UPDATE ON EMERGENCY CARDIAC CARE

GUIDELINES

Mark L. Greenberg, MDAssociate Professor of Medicine

Director, Clinical Electrophysiology and Pacing

1

BLS and ACLS--Historical Perspective

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

The Chain of Survival of Cardiopulmonary Resuscitation

Valenzuela, et al. Circulation. 1997;96:3308-13.

Interdependence of Early CPR and Early Defibrillation

The physiologic mechanism of chest compressions: cardiac pump (A) or

thoracic pump (B)?

What’s New in BLS

New Chest Compression Rate and Compression-Ventilation Ratio for Adults

Interposed Abdominal Compression CPR (IAC-CPR)

INTERRUPTIONS IN CHEST COMPRESSIONS ARE

DETRIMENTAL

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)

Interposed Abdominal Compression CPR (IAC-CPR)

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

Handle

Suction Cup

Inspiratory Impedance Threshold Valve (ITV)

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.

Concept: Lower intrathoracic pressure in the chest during the decompression phase of CPR enhances venous return to the thorax.

ResQValve (CPRx)

Disposable, one-way valve that fits into the respiratory circuit and impedes

inspiratory gas exchange during decompression

ResQValve Placement

BrainLeft Ventricle

STD CPR

STD CPR + ITV

ACD CPR

ACD CPR + ITV

0.0

0.2

0.4

0.6

0.8

1.0

Blood Flow During CPR

(Porcine VF Model) B

lood

Flo

w (

ml/m

in/g

m)

Lurie et al. Improving ACD CPR with an inspiratory impedance valve. Circulation 1995;91:1629-32.

Blood Pressure During CPR in Humans

0

20

40

60

80

100

120

mm

Hg

Systolic Diastolic

STD CPR

ACD + ITV

Cohen et al, JAMA 1992 and Plaisance et al, Circulation 2000

Baseline (Normal)

RCT of ACD/ITV CPR vs. STANDARD CPR

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

More emphasis on early defibrillation

Automatic External Defibrillation (AED) and Public Access Defibrillation (PAD)

Defibrillation with a biphasic waveform

04/19/23

Defibrillation The Time Factor*

Survival rates after VF cardiac arrest decrease approximately 7% to 10% with every minute that defibrillation is delayed.

Guidelines 2000 for Cardiovascular Resuscitation and Emergency Cardiovascular Care.Circulation. 2000;102(suppl I)8. August 22,2000

Time (min)

100

80

90

70

60

50

40

30

20

10

01 2 3 4 5 6 7 8 9

Per

cen

t o

f S

urv

ival

10

* Non-linear

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?

President Bill Clinton, 5/20/00 radio address.

“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.”

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)

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

04/19/23

Defibrillation

Current Flow

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

04/19/23

Biphasic Defibrillation

Risk of Damage

Source: SL Higgins, Prehospital Emergency Care 2000; 4:305-313

Much less peak current and better efficacy than monophasic

Biphasic Peak Current

Monophasic Peak Current

40% Difference

-20

-10

0

10

20

30

40

0 5 10 15 20

Time (msec)

Cur

rent

(am

ps)

Transthoracic Impedance

Measured by the defibrillator

Higher impedance • Skin surface—especially dry• Hair• Fat• Bone• Air in chest

04/19/23

Impedance

The current a heart receives from a 200J shock depends on the patient’s impedance

0

10

20

30

40

50

60

25 50 75 100 125 150

Patient Impedance (ohms)

Pea

k C

urre

nt (

amps

)

Current variance due to impedance, energy held constant

04/19/23

Impedance Distribution

30 40 50 60 70 80 90 100 110 120 130 140 150 More0

2

4

6

8

10

12

14

16

Histogram of patient impedances

Impedance (ohms)

Per

cen

tag

e o

f P

atie

nts

Medtronic Physio-Control: Impedance data on 723 SCA patients.

Biphasic Defibrillators Are NOT All the Same

Waveforms vary (with regard to voltage or pulse duration) in their response to transthoracic impedance measurements.

Energy settings may be fixed, low-dose escalating, or “standard” dose escalating.

No clear superiority among manufacturers.

IMPEDANCE ADJUSTMENT WITH PHILIPS FR2

50

40

30

20

10

0

-10

-200 5 10 15 20 25 30 35 40

Current (A)

Time (msec)

SMART Biphasic 150-150-150 J Current adjusted for

impedance Customized

waveform shape for each patient and each shock

5050, 150 J, 150 J

7575, 150 J, 150 J

125125, 150 J, 150 J

Why Will Biphasic Defibrillators Replace Standard Monophasic

Models?

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.

1st shock

%

Biphasic Monophasic

p <0.000196% (52/54)

59%(36/61)B

3 shocksBiphasic Monophasic

p < 0.000198% (53/54)

69% (42/61)

Schneider T, et al, Circulation 2000;102:1780-1787.

What’s New in ACLS?

Airway ManagementVasopressinIV amiodarone as a first-line drug

What’s New in Airway Management

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

Esophageal-tracheal combitube

Advanced Airway Devices

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?

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

Advantage lidocaine: rapid onset of action, no hypotension

Game, set, and match amiodarone: minimal proarrhythmia, much stronger evidence for efficacy

Kudenchuk et. al. NEJM 1999;341:871-8.

Amiodarone vs. Placebo in 504 Pts. with Shock Refractory Out-of-

Hospital VT/VF

Amiodarone vs. Lidocaine for Shock-Resistant VF

Dorian et al. N Engl J Med 2002;346:884-90.

Stable Ventricular Tachycardia

A m io d aro ne* 1 50 m g IV ove r 1 0 m inu tes

orL ido caine

* 0 .5 to 0 .7 5 m g /kg IV pu shThen use

S ynch ro n ized card iovers ion

M edica tio n s: * Procainam ide

O th ers acceptab le * Am iodarone * Lidocaine

Reasonable LV function Poor LV function

M onom orphic VTIs ca rd ia c fu n ctio n im p a ire d?

Polymorphic Ventricular Tachycardia

L o n g b ase line Q TIn te rval* Correct abnorm alelectrolytes

Interventions: * Magnesium * Overdrive pacing * Isoproterenol * Lidocaine

N o rm a l b ase line Q TIn te rval * Treat ischem ia * Correct electrolytes

M edications: * Beta Blockers or * Lidocaine or * Am iodarone or * Procainam ide or * Sotalol

N o rm a l b ase lineQ T Inte rval

P ro lo n ged b ase lineQ T Inte rval

(su gg es ts T o rsades)

P o lym o rp hic VT* Is QT baseline interval prolonged?