U.S. patent number RE40,471 [Application Number 10/255,988] was granted by the patent office on 2008-08-26 for aed with force sensor.
This patent grant is currently assigned to Cardiac Science, Inc.. Invention is credited to James E. Brewer, Allen W. Groenke.
United States Patent |
RE40,471 |
Groenke , et al. |
August 26, 2008 |
AED with force sensor
Abstract
A force sensor, for use in combination with an automated
electronic defibrillator (AED), includes a first conductive layer.
A second conductive layer is spaced apart from the first conductive
layer such that no electrical communication occurs between the
first and second conductive layers. An electrical communication
device is provided for establishing electrical communication
between the first and second conductive layers responsive to the
application of a force to said electrical communication means. A
method of prompting a rescuer in the application of cardiopulmonary
resuscitation to a victim includes the steps of: sensing a force
applied by the rescuer to the victim's sternum; sensing an interval
between successive applications of force to the victim's sternum;
comparing the force applied by the rescuer to the victim's sternum
to a standard of force known to effect resuscitation; providing a
prompt to the rescuer that prompts the rescuer to vary the force
delivered to approximate the force that is known to effect
resuscitation, comparing the interval between successive
applications of force to the victim's sternum to a standard
interval known to effect resuscitation; and providing a prompt to
the rescuer that prompts the rescuer to vary the interval of force
application to approximate the interval that is known to effect
resuscitation.
Inventors: |
Groenke; Allen W. (Bloomington,
MN), Brewer; James E. (Cottage Grove, MN) |
Assignee: |
Cardiac Science, Inc. (Bothell,
WA)
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Family
ID: |
22670234 |
Appl.
No.: |
10/255,988 |
Filed: |
September 25, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09182831 |
Oct 29, 1998 |
06125299 |
Sep 26, 2000 |
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Current U.S.
Class: |
607/6; 600/16;
607/3; 607/5 |
Current CPC
Class: |
A61H
31/007 (20130101); A61N 1/3925 (20130101); A61H
2201/5007 (20130101); A61H 2201/5048 (20130101); A61H
2201/5061 (20130101); A61H 2201/5043 (20130101) |
Current International
Class: |
A61N
1/39 (20060101); A61H 31/00 (20060101) |
Field of
Search: |
;607/5-6,3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1 157 717 |
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Nov 2001 |
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EP |
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WO 99/24114 |
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May 1999 |
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WO |
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Primary Examiner: Layno; Carl
Attorney, Agent or Firm: Patterson, Thuente, Skaar &
Christensen, PA
Claims
What is claimed is:
1. An automated electronic defibrillator (AED) for use by an
operator in assisting in resuscitating a victim, comprising: a
force sensor applicable to a skin surface of the victim and being
responsive to the application of a force to said force sensor, an
AED control system being in electrical communication with the force
sensor, the AED control system processing a signal communicated
from the force sensor related to the magnitude of force applied
thereto and to the frequency of application of the force thereto;
and AED prompting means operably coupled to the AED control system
for receiving communication signals from the AED control system and
for communicating prompts to the operator for use by the operator
in resuscitating the victim, the prompts being related to the
signal communicated to the AED control system by the force sensor
related to the magnitude of force applied to the force sensor and
to the frequency of application of the force to the force
sensor.
2. The AED of claim 1 wherein the force sensor is responsive to the
relative magnitude of the force applied thereto and communicates a
signal related to said force magnitude to the AED control
system.
3. The AED of claim 2 wherein the AED control system communicates
signals relating to the relative magnitude of force applied to the
force sensor to the AED prompting means for transmission as a
prompt to the rescuer.
4. The AED of claim 1 wherein the AED control system determines the
interval between a succession of force applications applied to the
force sensor.
5. The AED of claim 4 wherein the AED control system communicates
signals relating to the interval between a succession of force
applications applied to the force sensor to the AED prompting means
for transmission as a prompt to the rescuer.
6. The AED of claim 1 wherein the force sensor comprises: a first
conductive layer; a second conductive layer being spaced apart from
the first conductive layer, the first and second conductive layers
being electrically isolated from one another; and electrical
communication means for establishing electrical communication
between the first and second conductive layers responsive to the
application of a force to said electrical communication means.
7. The AED of claim 6 wherein at least a part of the electrical
communication means of the force sensor are formed of an
extrudable, electrically conductive material, the electrical
communication means being extruded by the application of a force to
said electrical communication means, at least one extrusion thereof
establishing a path of electrical communication between the first
and second conductive layers responsive to the application of said
force.
8. The AED of claim 7, the force sensor further including a
flexible, nonconductive layer being disposed between the first and
second conductive layers.
9. The AED of claim 8 wherein the first and second conductive
layers of the force sensor are formed of conductive ink printed on
opposed sides of the nonconductive layer.
10. The AED of claim 9, the force sensor further including a
plurality of holes defined through the nonconductive layer and
through the first and second conductive layers printed thereon.
11. The AED of claim 10, the force sensor further including a first
extrudable, conductive layer disposed on the first conductive layer
and a second extrudable, conductive layer disposed on the second
conductive layer, the first and second extrudable, conductive
layers being extrudable into the plurality of holes defined through
the nonconductive layer and through the first and second conductive
layers responsive to a force applied thereto to form an
electrically communicative connection between the first and second
conductive layers.
12. The AED of claim 6 wherein the first and second conductive
layers of the force sensor are formed of conductive, metallic
foil.
13. The AED of claim 1 wherein the force sensor is disposed in a
hole defined in an electrode.
14. The AED of claim 6 wherein the magnitude of the force applied
to the force sensor is inversely proportional to the impedance
existing between the first and second conductive layers.
15. The AED of claim 6 wherein the impedance existing between the
first and second conductive layers of the force sensor is related
to the magnitude of the force applied to the force sensor.
16. A method of prompting a rescuer in the application of
cardiopulmonary resuscitation to a victim comprising the steps of:
sensing a force applied by the rescuer to the victim by means of a
force sensor; sensing an interval between successive applications
of force to the victim's sternum; by means of a processor operably
coupled to the force sensor, the processor comparing the force
applied by the rescuer to the victim's sternum to a standard of
force known to effect resuscitation; the processor providing a
prompt to the rescuer that prompts the rescuer to vary the force
delivered to approximate the force that is known to effect
resuscitation; the processor comparing the interval between
successive applications of force to the victim's sternum to a
standard interval known to effect resuscitation; and the processor
providing a prompt to the rescuer that prompts the rescuer to vary
the interval of force application to approximate the interval that
is known to effect resuscitation.
.[.17. An automated electronic defibrillator (AED) for use by an
operator in assisting in resuscitating a victim, having a charging
circuit for developing a high voltage charge, at least two
electrodes for application to the person of a victim, the at least
two electrodes being in electrical communication with the charging
circuit, a control circuit communicatively coupled to the charging
circuit and the electrodes for detecting certain biological
parameters of the victim and for controlling the delivery of a
voltage charge from the charging circuit through the at least two
electrodes to the victim, comprising: means for prompting a rescuer
in the delivery of cardiopulmonary resuscitation (CPR) to the
victim, the means for prompting a rescuer further including the
control system being in electrical communication with a force
sensor, the AED control circuit processing a signal communicated
from the force sensor related to the magnitude of force applied
thereto and to a frequency of application of the force
thereto..].
18. The AED of claim 17 wherein the means for prompting a rescuer
includes a force sensor applicable to a skin surface of the victim
and being responsive to the application of a force to said force
sensor.
