WEARABLE MONITORING AND TREATMENT DEVICE
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional
Application Serial No. 61/530,261 titled "WEARABLE MONITORING AND
TREATMENT DEVICE," filed September 1, 2011, and to U.S. Provisional
Application Serial No. 61/679,143 titled "WEARABLE MONITORING AND
TREATMENT DEVICE," filed August 3, 2012, each of which is incorporated herein
by reference in its entirety.
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
At least one embodiment of the present invention relates generally to a
wearable therapeutic device, and more specifically, to a wearable therapeutic device
configured to monitor or treat a subject.
2. DISCUSSION OF RELATED ART
Cardiac arrest and other health ailments are a major cause of death worldwide.
Various resuscitation efforts aim to maintain the body's circulatory and respiratory
systems during cardiac arrest in an attempt to save the life of the victim. The sooner
these resuscitation efforts begin, the better the victim' s chances of survival. Health
care professionals also attempt to detect and prevent conditions conducive to cardiac
ailments by treating patients with drugs or by suggesting lifestyle changes. These
efforts are expensive and have a limited success rate, and cardiac arrest, among other
conditions, continues to claim the lives of victims.
SUMMARY OF THE INVENTION
Aspects and embodiments of the present invention are directed to a wearable
therapeutic device that is configured to be worn by a subject. Electrodes sense
information about the subject's health, and can apply treatment to the subject. At
least one inductive or capacitive element is included in a portion of the therapeutic
device. Characteristics of the inductive or capacitive element, such as its radius or
shape, change when the wearable therapeutic device expands, stretches, or otherwise
changes shape, which changes the inductance of the inductive element or the
capacitance of the capacitive element. Based at least in part on changes in the
inductance or the capacitance as the wearable therapeutic device changes shape, the
wearable therapeutic device can provide notifications to the subject regarding
arrhythmias, cardiac events, the condition of the wearable therapeutic device, and the
positioning of electrodes or other wearable therapeutic device components relative to
the subject.
At least one aspect is directed to a wearable therapeutic device. The wearable
therapeutic device includes a garment that is configured to include a sensing
electrode. At least one of an inductive element and a capacitive element is included in
at least part of the garment, and a controller is configured to determine a confidence
level of information received from the sensing electrode based on at least one of an
inductance of the inductive element and a capacitance of the capacitive element.
At least one other aspect is directed to a method of facilitating care of a
subject. The method provides a wearable therapeutic device configured to include a
sensing electrode, and receives, from the sensing electrode, information about the
subject. The method also determines inductance of an inductive element or
capacitance of a capacitive element included in the wearable therapeutic device, and
determines a confidence level of the information about the subject based on the
inductance or the capacitance.
At least one other aspect is directed to a non-transitory computer readable
medium having stored thereon sequences of instruction. The instructions include
instructions that will cause a processor to receive, from a sensing electrode of a
wearable therapeutic device, information about a subject, and to determine inductance
of an inductive element or capacitance of a capacitive element included in the
wearable therapeutic device. The instructions also cause the processor to determine a
confidence level of the information about the subject based on the inductance or the
capacitance.
In some embodiments, the wearable therapeutic device includes an alarm
module coupled with the controller and configured to provide a notification to a
subject based on the confidence level. In one embodiment, the controller determines
at least one of the inductance of the inductive element or the capacitance of the
capacitive element. Based on the confidence level, in some embodiments a
notification to the subject is provided regarding at least one of a diagnosis and
information about the wearable therapeutic device.
In various embodiments, a therapy electrode is included in the garment. The
controller can determine information regarding positioning of the therapy electrode or
the sensing electrode based on the inductance of the inductive element or the
capacitance of the capacitive element. A defibrillator is coupled to the therapy
electrode and together with the therapy electrode can apply treatment to the subject,
based on the confidence level of the information received from the sensing electrode.
The controller can identify, based on the inductance or the capacitance, an expansion
of the garment, and can determine, based on the expansion, that positioning of at least
one of the sensing electrode and the therapy electrode is outside a tolerance range. In
one embodiment, the controller can withhold treatment of the subject based on the
positioning of at least one of the sensing electrode and the therapy electrode. The
controller can determine, based on the expansion of the garment, respiratory function
of the subject. In one embodiment, the alarm module can provide instructions to the
subject regarding positioning of the sensing electrode or the therapy electrode based
on the expansion of the garment. The controller can determine a second inductance
value of the inductive element and can determine the confidence level based on a
differential between the first inductance value and the second inductance value. The
controller can also determine a second capacitance value of the capacitive element
and can determine the confidence level based on a differential between the first
capacitance value and the second capacitance value.
In some embodiments, a belt or a strap is configured to include at least one of
the inductive element and the capacitive element, and at least one of the sensing
electrode, the controller, the alarm module, a therapy electrode, and a defibrillator. In
on embodiment in which the belt or strap includes an inductive element, the belt can
include a core, wherein the inductive element is coiled around the core. The
notification can indicate that the garment is properly positioned about the subject, too
loose about the subject, too tight about the subject, soiled, or expired.
In some embodiments, the information received from the sensing electrode
includes electrocardiograph information of the subject, and the confidence level can
be determined based on the expansion of the garment and the electrocardiograph
information of the subject. An arrhythmic cardiac event can be identified based on
the confidence level, positioning of the therapy electrode can be verified, and the
therapy electrode can be instructed to apply treatment to the subject. The controller
can determine the confidence level based on the electrocardiograph information of the
subject. The controller can also determine an absence of an arrhythmic cardiac event
based on the inductance of the inductive element or the capacitance of the capacitive
element and the electrocardiograph information of the subject.
In some embodiments, the wearable therapeutic device includes a therapy
electrode and a defibrillator. The positioning of the sensing electrode or the therapy
electrode can be verified based on the inductance of the inductive element or the
capacitance of the capacitive element. Treatment can be applied to the subject using
the therapy electrode and the defibrillator. The inductive element or the capacitive
element can be included in a belt of the wearable therapeutic device, and an expansion
of a circumference of the belt can be identified based on the inductance of the
inductive element or the capacitance of the capacitive element. The confidence level
of the information about the subject can be determined based on the expansion of the
circumference of the belt. In one embodiment, the inductive element or the capacitive
element is in a garment of the wearable therapeutic device, and an expansion of the
garment can be identified based on the inductance of the inductive element or the
capacitance of the capacitive element. Instructions can be provided to the subject
regarding positioning of the sensing electrode or the therapy electrode based on the
expansion of the garment.
In various embodiments, the diagnosis includes a diagnosis of an arrhythmic
cardiac event. Electrocardiograph information of the subject can be sensed, and an
expansion of a portion of the wearable therapeutic device that includes at least one of
the inductive element and the capacitive element can be identified. The confidence
level can be determined based on the expansion of the portion of the wearable
therapeutic device and the electrocardiograph information of the subject, and the
arrhythmic cardiac event can be identified based on the confidence level. An absence
of an arrhythmic cardiac event can also be determined based on the confidence level.
In one embodiment, improper positioning of the sensing electrode or the therapy
electrode can be identified based on the expansion. An absence of an arrhythmic
cardiac event can be identified based on the improper positioning of the sensing
electrode. In one embodiment, treatment of the subject can be withheld based on the
improper positioning of the sensing electrode or the therapy electrode.
In some embodiments, instructions to operate the wearable therapeutic device
can be provided. In one embodiment, instructions can cause a processor to receive
sensed electrocardiograph information of the subject, and identify an expansion of a
portion of the wearable therapeutic device that includes the inductive element or the
capacitive element. The instructions can cause the processor to determine the
confidence level based on the expansion of the portion of the wearable therapeutic
device and the electrocardiograph information of the subject, and to identify an
arrhythmic cardiac event based on the confidence level. The instructions can cause
the processor to control the therapy electrode of the wearable therapeutic device to
apply treatment to the subject. In one embodiment, the instructions can cause the
processor to determine an absence of an arrhythmic cardiac event based on the
confidence level.
