Electrical Therapies in CPR

By : Mohammed suleiman al-jajeh

Phase V 20133422

NEAR EAST UNIVERSITY

HOSPITAL

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Contents :

Definition

Indications & contraindications

Defibrillation Waveforms and Energy Levels

Electrode Placement

Procedure of Electrical defibrillation

Complication of defibrillation

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Definition :

The most common electrical therapy in ER is

Defibrillation.

Defibrillator is a device used to shock the heart

back into action when it stops contracting due

to a disorder of the rhythm as ventricular

fibrillation (VF). The electrodes used to deliver

the shock could be either defibrillator paddles

or patches, directly applied to the chest below

the left clavicle and at the apex of the heart.

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Other type of electrical therapy :

Cardioversion

is a corrective

procedure where an

electrical shock is

delivered to the

heart to convert or

change abnormal

heart rhythm back to

normal sinus rhythm .

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electrical cardioversion Indications :

Supraventricular tachycardia

Atrial fibrillation

Atrial tachycardia

Monomorphic VT with pulses

Reentrant tachycardia with narrow or wide QRS

complex (ventricular rate >150 bpm) who is

unstable (eg. ischemic chest pain, acute

pulmonary edema, hypotension, acute altered

mental status, signs of shock )5

Defibrillator INDICATIONS :

ventricular arrhythmia (ventricular tachycardia

or ventricular fibrillation)

cardiac arrest (unresponsive patient without a pulse)

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Defibrillator Contraindications :

The main contraindication is in a patient who

has made it clear that he does not wish to be

resuscitated (awake patients) .

Defibrillation should not be used for

arrhythmias other than ventricular tachycardia

or ventricular fibrillation.

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Shock First vs. CPR First ?

start CPR and use the AED as soon as possible

So the time from VF to defibrillation should be

under 3 minutes.

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Defibrillation Waveforms :

① Monophasic Waveform Defibrillators

② Biphasic Waveform Defibrillators

from one electrode to the other9

Energy Levels :

Biphasic shocks are more effective than

monophasic shocks and need lesser energy.

Typically when 360 Joules are delivered for

monophasic defibrillator, 200 Joules are given in a

biphasic defibrillator. This could reduce the potential

damage to the heart muscle.

For pediatric patients, it is acceptable to use an

initial dose of 2 to 4 J/kg. not to exceed 10 J/kg or

the adult maximum dose

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Biphasic wave forms were initially

developed for use in implantable

cardioverter-defibrillator (ICD) and

later adapted to external

defibrillators.

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Electrode Placement :

Antero-apical position:one paddle is placed to the right of the sternum just below the clavicle. Another paddle is placed to the normal cardiac apex .Antero-posterior position:the anterior paddle placed over the apex, and the posterior paddle on the back in the left or right infrascapular region. Proper position of the paddles

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Procedure of Electrical defibrillation :

(1) perform CPR untill the equipment arrive.

(2) Assess the patient’s pulse and ECG.

(3) Seletion of proper energy level

(4) Apply electrode gel between paddles and skin

(5) Proper position of the paddles

(6) Clear the area. no contact with anyone otherthan the victim.

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Cont.

(7) Recheck the ECG

(8) Activate the firing button.

(9) If no skeletal muscle spasm has occurred ，you should check the equipment，contacts，and synchronizer switch.

(10) The rhythm should be assessed after each countershock and the patient should be checked for a pulse at appropriate time.

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Recommendation :

For defibrillation when using

biphasic defibrillators, self-

adhesive defibrillation pads

are safe and effective and

offer advantages (eg.

facilitating pacing, charging

during compressions, safety

[including removing risk of

fires]) over defibrillation

paddles

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Complication of defibrillation :

Skin burns(common)

Skeletal muscle injury or thoracic vertebral fractures (uncommon)

Myocadial injury and post-defibrillation dysrhythmias (high-energy shocks)

The rescuer can receive electrical injures (due to electrical contact with the patients during defibrillation )

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FAILURE OF DEFIBRILLATION :

If the attempt at defibrillation is unsuccessful:

Start CPR with oxygen.

Check paddle or electrode position.

Check that there is adequate skin contact. (Clipping or shaving of body hair under the defibrillator paddle/pad

may be required).

Consider changing the defibrillator pads.

If several shocks fail to stop VF , optimal chest

compression, oxygen , intermittent positive-pressure

ventilation and epinephrine should be given in this

sequence.17

Be carful :

AVOID charging the paddles unless they are placed on

the victim’s chest

AVOID placing the defibrillator paddles/pads over ECG electrodes (risk of burns or sparks) or an implanted device

(e.g. a pacemaker)

AVOID having, or allowing any person to have, any

direct or indirect contact with the victim during defibrillation

AVOID allowing oxygen from a resuscitator to flow onto

the victim’s chest during delivery of the shock when using

paddles (risk of fire).

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References :

Highlights of the 2010 American Heart Association

Guidelines for CPR and EC

2010 American Heart Association Guidelines for

Cardiopulmonary Resuscitation and Emergency

Cardiovascular Care

AUSTRALIAN RESUSCITATION COUNCIL

www.mayoclinic.org

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Thank you for listening

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