19. .[.The AED of claim 17 wherein the means for prompting a
rescuer.]. .Iadd.An automated electronic defibrillator (AED) for
use by operator in assisting in resuscitating a victim, having a
charging circuit for developing a high voltage charge, at least two
electrodes for application to the person of a victim, the at least
two electrodes being in electrical communication with the charging
circuit, a control circuit communicatively coupled to the charging
circuit and the electrodes for detecting certain biological
parameters of the victim and for controlling the delivery of a
voltage charge from the charging circuit through the at least two
electrodes to the victim, comprising: means for prompting a rescuer
in the delivery of cardiopulmonary resuscitation (CPR) to the
victim, the means for prompting a rescuer including the control
system being in electrical communication with a force sensor, the
AED control circuit processing a signal communicated from the force
sensor related to the magnitude of force applied thereto and to a
frequency of application of the force thereto and .Iaddend.further
includ.[.es.]. .Iadd.ing .Iaddend.prompting means operably coupled
to the AED control circuit for receiving communication signals from
the AED control circuit and for communicating prompts to the
rescuer for use by the rescuer in resuscitating the victim, the
prompts being related to the signal communicated to the AED control
circuit by a force sensor related to the magnitude of force applied
to the force sensor and to the frequency of application of the
force to the force sensor.
20. The AED of claim 19 wherein the force sensor is responsive to
the relative magnitude of the force applied thereto and
communicates a signal related to said force magnitude to the AED
control system.
21. The AED of claim 20 wherein the AED control circuit
communicates signals relating to the relative magnitude of force
applied to the force sensor to the AED prompting means for
transmission as a prompt to the rescuer.
22. The AED of claim 21 wherein the AED control system determines
the interval between a succession of force applications applied to
the force sensor.
23. The AED of claim 22 wherein the AED control circuit
communicates signals relating to the interval between a succession
of force applications applied to the force sensor to the AED
prompting means for transmission as a prompt to the rescuer.
24. An automated electronic defibrillator (AED) for use by an
operator in assisting in resuscitating a victim, having a charging
circuit for developing a high voltage charge, at least two
electrodes for application to the person of a victim, the at least
two electrodes being in electrical communication with the charging
circuit, a control circuit communicatively coupled to the charging
circuit and the electrodes for detecting certain biological
parameters of the victim and for controlling the delivery of a
voltage charge from the charging circuit through the at least two
electrodes to the victim, comprising: means for prompting a rescuer
in the delivery of cardiopulmonary resuscitation (CPR) to the
victim, the means for prompting a rescuer including a force sensor
applicable to a skin surface of the victim and being responsive to
the application of a force to said force sensor, the force sensor
having, a first conductive layer; a second conductive layer being
spaced apart from the first conductive layer, the first and second
conductive layers being electrically isolated from one another; and
electrical communication means for establishing electrical
communication between the first and second conductive layers
responsive to the application of a force to said electrical
communication means.
25. The AED of claim 24 wherein at least a part of the electrical
communication means of the force sensor are formed of an
extrudable, electrically conductive material, the electrical
communication means being extruded by the application of a force to
said electrical communication means, at least one extrusion thereof
establishing a path of electrical communication between the first
and second conductive layers responsive to the application of said
force.
26. The AED of claim 25, the force sensor further including a
flexible, nonconductive layer being disposed between the first and
second conductive layers.
27. The AED of claim 26 wherein the first and second conductive
layers of the force sensor are formed of conductive ink printed on
opposed sides of the nonconductive layer.
.Iadd.28. A patient interface for use with an automated electronic
defibrillator (AED) comprising: a patient connection interface
adapted to be positioned externally on a victim and operably
connected to the AED, the patient connection interface including:
means for selectively delivering a signal to the AED representative
of the victim's cardiac electrical signal; means for selectively
delivering a defibrillation shock pulse from the AED to the victim;
and means for selectively delivering a signal to the AED indicative
of a magnitude of chest compression when the victim is receiving
cardiopulmonary resuscitation (CPR)..Iaddend.
.Iadd.29. The patient connection of claim 28, wherein the means for
selectively delivering a signal to the AED comprises at least one
sensor having at least one lead wire attached to the
sensor..Iaddend.
.Iadd.30. The patient connection of claim 29, wherein the sensor is
a force sensor, and the signal delivered to the AED is related to a
force applied to the sensor..Iaddend.
.Iadd.31. A method of interfacing an automated electronic
defibrillator (AED) with a victim comprising the steps of:
positioning a patient interface externally on the victim, the
patient interface having at least two electrodes and at least one
sensor; connecting the patient interface to the AED; using the AED
to sense a signal representative of the victim's cardiac electrical
signal from the at least two electrodes; using the AED to sense a
signal from the sensor indicative of a magnitude of chest
compression when the victim is receiving cardiopulmonary
resuscitation (CPR); determining if the magnitude of chest
compressions received by the victim during CPR is effective for
resuscitation by using the AED to analyze the signal from the
sensor; prompting the rescuer in response to the step of
determining if the magnitude of chest compressions received by the
victim during CPR is effective; and using the AED to selectively
deliver a defibrillation shock pulse from the AED to the victim
through the at least two electrodes..Iaddend.
.Iadd.32. The patient connection of claim 29, wherein the sensor
senses a force applied to the sensor, and wherein the signal from
the sensor is proportional to the force applied to the
sensor..Iaddend.
.Iadd.33. The method of claim 31, wherein the step of determining
if the magnitude of chest compressions received by the victim
during CPR is effective determines whether the rescuer effectively
depressed the sternum between about 4 and 5 cm..Iaddend.
.Iadd.34. An automated external defibrillation system for use by a
rescuer to resuscitate a victim comprising: a patient connection
interface adapted to be positioned externally on a victim, the
patient connection interface including: at least two electrodes,
each having at least one lead wire attached to the electrode that
selectively delivers a signal representative of the victim's
cardiac electrical signal (EKG) and that selectively delivers a
defibrillation shock pulse to the victim; and at least one sensor
having at least one lead wire attached to the sensor that
selectively delivers a signal indicative of a magnitude of chest
compression when the victim is receiving cardiopulmonary
resuscitation (CPR); and an automatic external defibrillator (AED)
having: charging circuitry that is in electrical communication with
the at least two electrodes via the lead wires and selectively
develops a high voltage charge for defibrillation of the victim;
EKG cardiac sensing circuitry that is in electrical communication
with the at least two electrodes via the lead wires and selectively
receives the signal representative of the victim's cardiac
electrical signal; CPR sensing circuitry that is in electrical
communication with the at least one sensor via the lead wires and
selectively receives the signal indicative of the magnitude of
chest compressions; voice circuitry that selectively generates
audio prompts for the rescuer; and a processor and associated
memory and control logic operably connected to the charging
circuitry, the EKG sensing circuitry, the CPR sensing circuitry and
the voice circuitry that executes programmed instructions to
selectively perform the steps comprising: automatically analyzing
the victim's cardiac electrical signal; automatically analyzing the
signal indicative of the magnitude of chest compression; generating
audio prompts to instruct the rescuer on appropriate instructions
to perform both CPR and defibrillation based on the steps of
analyzing the magnitude of chest compression and the victim's
cardiac electrical signal; and controlling delivery of the high
voltage charge from the charging circuitry to the victim via the at
least two electrodes at a time coordinated with audio prompts that
instruct the rescuer..Iaddend.
.Iadd.35. The system of claim 34 wherein the processor analyzes the
signal indicative of the magnitude of chest compression to
determine if the indicated magnitude of chest compression is within
a desired range..Iaddend.
.Iadd.36. The system of claim 35 wherein the desired range is based
on a force and the sensor senses a force applied to the
sensor..Iaddend.
.Iadd.37. The system of claim 35 wherein the desired range is based
on a chest compression and the processor analyzes the signal
indicative of the magnitude of chest compression to determine
whether the rescuer effectively depressed the sternum between about
4 and 5 cm..Iaddend.
.Iadd.38. The system of claim 35 wherein the desired range is based
on a rate and the processor analyzes the signal indicative of the
magnitude of chest compression to determine a rate of chest
compressions..Iaddend.
