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Definition: Defibrillation is a process in which an electronic device sends an electric shock to the heart to stop an extremely rapid, irregular heartbeat, and restore the normal heart rhythm.

Defibrillationis a common treatment for life threatening cardiac dysrhythmias,ventricular fibrillation, and pulseless ventricular tachycardia.

Defibrillation is performed to correct life-threatening fibrillations of the heart, which could result in cardiac arrest. It should be performed immediately after identifying that the patient is experiencing a cardiac emergency, has no pulse, and is unresponsive.

Ventricular fibrillation is a serious cardiac emergency resulting from asynchronous contraction of the heart muscles.

Due to ventricular fibrillation, there is an irregular rapid heart rhythm.Fig. Ventricular fibrillation

Fig. Normal heart beat

Ventricular fibrillation can be converted into a more efficient rhythm by applying a high energy shock to the heart. This sudden surge across the heart causes all muscle fibres to contract simultaneously. The instrument for administering the shock is called a DEFIBRILLATOR. Possibly, the fibres may then respond to normal physiological pace making pulses.

Unconscious/decreased level of consciousness Collapse, falls Syncopal episodeChest painStroke/TIAShortness of breathSeizuresOverdoseElectrocutionDrowning/scuba diving incidentsHypothermia and heat related illnessUnknown

Internal defibrillatorElectrodes placed directly to the hearte.g..-PacemakerExternal defibrillator Electrodes placed directly on the heart e.g..-AED

InternalExternal

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Spoon shaped electrode Applied directly to the heart.

Paddle type electrode Applied against the chest wall

Pad type electrodeApplied directly on chest wall

fig: Electrodes used in defibrillator (a) a spoon shaped internal electrode that is applied directly to the heart. (b) a paddle type electrode applied against the anterior chest wall.

Fig.- Pad electrode

There are two general classes of waveforms:

Mono-phasic waveform

Energy delivered in one direction through the patients heart

Biphasic waveform

Energy delivered in both direction through the patients heart

Monophasic pulse or waveformBi-phasic pulse or waveform

Fig:- Generation of bi-phasic waveform

The biphasic waveform is preferred over monophasic waveform to defibrillate.

A monophasic type, give a high-energy shock, up to 360 to 400 joules due to which increased cardiac injury and in burns the chest around the shock pad sites.

A biphasic type, give two sequential lower- energy shocks of 120 - 200 joules, with each shock moving in an opposite polarity between the pads.

AED is a type of external defibrillation process. AED is a portable electronic device that auto- matically diagnoses the ventricular fibrillation in a patient.Automatic refers to the ability to autonomously analyse the patient's condition.

AEDs require self-adhesive electrodes instead of hand held paddles. The AED uses voice prompts, lights and text messages to tell the rescuer what steps have to take next.

Fibrillations cause the heart to stop pumping blood, leading to brain damage.Defibrillators deliver a brief electric shock to the heart, which enables the heart's natural pacemaker to regain control and establish a normal heart rhythm.

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Check for consciousness/responsiveness.Access ABCs. If not breathing, open airway & begin ventilations.Check pulse. If pulse not present, initiate CPR.

After help is called for, cardiopulmonary resuscitation (CPR) is begun and continued until the caregivers arrive and set up the defibrillator. Electrocardiogram leads are attached to the patient's chest. Gel or paste is applied to the defibrillator paddles, or two gel pads are placed on the patient's chest. *

Pad placement critical for effective delivery of biphasic shock. Key is to minimize impedance from bone (clavicle, sternum, ribs) and allow maximum energy delivery to heart. Defib tech must be able to place pads without interfering with CPR.

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When using an AED, follow these precautions:Do not touch the victim while the AED is analyzing.Do not touch the victim while defibrillating. Do not use alcohol to wipe the victims chest dry.Do not defibrillate someone around flammable materials.Do not use an AED in a moving vehicle.Do not use an AED on a victim in contact with water.