Other aspects and embodiments are discussed in detail below. The foregoing
information and the following detailed description include illustrative examples of
various aspects and embodiments, and are intended to provide an overview or
framework for understanding the nature and character of the claimed aspects and
embodiments. The drawings provide illustration and a further understanding of the
various aspects and embodiments, and are incorporated in and constitute a part of this
specification. The drawings, together with the remainder of the specification, serve to
describe and explain the claimed aspects and embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are not intended to be drawn to scale. In the
drawings, each identical or nearly identical component that is illustrated in various
figures is represented by a like numeral. For purposes of clarity, not every component
may be labeled in every drawing. In the drawings:
Figure 1 is a block diagram depicting a wearable therapeutic device in
accordance with an embodiment;
Figure 2 is a schematic diagram depicting a wearable therapeutic device in
accordance with an embodiment;
Figure 3A is a schematic diagram depicting a portion of a wearable therapeutic
device that includes an inductive element in an unstretched position in accordance
with an embodiment;
Figure 3B is a schematic diagram depicting a portion of a wearable therapeutic
device that includes a capacitive element in an unstretched position in accordance
with an embodiment;
Figure 4A is a schematic diagram depicting a portion of a wearable therapeutic
device that includes an inductive element in a stretched position in accordance with an
embodiment;
Figure 4B is a schematic diagram depicting a portion of a wearable therapeutic
device that includes a capacitive element in a stretched position in accordance with an
embodiment;
Figure 5 is a functional block diagram depicting a wearable therapeutic device
controller in accordance with an embodiment;
Figure 6 is a graph depicting tolerance stretch ranges of a wearable therapeutic
device in accordance with an embodiment; and
Figure 7 is a flow chart depicting a method of facilitating care of a subject in
accordance with an embodiment.
DETAILED DESCRIPTION
The systems and methods described herein are not limited in their application
to the details of construction and the arrangement of components set forth in the
description or illustrated in the drawings. The systems and methods described herein
are capable of other embodiments and of being practiced or of being carried out in
various ways. Also, the phraseology and terminology used herein is for the purpose
of description and should not be regarded as limiting. The use of "including"
"comprising" "having" "containing" "involving" and variations thereof herein, is
meant to encompass the items listed thereafter, equivalents thereof, and additional
items, as well as alternate embodiments consisting of the items listed thereafter
exclusively.
Various aspects and embodiments are directed to a wearable therapeutic
device. The wearable therapeutic device includes at least a sensing electrode. An
inductive or capacitive element is integrated into the wearable therapeutic device.
Inductance of the inductive element or capacitance of the capacitive element varies as
these elements change shape, for example due to stretching with use of the wearable
therapeutic device. A controller determines the inductance of the inductive element
or capacitance of the capacitive element and together with an alarm module or other
interface or output, can provide a notification to the subject regarding, for example,
the wearable treatment device, a diagnosis, or a treatment regimen.
Figure 1 is a block diagram of a wearable therapeutic device 100 in
accordance with an embodiment. In one embodiment, the wearable therapeutic
device 100 can be a wearable cardioverter defibrillator as described in commonly
owned U.S. Patent Application Serial No. 13/109,079, titled "Wearable Therapeutic
Device," filed on May 17, 2011, which is incorporated by reference herein in its
entirety.
Wearable therapeutic device 100 can include at least one garment 105 in the
shape of a vest or shirt. Garment 105 may also include at least one belt 110. Belt 110
may be worn about a subject's waist, at a higher location about the subject's chest, or
at other locations between the subject's waist and shoulders. Components of
wearable therapeutic device 100, including garment 105, can be worn under, over, or
partially under and partially over a subject's clothes.
In one embodiment, wearable therapeutic device 100 includes at least one of
the following elements: garment 105, belt 110, defibrillator 115, alarm module 120,
monitor 125, controller 130, sensing electrode 135, therapy electrode 140, strap 145,
inductive element 150, and capacitive element 155. In one embodiment, at least one
of defibrillator 115, alarm module 120, monitor 125, controller 130, sensing electrode
135, therapy electrode 140, inductive element 150, and capacitive element 155 are
included in or attached to belt 110 or strap 145. For example, wearable therapeutic
device 100 components can be fitted into open or closed pockets of belt 110 or strap
145, or otherwise attached to these elements via buckles, hook and loop fasteners,
holsters, loops, or sleeves that form part of belt 110 or strap 145. These elements may
also be integrated into belt 110 or strap 145, and these elements may be a permanent
part of belt 110 or strap 145, or releasable from belt 110 or strap 145. Garment 105
may include a series of belts 110 or straps 145, and need not constitute an article of
clothing. Wearable therapeutic device 100 may include one, more than one, or all of
the above mentioned elements, as well as additional elements such as at least one
power supply to provide power to controller 130, defibrillator 115, alarm module 120,
monitor 125, sensing electrodes 135, or therapy electrodes 140.
Defibrillator 115 can be included as part of wearable therapeutic device 100.
For example, defibrillator 115 can be included in garment 105, attached to strap 145,
or disposed in belt 110. In one embodiment, defibrillator 115 is electrically coupled
to therapy electrode 140. Defibrillator 115 can be an external defibrillator. Wearable
therapeutic device 100 may include at least one receptacle having a conductive fluid
encapsulated therein and housed in garment 105. For example, the receptacle can be
disposed in belt 110 or strap 145, proximate to at least one of sensing electrode 135
and therapy electrode 140. In one embodiment, electrodes 135 and 140 are dry
electrodes. Controller 130 or defibrillator 115 can release the conductive fluid from
the receptacles to enhance an electrical connection between sensing electrode 135 or
therapy electrode 140 and a subject wearing wearable therapeutic device 100 to, for
example, sense electrocardiograph information about the subject or to apply treatment
to the subject. The receptacles can be replaced after their conductive fluid has been
released, or upon their expiration. When a shock is applied, therapy electrodes 140,
the subject's body, and defibrillator 115 form at least part of a current path. One
embodiment includes at least one sensing electrode 135, one therapy electrode 140
disposed in front of the subject, e.g., proximate to the subject's chest, and two therapy
electrodes 140 disposed in back of the subject, e.g. proximate to the subject's back.
Garment 105 can hold electrodes 135 and 140 in position, for example against
the subject's skin around the subject's torso. Clothes or other material may be present
between garment 105 and the subject's skin. When positioned against the subject,
sensing electrodes 135 can sense electrocardiogram signals used by controller 130 to
monitor the subject's cardiac activity. When controller 130 identifies an arrhythmia
or other cardiac event, therapy electrodes 140, when positioned against the subject can
deliver defibrillating energy to the subject to convert the arrhythmia to a normal sinus
rhythm.
In one embodiment, sensing electrodes 135 and therapy electrodes 140 are
securely positioned against the subject's body in order for sensing electrodes 135 to
sense cardiac, respiratory, or other information about the subject; and for therapy
electrodes 140 to apply treatment to the subject. For example, sensing electrode 135
can include electrocardiogram electrodes that directly or indirectly (e.g., via clothes, a
conductive protective barrier, or a conductive fluid) contact the subject's skin to sense
an electrocardiogram signal with minimal artifacts. Further, therapy electrode 140
can directly or indirectly contact the subject's skin to reduce impedance between
therapy electrode 140 and the subject's skin and to efficiently deliver defibrillating
energy to the subject, without causing burns, blisters, inflammation, or other damage
to the subject's skin. In one embodiment, conductive fluid is released from
replaceable receptacles that are disposed in wearable therapeutic device 100 to contact
the subject's skin and surfaces of sensing electrode 135 or therapy electrode 140 to
reduce impedance and improve the quality of sensed electrocardiogram signals.
