Electrosurgery.ppt
- 1. Energy Sources in Surgery Dr. M. Ramesh Director, B.E.S.T. Institute & Research Centre. A V Hospital, Bangalore, India.
- 2. Dr.M.Ramesh ELECTROSURGERY DEFINITION • Electrosurgery is the use of radiofrequency alternating current to raise cellular temperature as a way to vaporize or coagulate tissue. • Cautery (Kauterion = hot iron) destruction or denaturation of tissue is by a passive transfer of heat or application of a caustic substance. B.E.S.T. Institute B.E.S.T. Institute
- 3. Dr.M.Ramesh Historical Background 16th Century Application of electrical current in living tissues 1890s d’Arsonal High frequency A.C. 1908 Lee de Forest H.F generator using vacuum tubes 1926 W.T. Bovie Low-cost spark-gap generator 1950s Nonflamable inhalation anasthetics B.E.S.T. Institute
- 4. Dr.M.Ramesh Current (I) is a measure of the electron moment past a given point in the circuit in a fixed period of times ~amperes. Voltage (V) is the pressure with which the electrons are pushed through the tissue ~volts. Resistance (R) is the measure of the difficulty that a given tissue presents to the passage of electrons ~ohms. Power (W) is the capacity to do work / unit time ~watts. B.E.S.T. Institute
- 5. Dr.M.Ramesh Odell water tower analogy B.E.S.T. Institute
- 6. Dr.M.Ramesh Ohm’s Law: I = V/R W = V x I = V x (V/R) = V2 / R I = Current V = Voltage R = Resistance P = Power B.E.S.T. Institute
- 7. Dr.M.Ramesh Electrosurgical Unit • Converts a 60 cycles / sec (60 Hz), low voltage alternating current into higher voltage radio frequency (500 KHz - 3.0 MHz) current. • Produces current with a variety of wave forms. B.E.S.T. Institute
- 9. Dr.M.Ramesh Biological effects of Electric Currents • Electrolytic effect - Low frequency AC & DC. • Faradic effect - High frequency AC upto 20 Khz. • Thermal effect - High frequency AC more than 300 KHz. B.E.S.T. Institute B.E.S.T. Institute
- 10. Dr.M.Ramesh Tissue effects of R.F.Electrical Current • Vaporization or cutting • Desiccation or coagulation both continuous or blended currents. • Fulguration - High voltage modulated current with a short duty cycle. Vaporization and fulguration - non contact procedures. B.E.S.T. Institute
- 11. Dr.M.Ramesh Tissue Effects of Electrosurgery B.E.S.T. Institute
- 12. Dr.M.Ramesh Monopolar Electrocautery ADVANTAGE • Easy to use • Cutting and Coagulation currents • Dissecting capabilities DISADVANTAGE • Larger volume of tissue injured • Can interfere with pacemakers • Requires distant return electrode B.E.S.T Institute
- 13. Dr.M.Ramesh Monopolar Cutting A higher voltage leads to a higher spark intensity and a higher spark intensity results in a deeper zone of coagulation during the cutting process. B.E.S.T. Institute
- 14. Dr.M.Ramesh Bipolar Electrocautery ADVANTAGE • Small volume of tissue injured • Less risk of burn injury • Safe with pacemakers • Effective in wet fields DISADVANTAGE • More skill required • Coagulation current only • No dissecting capabilities B.E.S.T Institute
- 15. Dr.M.Ramesh Electrodes & Tissue Contact B.E.S.T. Institute
- 16. Dr.M.Ramesh Variables affecting the tissue effects of radio frequency current. • Generator output • Power density(size & shape of electrodes) • Electrode tissue proximity. • Tissue impedance • Electrode speed/time on tissue • Distension media B.E.S.T. Institute
- 17. Dr.M.Ramesh Advantages of Electrocutting • Reduced bleeding • Preclution of germ implantation • Avoidance of mechanical damage to the tissue • Endoscopic applicability B.E.S.T. Institute
- 18. Dr.M.Ramesh Tissue effects of heating B.E.S.T. Institute Temperature (Centigrade) --------------------------------------------------------------------------- 34 - 44 44 - 50 50 - 80 --------------------------------------------------------------------------- Effect : Visible None None Blanching Delayed Edema Necrosis Sloughing --------------------------------------------------------------------------- Mechanism Vasodilatation, Disruption Collagen Inflammation of cell denaturation metabolism ---------------------------------------------------------------------------
