Radiofrequency- principles and uses in ENT practise

1. Principles of radiofrequency and
its ent applications
Dr. Juveria Majeed,
MS ENT,
Govt.ENT Hospital/Osmania
Medical College

2. • Within the surgeon’s armamentarium,
electrosurgical devices stand out as some of
the most useful and most used instruments.
• William T Bovie - father of elecrosurgical
devices.
• The use of cautery dates back as far as
prehistoric times, when heated stones were
used to obtain hemostasis.

3. APPLICATIONS OF DIFFERENT
CURRENT FREQUENCIES

4. • Electrosurgery: high-frequency electrical
current passed through tissue to create a
desired clinical effect. As the current is
delivered, it passes through and heats the
tissues.
• This differs from electrocautery, in which
electrical current heats an instrument and
a clinical effect is realized when the
heated tool is applied to the tissues.

5. Principles of radiofrequency:
• Central to the understanding of electrosurgery is an
understanding of electrical circuits and Ohm’s Law. Circuit is
an uninterrupted pathway of flowing electrons and Ohm’s
Law describes the actions of a given circuit:
• Voltage = Current*Resistance
• Current -flow of electrons during a given period of time.
• Voltage -the force driving a current against the resistance of
the circuit.
• In electrosurgery, voltage is provided by the generator, and
current is delivered to the tissues through the electrode tip
of the instrument.
• Resistance to current is inherent within all human tissues.
• The higher the inherent resistance, the greater the voltage
needed for the current to pass

6. • Electrosurgical generators were
“ground referenced,” ie, the
flow of energy was in relation
to earth ground. In this
situation, anytime the patient
came in contact with a potential
path to ground, the current
would choose the path of least
resistance. This potential
hazard was eliminated with the
introduction of generators that
were isolated from ground,
confining the current flow to
the circuit between the
electrode and the patient
return electrode, which offers a
low-resistance pathway for
current to return to the
generator from the patient.

7. • The transformation of electrical energy into heat
occurs in accordance with Joules Law and can be
expressed by the following formula:
• Energy= (current/cross-sectional area)2
*resistance*time.
• Heat produced is inversely proportional to the
surface area of the electrode, ie, the smaller the
surface area, the more localized heating energy is
produced.

8. How does it work?
• The rate at which tissues are heated plays a crucial role in
determining clinical effect.
• When an oscillating current is applied to tissue, the rapid
movement of electrons through the cytoplasm of cells causes the
intracellular temperature to rise.
• The amount of thermal energy delivered and the time rate of
delivery will dictate the observed tissue effects.
• In general, below 45°C, thermal damage to tissue is reversible.
• As tissue temperatures exceed 45°C (as in coblation and RF), the
proteins in the tissue become denatured, losing their structural
integrity.
• Above 90°C, the liquid in the tissue evaporates, resulting in
desiccation if the tissue is heated slowly or vaporization if the heat
is delivered rapidly.
• Once the tissue temperatures reach 200°C( as in laser or cautery),
the remaining solid components of the tissue are reduced to
carbon. which can cause granulations, post op infections,
morbidities like excessive scar tissue formation.

9. Types of electrosurgical
instruments
• Electrosurgical technology offers essentially two
types of devices for energy delivery:
monopolar and bipolar.
• The monopolar instrument delivers current
through an active electrode which then travels
through the patient and back to the generator
through a conductive adhesive grounding pad
applied to the patient before beginning the
procedure.
• Bipolar instruments resemble surgical forceps,
with both the active electrode and the return
electrode functions being performed at the

10. Types of RF Units
• Single Frequency
A) low frequency- Machines operating at 1.0-
2.9 MHz
B) High frequency- Machined operating
>3.0MHz
• Dual Frequency
Machines operating at 1.7 & 4 MHz

11. • Coblator- Coblation is derived from the word
‘Controlled Ablation’
• It is actually cold ablation
• It combines radiofrequency energy with a
natural saline solution.

12. What Is Coblation?
• Bipolar configuration
• RF current through conductive
solution
– 100-300 V, 100-500 kHz
• Plasma field by RF current
– In NaCl, orange glow
• Not heat-driven
• Molecular dissociation
• Minimal thermal penetration
– Cell death (<125 mm)

13. Coblation
• Low frequency
– Decreased tissue penetration
– Minimal collateral tissue damage
– Surface temperatures 40° to 70° C
• Shorter current path
– Control of energy delivery
• Volumetric tissue removal
• Monopolar spark between
electrode and tissue
• Localized tissue heating
– 450° to 600° C
• Tissue desiccation and
vaporization
Electrocautery

