GIMA SpA
DIATERMO MB250 – DIATERMO MB400
MA303IGBa-19-03-2007 Manuale
d’Istruzioni / Instruction’s Manual
38
5.3.2
C
ORRECT
P
OSITION OF THE
P
ATIENT
-
PLATE
the use of the neutral electrode (or patient-plate for the leakage of current) is necessary in the monopolar tecnique, because it
allows the “return” of the cutting or coagulation current to the scalpel. The types of the neutral electrode are two:
neutral electrode by single surface
(with joint cables) where there is not a check on the contact between neutral
electrode and patient.
neutral electrode by two surfaces
(with divided cables) where there is a check on the contact between neutral
electrode and patient.
Keep attention on the correct position of the patient-plate to avoid burns and other risks for the patient, we recommended
regard to this by the following information.
(correct position)
In this picture it is shown the correct position of the neutral electrode by the two
surfaces. The patient-plate must be placed perpendicularly to the operative field.
It is important to avoid the transversal way and prefer the vertical or diagonal one,
thereby it is allowed an uniform delivery of the current on all two surfaces and
reduce the risk of burns for the patient.
(incorrect position)
Neutral electrode is often applied in an incorrect way, in parallel to the operative
field. So the current delivery is not uniform on the two surfaces, the acoustic
signal is started and the unit starting is not allowed.
Before to apply the neutral electrode, clean and eliminate any external substances from its surface.
Do not apply the neutral electrode oon cicatix, bony protrusion or near prothesis or monitoring electrodes. But apply it on
sprinkled tissues, such as muscles and near the operative site. If you use a disposable neutral electrode respect the date of use,
if you use a not disposable neutral electrode make sure that the fixing systems guarantee stability.
It is very important that the neutral electrode is firmly applied on all its surface to avoid burns. When the neutral electrode is
partially taken off from the patient, the current density on the remaining applied part is higher. Because the density of the
current flow under the neutral electrode is not uniform, it verifies a not uniform heating, exspecially near the bordes of the
neutral electrode.
If the electrode is applied in corrispondence of a zone subjected to pressure during operation, the compression load causes a
reduction of the skin perfusion. So the heat created can be partially eliminated, and so the risk of burns increases. The hazard
of decubitus increases too, because for the produced heating the O
2
and energy necessity increase in this part.
5.3.3
HF
E
LECTROSURGERY IN
L
APAROSCOPY
Since its introduction minimally invasive surgery has revolutionized surgical operation offerring any significant benefits to the
patient of faster healing and less postoperative pain. In laparoscopy the monopolar HF electrosurgery is the most used because
it is highly versatile (pure cut, coagulation, blended cut that combines these two functions), but tis modality can compromise
patient safety by burns.
The constricted view of the surgical field, the poor maintenance of the laparoscopic instrumentation, interference on the video
monitor, the insufficient training of the surgeon or his inattention, the smoke, the insulation failure, the capacitive currents, the
contact of the tip of the active electrode with the surrounding tissue, these are all factors that increase the hazard of burns,
intra-abdomen lesions, necrosis of the tissue, perforation of internal organs. The nature of the surgical environment – in which
the active electrode is in close proximity to other conductive instruments and to tissue- may make the electical currents
transmission to unseen tissue off the laparoscope, causing unintentional tissue burns at non-targeted sites, by:
-
direct coupling
-
insulation failure
-
capacitive coupling
Direct coupling occurs when the active electrode touches another metal instrument, transferring electrical current to itand
possibly injuring tissue with which it comes in contact (for example bowel or other organs).
Insulation failure occurs when there is an excessive voltage, abuse, wear and tear, poor handling, or mechanical accident of the
electrode shaft that happens during a single laparoscopic procedure or during disinfection and sterilization procedures. The
breakdown along the unseen shaft of an activated electrode can allow electrical current to leak into surrounding non-targeted
tissues, causing unobserved damage. Paradoxically, small cracks are more dangerous than large breaks because the current is
more focused, and is therefore more likely to produce burns.
Capacitive coupling occurs when electrical current is induced from the active electrode to nearby conductive material, despite
intact insulation. During HF electrosurgical operations the rapidly varying electrical field around the active electrode is only
partially impeded by electrical insulation and creates stray electrical currents by alternately attracting and repelling ions in