.Iadd.39. An automated external defibrillation system for use by a
rescuer to resuscitate a victim comprising: a patient connection
interface adapted to be positioned externally on a victim, the
patient connection interface including: means for selectively
sensing and delivering a signal representative of the victim's
cardiac electrical signal (EKG) and for selectively delivering a
defibrillation shock pulse to the victim; and means for selectively
sensing and delivering a signal indicative of at least one
parameter associated with the victim receiving cardiopulmonary
resuscitation (CPR); and an automatic external defibrillator (AED)
having: means for selectively developing a high voltage charge for
defibrillation of the victim in electrical communication with the
patient interface; means for selectively generating audio prompts
for the rescuer; and means operably connected to the means for
selectively developing a high voltage charge and the means for
selectively generating audio prompts for the rescuer for
selectively controlling operation of the AED, including: means for
automatically analyzing the victim's EKG signal; means for
automatically analyzing the CPR signal; means for generating audio
prompts to instruct the rescuer on appropriate instructions to
perform both CPR and defibrillation in response to the means for
automatically analyzing the EKG signal and the means for
automatically analyzing the CPR signal; and means for selectively
delivering the high voltage charge from the means for selectively
developing a high voltage charge at a time coordinated with audio
prompts generated by the means for generating audio
prompts..Iaddend.
.Iadd.40. The system of claim 39, wherein the means for selectively
sensing and delivering a signal representative of the victim's
cardiac electrical signal (EKG) and for selectively delivering a
defibrillation shock pulse to the victim comprises a pair of
electrodes, each electrode having at least one lead wire attached
thereto..Iaddend.
.Iadd.41. The system of claim 39, wherein the means for selectively
sensing and delivering a signal indicative of at least one
parameter associated with the victim receiving CPR comprises a
sensor having at least one lead wire attached thereto..Iaddend.
.Iadd.42. The system of claim 41, wherein the CPR signal includes a
signal indicative of the magnitude of chest compression and the
means for automatically analyzing the CPR signal analyzes the
signal indicative of the magnitude of chest compression to
determine if the magnitude of chest compression is within a desired
range..Iaddend.
.Iadd.43. The system of claim 42, wherein the desired range is
based on a force..Iaddend.
.Iadd.44. The system of claim 42, wherein the desired range is
based on a rate..Iaddend.
.Iadd.45. The system of claim 42 wherein the desired range is based
on a chest compression and the means for selectively controlling
operation of the AED analyzes the signal indicative of the
magnitude of chest compression to determine whether the rescuer
effectively depressed the sternum between about 4 and 5
cm..Iaddend.
.Iadd.46. A method of prompting a rescuer in the resuscitation of a
victim comprising the steps of: positioning a patient connection
interface externally on a victim, the patient connection interface
including at least two electrodes and at least one sensor;
connecting the patient connection interface to an automatic
external defibrillator (AED); using the AED and the at least two
electrodes to selectively sense and automatically analyze a signal
representative of the victim's cardiac electrical signal (EKG);
using the AED and the at least one sensor to selectively sense and
automatically analyze a signal indicative of a magnitude of chest
compression when the victim is receiving cardiopulmonary
resuscitation (CPR); automatically causing voice circuitry in the
AED to generate audio prompts to instruct the rescuer on
appropriate instructions to perform both CPR and defibrillation
based on the steps of automatically analyzing the victim's EKG and
automatically analyzing the signal indicative of a magnitude of
chest compression when the victim is receiving CPR; and
automatically causing the AED to selectively deliver a high voltage
charge from a charging circuitry to the victim via the at least two
electrodes at a time coordinated with audio prompts generated by
the voice circuitry..Iaddend.
Description
TECHNICAL FIELD
The present invention relates to devices useful for assisting in
the administration of cardiopulmonary resuscitation (CPR). More
particularly, the present invention relates to a sensor for being
disposed on the body of a victim to measure parameters related to
the CPR.
BACKGROUND OF THE INVENTION
CPR is a technique used by a rescuer in an emergency situation to
get oxygen into a victims blood when that persons heart has stopped
beating and/or they are not breathing spontaneously. When
performing CPR the rescuer creates blood circulation in the victims
body by periodically compressing the victims chest.
The American Heart Association (AHA) recommends that the rescuer
press down on the sternum with a force sufficient to depress it
between 4 and 5 cm. The recommended rate for these periodic
depressions is 100 times a minute (ILCOR Advisory Statement for
Single-Rescuer Adult Basic Life Support). Chest compressions
produce blood circulation as the result of a generalized increase
in intrathoracic pressure and/or direct compression of the heart.
The guidelines state "Blood circulated to the lungs by chest
compressions will likely receive enough oxygen to maintain life
when the compressions are accompanied by properly performed rescue
breathing." A victim can be kept alive using CPR provided the
rescuer(s) are able to continue delivering properly performed chest
compressions and rescue breaths.
Administering chest compressions and rescue breaths is a very
physically demanding task. The quality of chest compressions and
rescue breaths delivered can degrade as rescuers become fatigued.
When a rescuer is fatigued they may not realize that they are
compressing the chest with inadequate force.
Administering CPR is a very physically demanding procedure which is
performed under stressful (i.e. life and death) circumstances.
Under these circumstances, the rescuer is given the difficult tasks
of estimating the time between compression's, and the distance
which the chest is being compressed. Much of the difficulty in
estimating the distance which the chest is being compressed stems
from the relative position of the rescuer and the victim. When
performing chest compression's, the rescuer positions his or her
shoulders directly above the victim's chest, and pushes straight
down on the sternum. In this position, the rescuer's line of sight
is straight down at the victim's chest. With this line of sight,
the rescuer has no visual reference point to use as a basis for
estimating the distance that he or she is compressing the
chest.
For this reason, there is a need in the art for a practical device
which provides the rescuer with feedback to indicate that the
rescuer is using proper compression force and that the rate of
compressions is correct. A device of this type will provide
rescuers with coaching which will enable them to deliver chest
compressions consistently and beneficently. To be practical, this
device should be one which is already at the rescue scene so that
the rescuer is not required to bring an additional piece of
equipment to the scene.
Because AEDs are being widely deployed, they are often present at a
rescue scene. Prior art AEDs are only capable of defibrillation.
There is a need in the industry for an AED which is capable of
aiding a rescuer in administering proper chest compressions to a
victim.
SUMMARY OF THE INVENTION
The present invention is an AED which is capable of detecting when
a rescuer is performing CPR on a victim. This AED is also capable
of providing a rescuer with helpful voice prompts to coach them
through a CPR procedure. Rescuers who are trained in the use of
AEDs are also trained in cardiopulmonary resuscitation (CPR) and
will be able to make ready use of the AED of the present invention.
AEDs are presently being widely deployed, and they are often on the
scene when CPR is administered.
The present invention substantially meets the aforementioned needs.
The present invention provides a sensor for sensing both the force
applied to the victim's chest and the frequency with which the
compressions are applied in order to assist a rescuer in
resuscitating a stricken victim. Feedback, preferably by means of
voice prompts, is provided to the rescuer by an emergency
electronic device in communication with the sensor in order to
optimally time the administration of chest compressions and to
deliver a chest compression that provides an optimal amount of
compression of the chest.
The present invention is a force sensor, for use in combination
with an automated electronic defibrillator (AED), includes a first
conductive layer. A second conductive layer is spaced apart from
the first conductive layer such that no electrical communication
occurs between the first and second conductive layers. Electrical
communication means are provided for establishing an electrical
communication path between the first and second conductive layers
responsive to the application of a force to said electrical
communication means.
