Post on 15-Apr-2017
Defibrillation: Issues and Challenges
Dr. K.S. Chew School of Medical Sciences
Universiti Sains Malaysia
Conflict of Interest
• No conflict of interest to declare
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Contents
• What are already known about defibrillation • CPR before defib – how long should we do? • Effect of perishock pauses. • Hands-on defibrillation • CPR devices as an alternative. But how effective? • More AEDs in public places in Malaysia?
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What Are Already Known
• Defibrillation works in VF/pulseless VT (Larsen et. al. Ann Emerg Med. 1993;22:1652 -1658)
• It should be given early – IHCA (Chan et al N Engl J Med . 2008;358:9–17) and – OHCA (Holmberg et al. Resuscitation. 2000;44:7–17)
• It should be integrated with CPR (Larsen et. al. Ann Emerg Med. 1993;22:1652–1658) – For every minute without CPR from collapse to
defibrillation, survival rate decreases 7% to 10%
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What Are Already Known
Lars Wik et al (2003): • Ambulance response time <5 min, CPR 1st vs Defib
1st: no difference (survival to discharge)
• Ambulance response time >5 min, CPR first for 3 min 22% (14/40); Defib first 4% (2/41), OR 7.42 (95% CI 1.61-34.3), p = 0.006
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Wik L et al. JAMA 2003. 289:1389-95
What Are Already Known
AHA Guidelines 2010 • OHCA
– witnessed: CPR first, shock ASAP when ready – Unwitnessed: CPR first, shock ASAP when ready (For how long? Full 5-cycle of CPR??)
• IHCA – unwitnessed: CPR first, shock ASAP when ready – Witnessed: ?? CPR first
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“time from onset of VF/pulseless VT to defibrillation within 3 minutes”
How Much CPR Before Defib?
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Stiell et al. N Engl J Med 2011;365(9):787-97
How Much CPR Before Defib?
• 10 Resuscitation Outcomes Consortium (ROC) sites in the U.S. and Canada.
• P = N = 9933 non-traumatic OHCA (unwitnessed) • I = CPR for 30 to 60s before defib (until pads were
applied) or • C = CPR for 180s before defib • O = Survival to hospital discharge with satisfactory
neurological outcome
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How Much CPR Before Defib?
• Survival to hospital discharge with satisfactory neurological function was 5.9% in both groups.
• Delaying analysis of cardiac rhythm during EMS-administered CPR provided no advantage.
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Perishock Pauses
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Cheskes et al. Circulation. 2011;124(1):58-66.
Perishock Pauses
• Definition: Perishock pauses are pauses in chest compressions before and after defibrillation
• N = 815 patients requiring at least one defibrillation; 11 centers in North America
• Association between pause durations and outcomes were analyzed
• Primary outcome: survival to hospital discharge
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www.PresentationPro.com Cheskes et al. Circulation. 2011;124(1):58-66.
Results
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Survival to Hospital Discharge as a Function of Maximum* Shock Pause
Results
• Odds of survival were significantly lower if: • preshock pause ≥20s vs preshock pause <10s
(OR 0.47; 95% CI 0.27 to 0.82) and • perishock pause ≥40s vs perishock pause <20s
(OR, 0.54; 95% CI 0.31 to 0.97) • Postshock pause – not associated with a significant
change in the odds of survival • survival to discharge decreases 18% and 14% for q
5s increase in preshock and perishock pauses (up to 40s and 50s), respectively
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Keep Hands On While Defibrillation?
• Hands-on defibrillation minimizes pre-shock & peri-shock pauses in cardiac compressions. – For every 5-second increase in both pre-
shock and peri-shock, a 18% & 14% decrease in survival to hospital discharge up to 40 and 50 seconds, respectively (Cheskes et al. Circulation. 2011 Jul 5;124(1):58-66. )
But are rescuers who use this technique at risk for exposure to electric shock?
Keep Hands On While Defibrillation?
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Lemkin et al. Resuscitation. 2014 Oct;85(10):1330-6.
• Cadaveric study, 6 cadavers
• Voltage measurements while rescuers performed defibrillation with 360J on cadavers.
• Cadavers not grounded
Keep Hands On While Defibrillation?
Lemkin et al. Resuscitation. 2014 Oct;85(10):1330-6.
