2. 2
DEFIBRILLATOR
™Defibrillator is a device that
deliver a therapeutic dose of
electrical energy to the affected
heart to force the heart to produce
more normal cardiac rhythm .
3. TO THE PAST……
• In 1899 Prevost and Batelli first introduced
the concept of electrical fibrillation
• In 1933 Hooker, Kouwenhoven and
Langworthy published an account of
successful alternating current (AC)
internal animal defibrillation
• 1950 -Kouwenhoven was able to
defibrillate dogs by applying the
electrodes to the chest wall.
• In 1956 Zoll defibrillated a human subject
in the same manner.
4. CONTD….
In1960s Edmark and Lown et al found
that direct current (DC) or pulse
defibrillators were more effective, the
DC pulse waveform was further
improved.
1970s -Experimental internal and
external devices were designed to
automatically detect ventricular
fibrillation.
1980s -The first automatic internal
5. HEART
Located between the
lungs in the middle of
chest.
An average heart pumps
2.4 ounces (70 millilitres)
per heartbeat.
An average heartbeat is
72 beats per minute.
Therefore an average
heart pumps 1.3 gallons
(5 Litres) per minute.
6. Contd….
Heart is divided into 4 chambers.
»Right Atria
»Left Atria
»Right Ventricle
»Left Ventricle
7. IMPULSE CONDUCTION & THE ECG
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
8. FIBRILLATION
• ‘ Fibrillate ’ means contract very fast
and irregularly.
Chaotic
Quivering
but
NO Heartbeat
NO Breathing
9. VENTRICULAR FIBRILLATION
Ventricular fibrillation results from
Coronary occlusion
Electrical shock
Abnormalities of body chemistry
The fibrillating EGG is
characterized by a lack of QRS
complexes .
10. ATRIAL FIBRILLATION
• Atrial fibrillation is a very fast , irregular
heart rhythm in the upper heart
chambers.
• Similar to normal waveform .
• Loss of ‘P’ waveform
11. DEFIBRILLATION
• Process in which a device sends an
electric shock to the heart to stop an
extremely rapid, irregular heartbeat,
and restore the normal heart rhythm.
13. PRINCIPLE
Energy storage capacitor is charged at
relatively slow rate from AC line.
Energy stored in capacitor is then
delivered at a relatively rapid rate to
chest of the patient.
Simple arrangement involve the
discharge of capacitor energy.
14. ENERGY CALCULATIONS
The amount of energy ,WA in units
of Joule is given by,
C = Capacitance in Farads
V = Voltage across the capacitor
The amount of energy typically
stored in the capacitor of a
defibrillator, ranges from 50 to 400
Joule.
2
2
V
CWA
18. WHAT IS JOULE?
• It is the unit of energy.
• “The energy released in one second by
a current of one ampere through a
resistance of one ohm”
• Also called as watt-second.
• The delivered energy is in the range of
50- 360 joule
28. BIPHASIC DEFIBRILLATORS
• 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
30. MANUAL DEFIBRILLATORS
Clinical expertise is
needed to
Interpret the heart
rhythm.
To decide whether to
charge the defibrillator
and deliver the shock to
the patient
Energy selection and
delivery is given to the
patient manually.
31. AUTOMATIC DEFIBRILLATORS
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.
Small, simple, safe and light
weight .
32. EXTERNAL DEFIBRILLATORS
Delivers the high energy
shock to patients.
Applies externally on
patient's chest by using a
Defibrillator Paddle.
The maximum energy
deliver to the patient is
about 360 Joule in
Monophasic & 200 Joules
in Biphasic Defibrillator.
35. Fully automatic models
• AED analyzes the ECG rhythm , decides and
determines whether a defibrillation counter-
shock is needed.
• The device automatically charges and
discharges.
Semi Automatic AED
User does not require special medical
training.
Used in public places – offices, airport,
shopping mall.
AED (CONTD…)
36. AED (CONTD…)
The electrodes transmit information about
the person's heart rhythm to a controller
in the AED.
