Transcript what`s new in acls and external defibrillation - Dartmouth

UPDATE ON
EMERGENCY CARDIAC
CARE GUIDELINES
Mark L. Greenberg, MD
Associate Professor of
Medicine
Director, Clinical
Electrophysiology and Pacing
BLS and ACLS-Historical Perspective
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1956: External defibrillation (Zoll)
1958: Mouth-to-mouth ventilation (Safar,
Elam)
1960: Chest compressions (Kouwenhoven)
1979: Automatic External Defibrillator
(AED) (Diack)
1996: Biphasic waveform approved for AED
use in USA
2000: First international evidence-based
resuscitation guidelines
1
The Chain of Survival of
Cardiopulmonary Resuscitation
Interdependence of Early
CPR and Early Defibrillation
Valenzuela, et al.
Circulation. 1997;96:330813.
The physiologic mechanism of chest
compressions: cardiac pump (A) or
thoracic pump (B)?
What’s New in BLS
 New
Chest Compression
Rate and CompressionVentilation Ratio for
Adults
 Interposed Abdominal
Compression CPR (IACCPR)
INTERRUPTIONS IN CHEST
COMPRESSIONS ARE
DETRIMENTAL
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Lay rescuers: 16 seconds to
administer 2 breaths (cf 3-4 sec.
for professionals).
Compression: ventilation ratio
of 5:1 yields higher PaO2 but
lower oxygen delivery than 15:2
(64 compressions, 8 ventilations
per minute).
New Chest Compression Rate
and Compression-Ventilation
Ratio for Adults
Compression rate approx.
100/min for adults and
children over age one
 Compression-ventilation
ratio 15:2 for both one and
two-rescuer CPR (5:1 after
trachea intubated)
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Interposed Abdominal
Compression CPR (IACCPR)
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An alternative for in-hospital
resuscitation
Abdomen compressed between
xiphoid and umbilicus during
relaxation phase of chest
compression
Increases forward blood flow during
CPR and appears to improve survival
IAC-CPR
Seesaw-like Function of
the Lifestick
ResQPump™
Metronome
Force Gauge
Suction Cup
Handle
Inspiratory Impedance
Threshold Valve (ITV)
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Concept: Lower intrathoracic pressure
in the chest during the decompression
phase of CPR enhances venous return
to the thorax.
Design: Each time the chest wall recoils
following a compression, the ITV
transiently blocks air/oxygen from
entering the lungs, creating a small
vacuum in the chest.
ResQValve (CPRx)
Disposable, oneway valve that
fits into the
respiratory
circuit and
impedes
inspiratory gas
exchange during
decompression
ResQValve
Placement
Blood Flow During CPR
(Porcine VF Model)
Blood Flow (ml/min/gm)
1.0
STD CPR
0.8
STD CPR + ITV
0.6
ACD CPR
ACD CPR + ITV
0.4
0.2
0.0
Left Ventricle
Brain
Lurie et al. Improving ACD CPR with an inspiratory impedance valve. Circulation 1995;91:1629-32.
Blood Pressure During CPR in
Humans
120
mmHg
100
80
STD CPR
60
ACD + ITV
40
20
Baseline
(Normal)
0
Systolic
Diastolic
Cohen et al, JAMA 1992 and Plaisance et al, Circulation 2000
RCT of ACD/ITV CPR vs.
STANDARD CPR
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220 patients, 157 with
witnessed events (Mainz,
Germany)
24 hr. survival 37% with
ACD/ITV CPR vs. 22% with
standard CPR (p=0.03)
Wolcke et. al. Circulation.2002;106:II-538.
What’s New in
External Defibrillation
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More emphasis on early
defibrillation
Automatic External
Defibrillation (AED) and Public
Access Defibrillation (PAD)
Defibrillation with a biphasic
waveform
Defibrillation
The Time Factor*
* Non-linear
Guidelines 2000 for Cardiovascular
Resuscitation and Emergency
Cardiovascular Care.Circulation.
2000;102(suppl I)8. August 22,2000
90
80
70
Percent of Survival
Survival rates
after VF cardiac
arrest decrease
approximately
7% to 10% with
every minute
that defibrillation
is delayed.
100
60
50
40
30
20
10
0
1
2
3
4
5
6
Time (min)
7
8
9
10
13 year old boy struck
by a pitch
Commotio Cordis
Goals For Early
Defibrillation
 In
hospital: defibrillation
within 3 minutes
 Out of hospital:
defibrillation within 5
minutes of activation of
the EMS (value of AED
and PAD)
Unconscious patient, no
pulse
Shock advised
Unconscious patient, no
pulse
No shock advised?
“It is time for the national
government to help bring AED’s to
public places all over America. . . I
am working with Congress to
complete a vital piece of legislation
that would not only encourage the
installation of AED’s in federal
buildings, but also grant legal
immunity to good Samaritans who
use them. .. It is now our
responsibility to bring this
technology , this modern miracle, to
every community in America.”
President Bill Clinton,
5/20/00 radio address.
Prevalence of AED’s
 National
Registry of CPR
Hospitals: 31%
 VA Hospitals: 14%
 Commerical Airliners:
100%
O’Hare International
Airport: 60-90 Second
Walk To An AED
Caffrey et. al. N Engl J Med 2002;347:1242-7.
CHICAGO AIRPORT
AED STUDY
Three airports, serving >100
million passengers/yr.
 21 cardiac arrests over 2
yrs; 18 had VF, 11 of whom
were resuscitated (10 alive
& well one yr. later)
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Caffrey et. al. N Engl J Med 2002;347:1242-7.
