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Sterilization ofEndoscopic Instruments
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6 Steps inEndoscopic Instrument
Reprocessing [21]
The steps in endoscopic instrument reprocessing
include the following:
1. Dismantling
2. Decontamination
3. Pre-cleaning
4. Cleaning and rinsing
5. Rinsing-ultrasonic cleaner
6. Drying-packaging for sterilization
7. Sterilization/disinfection
8. Instrument storage
6.1 Dismantling
Most laparoscopic hand instruments exist as
articulations of different parts which should be
separated as the rst step in processing. This
exposes the grooves and crevices which may harbour tissue debris and microorganisms. The ports
(trocars and cannulae) and sheaths used in hysteroscopy should all be dismantled for proper
processing.
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6.2 Decontamination
This process should start in the operating room; it
reduces the load of microorganisms and renders
the instruments safe for handling prior to further
processing and transfer to the CSSD.The trained
healthcare worker (nurse or certied surgical technician) should wipe off any visible tissue, debris,
body uid or bloodstain from the instrument with
a sterile but damp sponge. The instruments are
then immersed inside a receiver containing disinfectant such as 0.5% chlorine or hypochlorite solution. They are allowed to soak for 10min. There is
no benet in soaking for longer as this predisposes
them to corrosive damage (Fig.1).
6.3 Pre-Cleaning
This should be done in the CSSD or in the theatre, away from the operating room or any
other controlled area within the theatre, but not
Fig. 1 Decontamination: the instruments should be
immersed in the disinfectant
where sterile instruments are kept. The preferred pre- cleaning method involves the use of
enzymatic products such as protease, lipase
and amylase. These proteases break down
blood and other protein stains on the instruments; they should, however, be thoroughly
removed from the instruments by cleaning. The
use of detergents and soap scrubs may not be
effective, because of their limited capacity to
lyse protein debris especially on the surfaces
of instruments with areas that are hard to reach
for cleaning (Fig.2).
6.4 Cleaning andRinsing
Cleaning should be done with soft brushes so that
debris can be removed from the groves of instruments. Rinsing is best done under running water
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J. O. Imaralu et al.
The solution used for ultrasonic cleaning should
have a neutral pH (to prevent corrosive damage) and
instruments should be immersed in it for 10–15min.
Instruments made of similar material—metals such
as aluminium—should be cleaned together separate
from other instruments made from, for example,
stainless steel and other materials. To allow optimum penetration and effect, the ultrasonic cleaner
should not be overloaded and all instruments must
be open. Rinsing must be done for all instruments
that have undergone ultrasonic cleaning.
6.5 Drying
It is necessary to exclude water droplets from the
instruments before they are packed for sterilization. This can be achieved with the use of an oven
in the CSSD or an air gun.
6.6 Sterilization or Disinfection
Fig. 2 Enzymatic products are preferred for
pre-cleaning
to clear all particulate matter and chemicals used
for decontamination, pre-cleaning and cleaning.
High-pressure running water taps or cleaning
guns, where available, can be used for rinsing.
These guns give a directed jet of water to long
instruments and instrument grooves. Stagnant
water in containers should be avoided during
manual cleaning as it may retain particles and
solutions which may get on to other instruments.
All instruments should be open during the cleaning process, to expose ratchets and locks and
indeed all parts of the instrument to the cleaning
agent. If cleaning and rinsing are done together,
re-rinsing or proper rinsing must be done again
after a brush or other forms of cleaning.
Ultrasonic cleaning is a method that is rapidly
increasing in popularity. The ease of use, time
saved and better efciency make it a better method
than manual cleaning. Ultrasonic cleaning is 16
times more efcient than hand cleaning.
It is widely recommended that rigid endoscopic
instruments should be sterilized or at least highlevel disinfected where sterilization is not feasible. Users of endoscopic instruments, however,
should take note of manufacturer information
regarding what to sterilize or high-level disinfect,
the method of sterilization, the type of disinfectant to be used, their dilution instructions and the
number of times or length of time a constituted
high-level disinfectant solution can be used.
