Automatic External Defibrillation
Past, Present & Future
Prof. John McC Anderson
CTO HeartSine Technologies Ltd
THE DISTRIBUTION OF ACUTE CORONARY DEATHS
Mc NEILLY (BELFAST), 1965-66, 818 DEATHS
100
PERCENTAGE ALIVE
90
80
70
60
50
40
30
20
10
0
0.1
HR
0.2
HR
1
DAY
INTERVAL AFTER ONSET
7
DAY
Modern Developments in Out-of-Hospital Defibrillation
Period
Defibrillator Operator
Comments
1960’s
Physicians
Physicians staff the first mobile
coronary care unit (Belfast, New
York City).
Early 1970’s
Paramedics
Extensively trained (400-1500
hours). Defibrillation added to
many advanced life support
skills.
Late 1970’s
EMT’s trained in
defibrillation
Rhythm recognition and skills of
defibrillation taught to EMT’s in
10 hour course.
The Semi-Automatic Defibrillator
Flow Diagram for Ventricular Fibrillation Detection
Energy Ratio Characteristic
Energy Ratio i.e. Yellow/Red ratio constant in Sinus Rhythm
Energy Ratio i.e. Yellow/Red ratio continuously variable in
Ventricular Fibrillation
Flow Diagram for Ventricular Fibrillation Detection
Flow Diagram for Ventricular Fibrillation Detection
The Future Management of Sudden Cardiac Death
Defibrillators in the Home (PDU)
The development of a CPR-ICG PAD
The evolution of ‘Smart Defibrillation’
The Personal Defibrillation Unit – PDU 400
Statistics
 More than 650,000 deaths per year from cardiovascular diseases
 In the US around 800,000 patients suffer an AMI annually of
whom 550,000 die
 Over 80% of the deaths occur in the home
 PEA accounts for over 65% of cardiac arrests
 In 2005 the ERC and AHA guidelines were updated to emphasize
the importance of effective chest compressions with minimal
interruptions
 In 2008 the AHA introduced the “hands-only” protocol
Design Features
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Smaller
Lighter
Complete Resuscitation System
High IP rating
Advanced Algorithm
Disposable
User Friendly
The Development of a CPR-ICG PAD
The History of Impedance Cardiography
Transthoracic Impedance:
“Change in thoracic impedance may be due to any change in
physical shape or content of the thorax, including ventilation,
cardiopulmonary blood flow ….”
Miller JC, Horvath SM. Impedance Cardiography.
Psychophysiology 1978; 15: 80-91
ECG/ICG Timing
Impedance Cardiography (ICG)
The ICG measures the cardiac impedance
during the cycle and gives a waveform
relating to the change in blood volume
within the heart during this time.
(Cardiac Output)
Example Cases from RVH Database
Patient required terminating shock ;
HR=189BPM, QRS width 201ms.
Patient conscious ; HR=330BPM,
QRS width varies between 133ms and
189ms.
ECG
ICG
Causes of change in Cardiac Output
 Blood Flow in the aorta
 Blood Flow through the
pulmonary vessels
 Contracting heart
 Changing resistivity of blood
 Improved contact with electrodes
Importance of Effective CPR
 PEA accounts for over 65% of cardiac arrests
 In 2005 the ERC and AHA guidelines were updated to
emphasize the importance of effective chest
compressions with minimal interruptions.
 In 2008 the AHA introduced the ‘hands-only’ protocol to
further minimize interruptions.
