DEFIBRILLATOR MACHINE BAsic TECHNICAL TRAINING

By: Armando Darino Ngojo

Senior Biomedical Engr.

Contents

Aims & Objectives

Introduction

Principle

Anatomy and Physiology

Application

Types

Operation

Safety

Maintenance

Troubleshooting

PPM

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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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History

1899 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 out

Depolarization

Potassium ions pumped out

Sodium ions pumped in

Repolarization

Potassium ions pumped in

Sodium ions pumped out NGOJO

Anatomy - Heart

Located 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 Atrium

Left Atrium

Right Ventricle

Left 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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Application

Emergency 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 Defibrillator

AED 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 Defibrillator

Delivers 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

patient

Press both 'DISCHARGE' button simultaneously

Observe patient and monitor ECG

If required, defibrillate again

When 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 chest

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

Press 'CHARGE' button

Wait 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 Placement

Anterior- 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.Time

Early 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 j

Second shock 200 j to 300 j

Third and above shocks 360 j

AHA Recommendation For Paeds

First shock 2 joules per Kg

Subsequent shock double the energy

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3. Paddle Size

Adult paddles should be 8 to 13 cm in

diameter

Child paddles should be 4.5 cm in

diameter

Infants 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 rectifier

In battery mode the DC is converted to AC

by inverter

This AC is amplified and then again rectified

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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 NGOJO

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

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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 rescuers

The 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 with

Alcohol 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.

TROUBLESHOOTIN

G

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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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THA

NK

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