the circuit diagram of FIGURE
24, it may be seen that the conducting lines 301 dud 303 are
connected to contacts 305 and 307, respectively, in the
connecting plug 293. Two other contacts 309 and 311 in plug
299 are electrically connected or short circuited by a jumper
or shorting bar 313.
When plug 299 is engaged with ESSAY electrode con-
nectar 277t conducting lines 301 and 303, and hence the
US ESSAY return pad 297~ are capacitively coupled to the
conducting leads 279 and 281 by the capacitors 291, 293
and 295. Actually, this capacitive coupling for the RF
return could be accomplished with a single conducting line
301 and a single conducting lead 279 capacitively coupled
i 30 by one or more of the capacitors 291, 293 or 295. For
some ESSAY instruments this system would be perfectly
- 46 -
acceptable Ivory, most ESSAY devices have a DC cord fault
test circuit to ensure that an RF return path is established
before the ESSAY may be ellergized. Thus, the preread
embodiment disclosed herein utilizes the two conducting
leads 279 and 281 to provide a DC cord fault test circuit.
This DC cord fault test loop is completed by the jumper
313 when contact 283 is electrically connected -to contact
309 and contact 285 is electrically connected to contact
311. Of course, this cord fault test arrangement could
be utilized with a single conducting line 301 capacitively
coupled to the leads 279 and 281. However, for an additional
safety margin, this preferred embodiment utilizes the second
conducting line 303.
Capacitive coupling between the ESSAY return pad
it conducting lines 301 and 303 and the lead 279 and 281
is extremely important as a result of the DC and low
frequency isolation that it provides. The most significant
aspect of this isolation is the protection that it provides
for the patient from low frequency or DC lockjaw from the
ESSAY and from low frequency and DC signals being returned
to the ESSAY as a result of rectification ox RF signals
during the electrosurgical process. In addition, the
isolation provided by the capacitive coupling also
protects the ESSAY instrument from high energy DC and low
frequency signals, such as defibrilla-ting pulses. Besides
the capacitive coupling provided by the capacitors 291~
293 and 295, additional capacitive coupling may be provided
on the connecting plug 299 side, such as my a capacitor
315 connected from one or both (with capacitive isolation
of the lines 301 and 303 to the jumper 313. As a matter
I
1 of fact, all of the capacitive coupling could be located
in the connecting plug 229, but safety and cost considerations
favor at least some of this capacitive coupling being located
in the ESSAY electrode connector 277.
Since the ESSAY return pad 297 would not suffice
for HOG monitoring or defibrillation, it is necessary to
ensure that the connectlny plug 299 cannot eying a connector
-I, designed for HOG or defibrillation use. In this preferred
, embodiment, this is accomplished by the pin arrangement
; 10 illustrated in FIGURE 25 in which male prongs 317 and 319
correspond to the contacts 309 and 311 and female prongs
321 and 323 correspond to contacts 305 and 3Q7.
FIGURES 26 and 27 illustrate the combination
of an HOG 35 and an ESSAY 3g to provide the multiple functions
of HOG monitoring and RF return to the ESSAY. The basic
electrode set 53 is employed in this preferred embodiment,
rather than the single ESSAY return pad. The same type of
ESSAY instrument connector 275 is employed in connection
with cable 47 as is used with cable 47'. An SUE electrode
connector 325, rather than the ESSAY electrode connector
277, is utilized to engage the connecting plug OWE In
addition, an ESSAY cable connector 327 has been added to
provide for the connection ox HOG cable 51 to the ESSAY cable
47. An HOG output terminal or connecting plug 329 having
US the same pin arrangement as plug 45 is located on the
connector 327 to engage an HOG electrode connector 87
In FIGURE 27 Kit may been seen that the HOG
electrode connector 87 has the body tissue impedance
matching circuit 97, thy high voltage protection circuit
I 30 99 and the low pass filter 101 of HOG cable 51. In addition,
1 the Us cable connector 327 includes another low pass
filter 331 in association with -the HOG output connector
329 in order -to further protect the HOG from RF end sub-
harmonic interference. It may also be seen that a shorting
jumper 333, corresponding -to -the jumper 313 in plug 299,
is provided in plug 45. Although shorting jumper 333 is
across the two center contacts, rather than two outer
contacts as in plug 299, it performs the same function
of providing a cord fault test loop with leads 279 and
281 when plug 45 and connector 325 are engaged. The same
capacitive coupling may be provided in connector 325 that
is provided in connector YO-YO In both cases, it should
be recognized that the use of the capacitors 291, 293 and
295 is only illustrative and various other capacitor
combinations may be utilized.
To provide a current path for the HOG signals
and any other electrical signals passing through the HOG
output connector 329, another pair of conducting leads
~35 and 337 is provided in cable 47 between connectors
325 and 327. Leads 335 and 337 are connected to contacts
in connector 335 that are electrically connected to the
contacts in plug 45 connected to electrode elements 31
and 33 when plug 45 and connector 325 are engaged. At
the other end, leads 335 and 337 are connected to HOG
output terminal 329 through the low pass filter 331.
With the combination of FIGURES 26 and 27~ it
is possible to achieve continuous HOG monitoring during
an electrosurgical operation trough the same electrode
elements that are providing an RF return path. Since the
HOG signals are obtained through the same electrode elements
I .
that are providing the RF return, the risk of RF burns occur
ring under the small COG electrodes is eliminated. Also,
the larger electrode element 33 is essentially the same as
the ESSAY return pad 297, which works very effectively by itself.
thus, if so desired, capacitive coupling in connector 325
or slug 45 could be such as to utilize only the electrode
33 for the RF return. I~owcver, in the preferred embodiment
disclosed herein, both electrode elements 33 and 31 are utilized
for RF return, which provides even greater RF dispersion and
further minimizes the risks of any RF burning. Thus, -the
addition of the electrode element Al not only permits the
utilization of a separate HOG 35 with the ESSAY 39, but it also
provides a very efficient RF return system for the ESSAY.