In one embodiment, controller 130 includes at least one processor as described
in commonly owned U.S. Patent Application Serial No. 12/833,096, titled "System
and Method for Conserving Power in a Medical Device," filed on July 9, 2010
(hereinafter "the '096 application"), which is incorporated by reference herein in its
entirety. The '096 application generally describes a processing architecture
configured to conserve energy and which may be used in a wearable therapeutic
device, such as a wearable defibrillator. Controller 130 can monitor a subject's
condition and control wearable therapeutic device 100 operations. For example,
sensing electrode 135 can sense electrical activity of the subject's heart signals, and
controller 130 can provide these signals for display as an electrocardiograph on
monitor 125. When an arrhythmic event or other form of cardiac distress is detected,
controller 130 can instruct alarm module 120 to provide a warning that the subject
wearing wearable therapeutic device 100 is in danger of, or is experiencing, for
example, cardiac arrest. Where the subject does not respond to the warning, the
controller 130 can direct the defibrillator 115 to apply an electric shock to the body of
the subject in an effort to restore a normal rhythm. Information concerning the
subject's condition, such as the subject's electrocardiocgram (ECG), information
relating to detected arrhythmic events, information pertaining to any defibrillation
shocks applied to the subject, and other information can be stored in memory units
associated with controller 130 for analysis by a doctor, rescuer, the subject, or a health
care provider.
In one embodiment, the functionality of defibrillator 115 may be performed at
least partially in software executed by the at least one processor of the controller 130
in a manner such as described in the '096 application. In other embodiments, the
functionality of defibrillator 115 may be implemented in a Field Programmable Gate
Array (FPGA), one or more Programmable Logic Devices (PLDs), a Complex PLD
(CPLD), a custom Application Specific Integrated Circuit (ASIC), or a dedicated
processor operating under the control of the at least one processor of the controller
130. It should be appreciated that other implementations may be used, as the present
invention is not limited to any particular implementation.
In one embodiment, alarm module 120 provides an alarm or warning that
indicates that the subject will receive an electric shock from defibrillator 115 and at
least one therapy electrode 140 when the subject is wearing wearable therapeutic
device 100, with therapy electrode 140 disposed proximate to the subject's body.
This alarm or warning may be audio, visual, haptic (e.g., vibrating alarm module 120)
or combinations thereof. Treatment in the form of an electric shock can be applied to
the subject wearing wearable therapeutic device 100 unless the subject takes some
action to prevent defibrillator 115 from applying the shock. For example, alarm
module 120 or monitor 125 may include an interface having at least one button or
touch screen. In this example, the subject can depress a button. This indicates that
the subject is conscious. In this example, the shock will not be applied while the
subject depresses the button for a sufficient amount of time, or until controller 130
determines that the electrical heart activity of the subject, detected for example by
sensing electrode 135, has returned to normal. Continuing with this example, if the
subject looses consciousness, the subject will release the buttons and defibrillator 115
can apply a shock via at least one therapy electrode 140.
Alarm module 120 can be part of monitor 125 or a separate element of
wearable therapeutic device 100. In one embodiment, alarm module 120 alerts and
instructs the subject to take corrective action to reposition sensing electrode 135 or
therapy electrode 140. For example, alarm module 120 can instruct the subject to
tighten belt 110 to position or reposition sensing electrode 135 or therapy electrode
140. This can reduce, for example, signal interference at sensing electrode 135 by
positioning this electrode proximate to the subject's skin, or proximate to a desired
portion of the subject's body where a stronger electrocardiogram signal can be sensed.
This can also reduce impedance between therapy electrode 140 and the subject, or
between a plurality of therapy electrodes 140, allowing for more efficient and
effective application of therapy to the subject.
In one embodiment, at least one sensing electrode 135 and at least one therapy
electrode 140 are permanent components of wearable therapeutic device 100.
Electrodes 135 and 140 can be housed anywhere in garment 105. For example, at
least one sensing electrode 135 can be integral to garment 105 and disposed
proximate to the subject's chest or abdomen when the subject is wearing wearable
therapeutic device 100. At least one therapy electrode 140 can be integral to garment
105 and disposed proximate to the subject's back when the subject is wearing
wearable therapeutic device 100. Sensing electrode 135 and therapy electrode 140
may include conductive surfaces such as a metal plate or foil in a generally circular,
ovoid, or quadrilateral shape.
In one embodiment, sensing electrode 135 and therapy electrode 140 include
conductive thread woven, sewn, or embroidered into wearable treatment device 100.
The conductive thread can provide connections between any of electrodes 135 and
140, and a battery powered defibrillator 115. In one embodiment, sensing electrode
135 senses the subject's electrocardiogram signals and provides that signal to
defibrillator 115.
The conductive thread that may form at least part of sensing electrode 135 and
therapy electrode 140 can have various patterns to achieve proper electrocardiogram
sensing and to administer therapy. In one embodiment, sensing electrode 135 or
therapy electrode 140 include only conductive stitching. Sensing electrode 135 or
therapy electrode 140 may also include conductive stitching that holds a metal foil or
other conductive component in place in garment 105, so that sensing electrode 135 or
therapy electrode 140 includes both conductive thread and a conductive foil.
The conductive thread can be sewn into garment 105 (e.g., belt 110) in a
zigzag pattern that can stretch as part of garment 105. This stretchable conductive
thread stitching connects sensing electrode 135 and therapy electrode 140 with
controller 130 or other garment 105 components (e.g., defibrillator 115) in the
absence of additional wires. In one embodiment, the conductive thread (e.g.,
conductive wiring) can face toward or away from the subject's skin.
In one embodiment, garment 105 includes breathable fabric, or a material that
wicks heat away from the subject's body. This can reduce heat buildup between the
subject's skin and sensing electrode 135 or therapy electrode 140. Using conductive
thread for electrodes 135 or 140 reduces heat buildup in one embodiment when
electrodes 135 or 140 are formed from conductive thread in the absence of any further
metallic or conductive foil. In one embodiment, sensing electrode 135 or therapy
electrode 140 are made of perforated materials that allow air flow proximate to the
subject's skin. This air flow can dry sweat or other fluid from the skin to avoid rashes
and other skin problems as a result of heat buildup and irritation.
Garment 105 can be adjusted to snugly fit the subject. For example, portions
of garment 105 that include sensing electrode 135 and therapy electrode 140 can be
substantially flush against the subject, e.g., electrodes 135 and 140 remain
substantially in a fixed position against the subject when the subject is moving about
as part of a daily routine, or undertaking moderate physical activity. Clothing may be
present between garment 105 and the subject. Where clothing is present between
garment 105 and the subject, the clothing preferably includes openings to permit
electrodes 135 to directly contact the subject's skin. Alarm module 120 can alert the
subject when wearable therapeutic device 100 is not sufficiently tight and snug about
the subject. For example, alarm module 120 can notify the subject when the portion
of garment 105 that includes sensing electrode 135 or therapy electrode 140 is not
flush with or fairly tightly pressed against the patient in a substantially fixed position.
Garment 105 or its components such as belt 110 or strap 145 may expand or
stretch with time or repeated use, which can loosen the fit and positioning of sensing
electrode 135 and therapy electrode 140 proximate to the subject. Further, the
subject's respiration will typically result in periodic expansion of garment 105.
Controller 130 can detect this expansion and where appropriate, instruct the subject to
reposition sensing electrode 135 or therapy electrode 140, for example by tightening
garment 105.
To identify garment 105 stretching, in one embodiment wearable therapeutic
device 100 includes at least one inductive element 150. Inductive element 150
includes a metallic or other conductive material, such as a conductive wire or thread
that is configured in a coiled pattern (e.g., spring shaped) that includes a plurality of
coils (e.g., windings or turns) with a substantially similar radius. In one embodiment,
inductive element 150 includes at least one coiled conductive element that acts as an
inductor when alternating current is applied to it. In some embodiments, a magnetic
core may be disposed within the plurality of coils.
