Presentation describing the modes of diathermy used in modern day surgery, its working principles, complications associated with diathermy use, precautions to be taken while using diathermy. Valuable for undergraduate students and post graduate residents of general surgery.

1. Surgical Diathermy
Principles and Precautions
Dr. Sudhir Kumar Jain
MBBS, MS, FRCS, MBA (HCA), FACS, FICS
Director-Professor
Department of Surgery
Maulana Azad Medical College

2. HOUR OF THINKING

4. Introduction
• Introduced by Bovie and Cushing in early 20th
century.
• William Bovie and Harvey W Cushing, are
credited with inventing the electrosurgical
unit known as “Bovie”.

5. • Faraday proposed:
Electric current through body tissues
Intense neuromuscular stimulation & alteration
of cardiac rhythm @normal frequency of 50Hz
• Neuromuscular stimulation gradually
decreases and disappears at 50 KHz

6. • Principle: Convert normal frequency alternating
current (50 Hz) to high frequency alternating current
(50 kHz)
• Ion Exchange is not possible at such a rapid rate of
change of current no stimulation
• Modern electrosurgical units can produce currents in
the range of 200–300 kHz.
• High frequency AC to a small area raised
temperature & coagulation.

7. Principle
• Whenever current is concentrated in a small
area heat is generated.
• This heat can be used for coagulating and
cutting tissue.

8. Electrocautery
• Used only for coagulation
• A metal heated by electrical current is applied to the
target tissue, to burn or coagulate the specific area
of tissue.
• No current is passed through tissue.
• A resistant metal wire is used as an electrode.

9. • This electrode when hot is placed directly onto the
treatment causing coagulation.
• Used in superficial surgeries by dermatologists,
ophthalmologists, plastic surgeons, urologists, and
related specialties.
• Compact, battery operated devices are used
that destroy the targeted tissues with physical heat.

10. Electrosurgery
• Used for cutting and coagulation both.
• uses electric current which passes through tissue and
patient body to achieve the desired result.
• Frequency of 500,000 Hz is used current passes
without causing neuromuscular contraction.
• The heat is generated at the point of resistance of
the tissue to the electrical current.

11. • Tools used to apply current are: electrodes, blades,
round ball, needle and loop configurations.
• Advanced radio-wave generator devices are used,
which pass modified current through the target
tissues to achieve the desired effect.

12. Uses of Diathermy
• For Coagulation (High Voltage Low amplitude interrupted
waveform)
– Soft Coagulation (No Electric arcs generated)
– Forced Coagulation (Electric arc generated), used in areas
of high vascularity
– Spray Coagulation (Intensely modulated high frequency
voltage), used for haemostasis

13. High Voltage Low amplitude interrupted waveform

14. • For Cutting (High amplitude low voltage continuous
waveform current)

15. • Blended Mode (Amplitude and Voltage are equal)-
both cutting & coagulation

16. Modes of Diathermy
• Monopolar
– Generator Electrode Patient Earth plate
ESU
– Base plate required to complete the circuit.
– Minimum area of contact: 300 cm2
– Heat produced depends on: current density, tissue
resistance and time

18. • Bipolar
– one prong intervening tissue other prong
– Current does not pass through patients body
• Uses:
– periphery of an organ with narrow pedicle
(Current pass through pedicle & thrombose the
vessel)
– pinpoint or micro coagulation is required
– With a pacemaker in situ

20. Precautions
• Check Equipment before use
• Atleast 300 cm2 plate contact area
• Plate must be placed on the same side & close to the
operative site
• Should be placed over a vascular and muscular area
• Hair should be shaved

21. • Do not place plate over bony prominence, scar
tissue, skin over implanted metal prosthesis or areas
distal to tourniquets.
• Plate should have uniform and good body contact.
• Avoid pooling of blood or fluids near diathermy plate
• Jewellery must be removed

22. • Avoid contact of patient with ground metal objects
• Re-inspect plate whenever patient’s position is
changed
• Avoid alcohol based solutions for preoperative skin
preparation
• Keep active electrode in an insulated quiver when
not in use

23. • Electrocautery Smoke contains:
– Toluene, benzene, hydrogen cyanide, formaldhyde
– Potential carcinogens
– Avoid inhalation using Inline filters, effective
evacuation systems, improved masks
• Do not use electrocautery in the vicinity of ECG
monitors, minimum 15cm away.

24. • Only the surgeon using the active electrode should
activate the machine
• Avoid using diathermy inside bowel as it contains
inflammable gasses: hydrogen, methane

25. Hazards in Minimal Access
Surgery
• Insulation failure:
– MC cause of burns in MAS
– due to insulation failure, mechanical trauma or
repeated sterilisation of the instrument
– Defect at tip- injury to non-target area
– Defect in shaft- injury to adjacent structures
– Defect in handle- injury to surgeon

26. Capacitative Coupling
• Electric current induces current in a nearby
conductor despite insulation
• Reason: due to Electromagnetic Induction
• Current leads to Magnetic field around instrument.
• Increased chances with high voltage

27. • Implications:
– in metallic ports used in MAS: current develops in
port
– Current may be induced in laparoscope
• May cause injury to surrounding structures or
surgeon

29. Direct Coupling
• When an active electrode touches another metal
instrument
• Direct transfer of current causing injury to
surrounding structrures
• Examples:
– active electrode may touch laparoscope
– active electrode may touch clip or staple line

31. Diathermy and Pacemakers
• Pacemakers may get inhibited during
diathermy use
• may revert to fixed rate of pacing
• Magnet used to reset it
• Alternative modes like ultrasonic scalpel
should be used

32. PRECAUTIONS
• Use Bipolar mode
• When using monopolar mode, place plate away
from the pacemaker
• Monitor heart throughout surgery
• Defibrillator must be available
• Cardiologist must be available
• Ensure facility for temporary pacing

33. KEY POINTS
• High frequency A.C > 50 KHz used, no neuromuscular
transmission
• Used for cutting, coagulation or both
• Cutting- low voltage, high frequency continuous
wave form
• Coagulation- high voltage, low amplitude,
interrupted waveform
• Bipolar better than monopolar as no current passes
through patient

34. • Plate- placed over well vascularised, muscular part
with atleast 300cm2 area
• Avoid placing plate over scars, bony prominence,
distal to tourniquet
• MAS- capacitative coupling, direct coupling or
insulation failure may develop
• Use bipolar in patients with pacemaker

35. Thank You