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Energy Sources in Surgery
1. Energy Sources in Surgery
Dr. M. Ramesh
Director,
B.E.S.T. Institute & Research Centre.
A V Hospital,
Bangalore, India.
2. Dr.M.Ramesh
ELECTROSURGERY
DEFINITION
• Electrosurgery is the use of radiofrequency
alternating current to raise cellular
temperature as a way to vaporize or
coagulate tissue.
• Cautery (Kauterion = hot iron)
destruction or denaturation of tissue is by a
passive transfer of heat or application of a
caustic substance.
B.E.S.T.
Institute
B.E.S.T.
Institute
3. Dr.M.Ramesh
Historical Background
16th Century Application of electrical
current in living tissues
1890s d’Arsonal High frequency A.C.
1908 Lee de Forest H.F generator using
vacuum tubes
1926 W.T. Bovie Low-cost spark-gap
generator
1950s Nonflamable inhalation
anasthetics
B.E.S.T.
Institute
4. Dr.M.Ramesh
Current (I) is a measure of the electron moment
past a given point in the circuit in a fixed period of
times ~amperes.
Voltage (V) is the pressure with which the
electrons are pushed through the tissue ~volts.
Resistance (R) is the measure of the difficulty that
a 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
6. Dr.M.Ramesh
Ohm’s Law: I = V/R
W = V x I
= V x (V/R) = V2
/ R
I = Current
V = Voltage
R = Resistance
P = Power
B.E.S.T.
Institute
7. Dr.M.Ramesh
Electrosurgical Unit
• Converts a 60 cycles / sec (60 Hz), low
voltage alternating current into higher
voltage radio frequency (500 KHz - 3.0
MHz) current.
• Produces current with a variety of wave
forms.
B.E.S.T.
Institute
9. Dr.M.Ramesh
Biological effects of Electric
Currents
• Electrolytic effect - Low frequency AC &
DC.
• Faradic effect - High frequency AC upto 20
Khz.
• Thermal effect - High frequency AC more
than 300 KHz.
B.E.S.T.
Institute
B.E.S.T.
Institute
10. Dr.M.Ramesh
Tissue effects of R.F.Electrical
Current
• Vaporization or cutting
• Desiccation or coagulation
both continuous or blended currents.
• Fulguration - High voltage modulated
current with a short duty cycle.
Vaporization and fulguration - non contact
procedures. B.E.S.T.
Institute
12. Dr.M.Ramesh
Monopolar Electrocautery
ADVANTAGE
• Easy to use
• Cutting and Coagulation currents
• Dissecting capabilities
DISADVANTAGE
• Larger volume of tissue injured
• Can interfere with pacemakers
• Requires distant return electrode
B.E.S.T
Institute
13. Dr.M.Ramesh
Monopolar Cutting
A higher voltage leads to a higher spark
intensity and a higher spark intensity results
in a deeper zone of coagulation during the
cutting process.
B.E.S.T.
Institute
14. Dr.M.Ramesh
Bipolar Electrocautery
ADVANTAGE
• Small volume of tissue injured
• Less risk of burn injury
• Safe with pacemakers
• Effective in wet fields
DISADVANTAGE
• More skill required
• Coagulation current only
• No dissecting capabilities B.E.S.T
Institute
16. Dr.M.Ramesh
Variables affecting the tissue
effects of radio frequency current.
• Generator output
• Power density(size & shape of electrodes)
• Electrode tissue proximity.
• Tissue impedance
• Electrode speed/time on tissue
• Distension media
B.E.S.T.
Institute
17. Dr.M.Ramesh
Advantages of Electrocutting
• Reduced bleeding
• Preclution of germ implantation
• Avoidance of mechanical damage to the
tissue
• Endoscopic applicability
B.E.S.T.
Institute
25. Dr.M.Ramesh
Argon Beam Coagulator
• Uses a spray of ionized argon gas as the
active electrode rather than a metallic blade
• Allows even, efficient and broad application
of the coagulating current to the tissues.
• Ideal for obtaining haemostasis along the
cut surface of the liver following hepatic
resection
26. Dr.M.Ramesh
Cryotherapy
• A technique of in situ tissue ablation that
uses freezing temperatures to cause cell
death
• Used for cutaneous lesions, tumours of the
head and neck, cervix, rectum, prostate,
breast and liver.
• Used in uresectable or multiple liver
metastases from colorectal cancer.
27. Dr.M.Ramesh
Cryotherapy
Mechanism of action:
Cold shock injury
Reduction in cell volume by osmotic dehydration
Denaturation of vital cellular enzymes
Perforation of cell membranes by intracellular ice
crystals
Destruction of tumour microvasculature
28. Dr.M.Ramesh
Infrared Coagulator
• Generates coagulation heat energy by
infrared irradiation
• Hand held wand is a round metallic cylinder
that generates the infrared light that
emanates through the crystal lens at the end
of the wand.
29. Dr.M.Ramesh
Ultrasound Dissector
• Uses high-frequency mechanical vibrations
to fragment tissue
• Used in ophthalmic, neuro, hepato-biliary
and oncologic cytoreductive surgery
• Fragments tissue by contact with high water
content cells – Vibration generate vapor
pockets within the cells that lead to
disruption and fragmentation
30. Dr.M.Ramesh
Ultrasonic knife
• Produces vibrations at 55.5KHz at the tip of
the blade via a hand piece transducer
• The moving blade couples with the tissue,
resulting in breakage of protein hydrogen
bonds and thus protein coagulum forms
• Can perform cutting and heamostasis with
minimal damage
• Limited lateral spread and thermal injury
• No electrical energy transferred to patients
31. Dr.M.Ramesh
LASER
• Light Amplification by the Simulated
Emission of Radiation
• Differs from regular light in the following
properties:
– Coherence
– Monochromaticity
– Collimation
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.