In an alternate embodiment, inductive element 150 may be formed from a
conductive wire or thread that is configured in a serpentine pattern similar in shape to
that shown in Figures 3B and 4B that includes a plurality of serpentine turns of
similar dimension.
In another embodiment, wearable therapeutic device 100 includes at least one
capacitive element 155 to identify garment 105 stretching. In one embodiment, the at
least one capacitive element 155 can be formed from a conductive material such as a
pair of wires with a round circumference or with at least one flat side, configured in
parallel with each other in a serpentine or coiled pattern in garment 105. A space may
be present between two capacitive elements 155, and may be occupied by an
insulator, dielectric material, or air so that the two capacitive elements 155 act as a
capacitor when supplied with power.
Inductive element 150 and capacitive element 155 may be shielded, jacketed,
or insulated, and can connect to a power supply of wearable therapeutic device 100.
This power supply can also be associated with defibrillator 115, controller 130, alarm
module 120, or monitor 125. In one embodiment, wearable therapeutic device 100
can include both inductive element 150 and capacitive element 155.
Inductive element 150 and capacitive element 155 can stretch or expand
together with garment 105. For example, inductive element 150 can include wire
configured in a serpentine pattern or a wire configured in a coiled pattern whose
radius and the number of turns or coils over a defined length change when stretched,
which changes the inductance of inductive element 150. When capacitive element
155 is stretched together with garment 105, the capacitance changes, for example
reducing when stretched. In one embodiment, controller 130 detects the inductance of
inductive element 150 or capacitance of capacitive elements 155 to determine if
sensing electrode 135 or therapy electrode 140 is properly or improperly positioned.
For example, inductance or capacitance outside of a tolerance range or above or
below a threshold value can indicate that sensing electrode 135 or therapy electrode
140 is improperly positioned or tensioned due to garment 105 stretching, and
inductance or capacitance within a tolerance range or above or below a threshold
value can indicate that no or minimal stretching of garment 105 has occurred and that
electrodes 135 and 140 are properly positioned about the subject.
In one embodiment, sensing electrodes 135 or therapy electrodes 140 are
properly positioned when they are adequately pressured by garment 105 to be firmly
pressed against the subject so that they are held in a substantially fixed position to
sense the subject's condition or deliver treatment. Properly positioned sensing
electrodes 135 and therapy electrodes 140 are generally held by garment 105 in a
fixed position with minimal movement and in contact the subject's skin. Conductive
fluid or other materials may be present between sensing electrodes 135 or therapy
electrodes 140 and the subject's skin.
Alarm module 120, which may include an interface and be part of monitor
125, can indicate both proper and improper positioning of electrodes 135 and 140, and
can instruct the user to take corrective action, for example when the determined
inductance of inductive element 150 or capacitance of capacitive element 155
indicates that stretching of garment 105 has displaced electrodes 135 or 140 so they
are improperly positioned.
Figure 2 is a schematic diagram depicting subject 200 wearing wearable
therapeutic device 100 in accordance with an embodiment. In the example of Figure
2, inductive element 150 is included in belt 110 and extends circumferentially around
subject 200, and capacitive element 155 is included in strap 145 in a tightly wrapped
pattern configured to stretch with strap 145. Other configurations are possible. For
example, inductive element 150 can be included in strap 145 and capacitive element
155 can be included in belt 110. Further, inductive element 150 and capacitive
element 155 can extend across or be disposed in any portion of garment 105, and need
not be circumferential as illustrated in Figure 2.
Wearable therapeutic device 100 can also include more than one inductive
element 150 and more than one capacitive element 155, and need not include both
types of elements. For example, a first inductive element 150 or capacitive element
155 can be included in a portion of belt 110 and a second inductive element 150 or
capacitive element 155 can be included in a portion of strap 145 on one side of the
subject, without extending around the subject. In one embodiment, a single inductive
element 150 or capacitive element 155 is included in portions of both belt 110 and
strap 145. Wearable therapeutic device 100 can include other elements not illustrated
in Figure 2, such as additional straps across the chest of subject 200 that can include
inductive element 150 or capacitive element 155.
In one embodiment, controller 130 determines the inductance of inductive
element 150, or the capacitance of capacitive element 155. Based on the determined
inductance or capacitance, controller 130 can instruct alarm module 120 to provide a
notification to subject 200. The notification can instruct subject 200 to loosen or
tighten at least a portion of garment 105 (e.g., belt 110). The notification can also
indicate that an arrhythmic cardiac event has been detected, based on information
from sensing electrode 135.
Figure 3A depicts a portion of wearable therapeutic device 100 that includes
inductive element 150 in an unstretched position, and Figure 4A depicts a portion of
wearable therapeutic device 100 that includes inductive element 150 in a stretched
position. In one embodiment, controller 130 can determine differences between the
inductance of inductive element 150 in the unstretched position of Figure 3A and the
stretched position of Figure 4A. For example, wearable therapeutic device 100 may
have the unstretched configuration of Figure 3A when it is not being worn by the
subject, or if it is too large for the subject; and may have the stretched configuration
of Figure 4A if it is too small for the subject or is currently being worn by the subject.
Figure 3B depicts a portion of wearable therapeutic device 100 that includes
capacitive elements 155 in an unstretched position, and Figure 4B depicts a portion of
wearable therapeutic device 100 that includes capacitive elements 155 in a stretched
position. An insulator, space, gap, or dielectric 160 may be present between the two
capacitive elements 155. In one embodiment, controller 130 can determine
differences between the capacitance of capacitive element 155 in the unstretched
position of Figure 3B and the stretched position of Figure 4B, as stretching or
movement of garment 105 changes the relative capacitive surface area and/or distance
between capacitive elements 155. Electrodes 135 and 140 can be either properly or
improperly positioned about the subject in the configurations of Figures 3A, 3B, 4A,
and 4B. It should be appreciated that inductive element 150 may alternatively have a
serpentine shape as shown in Figures 3B and 4B instead of the coiled shape shown in
Figures 3A and 4A.
Inductive element 150 and capacitive element 155 can include a wire or thread
sewn into garment 105. In one embodiment, inductive element 150 or capacitive
elements 155 can expand and contract with garment 105, but otherwise substantially
maintain their shape. Inductive element 150 and can also be wrapped around a core
included in belt 110, strap 145, or other portion of garment 105.
Figure 5 depicts an example configuration of controller 130. In one
embodiment, interface 505 connects inductive element 150 or capacitive element 155
with detector 510 (e.g. a logic device or circuit) to measure the inductance of
inductive element 150 or the capacitance of capacitive element 155. Stretch detector
515 determines if at least a portion of garment 105 has stretched based upon the
measured inductance or capacitance value. For example, controller 130 can
determine the inductance or capacitance with garment 105 in an unstretched position
at a baseline first time when wearable therapeutic device 100 is not being worn; and
in a stretched position at a second time when wearable therapeutic device 100 is being
worn. In one embodiment, comparator circuit 520 compares the unstretched baseline
inductance or capacitance value with the stretched inductance or capacitance value to
determine whether or not garment 105 has expanded or stretched, or to determine
relative stretching between the baseline and stretched values. Based on this
comparison, controller 130 and alarm module 120 can alert the subject to a number of
conditions, such as garment 105 being too loose or too tight, that garment 105 is
appropriately snug against the body of the subject, or that garment 105 is soiled and
needs to be laundered to restore its elasticity, or that the garment should be replaced
for example, due to its age.
Figure 6 is a graph depicting tolerance stretch ranges of wearable therapeutic
device 100 in accordance with an embodiment. In the example of Figure 6, when
worn by subject 200, wearable therapeutic device 100 can be classified in under
stretch range 605, tolerance range 610, or over stretch range 615. These
classifications can change with time, and subject 200 can adjust wearable therapeutic
device 100 components such as belt 110 to change the classification between these
ranges.