Sterilization is superior to HLD, for infection
control; however, because of the fragile nature of
some instruments, sterilization methods may not be
feasible. The cost and availability of the sterilization methods are also important considerations.
6.6.1 Sterilization
There are three major sterilization methods:
1. Steam sterilization
2. Gas sterilization
3. Peracetic acid sterilization
• Steam Sterilization
The use of the autoclave for sterilization is one
of the commonest methods employed. It is
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cheap and non-toxic yet an effective method.
Autoclaving at 121°C for 15min is sufcient
for all reusable metal instruments. This
method is effective for all rigid endoscopic
instruments and some telescopes. Packaging
of instruments for steam sterilization should
be such that all items that can be damaged by
heat conduction like silicone tubing, rubber
insulations and coatings on cables and instruments are shielded by wrapping in two layers
of linen to prevent contact with the metal container of the autoclave.
Some Notes on Flash and Vacuum
Sterilization
1. Flash Sterilization
This was dened by Underwood and
Perkins as sterilization of unwrapped items at
132°C for 3min at 27–28 lbs of pressure in a
gravity displacement sterilizer [22]. It was
designed for use in the theatre for emergent and
immediate use of a forgotten or unanticipated
instrument or one that was accidentally dropped
on the oor. It is a modication of conventional
steam sterilization whereby the ashed item is
placed in an open tray or is placed in a specially
designed, covered, rigid container to allow for
rapid penetration of steam. The term “immediate-use sterilization” currently replaced ash
sterilization. It is sterilization with little or no
dry time available. It is safe and efcacious
when done correctly and when only used to
process instruments intended for immediate
use. It should not be used for reasons of convenience or to save time.
2. Vacuum Sterilization
A sterilizer congured to run a vacuum
cycle is equipped with a vacuum system. A
typical vacuum cycle will begin with a series of
alternating steam pressure injections and vacuum draws (also called pulses) to dramatically
remove the air from the chamber. This will
allow steam to be sucked into areas where it
would otherwise have difculty penetrating.
• Low-Temperature Steam and Formaldehyde
Sterilization
This method is especially suited for heatsensitive instruments like cables, insulations,
tubes and instruments with blind-ending
lumina. It employs heat at temperature ranges
of 55–80°C, for about 5–6h. It is important to
note that the use of formaldehyde for sterilization is fast diminishing in popularity; some
reasons for this include the potential risk for
toxicity and irritation when in contact with the
skin, eyes, nose and respiratory tract. Its efcacy in the sterilization process is being queried in reports from some studies.
• Gas Sterilization
Gas sterilization is useful for hand instruments
that are coated with insulation material, light
cables and tubing for gas and suction irrigation. Disposable instruments can also be
reprocessed using this method. Ethylene oxide
(ETO) is the gas that is used for gas sterilization. Cold ETO sterilization is done at a
temperature of 85 °C and instruments are
exposed to the gas for 4h 30min, and they are
then aerated for 12h. Warm ETO sterilization
is, however, done at a temperature of 145 °C
with instrument exposure of 2h 30min and a
shorter aeration time of 8h. Gas sterilization
has the advantage of ensuring that porous
materials and deeper instrument areas are
reached without corrosive damage to them. Its
demerit, however, is that the set-up is expensive and the required steps of exposure and
aeration consume a lot of time.
• Newer Methods of Sterilization
This method uses the plasma chamber
(STERRAD) developed by Johnson and
Johnson. It uses hydrogen peroxide vapour
and low- temperature gas plasma. The entire
process with this method takes only about
25 min. The instruments should have undergone the earlier decontamination-cleaning
cycle and should have been properly packaged. A vacuum is created inside the equipment chamber and 59% aqueous H2O2 is
vaporized into it, enveloping all the items until
when the H2O2 vapour is well diffused. The
chamber pressure is then reduced to allow the
generation of low- temperature gas plasma. A
radiofrequency amplier is used at this time to
introduce radiofrequency energy into the
chamber—thus causing the generation of
reactive free radical species from the
vapourized H2O2 which comes in contact with
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the instruments. The reactive energy species
also react with each other to form water
vapour, oxygen and other non-toxic byproducts. The instruments are then dried by
the equipment and are ready for use or storage. The advantages of this new method that
make it cost-effective include the fact that it
can be used in areas where there is rapid turnover and a shorter processing time is required.
