Electro surgical unit q PURPOSE ESU are used

Electro surgical unit

q 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

q 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

q Effect of RF on cell • When a high frequency current applied to the tissues gets turn apart and get the following effect: 1. Thermal effect. 2. Electrolytic effect. 3. Faradic effect.

q Operating frequency and typical value • Operating frequency of solid state surgical diathermy machine is 300 KHz –to-3 MHz • 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

q Types of ESU Ø 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.

Ø 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.

Ø 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 ?

q Modes of Electro surgery Monopolar surgery Bipolar surgery

q Modes • • of electrosurgery Electrotomy/cutting desiccation / coagulation Blend fulgurations

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