2. HISTORY OF DIATHERMY:
Diathermy, which literally means "through Heat" is a
technique using high frequency energy to directly
heat deep seated tissues and produce a therapeutic
response.
Diathermy was first used in 1907 by Nagelschmidt, a
Berlin Physician.
3. Fundaments of radiofrequency
electrosurgery
CURRENT (I) =Flow of electrons past a point in circuit/unit time (Amperes
CIRCUIT =Pathway for the uninterrupted flow of electrons
VOLTAGE(V) =Force pushing current through the resistance, measured in
volts
RESISTANCE(R) = Obstacle to the flow of current, measured in ohms
(impedance = resistance)
POWER= amount of energy per unit time (P= V x I ) watts
I= V/R (ohms law)
4. Electrosurgery
Electrosurgery is a simple method of making surgical incisions,
controlling bleeding and destroying unwanted tissue cells by the
use of a high frequency “electrosurgical current”.
Electrosurgical devices (Surgical Diathermy Machine) are frequently
used during surgical operations helping to prevent blood loss in
hospital operating rooms or in outpatient procedures.
12. Surgical surgical Machine
It is a dedicated medical therapeutic equipment
cut, coagulate, desiccate, or fulgurate tissues
Electrosurgical units/ generator- fxn
1)conversion of low frequency to RF output
2) adjustment of wattage and indirectly voltage
3)control of duty cycle
16. Some Basics of Monopolar
Surgery
Diathermy currents (HFAC) may be generated by transistor circuits
and may include a range of protection.
The frequencies used are typically in the range 0.5 to 3 MHz.
Most versions have power output up to a few hundred watts.
Higher power necessary for urology applications where the surgery
often takes place under water (in the bladder).
Low power versions exist, sometimes called hyphenators, for excision
of warts, polyps, and skin flaps.
18. Some Basics of Bipolar
Surgery
Diathermy currents may be generated by valve or transistor
circuits and may include a range of protection and monitoring
systems.
The frequencies used are typically in the range 0.5 to 3 MHz.
Bipolar systems are available in which the heating currents only
flow between the two tips of special forceps.
Bipolar systems are useful for fine work and when the patient has
a pacemaker which might malfunction in the presence of the very
large circulating high- frequency current.
20. Types of ESU Electrodes
Active Electrode
Passive Electrode
21. Electrodes are connected to the RF power generator.
Switching on the high frequency current can be done
with a finger-tip switch in the electrode or a foot
switch.
Small size (thickness in mm (1mm) and wideness till
10 mm).
Active Electrodes
23. The amount of power delivered to the tissue
for a given ESU voltage depends on the active
electrode-to-skin resistance RE.
RI: Internal resistance of active electrode
RE: active electrode-to-skin resistance
RB: Body resistance
RR: Return electrode resistance
Active Electrode Resistance
24. Passive (Neutral, Return)
Electrode
The function of the patient return electrode is to remove current
from the patient safely.
A return electrode burn occurs when the heat produced, over
time, is not safely dissipated by the size or conductivity of the
patient return electrode.
Two points are of practical importance:
(i) Sufficiently large contact area.
(ii) High electrical conductivity between the body and
electrode.
25.
26. Patient Return Electrodes
Assessment of Pad Site Location
Choose: -Well vascularized muscle mass
Avoid: -Vascular insufficiency
-Irregular body contours
-Bony prominences
Consider: -Incision site/prep area
-Patient position
-Other equipment on patient
27. Effects on Body Tissue
Cutting
Coagulation/Desiccation
Fulguration
29. Coagulation
Coagulation is the process by which h blood forms
clots. Every damaged blood vessel wall is covered
by a platelet and fibrin-containing clot to stop
bleeding and begin repair of the damaged vessel.
30. Desiccation
Desiccation is the state of extreme dryness, or the
process of extreme drying. A desiccant is a
hygroscopic (attracts and holds water) substance
that induces or sustains such a state in its local
vicinity in a moderately sealed container.
41. Avoid complications of lap.electrosurgery
Inspect insulation carefully
Use lowest possible power setting &low voltage waveform (cut)
Use brief intermittent activation vs. prolonged activation
Do not activate in open circuit & close proximity or direct contact
with another instrument
Use bipolar electrosurgery when appropriate
42. Cont.
Select an all metal cannula system as the safest choice.
Do not use hybrid cannula systems that mix metal with plastic
Utilize available technology, such as a tissue response generator to
reduce capacitive coupling or an active electrode monitoring system,
to eliminate concerns about insulation failure and capacitive coupling.
44. Cont.
Enseal ----Ligasure ( good vessel sealer 7mm) +
harmonic (good dissector)
Thunderbeat --- harmonic + ligasure (bipolar) in
same devices
45. REFERENCES
Society of American Gastrointestinal and
Endoscopic Surgeons (SAGES) LECTURE ON
FUSE (Fundamental Use of Surgical Energy
(FUSE)
PRINCIPLES OF ELECTROSURGERY BY
COVIDIEN ( medical device company)