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.
Energy Sources in SurgeryDr. M. RameshDirector,B.E.S.T. Institute & Research Centre.A V Hospital,Bangalore, India.
Dr.M.RameshELECTROSURGERYDEFINITION• Electrosurgery is the use of radiofrequencyalternating current to raise cellulartemperature as a way to vaporize orcoagulate tissue.• Cautery (Kauterion = hot iron)destruction or denaturation of tissue is by apassive transfer of heat or application of acaustic substance.B.E.S.T.InstituteB.E.S.T.Institute
Dr.M.RameshHistorical Background16th Century Application of electricalcurrent in living tissues1890s d’Arsonal High frequency A.C.1908 Lee de Forest H.F generator usingvacuum tubes1926 W.T. Bovie Low-cost spark-gapgenerator1950s Nonflamable inhalationanastheticsB.E.S.T.Institute
Dr.M.RameshCurrent (I) is a measure of the electron momentpast a given point in the circuit in a fixed period oftimes ~amperes.Voltage (V) is the pressure with which theelectrons are pushed through the tissue ~volts.Resistance (R) is the measure of the difficulty thata 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
Dr.M.RameshOdell water tower analogyB.E.S.T.Institute
Dr.M.RameshOhm’s Law: I = V/RW = V x I= V x (V/R) = V2/ RI = CurrentV = VoltageR = ResistanceP = PowerB.E.S.T.Institute
Dr.M.RameshElectrosurgical Unit• Converts a 60 cycles / sec (60 Hz), lowvoltage alternating current into highervoltage radio frequency (500 KHz - 3.0MHz) current.• Produces current with a variety of waveforms.B.E.S.T.Institute
Dr.M.RameshBiological effects of ElectricCurrents• Electrolytic effect - Low frequency AC &DC.• Faradic effect - High frequency AC upto 20Khz.• Thermal effect - High frequency AC morethan 300 KHz.B.E.S.T.InstituteB.E.S.T.Institute
Dr.M.RameshTissue effects of R.F.ElectricalCurrent• Vaporization or cutting• Desiccation or coagulationboth continuous or blended currents.• Fulguration - High voltage modulatedcurrent with a short duty cycle.Vaporization and fulguration - non contactprocedures. B.E.S.T.Institute
Dr.M.RameshTissue Effects of ElectrosurgeryB.E.S.T.Institute
Dr.M.RameshMonopolar ElectrocauteryADVANTAGE• Easy to use• Cutting and Coagulation currents• Dissecting capabilitiesDISADVANTAGE• Larger volume of tissue injured• Can interfere with pacemakers• Requires distant return electrodeB.E.S.TInstitute
Dr.M.RameshMonopolar CuttingA higher voltage leads to a higher sparkintensity and a higher spark intensity resultsin a deeper zone of coagulation during thecutting process.B.E.S.T.Institute
Dr.M.RameshBipolar ElectrocauteryADVANTAGE• Small volume of tissue injured• Less risk of burn injury• Safe with pacemakers• Effective in wet fieldsDISADVANTAGE• More skill required• Coagulation current only• No dissecting capabilities B.E.S.TInstitute
Dr.M.RameshVariables affecting the tissueeffects of radio frequency current.• Generator output• Power density(size & shape of electrodes)• Electrode tissue proximity.• Tissue impedance• Electrode speed/time on tissue• Distension mediaB.E.S.T.Institute
Dr.M.RameshAdvantages of Electrocutting• Reduced bleeding• Preclution of germ implantation• Avoidance of mechanical damage to thetissue• Endoscopic applicabilityB.E.S.T.Institute
Dr.M.RameshArgon Beam Coagulator• Uses a spray of ionized argon gas as theactive electrode rather than a metallic blade• Allows even, efficient and broad applicationof the coagulating current to the tissues.• Ideal for obtaining haemostasis along thecut surface of the liver following hepaticresection
Dr.M.RameshCryotherapy• A technique of in situ tissue ablation thatuses freezing temperatures to cause celldeath• Used for cutaneous lesions, tumours of thehead and neck, cervix, rectum, prostate,breast and liver.• Used in uresectable or multiple livermetastases from colorectal cancer.
Dr.M.RameshCryotherapyMechanism of action:Cold shock injuryReduction in cell volume by osmotic dehydrationDenaturation of vital cellular enzymesPerforation of cell membranes by intracellular icecrystalsDestruction of tumour microvasculature
Dr.M.RameshInfrared Coagulator• Generates coagulation heat energy byinfrared irradiation• Hand held wand is a round metallic cylinderthat generates the infrared light thatemanates through the crystal lens at the endof the wand.
Dr.M.RameshUltrasound Dissector• Uses high-frequency mechanical vibrationsto fragment tissue• Used in ophthalmic, neuro, hepato-biliaryand oncologic cytoreductive surgery• Fragments tissue by contact with high watercontent cells – Vibration generate vaporpockets within the cells that lead todisruption and fragmentation
Dr.M.RameshUltrasonic knife• Produces vibrations at 55.5KHz at the tip ofthe blade via a hand piece transducer• The moving blade couples with the tissue,resulting in breakage of protein hydrogenbonds and thus protein coagulum forms• Can perform cutting and heamostasis withminimal damage• Limited lateral spread and thermal injury• No electrical energy transferred to patients
Dr.M.RameshLASER• Light Amplification by the SimulatedEmission of Radiation• Differs from regular light in the followingproperties:– Coherence– Monochromaticity– Collimation
Dr.M.RameshLASERLasers primarily being used for surgery• Carbon Dioxide• Nd:YAG• Argon• Ho:YAG• KTP• Diode