There are no toxic residues and there is no
requirement for aeration or water hook- up
within the set-up. The equipment is not big
and does not take space; it requires only a reliable source of electricity supply.
6.6.2 Disinfection
High-level disinfection (HLD) is particularly
useful for semi-critical instruments and fragile
heat-sensitive instruments. Its effect on spores is,
however, relative and depends on the duration of
exposure of microorganisms to disinfectant, the
concentration and temperature of the disinfectant, the amount and kind of microorganisms,
organic material (blood, other uids, tissues) and
other matter (for example, dirt) present on the
instrument or other item and the access to the
microorganisms (for example, grooves can shield
microorganisms). It is therefore pertinent that
instruments for HLD undergo the preliminary
phases for thorough decontamination.
HLD destroys all pathogenic microorganisms
and some bacterial spores (e.g. Clostridium dif-
cile) during short exposure. During long exposure, it is sporicidal for a higher number of
bacterial endospores and has a limited sporicidal
capability for mycobacteria, viruses and fungi.
Mycobacteria are used as indicators of effectiveness. The agents that are popularly used for HLD
include 2% glutaraldehyde, 6% stabilized hydrogen peroxide and peracetic acid (a mixture of
acetic acid and hydrogen peroxide).
The ideal chemical high-level disinfectant
should have the following characteristics:
1. Rapid turnover rate HLD (<10min).
2. Effective against a wide range of organisms
including blood-borne viruses and prion
proteins.
3. There should not be any disinfectant residue
after rinsing.
4. Excellent compatibility with endoscopes and
other instrument materials.
5. Long shelf-life.
6. Non-irritant and non-toxic to users.
7. Environment-friendly, i.e. have no disposal
problems.
• Glutaraldehyde
This is the most recommended chemical disinfectant agent, by most laparoscopic instrument manufacturers. Some of its advantages
include the following: it is safe, is relatively
inexpensive, has good microbicidal activity, is
non-corrosive to optics, and is effective in the
presence of protein matter. It is, however, irritating to the eyes, skin (allergic contact dermatitis), and respiratory mucosa especially at
higher concentrations ≥0.3 parts per million
(ppm). It has a pungent and irritating odour
and can coagulate and x blood and tissues to
surfaces. It thus requires thorough rinsing off
from the instrument before use. Most commercially available glutaraldehyde solutions
can be used (after preparation) for between 14
and 30 days. The manufacturer’s preference
for the duration of usage varies and it is advisable that this is followed. The effectiveness of
glutaraldehyde as an HLD depends on its concentration, the instrument contact time, the
physical conguration of the instrument, temperature, pH and the amount of organic matter
on the instruments. The OSHA recommends
that the maximum allowable concentration of
glutaraldehyde is 0.2 ppm. Instrument exposure can however be varied to suit the HLD
needs, for instance, bre-optic light source
cables and telescopes should be soaked for a
minimum of 10min. The endocamera (chargecouple device [CCD] only) can also be soaked
in 2% glutaraldehyde for 10 min, but care
must be taken to avoid soaking the plug part of
the cable. Soaking of optical instruments
should be for not more than 20min. Metallic
hand or accessory, trocars, reducers, ring/clip
applicators and dye injectors should be soaked
Sterilization ofEndoscopic Instruments
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in 2% glutaraldehyde for 60min (long exposure) to achieve better destruction of mycobacterial spores. Glutaraldehyde is marketed
with trade names as Cidex or MetriCide.
Another form known as rapid Cidex or
Rapicide exists which provides for shorter
instrument exposure of 5min.