Wearable therapeutic device 100 can be determined by controller 130 to be in
or under stretch range 605, (e.g., Point A), tolerance range 610 (e.g., Point B), or over
stretch range 615 (e.g., Point C). Under stretch range 605 can indicate that wearable
therapeutic device 100 is too loose or not sufficiently expanded, so that sensing
electrode 135 or therapy electrode 140 is not in a substantially fixed position, or is not
tightly fitted against subject 200. When controller 130 determines that wearable
therapeutic device 100 is in under stretch range 605 based on the inductance of
inductive element 150 or the capacitance of capacitive element 155, alarm module
120 can instruct subject 200 to take some action, such as to tighten belt 110 or straps
145, to launder garment 105 to improve its elasticity, or to replace garment 105 with a
new one or one of a smaller size. For example, when the amount of stretching
deteriorates from a baseline value over time, garment 105 may be losing elasticity and
can be laundered to reintroduce elasticity to make garment 105 tighter fitting. When
stretching deteriorates too rapidly between launderings from a baseline value, e.g., is
below minimum tolerance threshold 620 and is too loose, garment 105 may be
nearing end of life and be in need of replacement. When controller 130 determines
that wearable therapeutic device 100 is over expanded or in over stretch range 615,
alarm module can instruct subject 200 to loosen belt 110 or straps 145, or to replace
garment 105 with a new one or one of a larger size. In one embodiment, controller
130 prevents application of treatment from therapy electrode 140 when garment 105
is determined to be in under stretch range 605 and/or over stretch range 615.
Controller 130 can also disregard or give less weight to information received from
sensing electrode 135 when garment 105 is determined to be in under stretch range
605 or over stretch range 615 because these positions outside tolerance range 610 can
indicate that sensing electrode 135 is not properly positioned about subject 200.
In one embodiment, controller 130 can determine that garment 105 is within
tolerance range 610 and thus properly fitted about subject 200 with sensing electrode
135 or therapy electrode 140 properly and snugly positioned with respect to subject
200. When controller 130 determines or verifies that wearable therapeutic device 100
is within tolerance range 610, controller 130 can evaluate information received from
sensing electrode 135 to determine that subject 200 is or is not in need of therapy to
treat, for example, an abnormal cardiac or respiratory event. Continuing with this
example, controller 130 can direct therapy electrode 140 and defibrillator 115 to apply
treatment to subject 200.
In one embodiment, minimum tolerance threshold 620 and maximum
tolerance threshold 625 are the limits of tolerance range 610. Thresholds 620 and 625
need not be linear as depicted in Figure 6. In one embodiment, thresholds 620, 625
can change with time. For example, as wearable therapeutic device 100 degrades or
becomes worn with time, minimum tolerance threshold 620 can increase, indicating
an increase in tightening may be necessary to position sensing electrode 135 or
therapy electrode 140. Alternatively, where a significant amount of noise on sensing
electrode 135 is detected at a particular stretch level, or where a number of fall-off
flags have been detected, or both; controller 130 may adjust the minimum tolerance
threshold to this level of stretch. In this example, controller 130 includes auto-learn
or adaptive features where controller 130 adjusts tolerance thresholds 620 or 625, or
tolerance range 610, based on sensed electrode positioning, electrode fall off events,
the force applied by garment 105 onto the subject, or feedback from the subject
regarding observed conditions or the subject's comfort level. Maximum tolerance
threshold 625 can also increase over time, as for example subject 200 becomes
accustomed to wearable therapeutic device 100 and is able to comfortably withstand a
tighter fit. In one embodiment, garment 105 exerts 0.050 lb of force on the subject's
body at minimum tolerance threshold 620 and 1.70 lb of force on the subject's body at
maximum tolerance threshold 625.
The auto-learn features of controller 130 can associate a particular fitting or
level of snugness of garment 105 about subject 200 with a substantially noise or
artifact free ECG signal measured by sensing electrode 135. For example, controller
130 can identify an amount of force exerted by garment 105 on subject 200 during
sensing of a usable ECG signal by sensing electrode 135. In this example, the amount
of force identified by controller 130 is based on the detected inductance of inductive
element 150 or the detected capacitance of capacitive element 155. Controller 130 in
this example identifies a tolerance range 610 that includes this detected amount of
force. If controller 130 detects that garment 105 is in under stretch range 605 (e.g.,
too loose) or over stretch range 615 (e.g., too tight), controller 130 can instruct subject
200 to tighten or loosen garment 105, for example via alarm module 120 or monitor
125, to bring the force level within that of tolerance range 610. In this example,
controller 130 identifies and continuously adjusts a custom tolerance range 610 for an
individual subject 200 and a particular garment 105 based on the fit of that garment
105 that provides sufficient force for a substantially artifact free ECG signal.
Thus, with the auto-learn feature, controller 130 can determine or adjust the
range of tolerance range 610 based on the quality of ECG signals sensed by sensing
electrode 135. For example, the force exerted by garment 105 on subject 200 during
sensing of a substantially noise or artifact free ECG can be evaluated by controller
130 to determine the scope of tolerance range 610, with the force associated with a
quality ECG signal being within tolerance range 610. Controller 130 can adjust this
range with time, for example as subject 200 gains or loses weight, or as garment 105
wears and its elasticity characteristics change. It should be appreciated that the level
of snugness associated with a quality ECG signal, and thus tolerance range 610, may
vary from subject to subject.
In one embodiment, when wearable therapeutic device is in tolerance range
610, garment 105 has an acceptable range of stretching. In this illustrative
embodiment, controller 130 can determine that sensing electrode 135 and therapy
electrode 140 are in proper position about subject 200. Based on changes in the
inductance or capacitance caused by garment 105 expansion, controller 130 can
determine respiration information (e.g., rates and volumes) of subject 200. Sensing
electrode 135, which may include an accelerometer, can also sense this information.
Respiratory information can also be determined based on the inductance or
capacitance, which may change as garment 105 expands or contracts with respiration.
In one embodiment, controller 130 evaluates respiration information and
electrocardiogram information to detect an arrhythmia.
Ranges 605, 610, and 615, and thresholds 620 and 625 can be indicated as
stretching distances of garment 105, belt 110, strap 145 or other components, as well
as changes in circumference, diameter, or radius of these components. These ranges
and thresholds can be determined based on inductance values of inductive element
150 or on the capacitance values of capacitive element 155. They can be indicated
with inductance values, capacitance values, or units of distance.
In one embodiment, controller 130 evaluates the inductance or capacitance and
determines that garment 105 stretching is within tolerance range 610. In this
example, sensing electrodes 135 sense cardiac (e.g., electrocardiogram) information
about subject 200. Respiratory information can also be sensed or deduced from
changes in inductance or capacitance. In this example, the cardiac information can
indicate that subject 200 is suffering an arrhythmia at the same time the respiratory
information indicates that subject 200 has stopped breathing. Because, in this
example, garment 105 is within tolerance range 610, controller 130 can determine
with a high level of confidence that sensing electrodes 135 are properly positioned.
Based on this confidence level and the sensed information, controller 130 can
determine that the sensed information is accurate and that subject 200 is experiencing
an arrhythmia and in need of treatment. With garment 105 within tolerance range
610, controller 130 can also determine with a high level of confidence that therapy
electrode 140 is properly positioned to apply an electric shock to subject 200 to treat
the arrhythmia. In one embodiment, where an arrhythmia has been detected but
controller 130 determines garment 105 is within tolerance range 610 and respiratory
information indicates normal breathing, controller 130 may reduce the confidence
level that the arrhythmia has been detected and/or that the subject is in need of
treatment.
