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

Body ..\ESU Principle.ppt Active electrode Patient 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: Thermal effect. Electrolytic effect. 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.

control so accurately the temperatures in the 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 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