Download DefibTaskForce

Second Chance Automated External
Defibrillator Pads
Defib Task Force ([email protected])
Lisa Jiang, Justin Lin, Joanna Nathan, Carl Nelson, Brad Otto
Department of Bioengineering, Rice University
Second Chance AED Pads
Motivation
Claiming 300,000 lives annually, sudden cardiac
arrest (SCA) is among the leading causes of
death in the US. SCA can be caused by cardiac
fibrillation, which is treated using Automated
External Defibrillators (AEDs). AEDs administer
an electric shock that resets the heart, returning
it to its regular rhythm. This treatment option is
only effective if administered within the first 10
minutes of SCA onset.
Effective defibrillation depends on quick and
accurate pad placement.
Incorrectly placed pads do not deliver the
electrical shock through the victim’s heart, and
will fail to resuscitate the patient.
Substituting the used pads with a new set
placed in a different area can fix this problem,
but most AED users will not know to do this, and
the process itself requires too much time to
complete. This increase in time to defibrillate the
heart greatly decrease survival in SCA victims.
Objective
Defib Task Force aims to create the Second
Chance AED Pads to allow untrained AED
users to quickly change the shock vector if
the initial AED shock fails. The design
criteria are displayed below.
Design Criteria
Criterion
Placement
Accuracy
Test
Ease of
Application
Test
Operation
Ease of
Time
Application
Test
Switch
Ease of
Operation
Application
Test
Durable Under Switch
High Voltage
Durability Test
Metric
> 86% of pads
placed correctly
<10 second
increase in average
application time
> 75% of
participants flip
switch
Switch can
withstand 200J
without malfunction
Secondary
Vector Change Switch successfully
Pad Success
Analysis
changes vector
circuit
Significant
Vector Change >3 degree change
Vector Change Analysis
in vector
Cost Effective Cost Analysis < $130 to produce
Testing and Modeling
Vector Change
Dual electrode pad
 Secondary cardiac vector in single pad unit
 Decreases severity of skin burns
 Two Electrodes
o 3 inches between centers of electrodes.
o Each electrode on pad conducts.
electricity only when manually selected by
switch.
Figure A: Pad Back
The back of the pad
consists of conducting
electrode gel and metal
plating.
Switch
 Withstands high voltage and current
 Resistant enough to prevent accidental
flips
Figure B: Switch
Details
Instructional Insert
 Color-coded:
The switch inside of the
project box. The white
wire is the main lead
from the AED. The blue
and green wires lead to
the dual electrode pad.
Blue wire to
electrode A
o
o


Aids placement
Orients pads/switch
Includes body landmarks
to aid pad placement
Easy-to-follow
Green wire to
electrode B
Wiring
 Plug connector is compatible
with standard AED units.
Testing Ease of Application
Purpose
 Determine optimal electrode separation distance
on the dual pad
Purpose
 Compare Second Chance AED pads to
contemporary pads
Test
Test
 65 untrained volunteers applied the Second
Chance AED pads onto a mannequin, using prerecorded voice instructions that simulate a
realistic AED operation scenario.
 Operation times and placement accuracy were
recorded.
Pad Orientation
Pad Placement
Pad Displacement
Figure C: Pad placement survey.
 Seven cardiologists completed surveys to
determine optimal placement of the secondary
electrode with respect to the first pad.
Results
 3 inch displacement between electrode centers
was determined to be the best displacement.
Conclusions
 Second Chance AED Pads meet or exceed all
design criteria.
 Total cost: $83 to produce
 Design significantly improves on control pad
application success rate (100% vs. 60%)
101
Determining Pad Placement
Purpose
 Determine if device applies the desired
change in vector angle
Testing
 Used six-electrode system, similar to an ECG
 Measured voltage along two different vectors
on porcine specimen
 Matlab model inputs dimensions and distances
between the electrodes and determines the
three-dimensional angle change between the
cardiac vectors for human and porcine models
Results
 The porcine trial produced a 4° change in
vector.
 The Matlab program predicted a 5.8° change
for the human model.
Results
Test
Correct
Switch Time to Time from
Group
Placement Flipped 1st Shock Shocks 2-3
60%
N/A
79.2 s
149 s
Control
SC Pads
100%
90%
88.0 s
149 s
 Statistical analysis shows that the there is no
significant difference between the times to first
shock (α = 0.1, p = 0.3).
Future Work
 Test and optimize design
o Animal trials
o Clinical trials
 Integrate switch design into AED systems
o Include switch in verbal commands
o Improved instructions
Acknowledgements
Defib Task Force would like to thank Dr. Renata Ramos, Dr.
Mehdi Razavi, Dr. Maria Oden, Carlos Amaro, the Rice
University OEDK, the Texas Heart Institute, and St. Luke’s
Episcopal Hospital.
References
 Deakin, Charles D. "European Resuscitation Council Guidelines for Resuscitation 2005
Section 3. Electrical Therapies: Automated External Defibrillators, Defibrillation,
Cardioversion and Pacing." Resuscitation 67 (2005): S25-37. Print.
 Bridy, Marie A., Thomas R. Burklow. “Understanding the newer automated external
defibrillator devices: electrophysiology, biphasic waveforms, and technology”. J Emerg
Nurs 2002;28:132-7.
 Gundry, et al. "Comparison of Naive Sixth-Grade Children With Trained Professionals in
the Use of an Automated External Defibrillator." Circulation 100 (1999): 1703-707. Print.