DEFIBRILLATOR MACHINE BAsic TECHNICAL

TRAINING

By: Armando Darino Ngojo Senior Biomedical Engr.

ContentsAims & ObjectivesIntroductionPrincipleAnatomy and PhysiologyApplicationTypesOperationSafetyMaintenanceTroubleshootingPPM NGOJO

Aims

To provide basic understanding about the Defibrillator Machine

To perform and understand the basic technical troubleshooting steps and PPM tasks

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Objectives

- as a result of completing this module, the biomedical technician / engineer should be able to:

understand the concept of the Defibrillator including its applications

perform and identify basic problems, errors and basic troubleshooting solutions.

Perform PPM tasks

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History1899 Prevost and Batelli first introduced the concept of electrical

fibrillation after  noticing that large voltages applied across the animal's heart could convert  ventricular fibrillation into a sinus rhythm.

1933

1950s

1956

Hooker, Kouwenhoven and Langworthy published an account of successful  alternating current (AC) internal animal defibrillation

Kouwenhoven was able to defibrillate dogs by applying the electrodes to  the chest wall, that was the external electric defibrillator.

Zoll defibrillated a human subject in the same manner .

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History

1960s

1970s

Edmark and Lown et al found that direct current (DC) or pulse defibrillators  were more effective and produced fewer side effects than AC defibrillator.  The DC pulse waveform was further improved.

Experimental internal and external devices were designed to automatically  detect ventricular fibrillation.

1980s

Present times

The first automatic internal defibrillator was implanted in human

A lot of improvements were introduced to the defibrillator with the aim of improving the survival rate of the cardiac arrested patient

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What is Defibrillator

- A device that reverses the Fibrillation of the heart. Fibrillation causes the heart to stop

pumping blood, leading to brain damage.

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Defibrillation

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.

It is a common treatment for life threatening cardiac dysrhythmia, ventricular fibrillation, and pulse less ventricular tachycardia.

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Principle

A high voltage electric current is applied to the Heart muscle either directly (Internal Defibrillator) through the open chest or indirectly (External Defibrillator) through the chest wall to terminate Ventricular Fibrillation.

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Physiology of Defibrillation

If enough current is delivered to the heart then a majority of Ventricular cells will be depolarized

A critical mass of cells should be simultaneously depolarized to achieve defibrillation

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Bio Electric Signal

Polarization Potassium ions pumped in Sodium ions pumped outDepolarization Potassium ions pumped out Sodium ions pumped in Repolarization Potassium ions pumped in Sodium ions pumped out

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Anatomy - HeartLocated between the lungs in the middle of chest, behind and slightly to the left of breastbone (sternum)

Size of ones fist and shaped like a cone.An average heart pumps 2.4 ounces (70 milliliters) per heartbeat. An average heartbeat is 72 beats per minute. Therefore an average heart pumps 1.3 gallons (5 Liters) per minute.

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Cont…

Heart is divided into four chambers

Right AtriumLeft AtriumRight VentricleLeft Ventricle

A wall of muscle called as a 'Septum', separates all chambers of heart.

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ECG tracingElectrical pattern

Normal Cardiac Conduction

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Normal ECG tracing

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whenABNORMALITIEShappen….

1. Ventricular Fibrillation

Ventricular Fibrillation is a very fast, irregular heart rhythm in the lower heart chambers (ventricles). During VF the heart quivers and pumps little or no blood to the body. Consciousness is lost in seconds. If not treated immediately, VF will cause sudden cardiac arrest

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Occlusion of the coronary artery leads to ischemia.

Ischemia leads to infarct which causes interruption of normal cardiac conduction

Infarct = VF/VT

Cardiac Arrest

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Ventricular Fibrillation Ventricular Tachycardia

SAMPLE SHOCKABLE RHYTHMS

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2. Atrial Fibrillation

Atrial Fibrillation is a very fast, irregular heart rhythm in the upper heart chambers. During AF, the waveform is almost similar to normal waveform but for the loss of 'P' waveform.

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AF treatment:

For Atrial fibrillation, the shock should be avoided to be delivered in the T period otherwise it will lead to Ventricular Fibrillation

This is achieved by Synchronous mode

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ApplicationEmergency department

Anesthesiology

Cardiology

Operation theatre

Intensive care areas

Ambulance services NGOJO

Types:

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1. Manual

Clinical expertise is needed to interpret the heart rhythm and decide whether to charge the defibrillator and deliver the shock to patient. Energy selection and delivery is given to the patient manually.

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2. Automatic

These defibrillators are small, safe, simple and lightweight with two pads that can be applied to the patient. The defibrillator guides the operator step-by-step through a programmed protocol. It records and analyses the rhythm and instructs the user to deliver the shock using clear voice prompts, reinforced by displayed messages.