The present invention includes a method of prompting a rescuer in
the application of cardiopulmonary resuscitation to a victim having
the steps of: sensing a force applied by the rescuer to the
victim's sternum; sensing an interval between successive
applications of force to the victim's sternum; comparing the force
applied by the rescuer to the victim's sternum in a standard of
force known to effect resuscitation; providing a prompt to the
rescuer that prompts the rescuer to vary the force delivered to
approximate the force that is known to effect resuscitation;
comparing the interval between successive applications of force to
the victim's sternum to a standard interval known to effect
resuscitation; and providing a prompt to the rescuer that prompts
the rescuer to vary the interval of force application to
approximate the interval that is known to effect resuscitation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an automated external
defibrillator;
FIG. 2 is an exploded view of an electrode having the force sensor
of the present invention;
FIG. 3 is a block diagram of an electrical system of the AED,
FIG. 4 is a perspective view of the force sensor used in
conjunction with a pair of electrodes;
FIG. 5 is a perspective view of the force sensor of the present
invention applied to a patent;
FIG. 6 is a perspective view of an electrode with the force sensor
of the present invention disposed therein,
FIG. 7 is a perspective view of the force sensor of FIG. 6 applied
to the chest of a victim;
FIG. 8 is a cross sectional side view of the electrode of the
present invention;
FIG. 9 is a top plan view of a further embodiment of the force
sensor of the present invention;
FIG. 10 is a bottom plan view of the force sensor depicted in FIG.
9;
FIG. 11 is a cross sectional side view of the electrode of the
present invention;
FIG. 12 is a cross sectional side view of the electrode of the
present invention;
FIG. 13 is a top plan view of a further embodiment of the force
sensor of the present invention;
FIG. 14 is a bottom plan view of the force sensor depicted in FIG.
13;
FIG. 15 is a cross sectional side view of the electrode of the
present invention;
FIG. 16 is a cross sectional side view of the electrode of the
present invention;
FIG. 17 is a top plan view of a further embodiment of the force
sensor of the present invention;
FIG. 18 is a bottom plan view of the force sensor depicted in FIG.
17; and
FIG. 19 is a cross sectional side view of the electrode of the
present invention;
FIG. 20 is a partial cut-away view of an embodiment of a packaged
electrode system;
FIG. 21 is a cross-sectional view of an embodiment of a packaged
electrode system and test apparatus;
FIG. 22 is a perspective assembly view an embodiment of a packaged
electrode system;
FIG. 23 is a cross sectional view of an embodiment of a packaged
electrode system;
FIG. 24 is an partial cut-away view of an embodiment of a packaged
electrode system;
FIG. 25 is cross sectional view of an embodiment of a packaged
electrode system;
FIG. 26 is partial cut-away view of an embodiment of a packaged
electrode system;
FIG. 27 is a cross-sectional view of an embodiment of a packaged
electrode system;
FIG. 28 is perspective assembly view an embodiment of a packaged
electrode system;
FIG. 29 is a cross-sectional view of an embodiment of a packaged
electrode system;
FIG. 30 is a perspective view of an embodiment of a packaged
electrode system;
FIG. 31 is a cross-sectional view of an embodiment of a packaged
electrode system;
FIG. 32 is a partial cut-away view of an embodiment of a packaged
electrode systsem;
FIG. 33 is a cross-sectional view of an embodiment of a packaged
electrode system;
FIG. 34 is a cross-sectional view of a partial embodiment of a
packaged electrode system;
FIG. 35 is a cross-sectional view of a partial embodiment of a
packaged electrode system;
FIG. 36 is a cross-sectional view of a partial embodiment of a
packaged electrode system; and
FIG. 37 is a cross-sectional view of a partial embodiment of a
packaged electrode system.
DETAILED DESCRIPTION OF THE DRAWINGS
An AED is shown generally at 22 in FIG. 1. AED 22 is used for
emergency treatment of victims of cardiac arrest and is typically
used by first responders. AED 22 automatically analyzes a patient's
cardiac electrical signal and advises the user to shock a patient
upon detection of (1) ventricular fibrillation; (2) ventricular
tachycardia; (3) other cardiac rhythms with ventricular rates
exceeding 180 beats per minute and having amplitudes of at
.[.lease.]. .Iadd.least .Iaddend.0.15 millivolts. When such a
condition is detected, AED 22 will build up an electrical charge
for delivery to the patient to defibrillate the patient with a
defibrillation shock. The operator of AED 22 is guided by voice
prompts and an illuminated rescue (shock) button. Olson, et al.
U.S. Pat. No. 5,645,571, incorporated herein by reference,
discloses the general construction and manner of use of an AED.
AED 22 includes case 12 with carrying handle 14 and battery 80, the
battery 80 being removably disposed within a battery compartment
(not shown) defined in case 12. Battery 80 functions as an energy
source for AED 22. Visual maintenance indicator 20 and data access
door 44 are located on the outside of case 12 to facilitate access
by the operator. A data communication serial port 42 is situated
behind data access door 44. Case 12 also includes panel 24 and
electrode compartment 26 defined in a top portion thereof. Panel 24
includes illuminable rescue switch 18 and diagnostic display panel
36 with "electrodes" indicator light 28. Panel 24 and electrode
compartment 26 are enclosed by selectively closeable lid 27.
Electrode compartment 26 contains connector 32 and electrode
package 60. Electrode compartment 26 hermetically encloses a
patient interface which includes a pair of electrodes 50 depicted
in FIG. 2, and a force sensor 200, FIGS. 4-16. Electrodes 50 and
force sensor 200 are removably connected to connector 32 by lead
wires 52 and lead wire connector 58. Electrodes 50 are attachable
to a patient prior to a rescue intervention procedure with AED
22.
AED 22 also includes a digital microprocessor-based electrical
control system (see the block diagram of FIG. 3) for controlling
overall operation of AED 22 and for delivering a defibrillation
shock pulse through electrodes 50 via connector 32 and lead wires
52. The electrical control system further includes an impedance
measuring circuit for testing the interconnection and operability
of electrodes 50 to detect several faults. For example, if the
conductive hydrogel adhesive on electrodes 50 is too dry or if
electrodes 50 are not properly connected to connector 32 a
relatively high impedance (e.g. greater than about 20 ohms) will be
present across connector 32. However, when fresh electrodes 50 are
properly connected, the impedance across connector 32 will be
between about 2 and 10 ohms.
To insure operable electrodes 50, an electrode self-test is
conducted (e.g., daily or upon opening lid 27) in which the
interconnection and operability of electrodes 50 are checked with
the impedance measuring circuit. If electrodes 50 are missing or
unplugged from connector 32, if electrodes 50 are damaged, or if
the conductive hydrogel adhesive on electrodes 50 is too dry, the
control system of AED 22 will illuminate "Electrodes" indicator
light 28 on diagnostic display panel 36.
.Iadd.Defibrillator 22 also includes electrocardiogram (EKG) filter
and amplifier 104 which is connected between electrode connector 32
and A/D converter 102. The EKG or cardiac rhythm of the patient is
processed by filter and amplifier 104 in a conventional manner, and
digitized by A/D converter 102 before being coupled to processor
74.
The rescue mode operation of defibrillator 22 is initiated when an
operator opens lid 27 to access the electrode package 60. The
opening of the lid 27 is detected by lid switch 90, which
effectively functions as an on/off switch. In response to this
action, power control circuit 88 activates power generation circuit
84 and initiates rescue mode operation of processor 74. Processor
74 then begins its rescue mode operation and initiates the
generation of an audible voice prompt "To attempt a rescue,
disconnect charger." if a charger is connected when lid 27 is
opened.
If the lid-opened self-test is successfully completed, processor 74
initiates the generation of an audible "Place electrodes." voice
prompt. In response to this voice prompt, and following the
instructions on the inside of lid 27, the operator should remove
electrode package 60 from compartment 26, open the package, peel
electrodes 50 from the release liner and place the electrodes on
the patient's chest. While this action is being performed,
processor 74 monitors the impedance signals received through A/D
converter 102 to determine whether the impedance across the
electrodes indicates that they have been properly positioned on the
patient. If the correct impedance is not measured, processor 74
initiates the generation of a "Check electrodes." voice prompt.
After detecting an impedance indicating the proper placement of
electrodes 50, and without further action by the operator (i.e.,
automatically), processor 74 begins a first analyze sequence by
initiating the generation of a "Do not touch patient. Analyzing
rhythm." voice prompt, and analyzing the patient's cardiac rhythm.