- 19. Dr.M.Ramesh Tissue effects of heating B.E.S.T. Institute Temperature (Centigrade) --------------------------------------------------------------------------- 80 - 100 100 - 200 > 200 --------------------------------------------------------------------------- Effect : Visible Shrinkage Steam Carbonization “popcorn” cratering Delayed Sloughing Ulceration Larger crater --------------------------------------------------------------------------- Mechanism Dessication Vaporization Combustion of tissue hydrocarbons ---------------------------------------------------------------------------
- 20. Dr.M.Ramesh Complications • Endogenous burns • Exogenous burns • Pseudo burns B.E.S.T. Institute
- 21. Dr.M.Ramesh Complications • Active Electrode Trauma • Current diversion – Alternate ground site burns – Direct coupling – Indirect coupling – Capacitive coupling • Dispersive electrode burns • Smoke inhalation B.E.S.T. Institute
- 22. Dr.M.Ramesh Direct & Indirect Coupling B.E.S.T. Institute
- 25. Dr.M.Ramesh Argon Beam Coagulator • Uses a spray of ionized argon gas as the active electrode rather than a metallic blade • Allows even, efficient and broad application of the coagulating current to the tissues. • Ideal for obtaining haemostasis along the cut surface of the liver following hepatic resection
- 26. Dr.M.Ramesh Cryotherapy • A technique of in situ tissue ablation that uses freezing temperatures to cause cell death • Used for cutaneous lesions, tumours of the head and neck, cervix, rectum, prostate, breast and liver. • Used in uresectable or multiple liver metastases from colorectal cancer.
- 27. Dr.M.Ramesh Cryotherapy Mechanism of action: Cold shock injury Reduction in cell volume by osmotic dehydration Denaturation of vital cellular enzymes Perforation of cell membranes by intracellular ice crystals Destruction of tumour microvasculature
- 28. Dr.M.Ramesh Infrared Coagulator • Generates coagulation heat energy by infrared irradiation • Hand held wand is a round metallic cylinder that generates the infrared light that emanates through the crystal lens at the end of the wand.
- 29. Dr.M.Ramesh Ultrasound Dissector • Uses high-frequency mechanical vibrations to fragment tissue • Used in ophthalmic, neuro, hepato-biliary and oncologic cytoreductive surgery • Fragments tissue by contact with high water content cells – Vibration generate vapor pockets within the cells that lead to disruption and fragmentation
- 30. Dr.M.Ramesh Ultrasonic knife • Produces vibrations at 55.5KHz at the tip of the blade via a hand piece transducer • The moving blade couples with the tissue, resulting in breakage of protein hydrogen bonds and thus protein coagulum forms • Can perform cutting and heamostasis with minimal damage • Limited lateral spread and thermal injury • No electrical energy transferred to patients
- 31. Dr.M.Ramesh LASER • Light Amplification by the Simulated Emission of Radiation • Differs from regular light in the following properties: – Coherence – Monochromaticity – Collimation
- 32. Dr.M.Ramesh LASER Lasers primarily being used for surgery • Carbon Dioxide • Nd:YAG • Argon • Ho:YAG • KTP • Diode
Editor's Notes
- #2: This is a presentation which is meant to describe the basic principles of Electrosurgery. Unlimke lasers, there has not been any regulatory body on the use of electrosurgery. Traditionally the use of electrosurgery has been learnt from the seniors during surgery, and surprisingly there has hardly anything written about it any of our standard text books of surgery. Inspite of its potential dangers, there is not enough effort put in to understand the occurance and prevention of the complications of electrosurgery. This article attempts to give an insight into this topic of utmost importance to any surgeon today.