Do not use an AED on a victim wearing a nitroglycerin patch or other patch on the chest.Do not use a mobile phone or conduct radio transmission within 6 feet of the AED.Do not place the pads directly over a pacemaker or other implanted device.Before the paddle is used, a gel must be applied to the patient's skinDo not use an AED and/or electrode pads designed for adult victims a child under age 8 or weighing less than 55 pounds unless pediatric pads specific to the device are not available.

shockable rhythm of VF/pulseless VT and deliver command to deliver shockORnon-shockable rhythm and deliver command to resume CPR

Ventricular FibrillationVentricular Tachycardia

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Clear patient from head to toe (SAFETY!)Deliver single shockImmediately begin CPR and continue for 2 minutes.Do not delay CPR for pulse check or post-shock rhythm analysis.

After 2 minutes of CPR, analyze rhythm (stop CPR)No pulse check requiredIf shock is indicated, clear patient, and deliver 2nd shock.Continue uninterrupted CPR for 2 minutes

After 2 minutes of CPR, analyze rhythm (stop CPR)No pulse check requiredIf shock is indicated, clear patient, and deliver 3rd shock.Continue uninterrupted CPR for 2 minutes.

After 2 minutes of CPR, analyze rhythm (stop CPR)No pulse check requiredIf shock is indicated, clear patient, and deliver shock.Continue uninterrupted CPR for 2 minutes.Continue process until Medic arrival

Immediately begin CPRContinue uninterrupted CPR for 2 minutesDo not delay CPR for pulse check

After 2 minutes of CPR, analyze rhythm (stop CPR)Do not check pulse before analyzing rhythmIf No Shock is advised, check pulse.No pulse, continue uninterrupted CPR for 2 minutes

If pulse is present after pulse check, obtain patients blood pressure, check airway to ensure it is clear, and assess breathing for adequate breathing.Assist ventilations if inadequate.If blood pressure < 60 mmHg systolic, perform uninterrupted CPR for 2 minutes

After 2 minutes of CPR, analyze patient (stop CPR)Do not check pulse before analyzing rhythmIf No Shock advised, check pulse.If no pulse, continue uninterrupted CPR for 2 minutesAfter 3rd No Shock, continue CPR without analyzing patient

*Place the AED opposite side of the CPR rescuer.Open the lid and follow the instructions.Remove clothing if not already done.Attach pads as shown on the AED.Clear the victim.

Allow the machine to analyze.Make sure the everyone is clear.The machine will deliver a shock. Start 30 to 2 cycles of compressions and breaths. Perform 5 cycles and continue until the victim wakes up or EMS directs you to stop.

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Ventricular Fibrillation (VF)Defibrillation (electrical shock) is the primary solution (cannot be used in other lethal heart rhythms)

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The patient's cardiac status, breathing, and vital signs are monitored until he or she is stable. An electrocardiogram and chest x ray are taken. The patient's skin is cleansed to remove gel or paste, and, if necessary, ointment is applied to burns. An intravenous line provides additional medication, as needed.

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Complete the chart. documentation should include:

time of arrest, witnessed/unwitnessed arrestduration of CPR,Defibrillation : number of shocks delivered in joules.Shockable rhythms : VT,VFphysical findings, treatments, patient response to treatments, vital signs,treatmentallergies) and detailed documentation of times (call time, arrival, departure, ER arrival).

Skin burns from the defibrillator paddles are the most common complication of defibrillation.

Other risks include injury to the heart muscle, abnormal heart rhythms, and blood clots.

Attach the external and internal paddles if the monitor reads, "No paddles."

Check to ensure that the leads are securely attached if the monitor reads, "No leads.

Connect the unit to AC power if the message reads, "Low battery."

Verify that the Energy Select control settings are correct if the defibrillator does not charge.

Change the electrodes and make sure that the electrodes adapter cable is properly connected if you receive a message of "PACER FAILURE." Restart the pacer.

Close the recorder door and the paper roll if the monitor message reads, "Check recorder.

What are the correct locations to place the AED pads?

Answer:Right of sternum just below clavicle and 5th to 6th ICS left anterior axillary line

Willis A Tacker, External Defibrillators, in The Biomedical Engineering Handbook, J. Bronzino (ed) CRC Press, 1995. www.google.com en.wikipedia.org/wiki/Defibrillationhttp://www.slideworld.org/viewslides.aspx/defibrillator

**********Goal is to initiate quality, uninterrupted CPR and initiated defib procedures to deliver a shock to these shockable rhythms.************