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3. External

External Defibrillator is the device which delivers the high energy shock to patients Heart externally on patient's chest by using a Defibrillator Paddle. The maximum energy deliver to the patient is about 360 Joules in Monophasic & 200 Joules in Biphasic Defibrillator.

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4. Internal

Internal defibrillator consist of sterilized internal Handle/Paddle through which shock is delivered directly to the heart.

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5. AED Automatic External DefibrillatorAED can be classified as either fully automatic or semiautomatic. In fully automatic models disposable paddles are kept connected to the patient whilst the AED analyzes the ECG rhythm , decides and determines whether a defibrillation counter-shock is needed. Then the device automatically charges and discharges.

Semi Automatic AED analyze the patient's ECG and notify the operator when defibrillation is indicated. The operator then activates defibrillator and discharge.

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AED

Semi Automatic Fully Automatic

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6. ICD

Implantable Cardioverter Defibrillator

If it detects an abnormally fast heart rhythm, it either electrically paces the heart very fast or delivers a small electrical shock to the heart to convert the heart rhythm back to normal. The rapid pacing is not felt by the patient but the electrical shock, if used, is felt as a strong jolt in the chest. The ICD is used to treat life-threatening heart rhythms that lead to sudden death.

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ICD

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7. Pacemaker

A pacemaker is an electronic stimulator that produces periodic electric stimulation to the heart It is classified into two types: Internal Pacemaker External Pacemaker

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Internal Pacemaker

Battery operated device that is implanted inside the patient’s body to pace the Heart

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External Pacemaker

This is used to pace the heart temporally. It may use leads or electrodes for the stimulation

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What is Joule?

It is the unit of energy delivered by the Defibrillator

It means - “The energy released in one second by a current of one ampere through a resistance of one ohm”

Also called as watt-second

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– intrinsic characteristics of patient – patient’s disease – duration of arrhythmia – patient’s age – type of arrhythmia (more energy required for

VF)– type of the machine used

- The delivered energy is in the range of 50-360 joules and depends on:

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Operating Principle

Monophasic Defibrillator

Bi- Phasic Defibrillator

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Monophasic DefibrillatorDelivers its current in one forward direction (positive)

Requires higher escalating energy levels (200-300J) to convert VF/ pulse-less VT

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Bi Phasic Defibrillator

The Biphasic waveform type defibrillator delivers the current in one direction during the first phase and in opposite direction during the second phase.

Biphasic waveform shocks of 200 J are safe, equivalent or higher efficiency than damped sinusoidal waveform shocks of 360 J.

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Generation of bi-phasic waveform

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Waveform Comparison

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Operation

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Defibrillator: Normal and Synchronous Mode Monitor

Recorder

Pacemaker

NIBP

SPO2

CO2

1. Manual Defibrillation

Switch 'ON' the Machine

Wait for initialisation and self test

Make sure it is not in SYNC Mode

Apply gel to the paddles

Place them properly on the chestNGOJO

Cont…

Select 'ENERGY' to be delivered( energy in Joules)

Press 'CHARGE' button

Wait for Charging to complete. This is usually denoted by a continuous /long beep sound.

Apply pressure to the paddles ( 12 Kg of pressure)

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Cont…

Make sure all the personnel are away from the patientPress both 'DISCHARGE' button simultaneouslyObserve patient and monitor ECGIf required, defibrillate againWhen finished, turn off and clean the paddles

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2. Synchronization Mode

Wait for initialization and self test.

Connect ECG leads to get a tall R wave

Select 'SYNC / CARDIOVERSION' mode..

Check for sync marker on the QRS waveform.

If possible sedate the patient and maintain airway

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Cont…

Apply gel on the paddles and place it properly on chestSelect 'ENERGY' to be delivered( energy in Joules)Press 'CHARGE' buttonWait for the Charge to be completed. This is usually denoted by a continuous /long beep sound.Press both 'DISCHARGE' button simultaneously and hold till energy is delivered.

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Cont…

Check patient condition and Heart rhythm.

If required, defibrillate again.

Monitor the patient for few hours.

Switch off and clean the paddles

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3. Internal Defibrillation

Connect the Internal Paddles to the machine

Place one paddle over the apex of the left ventricles and the other over the base of the right ventricles

Switch on the machine Select Energy Charge and Discharge

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What are the types of Paddles?

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Paddle Placement

There are two notable methods of paddle placement recommended by AHA

Anterior- Anterior

Anterior-Posterior

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Paddle PlacementAnterior- Anterior Place one paddle near

the second or the third right sternal border and the other on the cardiac apex.