CPR Feedback Indicator
 ICG can offer feedback on cardiac output during chest
compressions
 The morphology of the ICG waveform during CPR is
distinctive
 HeartSine has developed an algorithm based on the
RVH database of CPR cases which uses a number of
parameters to enable feedback on CPR efficacy for
the user
ICG Waveform During CPR
ICG Waveform During Sinus Rhythm
ICG Waveform During PEA
ICG not present due to absence of
CARDIAC OUTPUT during PEA
ICG During VF
ICG not present due to absence of
CARDIAC OUTPUT during VF
Challenges in Algorithm Development
 Noise due to motion artifact
 Noise due to incorrect pad or hand placement
 Initial ICG algorithm classified some cases of
noise as CPR
Results from initial Bench Tests
It was found through a number of bench tests
that excessive noise could be eliminated by
measuring the rate and pulse width of the signal
and by focusing efforts on good CPR training to
ensure the correct hand positioning and applied
force
Recording of Correctly Applied CPR During Initial Bench Testing
Recording of Poor CPR (No Compressive Force Applied)
Recording of CPR on Top of Pads
Proposed CPR-ICG Algorithm
“PUSH HARDER”
“PUSH FASTER/SLOWER”
“GOOD COMPRESSIONS”
Algorithm Results to Date
CPR Criteria
ICG Test
Sample Size
Performance
Specifications
Performance
Results (%)
90% One-Sided Lower
Confident Limit (%)
CPR Speed
Good
82377
Sensitivity: > 90%
Specificity: > 90%
Sensitivity: 95.38
Specificity: 93.11
Sensitivity: 83.40
Specificity: 82.19
CPR Force
Adequate
108728
Sensitivity: > 90%
Specificity: > 90%
Sensitivity: 99.96
Specificity: 98.47
Sensitivity: 99.54
Specificity: 96.29
Animal Study Results
ICG amplitude at varying compression depths:
1-
ICG Amplitude in Ohms
Thrust/depth
2cm = 20kg
4cm = 30-40kg
6cm = 60-70kg
0-
2cm
4cm
5cm
The ICG amplitude (in ohms) is higher for higher CPR compression depths and
values of ET CO2.
Summary
“In order to maintain high-quality CPR, feedback to rescuers is important.
The use of prompt/feedback devices during CPR will enable immediate
feedback to rescuers, and the data stored in rescue equipment can be
used to monitor the quality of CPR performance and provide feedback to
professional rescuers during debriefing sessions .”
ERC Guidelines 2010 - European Resuscitation Council Guidelines for Resuscitation 2010 Section 2. Adult
basic life support and use of automated external defibrillators
 HeartSine samaritan PAD 500P with CPR advisor was launched in August 2009 in Europe
 Preparations are under way for FDA 510(k) clearance in the US
The Development of a SMART Defibrillator
Optimal treatment for Sudden Cardiac Arrest (SCA)
Interactive CPR
Accurate decision to defibrillate/CPR
Management of PEA
The FUTURE of Defibrillation
Features to be included in the SMART AED:
1. CPR-ICG Indicator
2. Pulse checker (Uses ICG to discriminate between PEA and SR)
3. Therapy Advisor (Uses DSP to extract information on frequency
content of the ECG signal during cardiac arrest to determine whether
CPR or defibrillation is the most appropriate therapy)
4. Using ICG to discriminate between CPR and shockable rhythms
during the “hands-off” period
5. Continuous chest compressions until administration of shock
3-Phases of a Sudden Cardiac Arrest
 Majority of customer queries result from nonadherence to the “hands-off” or analysis period of the
PAD
 Using ICG technology we plan to develop an algorithm
to discriminate between CPR and a shockable rhythm
to prevent the device from charging and then disarming
following the discontinuation of CPR
 The algorithm can output audio voice prompts which
will advise the user to discontinue CPR
Failure to adhere to CPR prompts
CPR continued during analysis
phase despite audio prompts
Shock advised due to
inappropriate CPR
 HeartSine Technologies currently has the basic science
to build a SMART defibrillator.
 A SMART defibrillator will provide the optimal treatment
for Sudden Cardiac Death
 SMART defibrillation will position HeartSine
Technologies as a world leader in this field.
In 1775 Abilgard recorded that he
“shocked a single chicken into lifelessness and upon repeating
the shock, the bird flew off and thus eluded further
experimentation”
Any
Questions?