Electro-Surgery

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Electro-Surgery
Helsinki, 23-24 September 2004
Nigel R Hircock
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Basic electro-surgical circuit (Monopolar)
Active cable/Path
Power supply
Source - Gen
Patient
Surgeon
Patient Return Electrode
Return cable/path
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High current density at the narrowing of an
electrical conductor creates heat
220 Volt 50 Hz
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Tissue on plate is part of the circuit
High current density heat development in tissue
220volt/50Hz
Active Electrode
Return Electrode
Low current density / No heat development in
tissue
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Why not 50 Hertz

• Alternating current at frequencies from
• 1 to 100,000 Hertz will interfere with the
  neuro-muscular system.
• Above 100,000 Hertz these stimuli occur too
  quickly to affect the neuro-muscular system.

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100 Khz
50 Hz
550 Khz
1550 Khz
54 880 MHz
350 KHz to 3.3 MHz Electrosurgery
Neuromuscular Stimulation ceases
Household Purposes
TV
AM Radio
FM Radio
Below 100 Khz Electrical shock
Above 100 Khz - No electrical shock
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What it does?

• Vapourises
• De-Hydrates
• across almost all tissue types

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Basic electro-surgical circuit - Monopolar
Active cable/Path
Power supply
Surgeon
Source - Gen
Patient
Patient Return Electrode
Return cable/path
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Vaporization De-Hydration

• Cut/Vaporization
• High current concentration at active electrode
  causes
• intense heat in tissue (above 100c)
• Coagulation (Dessication)
• Intermittent supply of current to a larger
  electrode
• causes less intense heat into tissue (below
  100c),
• allows heat dispersion

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Coagulation
Energy
Coagulated cell
Cut
Dehydration through heating
Intense Energy
Exploded cell
Cell expands through increase in pressure
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Wave forms
pure cut
blend cut
desiccation
fulguration
Pure cut uses the lowest level of voltage
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Monopolar Electrosurgery
Cut
Coagulation
Pure
Blend
Dessication
Fulguration
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Pure cut
Blend
Fulguration/non contact coag
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Dessication 1
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Dessication 2
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Dessication 3
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Spray coagulation or fulguration
Blade electrode
Principle Current follows Path of
least resistance
Bleeding vessel
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Limiting power settings by limiting contact
Blade electrode
Micro Needle electrode
Choice of electrode technique determines tissue
effect
Forceps - tips
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The electrosurgical effect is influenced by

1. Contact Time
2. Power Settings of Generator
3. Type of electrode used (Current Density)
4. Whether Cut or Coag activated
5. Tissue Impedance
6. Distance from Active to Return

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Bipolar electrosurgery in egg white/glass
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Bipolar Forceps coagulation
Saline
Correct
Incorrect
Correct
Incorrect
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Some Issues

• Usually, a very safe device to use, however,
  these machines are often seen as the most
  hazardous device used in an OR!
• WHY?

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• The patient return electrode
• General rules for safe practice
• Minimally Invasive Surgery issues

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Pad site burns are prevented by assuring optimal
conditions at the pad-patient interface.
High current concentration/density
Low current concentration/density
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Pad site burns are caused by adverse conditions
at the pad-patient interface which result in
increased current density.

• Current density increases when
• current removal area is too small
• heat is applied for too long
• power setting is too high

High current concentration/density
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Plate Burns !!!
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• A burn under the patient plate is
• ALWAYS
• negligence

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RF Current
RF Current
Monitoring Current
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Basic rules

1. Position plate as close as possible to surgical
   site
2. Check contact of plate throughout procedure

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Avoid the following patient plate locations

• Scar tissue
• Metal implants
• Pacemakers
• Bony structures
• Monitoring electrodes
• Areas of moisture concentration

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Glove burn (Bovie-bite)
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Result glove burn
!
!
Whoops???
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Causes of glove burn

• Activation of fulgurate or spray output
• High power settings
• Surgeons technique
• Open circuit activation
• Removal of forceps whilst activating
• Carbonisation causes higher leakage current due
  to increased resistance
• Quality of gloves
• Recommendation Use Cut or Dessicate

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Other Complications

• Bowel gas ignition
• Staple line/clip conductivity
• Current Density Complications
• Prep fluid

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Electrosurgery Safety Considerations for
Minimally Invasive Procedures
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Direct Coupling
Telescopewith Camera
Active Electrode
LaparoscopeView
Bowel
MetalInstrument
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Insulation Failure
Abdominal Wall
Metal Trocar Cannula
Electrode Insulation Failure
Electrode Tip
Bowel
Laparoscopic View
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Insulation Failure
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Thermal injury caused by Insulation Failure of
electro-surgical instrument during Laparoscopic
Cholecystectomy
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Capacitor

• Metal Coil
• Conductor

Induced Current
Intended Current Flow
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Capacitance Increases with Use of

• Longer instruments
• Higher voltages
• Narrower diameter cannulas

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Instrument/Metal Cannula ConfigurationCreating a
Capacitor
Abdominal Wall
Conductor (Metal Cannula)
Conductor(Electrode Tip)
Insulator (Electrode Insulation)
Laparoscopic View
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Instrument/Plastic Cannula ConfigurationCan
capacitive coupling occur?
Abdominal Wall
Conductor (Electrode Tip)
Insulator (Plastic Cannula)
Insulator (Electrode Insulation)
Laparoscopic View
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Instrument/Hybrid Cannula ConfigurationCapacitive
ly Coupled Fault Condition
Capacitively Coupled Energy to Metal Cannula
Plastic Collar
Electrode Tip
Bowel
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Energy dispertion
Energy Dispertion
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Hybrid Trocar/Cannula System

• You make one yourself.

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Conclusion

• Electro-Surgical devices can be a potential
  hazard in an Operating Room.
• However, they can also be very safe,
• its always the driver in control!