Diathermy in surgeryByDr Osagie O. E.Registrar, Dept of surgeryJUTH

Outline IntroductionDefinitionHistorical perspectiveComponentsClassificationPrinciples of actionEffect on tissueUses

Outline Dangers / complicationsSafety measures / precautionsAlternativesFuture trendsConclusion

IntroductionUse of electricity as an alternating current to cut, coagulate, incise, divide or otherwise deal with tissue during a surgical procedure Uses high frequency alternating current to generate deep heat for use in cutting coagulation or fulguration

Introduction History300BC Egyptians used to treat tumorsHippocrates in 460 used heat to treat suprapubic abscessesIn AD1 Celsius used cautery for haemostasisWJ Morton applied the principle of electricity to medicineNagelschmidt in 1910 coined the term

Classification Based on the number of electric poles at the site of applicationMonopolar active electrode held by the surgeon and indifferent electrode attached to a point on the body of the patientBipolar active and indifferent electrodes incorporated in one unitQuasi-polar standard bipolar set up with specially designed active and return electrodes to apply unmodulated current

ComponentsActive electrode needle, blade, forceps)Generator high frequency current generated here. Can beGrounded return current passes through the generatorIsolated which could be earthed (primary) or not earthed (secondary)Indifferent electrodeConnecting cables

PrinciplesRadio frequency electric current produced in the range of 0.3 3MHzAt 50-60Hz1mA = threshold for muscle activation5mA = pain15mA = let go50mA = respiratory muscle spasm80-100mA = ventricular fib>1A = sustained myocardial contraction

Principles>4MHz inductance takes place with capacitance coupling and harmful effects re-introducedPassage of current through a tissue leads to a heating effect beneath each electrodei.e. Current (I2) *resistance (ohms)Active electrode has a small cross sectional area so heat is concentrated in the immediate vicinity of this electrode

PrinciplesIn monopolar systems the indifferent electrode has a wide cross sectional are so heating effect is reduced and dissipates fastThe amount of heat produced depends on the followingIntensity of the current High voltage (200-500V for cutting and low voltage (

PrinciplesAn unmodulated continuous sine wave with a duty cycle of 100% for cuttingUnmodulated low frequency for soft coagulationUnmodulated high frequency for force coagulationModulated high frequency for spray coagulationElectric properties of tissue Relative size of the electrode

PrinciplesDuty cycle is the duration of time current is active during applicationFor pure cutting = 100% and pure coagulation is 6% Cycle can thus be blended based on duty cycle at 80%, 60% 50% and 25% to have both cutting and coagulation activity

PrinciplesBipolar diathermy has a reduced risk of collateral damage and so is saferHeat passes thru tissue held in the tines of the forcepsMinimum power settings can be used Cannot be used for cutting

Effects on tissueCuttingVaporization of tissue in contact by bursting cells, evaporating water and pyrollization of proteinsAchieved by a very hot cutting arc produced by a smooth sine waveMost of the heat produced is used up at the point so charring of adjacent tissue does not take placeCoagulation

Effects on tissueMost widely used functionDirect application of heat to vessels leads toCoagulation of blood proteinsDrying up off vessel wallsShrinkage and retraction of vessel endsThrombus formationAchieved by an interrupted burst of currentCoagulation could beSoft coagulation safest for laparoscopy

Effects on tissue300VElectric arcs generatedNeeded for vascular areas with an increased risk of collateral damageSpray coagulation electrode and tissue not in contact so inaccessible tissue can be coagulated

Effects on tissueFulgurationDestructive coagulation with charring of adjacent tissueAccompanied by sparks and soundsAchieved by high intensity currentUsed for destroying small tissue

UsesGeneral surgeryHaemostasisGall bladder dissectionGastrostomyColostomyHaemmorhoidectomyUrologyTURP/ TURBTCoagulation of bladder growths

UsesExcision of hydrocele sacsNeurosurgeryHaemostasisExcision of CNS tumoursStereotactic surgery for dyskinesiasFrontal leucotomy and choroid plexectomyTreatment of paroxysmal trigeminal neuralgia by Gasserian ganglion coagulationPlastic wart excision

UsesMinimal access surgeryCholecystectomyBleeding PUDExcision of Schatzki ringThoracic sympathectomyClearing of stents infiltrated by tumoursENT Turbinectomy Tonsillectomy

Dangers and complicationsPatientBurns to skin or cavities Improper placement of indiff electrodeUsed close to skinDisconnectionExplosion due to reaction with volatile gasesChanneling effectInfectionSecondary haemorrhage

Dangers and complicationsPoor wound healingPost operative painPerforation of hollow visceraElectrocutionNecrotizing granuloma of peritoneumAdductor spasmProduction of gases which include

Dangers and complicationsHydrocarbons 2,3, dihydromdene, 1 decene 1 undecene 6 ethyl benzene, ethyl benzeneNitrites 3 butenenitrene, benzonitride, 2 propelenenitreneAminesPyrole, 6 emthylindole, indoleAldehydes 3 methyl propanolol, benzaldehydeMiscellaneous - 5 dimethylfuran, hexadecanoic acid

Dangers and complicationsTo SurgeonBurnsElectrocution

Safety measures / precautionsPre operativelyDo not prepare bowel with manitolShave skin at site for indifferent electrodeCheck equipment regularlyAlarm systems must be functionalStaff should understand the mode of operationIntra- operativelyPrevent patient contact with metal parts of couch and drip stands

Safety measures / precautionsPlace active electrode in a quiverAllow alcohol disinfectant to dry before useApply indifferent electrode to dry flat skin bearing no scarsAllow at least 50cm b/w diathermy and anaesthetic machineDO NOT USE in the presence of etherPlace struct at risk for channeling on the ant abdominal wall

Safety measures / precautionsChoose the appropriate mode

If ineffectiveCheck for faulty connectionsCheck the active electrodeCheck indifferent electrodeIncrease power

AlternativesLASERLess tissue damageNo smoke producedHarmonic scalpelUses USS energy converted to a frequency of 55.5HzNo risk of electrocution

Future trendsDevelopment of micro-chip diathermy machines

ConclusionAn important addition to the armamentarium of a Surgeon diathermy confers proven advantages that aids in the simple, cost effective, user friendly and relatively safe delivery of health services

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