Electro surgical unit
 PURPOSE
•ESU are used for surgical cutting and for controlling
bleeding by causing coagulation “hemostasis” at the
surgical site.
•It is “high frequency diathermy” involves the
transference of electrical energy into heat which ,when
impact to the bodily tissues, will heat the normal cell
fluid, eventually through it is boiling point.
•What dose “DIATHERMY” mean?
DIA = through
THERMO = temperature heat
 Principle
• ESU machine is an alternating current source that
operates at radio frequency “RF”.
• A high frequency current flowing through active electrode
“high current concentration”.
• Cell ruptured-fumes or evaporates.
• Return path through dispersive electrode “low current and
heat dissipates”.
• Patient is included in circuit.
• Current concentration or density depends on the size of
the area through which the current flows.
• HF generation can be activated by a foot switch or finger
switch on the surgical handle.
System
Components
Electrosurgery
Unit
Dispersive Electrode
Active Electrode
Active
electrode
RF
Generator
Body
Patient
electrode
..\ESU Principle.ppt
 Effect of RF on cell
•
When a high frequency current applied to
the tissues the tissues gets turn apart and
get the following effect:
1. Thermal effect.
2. Electrolytic effect.
3. Faradic effect.
 Operating frequency and typical
value
• Operating frequency of solid state surgical
diathermy machine is 300 KHz –to-3MHz
• Monopolar :CUT “0-to-350”watts for load 5
COAG”0-to-100” watts
• Bipolar : CUT “0-to-50” watts
COAG “0-to-10” watts
 Types of ESU
Spark gap generator – 1924
• Still in use today “urology , open- heart surgery”.
• Spark gap / vacuum-tube device use spark –gap
circuits to generate high frequency waveforms.
• It is not offer the same safety feature as solid
state unites.
 Recent technology
• Argon/argon enhanced technology.
• It uses a computer-controlled tissue feedback
system that senses tissue impedance and
automatically adjusts the current and output
voltage to maintain a constant surgical effect .
• It is reduces the need to adjust power setting for
different types of tissue.
• It is also gives improved performance at low
power setting to reduce the risk of patient injury.
 Solid state device - 1968
• It is more recent and more prevalently used
technology.
• Contain oscillator circuits and transistor-based
amplifier that vary the frequency and modify the
shape of the line signal to create an array of
different waveforms for pure CUT,COAG,
BLEEND .
• Highly safety.
OK!, but how can I
control so accurately the
temperatures in the
tissues ?
 Modes of Electro surgery
Monopolar surgery
Bipolar surgery
 Modes
•
•
•
•
of electrosurgery
Electrotomy/cutting
desiccation / coagulation
Blend
fulgurations
General Block Diagram
Audio tone
generator
Front panel
Main
CPU
LED display
Logic/
Control
Board
Rely
board
Power
supply
Isolation
transformer
Power O/P or
RF board
Foot
switch
Patient return
electrode
RF output