1. Electro surgical unit

2. 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

3. 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.

4. System Components Electrosurgery Unit Dispersive Electrode
Active Electrode

5. Body ..\ESU Principle.ppt Active electrode Patient electrode RF
Generator
Body
Patient
electrode
..\ESU Principle.ppt

7. Effect of RF on cell
When a high frequency current applied to the tissues the tissues gets turn apart and get the following effect:
Thermal effect.
Electrolytic effect.
Faradic effect.

8. Operating frequency and typical value
Operating frequency of solid state surgical diathermy machine is KHz –to-3MHz
Monopolar :CUT “0-to-350”watts for load COAG”0-to-100” watts
Bipolar : CUT “0-to-50” watts
COAG “0-to-10” watts

9. 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.

10. 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.

11. Solid state device
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.

12. control so accurately the temperatures in the
OK!, but how can I
control so accurately the temperatures in the
tissues ?

13. Modes of Electro surgery
Monopolar surgery
Bipolar surgery

14. Modes of electrosurgery
Electrotomy/cutting
desiccation / coagulation
Blend
fulgurations

15. General Block Diagram RF output Audio tone generator Power supply
Logic/
Control
Board
Rely
board
Main
CPU
Front panel
Isolation
transformer
LED display
Power O/P or
RF board
Foot
switch
Patient return
electrode
RF output