The controller examines the electrical
output from the heart and determine if
the patient is in a shockable rhythm or
not and whether shock is needed.
The AED uses voice / visual prompts to
tell user.
39. . 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 minutes neurological damage sets
in
>10 mins survival probability becomes
very low
40. Contd..
• 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 paediatrics
First shock 2 joules per Kg
41. Contd..
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.
42. Contd..
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
43. PROCEDURE
Steps- Manual Defibrillator
Switch 'ON' the Machine
Wait for initialisation and self test
Apply gel to the paddles
Place them properly on the chest .
Select 'ENERGY' to be delivered
( energy in Joule) .
Press 'CHARGE' button
Wait for Charging to complete.
44. Contd..
This is usually denoted by a continuous
/long beep sound.
Apply pressure to the paddles ( 12 Kg of
pressure) .
Press both 'DISCHARGE' button
simultaneously .
Observe patient and monitor ECG
If required, defibrillate again .
When finished, turn off and clean the
paddles.
45. SPECIFICATION
Charging time maximum 5 sec for
200J.
Momentary energy selection
access on front panel.
Should have adult and pediatric
paddles integrated on same handle.
Momentary charge key on front
panel and on the apex hand.
46. Contd…
Should have battery back up for 50
discharges of 200J.
Should have ECG inputs through
paddles or 3 lead cables.
Should have display for heart rate.
Should have alarm for high and
low HR.
47. Contd…
Should supply internal
defibrillation paddle, 2 bottle of
jelly, 12 roll of thermal paper.
Should operate on mains 230V,
50Hz
It should have
national/international standards for
safety/quality.
48. SAFETY PRECAUTIONS DURING
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 ('blind defibrillation') to
be avoided.
49. 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
50. • “Don’t call the world dirty because you forgot
to clean your glasses”
Editor's Notes
In Switzerland, 1899, Prevost and Batelli discovered that small electric shocks could induce
ventricular fibrillation in dogs and that larger charges would reverse the condition.
after noticing that large voltages applied across the animal's heart could convert ventricular fibrillation into a sinus rhythm.
1950-after noticing that large voltages applied across the animal's heart could convert ventricular fibrillation into a sinus rhythm.
A lot of improvements were introduced to the defibrillator with the aim of improving the survival rate of the cardiac arrested patient .
1960s Edmark and Lown et al found that direct current (DC) or pulse defibrillators were more effective and produced fewer side effects than AC defibrillator.
, behind and slightly to the left of breastbone (sternum)
This irregular contraction of the muscle fibers causes non effectively blood pumping and that results in a steep fall of cardiac output.
That is, the capacitor stores energy, WA, which develops a voltage, V, across its metal plates.
The amount of energy in units of joules is given by
where C is the value of the capacitance measured in units of farads and V is the voltage across the capacitor.
The energy stored in the capacitor is proportional to the square of the voltage between its plates.
The amount of energy typically stored in the capacitor of a defibrillator, so that it can be later delivered to the patient, ranges from 50 to 400 joules.
All of this energy does not get into the patient.
Some is lost in the internal resistance of the defibrillator circuit, RD and some is wasted in the paddle—skin resistance, RE .
Therefore, the current in each of them is the same.
And the energy absorbed by any one resistor is proportional to the total available energy, according to the voltage division principle.
The formula for the energy absorbed by the thorax, WT is
It is the unit of energy delivered by the Defibrillator
“The energy released in one second by a current of one ampere through a resistance of one ohm”
Also called as watt-second NGOJO
The delivered energy is in the range of 50- 360 joules and depends on: – 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
2 types :-
The Monophasic damped sinusoidal waveform (MDS) returns to zero gradually
Monophasic truncated exponential waveform (MTE) current is abruptly returned to baseline (truncated) to zero current flow
It records and analyses the rhythm and instructs the user to deliver the shock using clear voice prompts, reinforced by displayed messages.
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
Analyze the patient's ECG and notify the operator.
The operator then activates defibrillator and discharge
. If a self-inflating bag with oxygen attached is connected to a tracheal tube it is not necessary to disconnect it
