GIMA SpA
DIATERMO MB250 – DIATERMO MB400
MA303IGBa-19-03-2007 Manuale
d’Istruzioni / Instruction’s Manual
33
3.
OPERATIVE TECHNICS
3.1 MONOPOLAR CUT
The monopolar cut is the biological tissue dissection obtained by the passage of the sinusoidal current (or parasinusoidal), with
constant amplitude and sufficiently high, through the active electrode. At the contact between the point (where the electric field
is present with an high intensity) of the active electrode and the tissue, arc springs up until the current runs (Leidenfrost effect).
The come temperature where the arc comes, is high and the current can be calibrated so that it exceeds the boiling point of
water in the cells and in the extra-cellular liquids, making the explosion of the cell, the water evaporation and the tissue
electrical resistance increment
.
This favours further the local temperature increment, moreover the ionization of the air
produced by the arc favours its maintenance.
The action of the cut shows itself in the tissue division caused by the cells explosion. The heat locally
developed is totally
absorbed by the water evaporation for which, since the rapidity of the event, it doesn’t develop (by conduction) toward the
surrounding tissue and for this the haemostatic effect shows itself in a moderate way. Because the alternate current used for the
cut has constant amplitude, the arc maintains always the same position (in axis) as to needle point, following it in its moving
never without interrupt itself and leaving back itself an open sulcus.
a good coagulation during the cut is one of the principal benefits of the electrosurgical, it is desirable a current with a
modulation ratio.
Examples of the electrodes suitable for the cut action are: needle electrode. lanceolate electrode, loop electrode in steel wire,
etc.
The following rules help the operator to obtain a good cut:
maintain the tissue damp but not wet;
maintain the electrode perpendicular to the tissue;
start the output circuit before make the contact with the tissue;
maintain clean the point of the electrode (for this scope it’s advisable using the electrode cleaning sponges F7520);
make to cool the tissue before a new cut.
When the output power level is right it would have to be obtained:
no resistance to the electrode moving through the tissue
no variation in colour of the cut surfaces
no tissue fibre residual on the electrode.
Transurethral resection
A particular use of the cut is represented by the immersion of the active electrode (for this scope it’s used a metal loop) in a
liquid, for re-move tissue from the bladder and prostate.
In this circumstance it’s realized an high dispersion of the energy
through the liquids and so it’s important to use cut current that compensate these energetical dispersions.
By using coagulation currents and/or mixed cut currents the blood loss are reduced.
3.2 MONOPOLAR COAGULATION
When there is a temperature increment, for the heat produced for Joule effect in the tissue, it’s realized the thermical
coagulation and that is the partial solidification of the liquids and so the precipitation of colloidal substances. In particular
fibrin forms in the blood and it, solidifying itself, obstructs the blood vessels.
To obtain the coagulation by the electrosurgical needle it needs to supply the active electrode with intermittent current so that
the water goes out from the cell without destroying it. However also with the intermittent current, if the intensity of the current
is too intense, the cut effect is realized.
Active electrodes particularly adapted for the coagulation are the electrodes with sphere shape, plate, or lanceolate used
laterally.
The coagulation can be obtained by two different methods: by
desiccation
and
fulguration
.
Coagulation by desiccation
It’s obtained supplying the electrode by low voltages that not generate sparks (this guarantees that the action is pure coagulum
and so every effects of the cut is absent). The electrode is placed in direct contact with the tissue and the quantity of heat
developed desiccates it.
Generally the coagulated cellular surfaces act like an insulation layer, that prevents that the heat had to the successive
applications of the current penetrates too much in depth.
The current normally used for the coagulation is the modulated type. In function of the percentage of the modulation is realized
the precision of the cut, the goodness of the haemostasis and the level of the tissue destruction. A bigger modulation of the
current gives a cut more irregular, and a bigger depth of tissue destroyed but a better coagulation.
The following rules help the operator to obtain a good coagulation:
select a ball electrode or a large wire;
localize the vessel bleeding after have been dried the exceeding blood from the area;
touch lightly the vessel bleeding before to activate the electrode;