Incidence of Unexpected
Cardiac Arrest
AEDs: UNANSWERED
QUESTIONS
 Does
formal training
improve performance?
 How are they best
deployed?
 Are they cost
effective?
DEFIBRILLATOR
WAVEFORMS
Defibrillation
Current Flow
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Biphasic defibrillation—current flows in two
phases, first in one direction from one
electrode, and then current flows the other way
from the other electrode
Biphasic Defibrillation
Risk of Damage
40
Monophasic Peak Current
Current (amps)
30
40% Difference
Biphasic Peak Current
20
10
0
-10
-20
0
5
10
15
20
Time (msec)
Much less peak current and better
efficacy than monophasic
Source: SL Higgins, Prehospital
Emergency Care 2000; 4:305-313
Transthoracic Impedance
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Measured by the defibrillator
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Higher impedance
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•
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•
Skin surface—especially dry
Hair
Fat
Bone
Air in chest
Impedance
60
Current variance due to impedance,
energy held constant
Peak Current (amps)
50
40
30
20
10
0
25
50
75
100
125
150
Patient Impedance (ohms)
The current a heart receives from a 200J
shock depends on the patient’s impedance
Impedance
Distribution
Histogram of patient impedances
Percentage of Patients
16
14
12
10
8
6
4
2
0
30
40
50
60
70
80
90
100
110
120
Impedance (ohms)
Medtronic Physio-Control: Impedance data on 723 SCA patients.
130
140
150
More
Biphasic Defibrillators
Are NOT All the Same
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Waveforms vary (with regard to
voltage or pulse duration) in their
response to transthoracic
impedance measurements.
Energy settings may be fixed, lowdose escalating, or “standard” dose
escalating.
No clear superiority among
manufacturers.
IMPEDANCE ADJUSTMENT
WITH PHILIPS FR2
50
SMART Biphasic
40
50, 150 J
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30
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75, 150 J
Current (A) 20
125, 150 J
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10
0
-10
-20
0
5
10
15
20
25
30
Time (msec)
35
150-150-150 J
Current adjusted for
impedance
Customized
waveform shape for
each patient and
each shock
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Why Will Biphasic Defibrillators
Replace Standard Monophasic
Models?
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Impedance compensating, lower
shock strength biphasic
waveforms have less potential
to damage cells.
Biphasic waveforms have
superior efficacy for treating
atrial fibrillation and ventricular
fibrillation.
Randomized, controlled trial of 150 J
biphasic shocks with 200-360 J monophasic
shocks in 115 patients with out-of-hospital
VF; time to first shock 8.9+/-3.0 min.
96% (52/54)
p <0.0001
98% (53/54)
p < 0.0001
69% (42/61)
59%(36/61)B
%
Biphasic
Monophasic
1st shock
Biphasic
Monophasic
3 shocks
Schneider T, et al, Circulation 2000;102:1780-1787.
What’s New in ACLS?
 Airway
Management
 Vasopressin
 IV amiodarone as a
first-line drug
What’s New in Airway
Management
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Emphasis on skilled bag-mask
ventilation with continuous cricoid
pressure
Validation of airway adjuncts like
the laryngeal mask and Combitube
Recommendation for secondary
confirmation techniques to verify
ETT placement (e.g.end-tidal CO2)
Cricoid Pressure Can
Minimize Gastric Inflation
Advanced Airway
Devices
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Esophagealtracheal
combitube
Advanced Airway
Devices
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Laryngeal mask airway (LMA)
Superior to ETT for BLS-level
personnel
Equal to ETT for ACLS-level
personnel
Laryngeal Mask
Confirming Tracheal
Tube Placement
Esophageal detector
devices
Vasopressin 40 U IV Before
Epinephrine 1 mg IV?
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Vasopressin appears at least as
effective as epinephrine (large RCT
underway in Europe).
Vasopressin is non-beta-adrenergic
and does not increase myocardial 02
consumption.
Longer half-life (10-20 min. vs. 3-5
min.) simplifies administration.
Amiodarone 300 mg IV Should
Be Given Before Lidocaine
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Advantage lidocaine: rapid
onset of action, no hypotension
Game, set, and match
amiodarone: minimal
proarrhythmia, much stronger
evidence for efficacy
Amiodarone vs. Placebo in 504
Pts. with Shock Refractory Outof-Hospital VT/VF
Kudenchuk et. al. NEJM
1999;341:871-8.
Amiodarone vs. Lidocaine for
Shock-Resistant VF
Dorian et al. N Engl J Med 2002;346:884-90.
Stable Ventricular
Tachycardia
Monomorphic VT
Is cardiac function impaired?
Reasonable LV function
Medications:
* Procainamide
Others acceptable
* Amiodarone
* Lidocaine
Poor LV function
Amiodarone
* 150 mg IV over 10 minutes
or
Lidocaine
* 0.5 to 0.75 mg/kg IV push
Then use
Synchronized cardioversion
Polymorphic Ventricular
Tachycardia
Polymorphic VT
* Is QT baseline interval prolonged?
Normal baseline
QT Interval
Normal baseline QT
Interval
* Treat ischemia
* Correct electrolytes
Medications:
* Beta Blockers or
* Lidocaine or
* Amiodarone or
* Procainamide or
* Sotalol
Prolonged baseline
QT Interval
(suggests Torsades)
Long baseline QT
Interval
* Correct abnormal
electrolytes
Interventions:
* Magnesium
* Overdrive pacing
* Isoproterenol
* Lidocaine