Maintaining an electrosurgical machine
o Principles of operation
function
use
scientific principles
o construction o preventive maintenance
components replacing
system diagram
components
inputs/outputs calibrating
o troubleshooting o safety considerations
identifying common user and patient
faults safety
replacing components electrical safety
rectifying faults o performance monitoring 13.5.4 Maintaining an electrosurgical machine
calibration
Unit B 13.6 Maintaining theatre and surgery equipment
quality assurance and
Module 279 18 B Medical Instrumentation I
control
dr. Chris R. Mol, BME, NORTEC, 2015
Electrosurgical machine: four common techniques
1. electro-dessication dessicate
a highly damped waveform is supplied to the contact point, to dry out thoroughly
active electrode, a ball, needle or blade which is placed on the
tissue before energizing and produces coagulation around the
site.
2. electro-fulguration fulgurate
a highly damped waveform is used but the active electrode is held the destruction of small growths or
1 to 2 mm above the tissue and - when energized - sparks spray areas of tissue using diathermy.
the area drying it out and leaving some burning of cell edges.
3. electro-section section
an undamped waveform is applied to the active electrode, which is also: slice, segment, part, …
placed on the tissue surface creating an incision.
4. electro-coagulation coagulate
a damped waveform is delivered to the patient to stop bleeding change to a solid or semi-solid state.
without doing any additional cutting. also: congeal, clot, solidify, thicken …
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Electrosurgical machine: monopolar electro-
surgery
All electrosurgery techniques require two connections to the patient, the active electrode (or pen, or bovie
pen) and the reference electrode (or dispersive or ground electrode).
For monopolar electro-surgery, the reference electrode is placed under the patient and the active electrode
is held in the surgeon’s hand.
low heating
at dispersive
electrode!
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Electrosurgical machine: use
The Bovie pen (or ESU pen) is held on the patient by
the surgeon.
The dispersive electrode can be a metal plate covered
with a conductive gel or saline soaked cloths.
Many are now using single use dispersive
electrodes. Single use devices are often pre-
gelled, conductive adhesive pads that include
multiple connections to the machine. The
multiple connections are used to allow the device
to constantly check for a good contact between
the patient and the dispersive electrode.
Poor contact with the dispersive electrode is the most common
cause of unintentional patient burns. In modern ESU machines, the
dispersive electrode must touch the patient to prevent an alarm.
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Electrosurgical machine: construction
The generating unit itself is often called a Bovie. It is generally a solid state device that can produce 300 to
3000 kilo Hertz. Most machines produce 25-200 Watts. Conceptually, the Bovie breaks up the 50 Hz from
the wall into many shorter pulses, then uses a transformer to generate the high voltage required (figure).
Activation of the electrosurgery is done by the surgeon using either a hand switch on the bovie pen
or by stepping on a foot switch. Both have two contacts one labelled CUT for electro-section and the
other COAG for electro-dessication or electrofulguration.
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Troubleshooting
The most common problems in electrosurgery are:
• burns, excessive tissue damage, damage to alternate sites (areas of the patient's body other
than the target surgical site)
• fires
• interference with other devices.
Skin burns are the most frequently reported of these problems, usually occurring at the return electrode
site. Partial or complete detachment of the electrode pad from the patient is the most common cause.
The dispersive electrode should always be placed on an area of the body that has good blood flow and is
not subject to high weight concentration. The side of the thigh is a very common location, under the
buttocks is not a good location as it generally is a high weight bearing point.
In older machines, the lack of contact with the electrode may not be detected by the system. The effect can
be patient burns where the electrical current finds an alternative path to ground. In newer machines, the
generator has two connections to the dispersive electrode. When connected to the patient, a small current
is passed between the two halves of the dispersive electrodes. When not properly connected to the
patient, the current cannot pass and an alarm will sound.
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Electrosurgical machine: Trouble shooting
If the tip is dirty, there can be little, or no, current passing through the patient. The bovie pens are not
intended to be reused. However, they are often reused in the developing world.
In addition to problems with dirty tips, the wires become
broken with reuse. They are simple wires which can be
re-soldered for repairs.
If the wire break is in the pen, the pen can be taken
apart, the wires reconnected and the pen glued together
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Electrosurgical machine: Safety considerations
The ESU is inherently a potentially dangerous device. All members of the surgical team using an ESU must
be fully aware of the hazards, understand the principles of operation and safe handling, and be familiar
with the abilities and limitations of their particular unit (training !)
The main risks associated with electrical surgery
Burns
Electrical interference with the heart muscle
Explosion/fire caused by sparks and
Electrical interference with pacemaker and other medical equipment.
Sparks are a common occurrence when electrosurgery is in use. When oxygen is being administered to
the patient, it may leak, creating an atmosphere where fires can quickly ignite. The drapes covering the
patients should be flame retardant but will burn under the right conditions. Special care is required when
doing neck or mouth surgery to avoid a flash fire.
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Electrosurgical machine: Performance monitoring
An electrosurgery unit can be checked and calibrated easily and efficiently through the use of an
electrosurgery tester.
• You cannot test the device by performing the operation on a resistor in most cases. Although 400
Ohms would work, only a resistor with a very large power rating will survive the procedure. Such
large power resistors are generally not available in the developing world.
In most cases, a bar of soap or a fresh piece of citrus fruit (like an orange) can be used to do your initial
testing. Be sure that both sides of the dispersive electrode are touching to prevent an alarm.
In many cases, you will want a final test on meat. A reasonable final test is to cut a raw piece of chicken, pork
or beef. Be sure that the indifferent electrode is touching the meat before testing. Both sides of a split
dispersive electrode must touch the meat to avoid an alarm! It is best to conduct the final test with the
physician present. In this way, you can not only assure that the device is minimally operating, but you can
also be sure that it is operating in a manner that satisfies the physician.
For more modern units, insure that the dispersive electrode alarm is working by disconnecting half of the
electrode from the meat, or pulling the dispersive electrode out of the machine.
dr. Chris R. Mol, BME, NORTEC, 2015 Electrosurgical machine
Electrosurgery Links
Electrosurgical Principles
• https://www.youtube.com/watch?v=7LW78yoaEe0
Principles of Electrosurgery in Laproscopy
• https://www.youtube.com/watch?v=mqmvaKxfq3A
Understanding Electrosurgery
• http://www.boviemed.com/products_boviemed_lit/pdfs/aaron_understanding_sc.pdf
Electrosurgery Manual
http://
www.klsmartin.com/fileadmin/Inhalte/Downloads_Prospekte/HF-Geraete/90-604-02-04_09_06_Handbuch_HF.pdf
Electrosurgical Checklist
• http://mdsr.ecri.org/summary/detail.aspx?doc_id=8271
Electrosurgery Self-study guide
• http://www.covidien.com/pace/clinical-education/273622
dr. Chris R. Mol, BME, NORTEC, 2015
END
The creation of this presentation was supported by a grant from THET:
see https://www.thet.org/