In one embodiment, processor 74 collects and analyzes a nine second
segment of the patient's cardiac rhythm. The cardiac rhythm
analysis program executed by processor 74 is stored in program
memory 76. Algorithms of the type implemented by the rhythm
analysis program are generally known and disclosed, for example, in
the W. A. Tacker Jr. book Defibrillation of the Heart, 1994. If the
processor 74 determines that the patient has a nonshockable cardiac
rhythm that is not susceptible to treatment by defibrillation
pulses (e.g., no pulse rather than a fibrillating rhythm), it
initiates the generation of a "Check pulse. If no pulse, give CPR."
voice prompt. One minute after this voice prompt, processor 74
repeats the initiation of the "Do not touch patient. Analyzing
rhythm." voice prompt and the associated cardiac rhythm
analysis.
When a shockable cardiac rhythm is detected, processor 74 begins a
first charge sequence by initiating the generation of a "Charging."
voice prompt, and causes high voltage generation circuit 86 to
operate in the charge mode. When the high voltage generation
circuit 86 is charged, processor 74 begins a first shock sequence
by initiating the generation of a "Stand clear. Push flashing
button to rescue." voice prompt, and the flashing illumination of
rescue switch 18. The operator actuation of rescue switch 18 will
then cause processor 74 to operate high voltage generation circuit
86 in the discharge mode, and results in the application of a
defibrillation pulse to the patient to complete the first series of
analyze/charge/shock sequences. In one embodiment, the first
defibrillation pulse delivered by defibrillator 22 has an energy
content of about two hundred joules.
Following the first series of analyze/charge/shock sequences,
processor 74 times out a short pause of about five seconds to allow
the heart to reestablish its cardiac rhythm before beginning a
second series of analyze/charge/shock sequences. The second series
of analyze/charge/shock sequences is identical to the first series
described above, except the energy content of the defibrillation
pulse can be about two hundred joules or three hundred joules. If
the second series of analyze/charge/shock sequences ends with the
delivery of a defibrillation pulse, processor 74 again times out a
short pause of about five seconds before beginning a third
analyze/charge/shock sequence. The third series is also identical
to the first series, but processor 74 controls the high voltage
generation circuit 86 in such a manner as to cause the
defibrillation pulse delivered upon the actuation of the rescue
switch 18 to have an energy content of about three hundred and
sixty joules.
Following the delivery of a defibrillation pulse at the end of the
third series of analyze/charge/shock sequences, or after
identifying a nonshockable cardiac rhythm, processor 74 initiates
the generation of a "Check Pulse. If no pulse, give CPR." voice
prompt. Processor 74 then times a one minute CPR period to complete
a first set of three series of analyze/charge/shock sequences.
Rescue mode operation then continues with additional sets of three
series of analyze/charge/shock sequences of the type described
above (all with three hundred and sixty joule pulses). Processor 74
ends rescue mode operation of defibrillator 22 when a total of nine
series of analyze/charge/shock sequences have been performed, or
lid 27 is closed.
Throughout the analyze, charge and shock sequences, processor 74
monitors the impedance present across connector 32 to determine
whether electrodes 50 remain properly positioned on the patient. If
the monitored impedance is out of range (e.g., too high if the
electrodes have come off the patient, or too low is shortened),
processor 74 initiates the generation of a "Check Electrodes."
voice prompt, and causes high voltage generation circuit 86 to
discharge any charge that may be present through internal load 98.
Rescue mode operation will resume when processor 74 determines that
the electrodes have been properly repositioned on the
patient..Iaddend.
FIG. 2 is an exploded view of a prior art electrode 50. Electrode
50 includes flexible, adhesive coated backing layer 53 (preferably
a polymeric foam), and patient engaging layer 54. Patient engaging
layer 54 is preferably a hydrogel material which has adhesive
properties and which is electrically conductive. Hydrogel adhesive
of this type is commercially available from LccTcc Corporation
(Minnetonka, Minn.) and Tyco International Ltd. (Hamilton,
Bermuda). Current disbursing flexible conductive portion 56 is
preferably located between backing layer 53 and patient-engaging
hydrogel layer 54. Conductive portion 56, as shown, need not be the
same size as backing layer 53 and is preferably a homogeneous,
solid, thinly deposited metallic substance, or a conductive
ink.
Insulated lead wire 52 is terminated with a wire terminal
.Iadd.1.Iaddend.70. Wire terminal .Iadd.1.Iaddend.70 is
electrically connected to conductive portion 56 via conductive
rivet .Iadd.1.Iaddend.74 and washer .Iadd.1.Iaddend.72. Conductive
rivet .Iadd.1.Iaddend.74 is covered on a first side with insulating
disk .Iadd.1.Iaddend.76. Conductive rivet .Iadd.1.Iaddend.74,
washer .Iadd.1.Iaddend.72, and wire terminal .Iadd.1.Iaddend.70 are
all covered on a second side with insulating pad
.Iadd.1.Iaddend.78. Further examples of electrode pad construction
for use with AED 22 are described and shown in U.S. Pat. Nos.
5,697,955, 5,579,919, and 5,402,884, all hereby incorporated by
reference.
.Iadd.For example, referring to FIGS. 20 and 21 an embodiment of a
packaged electrode system 310 is shown to comprise an electrode 311
and a package or enclosure 312. Also shown in FIG. 21 is a test
apparatus 313. The electrode 311 is shown to comprise a
non-conductive base or backing layer 314, a conductor or conductive
layer 315, a lead 316, and a conductive contact layer 317. The base
layer 314 is preferably constructed of a thin, flexible polymeric
substance such as a urethane foam, or a polyester or polyolefin
laminate which provides structural base and insulative properties.
Although the base layer 314 is shown to have a surface area which
is substantially coextensive with the surface of the contact layer
317, it alternatively may be slightly larger. In such larger
configurations, the base layer 314 may have a pressure sensitive
adhesive disposed on its patient contact side for increased
adhesion to the patient body.
The conductive layer 315 is shown to be disposed on the first or
patient side of base layer 314. It functions to transfer (disperse)
current or voltage from the lead 316 (or to the lead in a sensing
application) to the patient contact layer 317. Although the
conductive layer 315 is shown to have a surface area which is
smaller than that of the base layer 314 or contact layer 317, it
may alternatively have a dimension which is larger than that shown,
or even on which is coextensive with the base and contact layers
314 and 317. The conductive layer 315 is preferably a homogeneous,
solid, thinly deposited metallic substance, or a conductive ink
material. Alternatively, the conductive layer 315 may be formed of
a flexible mesh material, a conductive adhesive or a deposited ink
pattern. Flexible conductive ink compounds known in the art have a
conductive filler of Gold, Silver, Aluminum or other conductive
materials.
The lead 316 is preferably an insulated wire conductor which
extends from a mating point with the conductive layer 315, through
the base layer 314, and then has a freely movable end. Various
alternatives of this lead 316 design exist and are useable
consistent with the general teachings of the invention, including
but not limited to uninsulated wire conductors and conductive
strips or traces deposited between the contact layer 317 and the
base 314 or conductive layers 315. Such a trace or strip may also
extend just beyond the base layer 314 for connection with an
ancillary connection means such as a wiring harness including
conductive clip means.
The conductive contact layer 317 is preferably a thin layer of
semi-liquid gel material. The gel maintains direct electrical
contact with the skin, to reduce variations in conductance, and it
permits such contact for long periods of time. The gel is a
conductive, gelatinous compound which is also flexible for
contoured adhesion to the body of a patient. The gel also
preferably has a pressure sensitive, moisture resistant adhesive
property. Compounds having these characteristics have been
developed by Minnesota Mining and Manufacturing, Medtronic, and Lec
Tec (Synkara TM), Corporations, all of Minnesota, U.S.A. Generally,
these compounds have low resistivities. The contact layer 317 is
for direct contact with the patient's body to transfer current or
voltage thereto or therefrom. Overall, although the electrode 311
and its constituent elements are shown to have circular
configurations, they may alternatively be formed in various other
shapes such as rectangular or square patches.