Controller 130 can also determine that garment 105 is stretched outside of
tolerance range 610, (e.g., over or under stretched). In this example, respiration and
cardiac information may be inconsistent with each other due to movement or
improper positioning with respect to subject 200. Noise artifacts can further interfere
with the sensed information. Continuing with this example, controller 130 can have a
low level of confidence that sensing electrodes 135 are properly positioned, (or a high
level of confidence that they are improperly positioned). Based on this confidence
level and the sensed information, controller 130 can determine that the sensed
information is inaccurate because the sensor is improperly positioned, and that subject
200 is not experiencing an arrhythmia and does not need treatment. In this example,
controller 130 can withhold, prevent, or block treatment from therapy electrode 140 to
subject 200 until controller 130 determines with sufficient confidence that information
from sensing electrodes 135 is reliable and that sensing electrodes 135 and therapy
electrode 140 are properly positioned. Further, controller 130 can adjust the behavior
of wearable therapeutic device 100 based on the confidence level. For example,
where the confidence level is low or decreasing with respect to a previous confidence
level, controller 130 (and sensing electrodes 135) can sense ECG signals more
frequently, or controller 130 can lengthen a response time during which the subject
can respond to an alarm indicating a detected arrhythmia, or both.
Wearable therapeutic device 100 can identify arrhythmic cardiac events and
apply treatment when garment 105 is in any range, including under stretch range 605,
tolerance range 610, and over stretch range 615. For example, while in tolerance
range 610, controller 130 can identify an arrhythmia with less sensed information due
to a high confidence level that the sensed information is accurate, and can direct
therapy electrodes 140 to apply treatment due to a high confidence level that they are
properly positioned. While in ranges 605 or 615, controller 130 may have a lower
confidence level that the sensed information is accurate and that electrodes 135, 140
are properly positioned. In this example, controller 130 may compensate for possible
artifacts or flaws in the sensed information by evaluating sensed information over a
longer period of time, or by evaluating information provided by additional sensors
135 to identify an arrhythmia. Via alarm module, controller 130 may prompt subject
200 for a response or ask the subject to indicate distress, where an affirmative
response or lack of any response indicates that the subject is in need of treatment. In
one embodiment, controller 130 may direct therapy electrode 140 to apply treatment
even when therapy electrode 140 is improperly positioned. The applied treatment
may still be effective even though there may be a higher impedance between therapy
electrodes 140 and the subject's skin in this example.
In one embodiment, controller 130 determines different degrees of confidence
that the sensed information is accurate and that electrodes 135 and 140 are properly
positioned. There can be two possible confidence levels (e.g., high/low, zero/one,
yes/no) or confidence levels can be provided as percentages (e.g., a 60% chance that
the sensed information is accurate). Based on the confidence level, controller 130 can
evaluate more or less sensed information, from sensing electrode 135, inductive
element 150, or capacitive element 155 to provide a notification to the subject
regarding positioning of wearable therapeutic device 100, detection of an arrhythmia,
or application of treatment. In one embodiment, suggestions or requirements are
provided to subject 200 to increase the confidence level, such as suggesting that
subject 200 tighten garment 105 if subject 200 can tolerate the tightening, or indicate
that sensors 135 and 140 are nonfunctional due to improper positioning and require
their tightening or replacement.
Figure 7 is a flow chart depicting a method 700 of facilitating care of a
subject. In one embodiment, method 700 includes an act of providing a wearable
therapeutic device (ACT 705). In one embodiment, providing the wearable
therapeutic device (ACT 705) includes providing a device that includes a sensing
electrode. The sensing electrode may be housed in a garment of the wearable
therapeutic device, and providing the wearable therapeutic device (ACT 705) may
include providing a device with an inductive element or capacitive element included
in at least part of the garment. Providing the wearable therapeutic device (ACT 705)
may also include providing a device having a controller configured to determine
inductance of the inductive element or capacitance of the capacitive element, and to
determine, based on the determined inductance or capacitance, a confidence level of
information received from the sensing electrode. This information may include
electrocardiograph or other information about the subject's body functions. Providing
the wearable therapeutic device (ACT 705) may also include providing a device with
an alarm module coupled with a controller to notify the subject of events, conditions,
or information about the subject's condition or about the condition of the wearable
therapeutic device, based on the confidence level of the information received from the
sensor and the determined inductance of the inductive element.
In one embodiment, method 700 includes an act of providing instructions
(ACT 710). For example, providing instructions (ACT 710) can include providing
instructions to operate the wearable therapeutic device, or providing instructions on
how to wear the wearable therapeutic device. In one embodiment, the instructions
include instructions to the subject regarding positioning of wearable therapeutic
device components, such as sensing or therapy electrodes. For example, instructions
can be provided (ACT 710) to the subject, based on an expansion of the wearable
therapeutic device or its components, to position an electrode proximate to an area of
the subject's body, such as the center of the back, or proximate to the chest and heart
of the subject, so that the electrodes are positioned to provide therapy to the subject or
sense cardiac or respiratory function of the subject.
In one embodiment, method 700 includes an act of receiving information
about the subject (ACT 715). In one embodiment, this information is received (ACT
715) from at least one sensing electrode. For example, receiving information (ACT
715) may include receiving sensed electrocardiograph information of the subject. In
this example, the received information includes information from a sensing electrode
that is part of the wearable therapeutic device and that can detect electrocardiograph
signals from a subject wearing the device. The received (ACT 715) information can
include cardiac, pulse, circulatory, respiratory, or pulmonary information of the
subject. In one embodiment, receiving information (ACT 715) includes receiving
information about the inductance of an inductive element or capacitance of a
capacitive element disposed in part of the wearable therapeutic device. The
inductance value, capacitance value or changes in these values with time can indicate
that the wearable therapeutic device is in a stretched, expanded, or unexpanded
position.
Method 700 also includes an act of determining inductance of an inductive
element included in the wearable therapeutic device (ACT 720). In one embodiment,
inductance is determined (ACT 720) with a sensor that is part of the wearable
therapeutic device that measures the inductance, or a logic device associated with the
controller calculates inductance based, for example, on the radius, number of turns, or
length of the coils of the inductive element disposed in the wearable therapeutic
device.
Method 700 alternatively or additionally includes an act of determining
capacitance of a capacitive element included in the wearable therapeutic device (ACT
723). In one embodiment, capacitance is determined (ACT 723) with a sensor that is
part of the wearable therapeutic device that measures the capacitance, or a logic
device associated with the controller calculates capacitance of the capacitive element.
In one embodiment, method 700 includes an act of determining a confidence
level (ACT 725) of the received (ACT 715) information about the subject. The
confidence level may be determined (ACT 725) based on changes in the inductance or
capacitance with respect to a baseline or threshold value. In one embodiment, the
confidence level is determined based on identified expansion or stretching of a portion
of the wearable therapeutic device or any of its components. For example, the
confidence level can be determined based on the expansion of the inductive element
or capacitive element, a belt or other portion of the wearable therapeutic device that
includes either of these elements, or a circumference of the wearable therapeutic
device, its belt, strap, or garment. In one embodiment, the confidence level is
determined based on an expansion of a portion of the wearable therapeutic device that
includes the inductive element or capacitive element and received information (ACT
715) about the subject that includes electrocardiograph information.
Determining the confidence level (ACT 725) may include determining that the
received information about the subject is accurate. For example, the determined
inductance (ACT 720) or capacitance (ACT 723) can indicate that the wearable
therapeutic device has not stretched, or has stretched less than a threshold amount, or
within a defined acceptable parameter or range. In this example, the confidence level
of the accuracy of the sensed information about the subject can be determined (ACT
725) to be high, e.g., the sensed electrocardiograph or other information about the
subject can be accepted as valid information about the subject's health and used as a
factor in diagnosing the subject, e.g., by identifying an arrhythmic cardiac event, or
applying treatment to the subject.
Determining the confidence level (ACT 725) may include determining that the
received information about the subject is not accurate. In this example, the
determined inductance (ACT 720) or capacitance (ACT 723) can indicate that the
wearable therapeutic device has stretched to a degree that the sensing electrode that
senses the received (ACT 715) information about the subject may have shifted about
the subject to a degree where it is no longer properly positioned to sense, for example,
a quality electrocardiogram signal. In this example, the confidence level in the
accuracy of the sensed information can be low, and the sensed information may be
disregarded or require further verification.
