Surgical diathermy involves the intra cellular conversion of high frequency alternating current to thermal energy in order to generate a variety of tissue effect during surgery

1. DIATHERMY IN SURGERY
(Radiofrequency Electrosurgery)
Dr. Chris Alumona

2. OUTLINE
• Introduction
• History
• Surgical Importance
• Physics
• Operational Principles
• Clinical principles
• Hazards
• Managing diathermy burns
• Future trends
• Conclusion
• Refrences

3. Introduction
• Greek: Dia =
through, Thermy =
heat
• Intracellular
conversion of RF
electromagnetic
energy to heat in
order to generate a
variety of tissue
effects
Electromagnetic Energy
Kinetic energy
Thermal energy
Tissue effects
Vaporisatio
n
Desiccation
/coagulatio
n
Fulguration
Intracellular conversion

4. History
• Pre-historic times: hot stones
• Goldwyn eras
– 1st era: Discovery of electricity
– 2nd era (Luigi Galvani-1786): Galvanization
– 3rd era: Electromagnetism
• Franz Nagelschmidt (1897): diathermy
• Bovie and Cushing: (1926) modern diathermy

5. Statement of Surgical Importance
• The simultaneous achievement of cutting and
coagulation with one handy instrument
reduces both blood loss and duration of
surgery thus impacting positively on surgical
outcome.
• Open surgeries, laparoscopic surgery,
intraluminal endoscopic procedures.

6. PHYSICS
• Current (amperes)
• Voltage (volts)
• Impedence (ohms)
• Energy (joules)
• Power (watts)
• OHMS law: I=V/R

7. Operational Principles
• The ESU / Generator
– generates radiofrequency ac output
– Adjusts wattage
– Controls duty cycle
– monitor impedence in the electrodes
– Mordern ESU are isolated circuits
PT
DE
ESU ESU
AE AE
PT
Ground
PT

8. Why Radiofrequency AC
• Controlable and predictible tissue effect
• Does not depolarize
Alternating polarity
DC
0
x
AC
x
0
fixed polarity
400 KHz – 10 MHz

9. Monopolar vs Bipolar

10. Thermal Tissue Effect
 Carbon (sugar) denaturation. Forms
porous charred substance
 Carbon denaturation. Forms a brown
substance
 Cellular contents converted to steam
 Membrane damage > leakage of cell
water > cell shrinkage. Hydrothermal
rupture of hydrogen cross-links of
collagen > unwound collagen
reforms on cooling to form seal
200° C
160
100
60-90
50
40
37
Carbonisation
(black coagulation)
Caramelisation
Vaporizatio
(cutting)
Instant cell death,
desication,
coagulation (white
coagulation)
Cell death in 1-
6min
No structural
damage
Normal temp

11. Creating Tissue Effects

12. Cutting vs Coagulation vs Blend
Cut Coagulation Blend
Voltage low high
Duty cycle Continuous wave
form (sine wave)
Pulsed output Continuous output
with pulses
Power density Must be high (tip of
electrode)
Energy transfer High. Temperatures
>100°C
Reduced energy
tranfer, <100°C
Tissue effect vapourization Membrane damage,
Desiccation,
collagen
denaturation

13. Forming a sound vessel seal
• Coaptive coagulation: use CUT to COAGULATE
– Should be done with low voltage continous
output (cut) not the modulated high voltage
output (coag)
– Vessels must be compressed
• To prevent heat dissipation by blood flow
• To allow sealing

14. Clinical Principles
• Pre Operative
– The surgeon
• Proper training
• Inspect connections
• Over all responsibility
– The Instrument
• Safety standards
• Regular maintenance

15. • The patient
– Clinical evaluation (pace makers)
• Avoid diathermy if possible or use bipolar inst.
• If monopolar inst. must be used, site dispersive electrode to
direct current flow away from pacemaker system
• Use only shot bursts
• Discontinue diathermy if any arrhythmias occur
– The Procedure
• Bowel surgeries, Neurosurgery

16. • Intra-operative
– Pt positioning
• Adequate insulation
– The dispersive electrode
• Adequate contact, avoid wrinkle, keep dry
• Close to op site/away from ECG and monitoring electrodes
• Apply in bulky areas with good blood supply
• Hairy areas, bony prominences, scar tissues

17. – Scrubbing and draping
• Allow volatile solutions eg spirit to dry before draping
• Safer to avoid alcohol based skin preparations
– Aneasthetic gasses
– Changing settings
• Verbally confirm adjustments

18. – Handling of electrodes
• Activate only in contact/proximity with target
• Electrode tip must be visualized before activation
• Return to reciever when not in use
• Same surgeon must activate footpad

20. • Post operative
– Pt inspection

21. Electrosurgical Injuries
• 40,000 pts burned by faulty ES devices/yr
– Up to 70% of burns in lap surgeries are
undetected at time of injury
• 18% of surgeons have experienced ES injuries
– insulation failures or
– capacitance coupling

22. Mechanism of thermal injuries
• Dispersive electrode
issues
– Application site
issues
– Partial detachment
– Synergistic heating

23. • Current diversion
– Insulation failures
– Direct coupling
– Capacitance
coupling

24. • Active Electrode Injuries
– In advertent activation
– Direct extension/lateral propagation
• High voltage
• Low tissue compression
– Chanelling effect
• Fire
– Volatile solutions
– Aneasthetic gases
– Manitol bowel prep, gut obstruction
• Smoke inhalation

26. Managing Diethermy Injuries
• Burns
– Usually full thickness burns
– Must be excised
– Pt must be informed
– Full investigation to ascertain cause
• Pacemaker malfunctions; arrhythmias, cardiac
arrest
– Reset pacemaker with magnet
– CPR

27. Future trends
• Advanced bipolar electrosurgery devices eg
ligasure system
• Adaptive generators
• Ablative therapies eg hepatocellular ca
• Bowel anastomosis
• Hernioraphy
• Skin grafting

28. Conclusion
• RF electrosurgery/surgical diathermy is an
indispensible tool in modern surgery,
adequate training and precautions must be
observed to ensure safely for both the patient
and the surgeon

29. • Thank you

30. Refrences
• R. M. Kirk, W. J. Ribbans. Clinical Surgery in General. 4th Edition.
Churchill Livingstone, (2004)
• Bailey, H., Love, R. J. M. N., Mann, C. V., & Russell, R. C. G. Bailey
and Love short practice of surgery. 27th Edition. London: Chapman
& Hall medical. (2018)
• Massarweh N., stakey D. (April 2006). Electrosurgery: History,
Principles, and Current and Future Uses. Journal of the
American College of surgeons.
https://www.researchgate.net/publication/7277726
• El-Sayed MM, Saridogan E. Principles and Sfe Use of Electrosurgery
in minimally invasive surgery. Gynecol Pelvic Med 2020
• FUSE lecture series:
https://www.youtube.com/playlist?list=PLo3VXJ3gAvqafv_aDE8HNr
4Coy7XwH6t3