The package structure 312 is shown to have an envelope-like
structure formed of a substantially continuous thin, homogeneous
layer 318 of a polymeric, preferably non-gas permeable, material.
Alternatively, as shown in FIG. 38, the package 387 embodiment may
have a pouch-like structure formed of a pair of thin, flat
homogeneous layers 388 and 389 which are sealed or otherwise merged
together at their peripheries or outer edges 390. And, although the
package 312 is shown to have a rectangular configuration various
other configurations and shapes are also useable.
The package further comprises a pair of conductive connectors 319
and 320 which are separated a predetermined distance from one
another for contact with separate areas of the contact layer 317 of
the enclosed electrode 311. The connectors 319 and 320 are
conductive areas which are shown to have a unitary construction
with the package layer 318. The contacts 319 and 320 may
alternatively be formed of thin layer strips of conductive
material, or a printed conductive ink, disposed on the interior
side of the package layer 318, extending from contact nodes to
peripheral contact areas on the exterior of the package 318. Yet
another snap-type embodiment 379 is shown in FIGS. 35 and 36
including a connective member 380 disposed on one side of the base
layer 318, and a current dispersion member 381 disposed on the
opposite side and being connected to the upper member 380 via an
aperture in the base 318. The upper member 380 is shown 360 have a
base 382 and a mating notch 383 for coupling the lower member
381.
Referring to FIG. 21, the system 310 may also include a test
apparatus 313. The test apparatus 313 includes a current source
323, preferably a battery, test circuitry 324, preferably including
measurement components and status indication components such as an
analog meter, LCD digital display or light emitting diodes, and
connectors 321 and 322 for coupling with the package 312 connectors
319 and 320. In use, the test apparatus 313 is connected to the
package connectors 319 and 320. The test circuitry 324 is then
activated to form a closed current loop to determine whether
continuity exists with respect to the enclosed electrode 311,
thereby indicating whether the electrode 311 is still functional.
Additionally, a load 386 formed of for example a conductive and
semi-conductive material layers 385 and 386, may be added to the
current loop as for example is shown in FIG. 37, for purposes of
measuring the magnitude of current flow for more precise
measurement of electrode 311 condition.
In the case of the electrode system 310, a current loop is formed
including the connector 319, the gel of the contact layer 317
(along a substantially horizontal plane), and the connector 320
which is located at a remote location on the contact layer 314 with
respect to the connector 319. Current conducts easily in fresh,
semi-liquid gel of the contact layer 317. In contrast, no current
conducts, or current conduction is attenuated, in stale, dried gel.
This is indicative of the need to dispose of the stored electrode
without using it. And, this condition is determinable without the
need to open the package 312 and thereby risk compromising the
freshness or sterility of a viable electrode 311.
Referring to FIGS. 22 and 23, another packaged electrode system 330
is shown to comprise an electrode 331 and a package or enclosure
332. The electrode 331 is shown to comprise a non-conductive base
layer 333, and a conductive gel layer 336. A conductive snap-type
connector having a connection member 335 disposed on one side and a
current dispersion member 334 disposed on the second side is also
shown. The package 332 is shown to have at least one body layer 337
with a pair of contacts 338 and 339 disposed at predetermined
locations to electrically connect with the gel layer 336 and
contact 335. In a test mode, a current loop is formed between the
connector 339, gel layer 336, connector portions 334 and 335 and
connector 338.
Referring to FIGS. 24 and 25, another packaged electrode system 345
is shown to comprise an electrode 346 and an enclosure 347. The
electrode 346 is shown to comprise a non-conductive base layer 348,
a conductive gel layer 355, and a pair of separate conductive
layers 349 and 350, each of which are shown to have a lead 351 and
352 extending therefrom and terminating in a connective node 353
and 354. The lead pair 351 and 352 (and layer pair 349 and 350)
provide a redundant circuit path for increased reliability of use
in emergency settings. The package 347 is shown to have at least
one body layer 356 with a pair of contacts 357 and 358 disposed at
predetermined locations to electrically couple with connective
nodes 353 and 354. In a test mode, a current loop is formed between
a connector 357 or 358, it's respective connective node 353 or 354
and lead 351 or 352, and its respective conductive layer 349 or
350. In a properly functioning electrode 346, current conducts
through the gel 355 from one conductive layer 349 to the other 350,
and then back to the test apparatus through the above-mentioned
path.
Referring to FIGS. 26 and 27, another packaged electrode system 364
is shown to comprise an electrode 365 and a unitary package 366.
The electrode 365 is shown to compromise a non-conductive base
layer 367, and a conductive gel layer 370. A snap-type connector
with members 368 and 369 electrically couples the gel layer
370.
The package 366 is shown to have at least one body layer 371 which
is coupled to the electrode 365 base layer 367 at tear-away
perforated lines 373. A connector 372 is shown disposed for contact
with the electrode 365 gel layer 370. In a test mode, a current
loop is formed between the connector 372, the gel layer 370, and
the connector members 368 and 369.
Referring to FIGS. 28 and 29, another packaged electrode system 397
is shown to comprise an electrode 398 and a package. The electrode
398 is shown to comprise a non-conductive base layer 401, a
conductive gel layer 402, and a lead 404 having a conductor 405 and
an insulator 406, which is shown to be embedded directly in the gel
layer 402. Alternatively, the lead may be connected to a conductive
current dispersion layer (not shown). A conductive test strip 403
is also shown to be adhered to the surface of the gel 402 at a
location remote from the lead 404 for test purposes, and which is
designed to release from the gel 402 upon removal of the package
layer 399.
The package is shown to have a pair of layers 399 and 400 which
overlap to form an interior cavity 407 and area sealingly connected
at their peripheries 408. In a test mode, a current loop is formed
between the lead 404, the gel layer 402 and the test strip 403,
which like the lead 404 is shown extended through the package
periphery 408 for contact with an external test apparatus.
Referring to FIGS. 31 and 32, another packaged electrode system 414
is shown to comprise an electrode 415 and an enclosure. The
electrode 415 is shown to comprise a non-conductive base layer 417,
and a conductive adhesive gel layer 418 which is connected to a
snap-type connection node 421 or the like, and an associated lead
420. The package is shown to comprise a single top layer of
non-conductive material 416 which is laminated or adhesively mated
to the electrode base layer 417. In use the gel layer 418 is
removable from the package layer 416. A test strip 419 is disposed
on the interior of the package, adhesively connected to the gel
layer 418, and extending to the package exterior. In a test mode, a
current loop is formed between the lead 420, node 421, gel layer
418 and the test strip 419.
Referring to FIGS. 33 and 34, another packaged electrode system 427
is shown to comprise a pair of electrodes 428 and 429 and a
package. The electrodes 428 and 429 are shown to comprise
non-conductive base layers 430 and 433, and conductive gel layers
431 and 434. Leads 432 and 435 extend from the respective gel
layers 431 and 434. The package is shown to have a pair of
overlapping layers 442 and 443 which are sealed at their
peripheries 441 to form an enclosure 440 housing the electrodes 428
and 429. Importantly, the electrodes 428 and 429 are oriented with
their respective gel layers 431 and 434 mating with a resistive
layer 437 (and an optional separator layer 436) formed of a
conductive/resistive material as known in the art. A conductive
lead 439 or strip extends from the resistive layer through the
package periphery 441, as do the electrode leads 432 and 435.
In a test mode, a current loop is formed between, for example, a
lead 432, a gel layer 431, the resistive layer 437, and the
remaining gel layer 434 and lead 435. The circuit can be altered to
include the lead 439..Iaddend.