• Results: • rescuers would be exposed to between 200 and
827 volts, depending on the cadaver and electrode location, and received between 1 and 8 joules of electrical energy, an amount that exceeds recommended exposure levels.
Keep Hands On While Defibrillation?
Lemkin et al. Resuscitation. 2014 Oct;85(10):1330-6.
Summary
• Give some chest compression while preparing for defib
• How long? 1 min until defib is ready or a full 3-min? • No difference! Probably should just shock! • DO NOT keep hand-off for >10s before shock • But be safe! Keep hands off while shock is
delivered.
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CPR Devices
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Should you buy one? Is it effective? Which one? What’s the evidence so far?
A solution to continuous CPR when shock is delivered
Two Types of CPR Devices
• Load-distributing band CPR devices (LDB) – Provide circumferential thoracic
compressions • Piston-driven CPR device (PD)
– Provide sternal compressions • In preclinical settings, CPR
devices improve coronary perfusion, cardiac output, ROSC.
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Why CPR Devices?
Advantages 1. Overcomes rescuer fatigue 2. Provides effective and consistent compression 3. Frees rescuers to perform other procedures 4. Allows defibrillation during on-going compression 5. Minimizes peri-shock delay Disadvantages 1. Technical difficulties in applying devices 2. No one-size fit all
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The Use of CPR Devices: What’s the Evidence?
Westfall M, Krantz S, Mullin C, Kaufman C. Mechanical versus manual chest compressions in out-of-hospital cardiac arrest: a meta-analysis. Crit Care Med.
2013;41(7):1782-9.
Are CPR Devices Effective In Clinical Setting? • A meta-analysis by Westfall et al in Crit Care Med.
2013;41(7) • P = OHCA victims (N = 6,538) • I = CPR devices (both LDB & PD) CPR • C = Manual CPR • O = ROSC (defined as palpable pulse with
measurable BP for at least 1 min)
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Westfall M, Krantz S, Mullin C, Kaufman C. Mechanical versus manual chest compressions in out-of-hospital cardiac arrest: a meta-analysis. Crit Care Med.
2013;41(7):1782-9.
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12 papers finally accepted for the meta-analysis Only English-language articles were searched
Test for Heterogeneity
• A random-effects model used
Note: • When the studies’ results differ only by the
sampling differences (homogeneous cases), a fixed-effects model is used
• When the study results differ by more than the sampling differences, which means including variations in study design (heterogeneous cases), a random-effects model is used
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Results
• 12 papers analyzed • A total of 6,538 subjects with 1,824 ROSC events
• Combined analysis of both types of CPR devices: • Treatment effect in favor of higher odds of ROSC
with mechanical CPR devices (odds ratio 1.53 [95% CI, 1.32, 1.78]; p < 0.001)
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Piston-Driven CPR (PD-CPR) devices vs Manual CPR (M-CPR)
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Load-distributing CPR (LDB-CPR) devices vs Manual CPR (M-CPR)
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Conclusion
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The combined meta-analysis of two types of CPR devices compared with manual chest
compressions showed a significant improvement in ROSC rates with
mechanical devices….when analyzed separately, only the LDB-CPR device was
found to be superior to manual chest compressions with odds of achieving ROSC
being 1.6 times greater
The CIRC Trial
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Wik L, Olsen JA, Persse D, Sterz F, Lozano M, Jr., Brouwer MA, et al. Manual vs. integrated automatic load-distributing band CPR with equal survival after out of hospital cardiac arrest. The randomized CIRC trial. Resuscitation. 2014;85(6):741-8.
CIRC Trial
• Randomized, unblinded, controlled group sequential trial involving 5 centers: 3 US sites, 2 European sites, N = 4231 cases; industry-funded
• P = OHCA victims • I = IA*-LDB device (n = 2099) • C = Manual CPR (n = 2132) • O = survival to hospital discharge (primary) • Caveat: excluded cases where the body sizes were
too big for the device
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*integrated = manual CPR was provided while device was applied
CIRC Trial: Results
Manual CPR (n = 2132)
LDB CPR (n = 2099)
Adjusted OR
Survival to hospital discharge
233 (11.0%) 196 (9.4%) 1.06 (CI: 0.83 –
1.10)
Secondary outcome:
Sustained ROSC until adm
689 (32.3%) 600 (28.6%)
24-hr survival 532 (25.0%) 456 (21.8%)
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Conclusion
• LDB device is as good as manual compression • LDB eliminates rescuer fatigue • LDB allows CPR in spaces and situations where
human could not provide effective compressions
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The PARAMEDIC Study
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Perkins GD, Lall R, Quinn T, Deakin CD, Cooke MW, Horton J, et al. Mechanical versus manual chest compression for out-of-hospital cardiac arrest (PARAMEDIC): a pragmatic,
cluster randomised controlled trial. Lancet. 2015;385(9972):947-55.