In one embodiment, method 700 includes an act of providing a notification to
the subject (ACT 730) based on the confidence level. The notification may be
audibly, visually, or haptically (e.g., a vibrating alarm) provided (ACT 730) to the
subject. The notification may also be provided (ACT 730) to another person such as
the subject's doctor, family member, friend, or health care provider, who may be
proximate to the subject or at a remote location, e.g., via a transmission over a
network. In one embodiment, the notification is provided to the subject (ACT 730) by
an alarm module, monitor, or interface that is part of the wearable therapeutic device.
Providing the notification (ACT 730) may include providing a diagnosis of an
arrhythmic cardiac event, fibrillation, cardiac arrest, abnormal respiratory activity, or
other condition that may require medical attention. The provided notification (ACT
730) can indicate that the subject has no immediate health issue requiring treatment,
e.g., a normal cardiac rhythm or normal pulmonary activity. Providing the
notification (ACT 730) can also include providing information unrelated to the
subject's health, such as information about the use or positioning of the wearable
therapeutic device. For example, information can be provided (ACT 730) indicating
that the sensing or therapy electrodes of the wearable therapeutic device are not
properly positioned with respect to the subject wearing the device. This may be due
to stretching of the wearable therapeutic device with time and use. This stretching
can cause the electrodes to shift position to a location where they are less effective or
ineffective to sense information about the subject or apply treatment to the subject.
In one embodiment, method 700 includes an act of verifying positioning of
wearable therapeutic device components (ACT 735), such as sensing or therapy
electrodes. For example, the position of wearable therapeutic device components can
be verified (ACT 735) when the identified inductance (ACT 720) or capacitance
(ACT 723) is analyzed to determine that the amount of stretching of the wearable
therapeutic device is less than a threshold amount, or within a tolerance range. This
minimal stretching can indicate a tolerable level of displacement of wearable
therapeutic device components. Method 700 may also include an act of applying
treatment to the subject (ACT 740). In one embodiment, applying treatment to the
subject (ACT 740) includes delivering an electric shock to the subject from therapy
electrodes that are included in the wearable therapeutic device and an associated
defibrillator.
Method 700 can also include an act of identifying improper positioning of
wearable therapeutic device components (ACT 745). For example, improper
positioning of wearable therapeutic device components can be identified (ACT 745)
when the identified inductance (ACT 720) or capacitance (ACT 723) is analyzed to
determine that the amount of stretching of the wearable therapeutic device is more
than a threshold amount, or outside a tolerance range. This stretching can indicate an
unacceptable level of displacement of wearable therapeutic device components during
use of the wearable therapeutic device. Method 700 may also include an act of
withholding treatment from the subject (ACT 750). In one embodiment, withholding
treatment from the subject (ACT 740) includes delaying delivery an electric shock to
the subject from therapy electrodes that are included in the wearable therapeutic
device and an associated defibrillator until the therapy electrodes are moved to an
appropriate location proximate to the subject, and until their positioning is verified
(ACT 735). Withholding treatment from the subject (ACT 750) can also include
delaying delivery of an electric shock to the subject until sensing electrodes are
moved to an appropriate location proximate the subject so that they can sense
information at a confidence level sufficient to rely on for diagnosing the subject's
condition.
Having now described some illustrative embodiments, it is apparent that the
foregoing is illustrative and not limiting, having been presented by way of example.
In particular, although many of the examples presented herein involve specific
combinations of method acts or system elements, it is understood that those acts and
those elements may be combined in other ways. Acts, elements and features
discussed only in connection with one embodiment are not intended to be excluded
from a similar role in other embodiments.
Note that in Figures 1 through 7, the enumerated items are shown as individual
elements. In actual implementations of the systems and methods described herein,
however, they may be inseparable components of other electronic devices such as a
digital computer. Thus, actions described above may be implemented at least in part
in software that may be embodied in an article of manufacture that includes a program
storage medium. The software may be executed by a processor of controller 130. In
one embodiment, the program storage medium is non-transient. The program storage
medium includes data signals embodied in one or more of a carrier wave, a computer
disk (magnetic, or optical (e.g., CD or DVD, or both)), non-volatile memory, tape, a
system memory, and a computer hard drive.
Any references to embodiments or elements or acts of the systems and
methods herein referred to in the singular may also embrace embodiments including a
plurality of these elements, and any references in plural to any embodiment or
element or act herein may also embrace embodiments including only a single element.
References in the singular or plural form are not intended to limit the presently
disclosed systems or methods, their components, acts, or elements to single or plural
configurations. References to any act or element being based on any information, act
or element may include embodiments where the act or element is based at least in part
on any information, act, or element.
Any embodiment disclosed herein may be combined with any other
embodiment, and references to "an embodiment," "some embodiments," "an alternate
embodiment," "various embodiments," "one embodiment" or the like are not
necessarily mutually exclusive and are intended to indicate that a particular feature,
structure, or characteristic described in connection with the embodiment may be
included in at least one embodiment. Such terms as used herein are not necessarily all
referring to the same embodiment. Any embodiment may be combined with any
other embodiment in any manner consistent with the aspects and embodiments
disclosed herein.
References to "or" should be construed as inclusive so that any terms
described using "or" may indicate any of a single, more than one, and all of the
described terms. Intervening embodiments, acts, or elements are not essential unless
recited as such.
Where technical features in the drawings, detailed description or any claim are
followed by reference signs, the reference signs have been included for the sole
purpose of increasing the intelligibility of the drawings, detailed description, and
claims. Accordingly, neither the reference signs nor their absence have any limiting
effect on the scope of any claim elements.
One skilled in the art will realize the systems and methods described herein
may be embodied in other specific forms without departing from the characteristics
thereof. For example, the subject may be a patient and the wearable therapeutic
device can store and transmit data concerning the patient's medical condition to a
physician. Because the wearable therapeutic device can operate essentially at all
times, this data can be used to generate a comprehensive real time record of the
subject' s health over an extended period of time. The foregoing embodiments are
illustrative rather than limiting of the described systems and methods. Scope of the
systems and methods described herein is thus indicated by the appended claims, rather
than the foregoing description, and changes that come within the meaning and range
of equivalency of the claims are embraced therein.

What is claimed is:
CLAIMS
1. A wearable therapeutic device, comprising:
a garment that includes a sensing electrode;
at least one of an inductive element and a capacitive element included in at
least part of the garment; and
a controller configured to determine a confidence level of information
received from the sensing electrode based on at least one of an inductance of the
inductive element and a capacitance of the capacitive element.
2. The device of claim 1, further comprising:
an alarm module coupled to the controller and configured to provide a
notification to a subject based on the confidence level.
3. The device of claim 2, wherein the notification indicates that the garment is one of:
properly positioned about a subject, too loose about the subject, and too tight about
the subject.
4. The device of claim 1, wherein the controller is further configured to identify an
expansion of the garment based on the at least one of the inductance of the inductive
element and the capacitance of the capacitive element, and to determine the
confidence level based on the expansion.
5. The device of claim 4, further comprising:
a therapy electrode included in the garment;
wherein the controller is further configured to determine, based on the
expansion, that positioning of at least one of the sensing electrode and the therapy
electrode is outside a tolerance range, and to withhold treatment of the subject by the
therapy electrode based on the positioning of the at least one of the sensing electrode
and the therapy electrode.
6. The device of claim 4, further comprising:
a therapy electrode included in the garment;
wherein the controller is further configured to determine respiratory function
of the subject based on the expansion of the garment.
7. The device of claim 4, further comprising:
an alarm module configured to provide instructions to the subject regarding
positioning of at least one of the sensing electrode and the therapy electrode based on
the expansion of the garment.