FIG. 3 is a block diagram of electrical system 70 of AED 22. The
overall operation of AED 22 is controlled by a digital
microprocessor-based control system 72 which includes a processor
74 interfaced to program memory 76, data memory 77, event memory 78
and real time clock 79. The operating program executed by processor
74 is stored in program memory 76. Electrical power is provided by
the battery 80 which is removably positioned within the battery
compartment of AED 22 and is connected to power generation circuit
84.
Power generation circuit 84 is also connected to lid switch 90,
watch dog timer 92, real time clock 79 and processor 74. Lid switch
90 is a magnetic read relay switch in one embodiment, and provides
signals to processor 74 indicating whether lid 27 is open or
closed. Data communication port 42 is coupled to processor 74 for
two-way serial data transfer using an RS-232 protocol. Rescue
switch 18, maintenance indicator 20, the indicator lights of
diagnostic display panel 36, the voice circuit 94 and piezoelectric
audible alarm 96 are also connected to processor 74. Voice circuit
94 is connected to speaker 34. In response to voice prompt control
signals from processor 74, circuit 94 and speaker 34 generate
audible voice prompts for consideration by a rescuer.
High voltage generation circuit 86 is also connected to and
controlled by processor 74. Circuits such as high voltage
generation circuit 86 are generally known, and disclosed, for
example, in the commonly assigned Persson .[.et al..]. U.S. Pat.
No. 5,405,361, which is hereby incorporated by reference. In
response to charge control signals provided by processor 74, high
voltage generation circuit 86 is operated in a charge mode during
which one set of semiconductor switches (not separately shown)
cause a plurality of capacitors (also not shown), to be charged in
parallel to the 12V potential supplied by power generation circuit
84. Once charged, and in response to discharge control signals
provided by processor 74, high voltage generation circuit 86 is
operated in a discharge mode during which the capacitors are
discharged in series by another set of semiconductor switches (not
separately shown) to produce the high voltage defibrillation
pulses. The defibrillation pulses are applied to the patient by
electrodes 50 through connector 32 connected to the high voltage
generation circuit 86.
Impedance measuring circuit 100 is connected to both connector 32
and real time clock 79. Impedance measuring circuit 100 is
interfaced to processor 74 through analog-to-digital (A/D)
converter 102. Impedance measuring circuit 100 receives a clock
signal having a predetermined magnitude from clock 79, and applies
the signal to electrodes 50 through connector 32. The magnitude of
the clock signal received back from electrodes 50 through connector
32 is monitored by impedance measuring circuit 100. An impedance
signal representative of the impedance present across electrodes 50
is then generated by circuit 100 as a function of the ratio of the
magnitudes of the applied and received clock signals (i.e., the
attenuation of the applied signal).
For example, if electrodes 50 within an unopened package 60 are
connected by lead wires 52 and connector 58 is properly connected
to connector 32 on AED 22, a relatively low resistance (e.g., less
than about 10 ohms) is present across electrodes 50. If the
hydrogel adhesive 54 on electrodes 50 is too dry, or the electrodes
50 are not properly positioned on the patient, a relatively high
resistance (e.g., greater than about two hundred fifty ohms) will
be present across the electrodes 50. The resistance across
electrodes 50 will then be between about twenty-five and two
hundred fifty ohms when fresh electrodes 50 are properly positioned
on the patient with good electrical contacts. It should be noted
that these resistance values are given as exemplary ranges and are
not meant to be absolute ranges. The impedance signal
representative of the impedance measured by circuit 100 is
digitized by A/D converter 102 and provided to processor 74.
Impedance measuring circuit 110 is connected to connector 32 and
real time clock 79, and is interfaced to processor 74 through
analog-to-digital (A/D) converter 102. Impedance measuring circuit
110 receives a clock signal having a predetermined magnitude from
clock 79, and applies the signal to force sensor 200 through
connector 32. The magnitude of the clock signal received back from
force sensor 200 through connector 32 is monitored by impedance
measuring circuit 110. An impedance signal representative of the
impedance present across force sensor 200 is then generated by
circuit 110 as a function of the ratio of the magnitudes of the
applied and received clock signals (i.e., the attenuation of the
applied signal). The impedance signal representative of the
impedance measured by circuit 110 is digitized by A/D converter 102
and provided to processor 74.
FIG. 4 is a plan view of a patient interface 120 for use with AED
22. Patient interface 120 includes connector 58 which is adapted to
releasably mate with connector 32 of AED 22. Four lead wires 52A,
52B, 52C, and 52D are all terminated with connector 58. Patient
interface 120 also includes a force sensing pad 102 which includes
a force sensor 200. Lead wires 52C and 52D are electrically
connected to force sensor 200. Electrodes 50A and 50B each include
backing layer 53, patient engaging hydrogel layer 54, conductive
portion 56, and insulating pad 78.
FIG. 5 is a plan view illustrating patient interface 120 applied to
human torso 98 of the victim 112. Force sensing pad 102 is applied
over the sternum of torso 98. Force sensing pad 102 may be adhered
with pressure sensitive adhesive. Force sensing pad 102 includes
force sensor 200 which is electrically connected to lead wires 52C
and 52D.
Electrode 50A is shown applied to the upper right chest of torso
98. Electrode 50A is electrically connected to lead wire 52A.
Electrode 50B is applied to the lower left side of torso 98 and is
electrically connected to lead wire 52B. Lead wires 52A, 52B, 52C,
and 52D are terminated with connector 58. Connector 58 is adapted
to make releasable, electrical contact with connector 32 of AED
22.
Those skilled in the art will readily recognize that electrodes
50A, 50B and force sensing pad 102 may be placed in locations on
torso 98 other than those shown in FIG. 5 without deviating from
the spirit or scope of this invention.
FIG. 6 is a plan view of a patient interface 130 for use with AED
22. Interface 130 includes a second preferred embodiment of force
sensor 200. Patient interface 130 includes connector 58 which is
adapted to releasably mate with connector 32 of AED 22. Four lead
wires 52A, 52B, 52C, and 52D are all terminated with connector 58.
Patient interface 130 also includes force sensor 200 which is
positioned between backing layer 153 and insulating pad 178 of
electrode 150A. Lead wires 52C and 52D are electrically connected
to force sensor 200. Electrodes 150A and 150B each include patient
engaging hydrogel layer 54, and conductive portion 56.
FIG. 7 is a plan view illustrating patient interface 130 applied to
torso 98. Force sensor 200 is positioned over the sternum of torso
98. Force sensor 200 is electrically connected to lead wires 52C
and 52D. Electrode 150A is shown applied to torso 98. Electrode
150A is electrically connected to lead wire 52A. Electrode 150B is
applied to the lower left side of torso 98 and is electrically
connected to lead wire 52B. Lead wires 52A, 52B, 52C, and 52D are
terminated with connector 58 (not shown). Connector 58 is adapted
to make releasable, electrical contact with connector 32 (not
shown) of AED 22.
FIG. 8 is a cross section illustrating an embodiment of a force
sensor 200. Force sensor 200 has a first side 210 and a second side
220. Force sensor 200 includes a substrate 202. A conductive
pattern 204A, 204B is situated on each side of the substrate layer.
Substrate 202 may be any thin (e.g. about 0.002'' to 0.020'')
nonconductive sheet of material. Plastic film materials such as
polyester, polycarbonate, PVC, etc. have been found to work well as
substrate 202. Conductive patterns 204A, 204B may be any conductive
material such as copper foil, nickel foil, or conductive ink. In a
preferred embodiment substrate 202 is 5 mil polyester and
conductive patterns 204A, 204B are silver conductive ink.
Substrate 202 includes apertures 208. Conductive pads 206A and 206B
are situated on each side of substrate 202 as shown in FIG. 8.
Conductive pads 206A, 206B are preferably made of a deformable,
conductive material. Materials which have been found suitable
include conductive silicone rubber, conductive foam rubber, and
conductive urethane rubber.
