Surgical Diathermy Machine What do you mean by Electrosurgery? What is Surgical Diathermy Machine? Explain Monopolar Electrosurgery Technique with block diagram. Where it is used? Explain Bipolar Electrosurgery Technique with block diagram. Where it is used? Explain Active and Passive electrodes of ESU. Describe different effects on body tissue during Electrosurgery.

Electrosurgery Electrosurgery is a simple method of making surgical incisions, controlling bleeding and destroying unwanted tissue cells by the use of a high frequency “electrosurgical current”. Its benefits include the ability to make precise cuts with limited blood loss. Electrosurgical devices (Surgical Diathermy Machine) are frequently used during surgical operations helping to prevent blood loss in hospital operating rooms or in outpatient procedures.

Surgical Diathermy Machine It is a dedicated medical therapeutic equipment used by surgical departmental doctors for the purpose of cut, coagulate, desiccate, or fulgurate tissue. Two modes are used as desired by Doctors- (i) Monopolar (ii) Bipolar

Block Diagram of Surgical Diathermy 4

Electro -Surgery Techniques Mono-polar technique Bi-polar technique 5

Monopolar electro surgery Monopolar electro surgery is the admittance of the HFAC from the diathermy machine via an active electrode through the patient body tissues and then returned back to the diathermy machine via a dispersive electrode (patient return pad) 6

Mono-polar technique 7

Some Basics of Monopolar Surgery Diathermy currents (HFAC) may be generated by transistor circuits and may include a range of protection. The frequencies used are typically in the range 0.5 to 3 MHz. Most versions have power output up to a few hundred watts. Higher power necessary for urology applications where the surgery often takes place under water (in the bladder). Low power versions exist, sometimes called hyphenators, for excision of warts, polyps, and skin flaps.

Bipolar electro surgery Bipolar electro surgery is the admittance of the HFAC from the diathermy machine down one prong of a bipolar forceps through the tissue that has been placed between the forceps tips and returned to the diathermy machine via the second prong. Bipolar diathermy does not require a dispersive electrode (patient return pad). 9

Bi-polar technique 10

Some Basics of Bipolar Surgery Diathermy currents may be generated by valve or transistor circuits and may include a range of protection and monitoring systems. The frequencies used are typically in the range 0.5 to 3 MHz. Bipolar systems are available in which the heating currents only flow between the two tips of special forceps. Bipolar systems are useful for fine work and when the patient has a pacemaker which might malfunction in the presence of the very large circulating high- frequency current.

Electro-Surgery Unit (ESU) An ESU consists of basically a high frequency power oscillator: Spark-gap oscillator: Generates damped high frequency current which is specifically suitable for the coagulation of all kinds of tissues. Solid-state oscillator: Generates un-damped high frequency current which is suitable for making clean cutting. 12

Solid-State ESU The heart of solid-state ESU is the logic and control part which produce the basic signal and provides various timing signals for the cutting, coagulation and haemostatic modes of operation. In the cutting it delivers 400 W in 500 Ω load at 2000V. In the coagulation it delivers 150W. The output circuit in ESU is generally isolated and carefully insulated from low frequency primary and secondary voltage by means of capacitors. 13

ESU Electrodes 14

Types of ESU Electrodes Active Electrode Passive Electrode 15

Active Electrodes Electrodes are connected to the RF power generator. Switching on the high frequency current can be done with a finger-tip switch in the electrode or a foot switch. Small size (thickness in mm (1mm) and wideness till 10 mm). 16

Active electrode for coagulation 17

Active Electrode Resistance The amount of power delivered to the tissue for a given ESU voltage depends on the active electrode-to- skin resistance RE. RI: Internal resistance of active electrode RE: active electrode-to-skin resistance RB: Body resistance RR: Return electrode resistance 18

Passive (Neutral, Return) Electrode The function of the patient return electrode is to remove current from the patient safely. A return electrode burn occurs when the heat produced, over time, is not safely dissipated by the size or conductivity of the patient return electrode. Two points are of practical importance: (i) Sufficiently large contact area. (ii) High electrical conductivity between the body and electrode. 19

Passive (Neutral, Return) Electrode 20

Effects on Body Tissue Cutting Coagulation Fulguration Desiccation 21

Cutting Cutting/Vaporization: High current concentration at active electrode causes intense heat in tissue (above 100c). Cutting is the separation of a physical object, or a portion of a physical object, into two or more portions, through the application of an acutely directed force. Implements commonly used for cutting are the knife and saw, or in medicine and science the scalpel and microtome. However, any sufficiently sharp object is capable of cutting if it has a hardness sufficiently larger than the object being cut, and if it is applied with sufficient force. Even liquids can be used to cut things when applied with sufficient force (see water jet cutter). Cutting is a compressive and shearing phenomenon, and occurs only when the total stress generated by the cutting implement exceeds the ultimate strength of the material of the object being cut. The simplest applicable equation is stress = force/area: The stress generated by a cutting implement is directly proportional to the force with which it is applied, and inversely proportional to the area of contact. Hence, the smaller the area (i.e., the sharper the cutting implement), the less force is needed to cut something. 22

Coagulation Coagulation is the process by which blood forms clots. Every damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel. Coagulation is the process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel. Disorders of coagulation can lead to an increased risk of bleeding (hemorrhage) or obstructive clotting (thrombosis).[1] Coagulation is highly conserved throughout biology; in all mammals, coagulation involves both a cellular (platelet) and a protein (coagulation factor) component.[2] The system in humans has been the most extensively researched and is therefore the best understood.[2] Coagulation begins almost instantly after an injury to the blood vessel has damaged the endothelium lining the vessel. Exposure of the blood to proteins such as tissue factor initiates changes to blood platelets and the plasma protein fibrinogen, a clotting factor. Platelets immediately form a plug at the site of injury; this is called primary hemostasis. Secondary hemostasis occurs simultaneously: Proteins in the blood plasma, called coagulation factors or clotting factors, respond in a complex cascade to form fibrin strands, which strengthen the platelet plug.[3] 23

Fulguration Fulguration, also called electrofulguration, is a procedure to destroy tissue (such as a malignant tumor) using a high-frequency electric current applied with a needlelike electrode. 24

Desiccation Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. 25

Safety aspects in electro-surgical unit Burns: caused by excess current density High frequency current hazard Explosion hazards: sparks with ether, alcohol, explosive anesthetic gas, etc. 26

Thanks To All