8. The device of claim 1, wherein the inductance of the inductive element is a first
inductance value, and wherein the controller is further configured to:
determine a second inductance value of the inductive element; and
determine the confidence level based on a difference between the first
inductance value and the second inductance value.
9. The device of claim 1, wherein the information received from the sensing electrode
includes electrocardiograph information of a subject, and wherein the controller is
further configured to:
identify the at least one of the inductance of the inductive element and the
capacitance of the capacitive element;
identify an expansion of the garment;
determine the confidence level based on the expansion of the garment and the
electrocardiograph information of the subject;
identify an arrhythmic cardiac event based on the confidence level;
verify positioning of a therapy electrode included in the garment based on the
confidence level; and
instruct the therapy electrode to apply treatment to the subject.
10. The device of claim 1, wherein the sensing electrode is further configured to
sense electrocardiograph information of a subject, and wherein the controller is
further configured to determine the confidence level based on the electrocardiograph
information of the subject.
11. The device of claim 1, wherein the sensing electrode is further configured to
sense electrocardiograph information of a subject, and wherein the controller is
further configured to determine an absence of an arrhythmic cardiac event based on
the at least one of the inductance of the inductive element and the capacitance of the
capacitive element, and the electrocardiograph information of the subject.
12. The device of claim 1, wherein the garment includes:
at least one of a belt and a strap configured to include the at least one of the
capacitive element and the inductive element, and to include at least one of the
sensing electrode, the controller, an alarm module, a therapy electrode, and a
defibrillator.
13. The device of claim 12, wherein the belt includes a core, and wherein the
inductive element is coiled around the core.
14. The device of claim 1, wherein the wearable therapeutic device includes both the
inductive element and the capacitive element, and wherein the controller is configured
to determine the confidence level of information received from the sensing electrode
based on both the inductance of the inductive element and the capacitance of the
capacitive element.
15. The device of claim 1, wherein the at least one of an inductive element and a
capacitive element included in at least part of the garment includes only the inductive
element, and wherein the controller is configured to determine the confidence level of
information received from the sensing electrode based on the inductance of the
inductive element.
16. The device of claim 1, wherein the at least one of an inductive element and a
capacitive element included in at least part of the garment includes only the capacitive
element, and wherein the controller is configured to determine the confidence level of
information received from the sensing electrode based on the capacitance of the
capacitive element.
17. A method of facilitating care of a subject, comprising:
providing a wearable therapeutic device that includes a sensing electrode;
receiving, from the sensing electrode, information about the subject;
determining at least one of an inductance of an inductive element and a
capacitance of a capacitive element included in the wearable therapeutic device; and
determining a confidence level of the information about the subject based on
the at least one of the inductance of the inductive element and the capacitance of the
capacitive element.
18. The method of claim 17, further comprising:
providing, based on the confidence level, a notification to the subject
regarding at least one of a diagnosis and information about the wearable therapeutic
device.
19. The method of claim 17, wherein receiving the information about the subject
includes receiving electrocardiograph information of the subject, the method further
comprising:
identifying an expansion of a portion of the wearable therapeutic device that
includes the at least one of the inductive element and the capacitive element;
determining the confidence level based on the expansion of the portion of the
wearable therapeutic device and the electrocardiograph information of the subject;
identifying an arrhythmic cardiac event based on the confidence level; and
applying treatment to the subject.
20. The method of claim 17, wherein the wearable therapeutic device includes a
therapy electrode, the method further comprising:
verifying positioning of at least one of the sensing electrode and the therapy
electrode based on the at least one of the inductance of the inductive element and the
capacitance of the capacitive element; and
applying treatment to the subject using the therapy electrode.
21. The method of claim 17, wherein the wearable therapeutic device includes a belt,
the method further comprising:
identifying an expansion of a circumference of the belt based on the at least
one of the inductance of the inductive element and the capacitance of the capacitive
element; and
determining the confidence level based on the expansion of the circumference
of the belt.
22. The method of claim 17, wherein the wearable therapeutic device includes a
garment and a therapy electrode, the method further comprising:
identifying an expansion of the garment based on the at least one of the
inductance of the inductive element and the capacitance of the capacitive element; and
providing instructions to the subject regarding positioning of at least one of the
sensing electrode and the therapy electrode based on the expansion of the garment.
23. The method of claim 17, wherein receiving the information about the subject
includes receiving electrocardiograph information of the subject, the method further
comprising:
identifying an expansion of a portion of the wearable therapeutic device that
includes the at least one of the inductance of the inductive element and the
capacitance of the capacitive element;
determining the confidence level based on the expansion of the portion of the
wearable therapeutic device and the electrocardiograph information of the subject;
and
identifying an absence of an arrhythmic cardiac event based on the confidence
level.
24. The method of claim 17, wherein receiving the information about the subject
includes receiving electrocardiograph information of the subject, the method further
comprising:
identifying an expansion of a portion of the wearable therapeutic device that
includes the at least one of the inductance of the inductive element and the
capacitance of the capacitive element;
identifying improper positioning of the sensing electrode based on the
expansion; and
identifying an absence of an arrhythmic cardiac event based on the improper
positioning of the sensing electrode.
25. The method of claim 17, wherein the wearable therapeutic device includes a
therapy electrode, and wherein receiving the information about the subject includes
receiving electrocardiograph information of the subject, the method the method
further comprising:
identifying an expansion of a portion of the wearable therapeutic device that
includes the at least one of the inductance of the inductive element and the
capacitance of the capacitive element;
identifying improper positioning of at least one of the sensing electrode and
the therapy electrode based on the expansion; and
withholding treatment of the subject by the therapy electrode based on the
improper positioning of the at least one of the sensing electrode and the therapy
electrode.
26. The method of claim 17, further comprising:
providing instructions to operate the wearable therapeutic device.
27. A non-transitory computer readable medium having stored thereon sequences of
instructions including instructions that cause a processor to:
receive, from a sensing electrode of a wearable therapeutic device, information
about a subject;
determine at least one of an inductance of an inductive element included in the
wearable therapeutic device and a capacitance of a capacitive element included in the
wearable therapeutic device; and
determine a confidence level of the information about the subject based on at
least one of the inductance of the inductive element and the capacitance of the
capacitive element.
28. The computer readable medium of claim 27, further comprising instructions that
cause the processor to:
provide, based on the confidence level, a notification to the subject regarding
at least one of a diagnosis and information about the wearable therapeutic device.
29. The computer readable medium of claim 27, wherein the information about the
subject is electrocardiograph information of the subject, the computer readable
medium further comprising instructions that cause the processor to:
identify an expansion of a portion of the wearable therapeutic device that
includes the at least one of the inductive element and the capacitive element;
determine the confidence level based on the expansion of the portion of the
wearable therapeutic device and the electrocardiograph information of the subject;
identify an arrhythmic cardiac event based on the confidence level; and
control a therapy electrode of the wearable therapeutic device to apply
treatment to the subject.
30. The computer readable medium of claim 27, wherein the information about the
subject is electrocardiograph information of the subject, the computer readable
medium further comprising instructions that cause the processor to:
identify an expansion of a portion of the wearable therapeutic device that
includes the at least one of the inductive element and the capacitive element;
determine the confidence level based on the expansion of the portion of the
wearable therapeutic device and the electrocardiograph information of the subject;
and
determine an absence of an arrhythmic cardiac event based on the confidence
level.
31. A wearable therapeutic device to be worn by a subject, comprising:
a garment that includes an electrode;
at least one of an inductive element and a capacitive element included in the
garment; and
a controller configured to determine at least one of an inductance of the
inductive element and a capacitance of the capacitive element, and determine that the
electrode is properly positioned on the subject based on the at least one of the
inductance of the inductive element and the capacitance of the capacitive element.
32. The wearable therapeutic device of claim 31, wherein the controller is further
configured to receive information from the electrode, and to determine a confidence
level of the received information based on the at least one of the inductance and the
capacitance.