14. Waveforms OF RF
Fully filtered cut:
• Microsmooth cutting
• Negligble lateral heat
• Minimal cellular
destruction
• Ideal for skin incision
and biopsy
• Best cosmetic results
• Fastest heating

15. • Partially Rectified Coagulation:
• Coagulation/shrinkage: Ideal for cutting with
hemostatic control.
• Hemostasis with controlled penetration
• Fully Rectified Cut/ Coagulation:
• Cutting with hemostasis
• Ideal for subcutaneous tissue dissection and
planing especially useful in vascular areas

16. • Fulgration:
• Maximum penetration and
controlled hemostasis
• Bipolar:
• Pinpoint microcoagulation
• No tissue adherance to
forceps
• No charring or tissue
necrosis
• Ideal for coagulation- in and
around critical anatomy

17. Mode Output waveform Output frequency Max. output
power
1. Cut 90% cut
10%coagulation
4.0 MHz 120W
2. Cut/Coagulation 50%cut
50%coagulation
4.0MHz 90W
3.Hemo 10% cut
90%coagulation
4.0MHz 60W
4. Fulgrate Spark- gap 4.0MHz 45W
5. Bipolar 10%cut
90%coagulation
1.7MHz 120w

19. • Physical Background: Injury to the tissue
depands on the lateral heat generated by the
probe of the instrument.
• Lateral heat formula
• T*I*F*W*E
• T- Time
• I- Intensity of power
• F- Frequency
• W- Waveform

20. Comparision with other
technologiesRadiofrequency Electrocautery
Simultaneous cut and coagulate Requires different mode for different
application
Minimal surrounding tissue damage Tissue damage is more
Less lateral heat More lateral heat
Minimal scarring Gross scarring and fibrosis
Faster healing Slow healing
Less slough
Minimal infection
More slough formation causes
infective nidus

21. Comparision with other
technologies
Radiofrequency Laser
More precise cutting and coagulation Less precise
Self controlled of coagulation depth Less control
Less lateral heat damage More lateral heat damage

22. APPLICATIONS OF RF
Surgeries for snoring
• Snoring is mostly caused
by the relaxed soft
palate tissues.
• RF can be used to
contract and stiffen the
lax tissues thereby
eliminating the main
cause of habitual snoring

23. • RF used in a procedure
where a part of tonsil tissue
is precisely coagulated. This
method leads to significant
reduction in the tissue
without compromising on
lymphatic tissue.
Hypertrophy of tonsils

24. • Submucosal coagulation of
hypertrophied turbinates all
along the length of
turbinated without
damaging the epithelium
and mucosa
Hypertrophy of turbinates

25. • A combination of variety of
surgeries can be done to
relieve obstruction:
• Nasal surgeries
• Palatal surgeries
• Tongue base reduction
• Hypopharyngeal surgeries
OSA syndrome

26. • Choanal atresia repair
• Nasopharyngeal obstruction: RF
suction adenoidectomy
• Uvelectomy- elongated uvula
touching base of tongue,
edematous uvula
• Somnoplasty: Palatal stiffening
using RF can be performed along
with uvelectomy, tonsillectomy,
minimal palatoplasty.
Webbing and enlarged uvula

27. • UPPP- uvulopalatopharyngoplasty
• Z palatoplasty
• Expansion sphincter pharyngoplasty
• (lateral pharyngeal wall collapse)
• RF tongue base reduction
• Partial glossectomy
• Lingual tonsillectomy
• Laryngomalacia- glossoepiglottopexy
• supraglottoplasty
• Laryngeal web excision
• Glottic and supraglottic lesions- excision

28. ADVANTAGES OF RF
• 1) Low Temperature
No risk of myoglobinuria as seen in laser
surgery
Scar tissue minimal
Skin incision can also be given
Painless
Healing fast
2) Cosmetic results superior

29. • 4) Cost effective
• 5) Does not take up valuable OT space
• 6) No special protective gear
• 7)No interferance with histopathological
reporting.

30. COMPLICATIONS
• Mainly occur due to improper technique
• Intraop: Lacerations, Deep wound,
Hemorrhage( Duration and coagulation with
ball electrodes helps in achieving hemostasis.)
• Mucosal ulcerations
• Scarring ( can be avoided using appropriate
electrodes) proper power settings and most
important by the technique of brief contact of
the electrode with tissues.
• RF is contraindicated in pts with pacemakers(

31. • RF is undoubetedly most useful and most-
often used tools at the surgeon’s disposal.
• But there are potential applications for which
these electrosurgical instruments are not
commonly used. For example, there is a
pervasive dogma in surgery that skin is to be
opened using the traditional scalpel, and
deeper tissues may then be opened using the
electrosurgical tool. The theory behind this
proposition is that use of the Bovie causes
worse cosmesis at closure and predisposes