Operative Technics; Monopolar Cut - Carlo De Giorgi SURGERY PLUS Mode D'emploi

According to the come temperature and in function of used pulse form, it's possible to
recognize many types of effects produced by the current in radiofrequency on the human
body:
Coagulation
Temperatures from 60 to 70 ºC in the area around the active electrode cause a slow
heating of intra-cellular liquid, the water contained in the cell evaporates and an action of
coagulum is obtained, so the blood flow is stopped.
Cut
Temperature over 100 ºC in the area around the active electrode determines the evapo-
ration of the intracellular liquid and the cell explosion. The vapor around the electrode
baits a chain reaction in the direction where the active electrode is worked, transmitting
the evaporation energy to the tissues around it.
The cut isn't, for this, a mechanical resection. If the temperature comes to 500 °C it's
verify the tissue with an action of cauterization.
Mixed currents
EN
They are obtained by the mixing of coagulation and cut effects. There is a reduction of
blood loss during the cut procedure, or like cut that develops a substantial eschar coat.
The high frequency used by electrosurgical needle, don't allow to the electromagnetic
field to penetrate deeply in the matter and so the current crosses the conductor mostly in
the external surface, reduces in an exponential way and becomes negligible in the cen-
tre of the conductor section. This effect, called 'skin-effect' cause a reduction of the use-
ful section for the current passage, an increase of the electrical resistance and becomes
an important problem in the neutral electrode. In fact in this electrode the current density
is very high (KA/m ) on the edge, where the excessive increase of temperature by Joule
2
effect causes burns for the patient. So it isn't accidental that the burns for the patient,
during the electrosurgical interventations, have the shape of the edge neutral electrode.
To reduce the burns risk have to dose opportunely the supply power (I ∙t) and to follow
2
the rules for the application of the neutral electrode on the patient (see cap. SAFETY).
2) Faradic Effect
The pulsed current causes the neuro-muscular stimulation, originated by stimulation
of physiologic process of ionic exchange, responsible of the transmission of stimulus
that cause muscular spasms and cardiac symptoms of extra systole and ventricular
fibrillation.
The effect of this stimulus is known like faradic effect and it is expressed by:
R= I / √F
The physiologic system of stimulus transmission follows a limit curve in which the
pulsed currents or by low frequency produce an impulse of stimulation. By alternating
current in high frequency (higher than 200 kHz), used in the electrosurgical needle,
don't have neuro-muscular reactions (the change of polarity is so fast that the patient
doesn't have consequences at a level of the neuro-muscular reactions), and there isn't
an electrolytic damage of the organism.
For this reason all the equipments generator of the high frequency for surgical use (elec-
trosurgical needle) work on base frequencies higher than 300 kHz so that they don't
produce electric stimulation.
3) Electrolytic Effect
The use of high frequency currents reduces the electrolytic effect (ionic division) in the
tissues, caused by the shortest period of unidirectional conduction of the current.
OPERATIVE TECHNICS
Monopolar Cut
Monopolar cut is the sectioning of the biological tissue achieved by the high-density pas-
sage of HF current, which is concentrated at point of the active electrode. The HF cur-
rent, when it is applied to the tissue, through the point of the active electrode, it creates
intense molecular heat in the cells so high that explosion of it is caused. The cut effect is
achieved by moving the electrode through the tissue and destroying the cells one after
the other. The movement of the electrode prevents the propagation of the side heat in
the tissue, thus limiting to a single line the cells' destruction.
The best HF current for cutting is pure sine wave without any modulation that cuts very
smoothly and provides the least thermal effect with poor haemostasis while cutting. Be-
cause its effects can be precisely controlled, it can be used safely without damage to the
EN 6
MA505a_IT-EN-ES-FR-DE