FIG. 9 is a plan view illustrating first side 210 of force sensor
200 with conductive pads 206A, 206B removed. Conductive pattern
204A is seen situated on substrate 202. Apertures 208 are cut
through conductive pattern 204A, substrate 202, and conductive
pattern 204B, underlying substrate 202.
FIG. 10 is a plan view illustrating second side 220 of force sensor
200 with conductive pads 206A, 206B removed. Conductive pattern
204B is seen situated on substrate 202. As also shown in FIG. 9,
apertures 208 are cut through conductive pattern 204B, substrate
202, and conductive pattern 204A, underlying substrate 202.
Referring now to both FIG. 9 and FIG. 10, conductive patterns 204A,
204B each include conductive traces 212A, 212B. Wire terminals
214A, 214B are arranged make electrical contact with conductive
traces 212A, 212B respectively. Wire terminals 214A, 214B are
attached to substrate 202 with rivets 216A, 216B and washers 218A,
218B. Lead wires 222A, 222B are terminated with wire terminals
214A, 214B.
Those with skill in the art will recognize that other methods may
be used to attach lead wires 222A, 222B to conductive traces 212A,
212B. Possible methods include soldering, the use of a connector
designed to mate with flexible circuits, and the use of conductive
adhesive.
FIG. 11 is a section view of force sensor 200 with a compressive
force F applied. When force sensor 200 is used, it is placed
between two objects, such as the sternum of a cardiac arrest victim
and the heel of a rescuer's hand. When the rescuer presses down
with the heel of his or her hand, the force results in pressure
distributed across the area of the heel of his or her hand.
When pressure is applied to force sensor 200, conductive pads 206A,
206B extrude through apertures 208. When pads 206A, 206B contact
each other, they complete an electrical circuit between conductive
layer 204A and conductive layer 204B. Increasing the force F
applied to force sensor 200 increases the surface area of the
electrical connection between conductive pads 206A, 206B, thereby
decreasing the electrical resistance between pads 206A, 206B. The
electrical resistance of the circuit between conductive layer 204A
and conductive layer 204B is therefore indicative of the magnitude
of the force F applied to force sensor 200.
FIGS. 12-14 illustrate a further preferred embodiment of force
sensor 200. Force sensor 200 includes a first substrate 222. A
conductive pattern 224 is situated on first substrate 222. As in
the previous embodiment, substrate 222 may be any thin (e.g. about
0.002'' to 0.010'') nonconductive sheet of material. Plastic film
materials such as polyester, polycarbonate, PVC, etc. have been
found to work well as substrate 222. Conductive pattern 224 may be
any conductive material such as copper foil, nickel foil, or
conductive ink. In a preferred embodiment substrate layer 222 is 5
mil polyester and conductive pattern 224 is silver conductive
ink.
Force sensor 200 includes second substrate 226. A conductive
pattern 228 is situated on second substrate 226. Second substrate
226 is situated on first substrate 222. First substrate 222 and
second substrate 226 may be held together with a layer of pressure
sensitive adhesive (not shown).
Substrate 222 includes apertures 230. A conductive pad 232 is
situated on, and makes electrical contact with conductive pattern
224 as shown in FIG. 14. Conductive pad 232 is preferably made of a
deformable, conductive material. Materials which have been found
suitable include conductive silicone rubber, conductive foam
rubber, and conductive urethane rubber.
FIG. 13 is a plan view illustrating second substrate 226 and
conductive pattern 228.
FIG. 14 is a plan view illustrating first substrate 222 and
conductive pattern 224.
FIG. 15 is a section view of the force sensor 200 of FIG. 12 with a
force F applied. When force sensor 200 is used, it is placed
between two objects, such as the sternum of a cardiac arrest victim
and the heel of a rescuers hand. When the rescuer presses down with
the heel of his or her hand, the force results in pressure
distributed across the area of the heel of his or her hand.
When a force F is applied to force sensor 200, conductive pad 232
extrudes through apertures 230. When conductive pad 232 contacts
conductive pattern 228 it completes an electrical circuit between
conductive pattern 224 and conductive pattern 228. Increasing the
force F applied to force sensor 200 increases the surface area of
the electrical connection between conductive pads 232 and
conductive pattern 228, thereby reducing the electrical resistance
between pad 232 and pattern 228. Accordingly, change in contact
area creates a change in electrical resistance which is indicative
of the force applied to force sensor 200.
FIGS. 16-18 illustrate another third embodiment of force sensor
200. In this embodiment force sensor 200 includes a first substrate
242. Two conductive patterns 244A, 244B are situated on first
substrate 242.
Force sensor 200 includes second substrate 246 which includes
apertures 250. Second substrate 246 is comprised of a
non-conductive material. Polyester, polyethylene, and polypropylene
have been found to be suitable materials for second substrate 246.
A conductive pad 252 is situated on second substrate 246. As in the
previous embodiments, conductive pad 232 is preferably made of a
deformable, conductive material.
FIG. 17 is a plan view illustrating first substrate 242 and
conductive patterns 244A, 244B. The conductive patterns 244A, 244B
are arranged so that they are in close proximity to each other.
Small gaps 256 are left between conductive paths 244A, 244B so that
there is no direct electrical contact between conductive paths
244A, 244B.
FIG 18 is a plan view illustrating second substrate 246 and
apertures 250.
FIG. 19 is a section view of the force sensor 200 of FIGS. 16-18
with a force F applied. When force sensor 200 is used, it is placed
between two objects, such as the sternum of a cardiac arrest victim
and the heel of a rescuers hand. When the rescuer presses down with
the heel of his or her hand, the force F results in pressure
distributed across the area of the heel of his or her hand.
When pressure is applied to force sensor 200, conductive pad 252
extrudes through apparatus 250. When conductive pad 252 contacts
conductive patterns 244A, 244B it completes an electrical circuit
between conductive pattern 244A and conductive pattern 244B.
Increasing the force applied to force sensor 200 increases the
surface area of the electrical connection between conductive pad
252 and conductive patterns 244A, 244B. This change in contact area
creates a change in electrical resistance which is indicative of
the force applied to force sensor 200.
Referring to FIGS. 4 and 5 in operation force sensor 200 is
positioned on the sternum of a victim 112. The rescuer places the
heel of his or her hand onto force sensor 200 and delivers chest
compressions to the chest of the victim 112. Force sensor 200 and
impedance measuring circuit 110 produce an electrical signal
proportional to the force applied to the victim's chest. This
signal indicates to processor 74 the rate and magnitude of the
chest compressions which the victim 112 is receiving. This signal
also allows processor 74 to determine the precise time that a
rescuer has begun (or stopped) CPR.
Processor 74 compares the measured rate of chest compressions to a
range of desired values.
If the current chest compression rate value delivered by the
rescuer is less than the desired range, processor 74 will produce a
control signal which causes voice circuit 94 and speaker 34 to
generate an appropriate voice prompt such as "faster". If the
current chest compression rate value is greater than the desired
range, processor 74 will produce a control signal which causes
voice circuit 94 and speaker 34 to generate an appropriate voice
prompt such as "slower".
Processor 74 also compares the measured chest compression force to
a range of desired values. If the chest compression force delivered
by the rescuer is less than the desired range, processor 74 will
produce a control signal which causes voice circuit 94 and speaker
34 to generate an appropriate voice prompt such as "harder". If the
chest compression force is greater than the desired range,
processor will produce a control signal which causes voice circuit
94 and speaker 34 to generate an appropriate voice prompt such as
"softer".
AED 22 may also provide other types of audible feedback to the
rescuer. For example, AED 22 may give an audible signal each time
the force measured using force sensor 200 reaches a desired
value.
The present invention may be embodied in other specific forms
without departing from the spirit of the essential attributes
thereof. Therefore, the illustrated embodiments should be
considered in all respects as illustrative and not restrictive,
reference being made to the appended claims rather than to the
foregoing description to indicate the scope of the invention.
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