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Paddle Placement

Anterior-Posterior - One paddle on sternum and the other on the left infra-scapular region

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Important Factors: 1.TimeEarly defibrillation allows more success or the longer period of VF, the less success of defibrillation.

Early initiation of CPR improves the success rate> 8 mins neurological damage sets in> 10 mins survival probability becomes very low

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2. Energy Level

AHA Recommendation for Adults

First shock 200 jSecond shock 200 j to 300 j Third and above shocks 360 j

AHA Recommendation For PaedsFirst shock 2 joules per KgSubsequent shock double the energy

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3. Paddle Size

Adult paddles should be 8 to 13 cm in diameterChild paddles should be 4.5 cm in diameterInfants use Anterior Posterior position

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4. Skin To Paddle Interface

Use the right gel

Too little gel increases possibility of burn

Too much gel causes electric current to arc from one electrode to another

If disposable paddles are used check the expire date

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Block Diagram of a typical Defibrillator machine

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Power Supply

Step up transformers used to convert 240 VAC to 5000 VAC

This is converted to DC by rectifierIn battery mode the DC is converted to AC by inverter

This AC is amplified and then again rectified to DC.

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Capacitor Most important part of Defibrillator

Stores large energy which can be discharged in a short burst

Unit of measurement is Farad

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Inductor

Coils of wire that produce a magnetic field when current flow through them

Used to prolong the duration of current flow Unit of measurement is Henry

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Safety

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Safety - General

The Defibrillator generates High voltage. It must be operated by trained, professional and qualified personnel only.

Never use defibrillator with improper grounding or electrical leak socket.

Keep away the Defibrillator from any x-ray, Ultrasonic or other electronic instruments.

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Cont…

Check the patient lead wire, cable and paddles for any damage or mishandling, otherwise replace the same immediately.

Recommend using proper size and placement of recording paper.

Clean the print head regularly for clear printout

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Safety - Monitoring

Use only the specified patient cable as recommended by manufacturer.

Place the patient cable in proper winding position or hang on to patient cable arm attached with Defibrillator trolley

Use good ECG electrodes to monitor ECG waveform.

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Cont…

Don't use damaged patient cable.

Confirm there is no ECG waveform because of electrical interference or defective patient cable. This may misinterpreted as QRS in synchronize mode.

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Safety - Defibrillation

Excessive Gels can cause arcing of the current along the chest wall

Malfunction of permanent pacemakers can result from placing defibrillator pads or paddles near the pacemaker

Defibrillation in the absence of an ECG rhythm (ie, 'blind defibrillation') to be avoided

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Cont…

A shock can be accidentally delivered to other rescuersThe initial three shocks should be delivered in sequence, without interruption for CPR, medication administration, or pulse checks.If transthoracic impedance is high, a low energy shock (< 100 J) may fail to generate enough current to achieve successful defibrillation.

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Cont…

Alcohol should never be used as conducting material for paddles because serious burns can result.

Never discharge the Defibrillator in Air to check its performance

Never discharge with paddles shorted

Always clean the paddles after useNGOJO

Maintenance - Cleaning

For Exterior surface of defibrillator and battery /battery well or compartment Isopropyl alcohol(70% in water) Mild soap and water Chlorine bleach (3% in water) While cleaning take care that solution should not go inside the defibrillator. Use soft cloth for cleaning display, to prevent scratching.

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Maintenance - Cleaning

For Paddles, pads, Electrodes & cables

Disposable pads & monitoring Electrodes do not require cleaning.The paddles, paddle cable and patient cable, may cleaned withAlcohol free hand soap Chlorine bleach solution 10%in water Isopropyl Alcohol

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Maintenance - Cleaning

Internal Paddles / Cables

Internal Paddle Handle/ Cable / Electrodes can be cleaned ultrasonically, autoclave or steam sterilized but follow the manufacturer's instruction for sterilization procedure

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The paddles used in the procedure should not be placed:-

• on a woman's breasts • over an internal pacemaker patients.

Before the paddle is used, a gel must be applied to the patient's skin

PRECAUTIONS

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• 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.

RISKS IN DEFIBRILLATION

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• 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.

TROUBLESHOOTING

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• 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”.

TROUBLESHOOTING

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PPM (Planned Preventive Maintenance)

Qualitative Task

PPM Task

Quantitative Task

Electrical Safety Test

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Test tool: Defibrillator Analyzer

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Defibrillator Analyzer

Basic Functions

Measures output energy Measures cardioversion delay time Measures output of pacemakers Simulates range of ECG waveforms Provides clinical training

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Practical Training and

Assessment

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Questions!!!

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THANK

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