Transcript Electrosurgical Principles for Minimally Invasive Surgery

Electrosurgery & Gyn Surgery:
Get the Point Across
M. Jonathon Solnik, MD, FACOG FACS
Director, Minimally Invasive Gynecologic Surgery
Dept OB/Gyn, Cedars-Sinai Medical Center
Assistant Clinical Professor
Dept OB/Gyn, David Geffen School of Medicine at UCLA
What’s the difference ?
Electrocautery: use of a direct electrical
current to heat up a metal conductor with a
high impedance to flow so that the metal
becomes physically hot.
Electrosurgery: manipulation of electrons
through living tissue using an alternating
current with enough concentration to create
heat within the tissue and cause destruction.
Electrosurgical Generator (ESU)
Machine that creates an alternating current with
enough current density (concentration) to heat
and destroy tissue
Sinusoidal waveform that is bidirectional
The waveform can be
altered to create
different surgical
effects
Radio Frequency (RF)
The frequency (>100 kHz) is above that which stimulates muscle or nerve
Look Familiar ???
How is tissue destroyed ?
Electric energy is converted to heat (no net change)
Each waveform passes through both positive and
negative ‘peaks’ – the intracellular polarity is interrupted,
creating cellular heat.
Visible
Delayed
MOA
44-50 C
50-80 C
80-100 C
100-200 C
>200 C
None
Blanching
Shrinkage
Steam
Carbonized
Necrosis
Sloughing
Sloughing
Ulceration
Crater
Metabolism
Denature
Desiccate
Vaporize
Combust
Odell RC. Surgical Energy Sources 2002
Waveforms
CUT
Continuous
Simple
Undamped
High current
Low Voltage
Rapid tissue heating 
vaporization
Non-contact
Less thermal spread
COAG
Intermittent
Cooling effect
Damped
Lower current
Higher voltage
Less cellular heat
Contact or non-contact
Risk of thermal injury
CUT Waveform
BLEND
Interrupted CUT current with increasing Voltage
Blend of surgical effects
Reduced current/time
1 – more cut / 3 – more coag
Improved hemostasis
Requires more time to CUT
COAGULATION
Fulguration (COAG)
Non-contact
Coagulates by ‘spraying’
Heat lost to air
Superficial eschar –
carbonization (HOT)
Oozing surfaces
Minimal depth of
necrosis (0.5-2mm)
Stop when bleeding
stops
Desiccation (CUT>COAG)
Contact
All heat transmitted to
tissue
Deep & wide tissue
necrosis
Discrete bleeder
Gaps in hemostasis can spark thru
coagulated tissue –
bipolar better
Electrode can stick to
tissue as it heats
Electrode-Surface Interface
Temperature at which the current heats the
tissue is directly related to the size of the
electrode and how it contacts the tissue
Temperature ∆ = (i x 2 / r x 4) X R x t
Small electrode (r) – HOT
Dispersive electrode (grounding pad) – minimal tissue change
High tissue tension (R)– affects tissue resistance
Video – CUT vs. COAG
Monopolar vs. Bipolar Current
Resectoscope Loop
Ultra-fine
Vapor pocket
Electrons do the work
Vapotrodes
aggregation of
electrons
Monopolar
nonconductive,
uncharged
Bipolar
doesn’t matter
Thermal Injuries in MIS
Active electrodes can be long
True visual field is limited -- flying blind !!!
Delayed Presentation
73% of injuries after L/S chole went unrecognized1
3-10 days or longer2
Evaluate pain, urinary retention, nausea or fever
SLS Survey 1995
13% of surgeons had at least 1 malpractice case
1.
2.
Tucker RD, et al. AORN J 1995
Reich H. Surg Laparosc Endosc 1992
The probability of incurring a thermal injury
during operative hysteroscopy increases
with monopolar energy.
True
False
Hazards of Electrosurgery
Direct injury with active electrode
These are high energy burns
Alternate Ground Burns
Division of current  ECG leads
Isolated ground circuitry
Patient Return Electrodes (dispersive)
Previously accounted for 70% of injuries
The large size
Low conductivity
Interpolated REM
Placement
Capacitative Coupling
This phenomenon cannot be eliminated
Abdominal wall often serves as a return to
ground
Plastic cannulas may not provide more
protection than metal cannulas
1.
2.
Tucker RD, et al. AORN J 1995
Reich H. Surg Laparosc Endosc 1992
Which setting should be used when
resecting an intracavitary myoma?
Bipolar resectoscope using Blend 2
Monopolar resectoscope using pure CUT
Monopolar resectoscope using pure COAG
Bipolar resectoscope using pure COAG
Insulation Failure
Instantaneous burns with HIGH-power density
Often occur in Zone 2 (outside of surgical field)
Can occur repeatedly causing serious injury
Prevention, prevention, prevention
Know and inspect your instruments
Adjust power according to desired effect
Use a low voltage waveform (CUT)
Use short & controlled bursts
Practice skill sets in the lab