With the assistance of the foregoing discussion,
it is now possible to more fully comprehend the multiple lung-
lion system of FIGURE 1, as shown in greater detail in the
schematic diagram of FIGURE 28. One additional detail provided
in this diagram is that the low pass filter 331 in ESSAY cable
connector 327 is illustratively indicated as a capacitor 339
and a resistor 341 connected in parallel between the leads
335 and 337~ Significant aspects of this circuit are that
the capacitor 339 essentially isolates the HOG from the ESV
RF signals or any other relatively high frequency interference,
and the resistor 341 provides DC offset compen~tion as well
as contributes to the filtering function.
It should also be noted that the numbers 291,
293 and 295 have been utilized to identify the capacitors
in connector 32~, thus corresponding them to the capacitors
in connector 277~ although the exact connections differ
somewhat Capacitor 235 is primarily a safety feature
.,
- S ()
Al I Pry I
_ to Clara that the leads 279 and 281 are essentially shout
circuited for I signals, although capacitors 291 and 293
would normally provide sufficient coupling for the RF
signals. The contacts in connector 325 and plug I have
not been separately identified, although they correspond
to the contacts 283, 285, 287 and 289 in connector 277
(FIGURE 24) and contacts 305, 307, 309 and 311 in plug
299 (FIGURE- 24). With reference to FIGURE 3, it may be
seen that the contacts 305 and 309 are actually the male
prongs 63 and 65, between which the jumper 333 is connected.
Also, the contacts 307 and 311 would correspond to the
female prongs I and 61. I.
By utilizing the cables I 49 and 51, the HOG
35, the defibrillator 37 and the ESSAY 39 may be simultaneously
connected to the electrode elements 31 and 33 to provide
a multiplicity ox functions through the single pair of
electrode elements. Not only are a multiplicity of functions
provided, but an improved physiological electrode system
performance is achieved for each of the functions, if all
of the features disclosed herein are utilized.
The significance of this multi-function capability
of the single pair of electrode elements 31 and 33 may
be illustrated by an example. In an emergency situation,
paramedics would apply electrode elements 31 and 33 to
the patient for HOG monitoring through an HOG cable 51
and a defibrillating cable 49, as illustrated in FIGURE
18. If fibrillation of the patient's heart is observed,
a defibrillating pulse of energy could be applied by
depression of the discharge control module plungers 139~ ¦
141, 143 and 145. it the same time/ HOG monitoring is
nearly contilluously maintained
The patient is than convoyed to a hospital. If
surgery is required, the patient is taken to the emerqellcy
, room, where plug 45 may be disengaged from connector 131
of -the paramedics' system and then engaged with a connector
325 in the system of FIGURE 1. Thus, the sclme electrode
elements 31 and 33 applied by the paramedics provide HOG
monitoring, an RF return path for the ESSAY and the possibility
of indite defibrillation, if required.
lo After surgery, the patient could then be taken
to the extensive care ward, where a system of cables 49 and
51 as shown in FIGURE 18 could then be connected to electrode
elements 31 and 33 for HOG monitoring. A defibrillator would
not normally be attached to each patient, but when the onset
of fibrillation was detected, a defibrillator could quickly
be attached by the connector 129 to apply a deEibrillating
pulse to the patient. Alternatively defibrillating cables
49 having a paddle converter 197 could be utilized, so that
the defibrillating discharge could be effected through condo-
tonal paddles without the necessity of having to attach
a connector 129 to the defibrillator.
Similarly, in an operating room the system of FIGURE
1 could be attached to the patient for electrosurgery. After
¦ surgery, the patient could by transferred to the system of
FIGURE 13 in intensive care, as described above.
n another example, if the electrosurgery did not
involve the cardiovascular structure and the HOG monitoring
was merely precautionary the system of ERR 26 could be
employed. If fibrillation were to unexpectedly occur, a
3Q defibrillator could be quickly connected to the EYE cable
connector 327 to apply a defibrillating pulse through electrode
elemellts 31 and 33c
In addition to the provision of a multiplicity
- 52 -
.; . -
$,~ I
of functions through a single pair of extrude clcmcnts,
this invention Allah provides for the separate connection
of each of the instruments to that pair of electrode
elements. Further, each of the electrode elements itself
involves a novel and improved form of physiological
electrode, and the electrode elements are combined in-to
an innovative disposable electrode set. Also, unique and
novel cables are utilized to connect the electrode set
to the various instruments. Wherefore this invention
not only relates to the unique system, but Kit also relates
to a number of novel and unobvious sub-systems and components
of that physiological electrode system. Some of the unique
features of these subsidiary portions of the system may
also be used with other devices that are not directly a
part of the physiological electrode system. Finally, the
invention also includes certain alternative or partially
modified variations.
While the preferred embodiments disclosed herein
utilize thy features shown and described, many of the
innovative features of the invention disclosed could be
utilized apart from the totality of features disclosed
and hence would still fall within the spirit and scope
of this invention. Therefore, although certain alternative
and modified approaches or aspects have been disclosed
herein, it also should be understood that various
modifications/ changes and variations may be made in the
arrangement, operation and details of construction of the
elements disclosed herein without departing from the spirit
and scope of this invention.
I, 30
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