The PARAMEDIC Study
• Randomized, pragmatic design to study the clinical outcomes of a piston-driven CPR device (LUCAS-2) vs manual CPR
• Intention-to-treat analysis • P = OHCA victims • I = Piston-driven CPR device, Lucas-2 (n = 1652) • C = Manual CPR (n = 2819) • O = survival at 30 days
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Pragmatic vs Explanatory Design (coined by Schwartz & Lellouch, 1967)
Pragmatic Explanatory Aim To evaluate the
effectiveness of the intervention in a broad and diverse routine clinical practice
To evaluate the efficacy of an intervention in a well-defined and controlled setting (ideal/optimal environment)
Sample Larger sample size Smaller sample size Confounders Poorly controlled Controlled as much as
possible Generalizability Probably more
generalizable Less generalizable
Bottomline whether an intervention actually works in real life
if and how an intervention works
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Note: “Survived event” is defined as sustained ROSC until hospital admission from ED
†Reasons LUCAS-2 not used: • 78 because of crew not trained; • 168 because of crew error; • 26 no device in vehicle; • 102 unsuitable patients (58 patient too large, 22 patient too small, 22 other reason–eg, chest deformity), • 14 device issues; • 140 not possible to use device; • 110 reason unknown.
Reasons for LUCAS-2 use in control group were crew error.
Perkins et al Lancet. 2015;385(9972):947-55.
Smekal et al Resuscitation. 2011;82(6):702-6. Rubertsson et al. The LINC randomized trial. JAMA. 2014;311(1):53-61.
The PARAMEDIC Study
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“We noted no evidence of improvement in 30 day survival with LUCAS-2 compared with manual
compressions. On the basis of ours and other recent randomised trials, widespread adoption of mechanical
CPR devices for routine use does not improve survival”
Conclusion:
Summary Of What’s Discussed So Far
• Meta-analysis by Westfall et al (2013): LDB device seems better than manual compression in achieving ROSC. Piston-driven device is no better.
• CIRC trial (2014): IA-LDB is no better than manual compression in survival to hospital discharge
• PARAMEDIC study (2015): Piston-driven device is no better than manual compression in survival to 30 days
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A Good Reason To Get A CPR Device?
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“The main thing…is to keep the main thing the main thing” – Stephen Covey
“Providing quality compression and minimize interruptions”
Placing More Automated External Defibrillators In Public Places in Malaysia
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“A defibrillator and code cart should be in close proximity to enable defibrillation of any patient in cardiac arrest within 2
minutes…”
“…placement of AEDs in areas where time from arrest to arrival of a defibrillator would be >3 minutes…..”
Morrison LJ et al. Circulation. 2013;127(14):1538-63.
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More public places with AEDs in Malaysia?
Which public places?
A Public Access Defibrillator Act
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List of Places with AEDs Under Manitoba Defibrillator Public Access Act • Fitness clubs, gyms,
swimming pools and other facilities – >150 members, or >20
hours of indoor group physical-activity programs are held in the majority of weeks in a year
• Community Centers • Golf Courses
• Colleges, universities • Airports, train stations • Casinos • Homeless shelters • Major shopping centers • Museums, other
popular destinations • City Hall • Law Courts
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Placing AEDs in Vending Machines?
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Other Ethical and Legal Issues, Privacy..
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Civil Responsibility, Vandalism, Theft
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Summary
• CPR before defib to be performed until defibrillator is ready
• Minimize preshock pauses to <10s • Hands-on defib is not recommended. Be safe! • CPR devices as an alternative for hands-on
defibrillation. • CPR devices are not shown to have an advantage
over high quality manual CPR • AEDs in public places – political will needed.
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Thank You For Your Attention