Olympus ESG-410 - Glossary; Key Term Definitions

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Glossary
19 Glossary
Ampere
The ampere or amp (symbol A) is the base unit of electric current in the International System
of Units.
Applied part
An applied part, according to standard IEC 60601-1, is a part of a medical electrical
equipment that comes into physical contact with the patient, e.g. an HF instrument. Or, it
is that part of an medical electrical equipment through which current can ow between the
patient and the medical electrical equipment, e.g. the neutral electrode socket.
Bipolar electrosurgery
Bipolar electrosurgical instruments are designed in a way that the current passes only
between the 2 electrodes that are implemented within the same device, e.g. between the
jaws of a bipolar forceps. In bipolar electrosurgery the current does not pass large parts of
the patient’s body but only through the tissue that is in contact with the two electrodes within
the electrosurgical instrument. Only the target tissue is part of the electrical circuit.
Compare with glossary entry “Monopolar electrosurgery”.
Coagulation
A temperature of 60 to 70 °C in the area around the instrument’s electrode gradually heats
the tissue cells until their intracellular uid escapes through the cell membranes. The
results are protein denaturation, shrinking of the cells and of vessels, clotting of blood and
hemostasis.
Coagulum
A semisolidied mass, as of blood or lymph, also called clot. Coagulum that sticks to the
electrodes can impede the performance.
CQM
Abbreviation for Contact Quality Monitor. The CQM is able to detect detachment of the
neutral electrode from the patient, if a split type neutral electrode is used. Refer to section
“6.1 Split type and non-split type neutral electrodes and CQM” on page 44.
Current density
The greater the current is that passes through tissue, the greater the effect is on the tissue.
With respect to electrode size, smaller electrodes provide a higher current density and
result in a concentrated heating effect at the site of tissue contact. Following the same
principle, the neutral electrode used in monopolar electrosurgery is large in relation to the
electrode of the electrosurgical instrument. By dispersing the current that is returning to the
electrosurgical generator the neutral electrode minimizes heat production at the attachment
site.
Cutting
When the generated heat causes the intracellular uid to rapidly evaporate, then this
results in an explosive burst of the cell membrane. To achieve this, a very high voltage of
approximately 200 Vp is required. Such a high voltage generates sparks between the tissue
and the instrument’s electrode/s. These sparks concentrate the HF current to specic points
of the tissue that heats up to more than 100 °C. The fast repetition of this effect around the
active electrode determines the cut.
Crest factor
The crest factor is a waveform parameter of alternating current. It shows the ratio of peak
values to the effective value. High crest factors indicate peaks.