Electro-Surgery by JR4C1E

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									Electro-Surgery




             Helsinki, 23-24 September 2004

                               Nigel R Hircock
                                         Basic electro-surgical circuit – (Monopolar)




                                Active cable/Path
Power supply

               Source - Gen

                                                            Patient
                                                                          Surgeon



                                                                Patient Return Electrode




                              Return cable/path
   High current density at the narrowing of
      an electrical conductor creates heat
220 Volt 50 Hz
              Tissue on plate is part of the circuit


  220volt/50Hz             High current density
                           = heat development in tissue




                                Active Electrode



                                                          Return Electrode



Low current density / No heat development in tissue
            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.
                   50 Hz      100 Khz        550 Khz
                                                           1550 Khz             54 – 880 MHz




                                                        350 KHz to 3.3 MHz
                                                           Electrosurgery
                                   Neuromuscular
                  Household        Stimulation ceases
                  Purposes                                                                TV


                                                            AM Radio         FM Radio


Below 100 Khz – Electrical shock       Above 100 Khz - No electrical shock
                         What it does?


         Vapourises
       & De-Hydrates
across almost all tissue types
                              Basic electro-surgical circuit - Monopolar




                                Active cable/Path
Power supply
                                                                   Surgeon
               Source - Gen

                                                    Patient




                                                        Patient Return Electrode




                              Return cable/path
    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
       Energy                                   Coagulation

                                                  Coagulated cell
                  Dehydration through heating
Cut
 Intense Energy


                                                       Exploded cell




                         Cell expands through
                         increase in pressure
Wave forms



       pure cut            blend cut            desiccation   fulguration




    Pure cut uses the lowest level of voltage
Monopolar Electrosurgery

           Cut                  Coagulation


    Pure         Blend   Fulguration   Dessication
Pure cut   Blend   Fulguration/non contact coag
Dessication 1
Dessication 2
Dessication 3
Spray coagulation   Blade electrode

or fulguration


 Principle:            Bleeding vessel
 Current follows
 Path of least
 resistance
Limiting power settings by limiting contact

   Blade electrode                              Micro Needle electrode



          Choice of electrode & technique determines tissue effect




                                                  Forceps - tips
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
Bipolar electrosurgery in egg white/glass
Bipolar Forceps coagulation

                     Saline
  Correct                     Incorrect




 Correct
                              Incorrect
                        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?
    The patient return electrode
   General rules for safe practice
 Minimally Invasive Surgery issues
   Pad site burns are prevented by assuring
     optimal conditions at the pad-patient
                   interface.



                                    High current concentration/density




Low current concentration/density
       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
Plate Burns !!!
   A burn under the patient plate is

                    ALWAYS

                    negligence
                                  RF Current




RF Current

             Monitoring Current
Basic rules

1.   Position plate as close as possible to
     surgical site
2.   Check contact of plate throughout
     procedure
Avoid the following patient plate locations

 Scar tissue
 Metal implants
 Pacemakers
 Bony structures
 Monitoring electrodes
 Areas of moisture concentration
Glove burn (“Bovie-bite”)
Result glove burn
                          !
                    Whoops???
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
Other Complications

• Bowel gas ignition
• Staple line/clip conductivity
• Current Density Complications
• Prep fluid
    Electrosurgery Safety
     Considerations for
Minimally Invasive Procedures
Direct Coupling
                    Active      Telescope
                   Electrode   with Camera
     Laparoscope
        View




                     Bowel
                                    Metal
                                 Instrument
Insulation Failure
         Abdominal Wall




                                                    Metal Trocar
 Electrode Insulation Failure                        Cannula
       Electrode Tip


                                            Bowel



                                Laparoscopic View
Insulation Failure
Thermal injury caused by Insulation Failure of electro-surgical instrument
                 during Laparoscopic Cholecystectomy
Capacitor
                                 Air
                              (Insulator
            Metal Coil                               Metal Coil
            Conductor                                Conductor




                   Intended Current        Induced
                         Flow              Current
Capacitance Increases with Use of

– Longer instruments
                          L
– Higher voltages
– Narrower diameter
  cannulas
Instrument/Metal Cannula Configuration
                     Creating a Capacitor


    Abdominal Wall



                                       Conductor (Metal Cannula)
  Conductor
(Electrode Tip)
                                 Insulator (Electrode Insulation)



                              Laparoscopic View
        Instrument/Plastic Cannula
               Configuration
           Can capacitive coupling occur?

    Abdominal Wall



  Conductor                         Insulator (Plastic Cannula)
(Electrode Tip)


                              Insulator (Electrode Insulation)


                         Laparoscopic View
Instrument/Hybrid Cannula Configuration
    Capacitively Coupled Fault Condition



  Capacitively Coupled
 Energy to Metal Cannula
                                Plastic Collar


     Electrode Tip
                               Bowel
                    Energy dispertion




Energy Dispertion
 Hybrid Trocar/Cannula System


You make one yourself.
                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!

								
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