A particular non-tubercolous mycobacterium, M. massiliense BRA100 strain, has
been found to be resistant to high-level disinfection with glutaraldehyde, even at high
concentrations (7% glutaraldehyde), thus
suggesting that glutaraldehyde may not be
effective for rapidly growing mycobacteria.
Orthophthalaldehyde (OPA) and peracetic
acid may substitute glutaraldehyde for HLD
with better efcacy [23].
• Orthophthalaldehyde (OPA)
This is sold as Cidex OPA and it exists in the
concentration of 0.55%. This agent can provide effective high-level disinfection and can
destroy all bacteria, fungi and mycobacterial
spores with instrument exposures of as short
as 5–12 min. Its minimum effective concentration is 0.3%, and after preparation, the solution can still be effective for 14 days. It is
non-irritant to the eyes and mucus membranes
and non-corrosive to instruments and has a
weak odour. Its disadvantages, however, are
that it is expensive and stains protein grey, and
hypersensitivity reaction has been reported in
some patients with a history of bladder cancer
[19] (Fig.3).
• Notes on Hydrogen Peroxide and Peracetic
Acid for High-Level Disinfection
The characteristics of an ideal chemical sterilant used as a high-level disinfectant should
include broad antimicrobial spectrum, rapid
activity and masterial compatibility. The ideal
HLD should be odourless, be safe, have prolonged shelf-life, and be generally costeffective. Hydrogen peroxide and peracetic
acid are both oxidizing agents that generate
free radicals which can attack membrane lip-
33
Fig. 3 Orthophthalaldehyde (OPA)
ids, DNA and other essential cell components.
Cidex PA is one brand of high-level disinfectant that contains 0.08% peracetic acid and
1.0% hydrogen peroxide [24, 25]. It inactivates all microorganisms within 20min with
the exception of bacterial spores. The risk of
corrosive damage to instruments is a major
drawback to this disinfectant. Olympus does
not endorse Cidex PA on any of their endoscopes and will not assume any liability for
chemical damage. The manufacturers of Cidex
PA currently are reformulating this product
(altering the buffer system and changing anticorrosive inhibitors) to improve its material
compatibility.
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6.6.3 Quality Control Measures
forSterilization
andDisinfection
• Bacteria indicator count: Cultures swabs
should be taken from the telescope and other
instrument tips and surfaces routinely.
• Strip checks on the disinfectant: Manufacturer
directions should be followed.
• Temperature and pH monitoring: They are
also essential, for optimal effect of the sterilants and chemical disinfectants.
• Keep a log for accountability: This includes a
log reporting entry and exit of instruments at
every stage of reprocessing with timing properly recorded. A log of both instrument and
sterilant usage frequency should also be kept.
7 Storage ofProcessed
Endoscopic Instruments
The proper storage of processed unused instruments is very important. It is recommended that
high-level disinfection be done when instruments
are needed for use, because of the short processing time involved. However, because sterilization
is more expensive, time-consuming and tedious
and has greater potential to eradicate all forms of
microbial existence, storage of sterilized instruments becomes expedient. In addition, thirdparty sterilized instruments would need storage
when they arrive at centres where they are
required before use, or before transport to centres
where they are required.
Effective storage of endoscopic instruments
to prevent contamination should take note of
the following points: the storage shelves and
cabinets (whether open or closed) should be
dry or have very low humidity, the material
used for wrapping the instruments should be
such that would remain intact and dry, handling of sterile packs not meant for use should
be limited, and the storage time should be kept
as minimal as possible, to prevent moisture and
contamination.
8 Notes onEmerging Disease
Pathogens Related
toEndoscopic Surgery
As minimal access surgery becomes increasingly
available, it becomes more accessible to patients
with chronic infectious diseases. Examples of
these infections include hepatitis C virus, HIV,
Clostridium difcile, Cryptosporidium,
antibiotic- resistant microbes (MDR-TB, VRE,
MRSA), Helicobacter pylori, newer strains of E.
coli, coronaviruses (SARS-CoV and MERsCoV) and Creutzfeldt-Jakob disease (no brain,
eye, or spinal cord contact).
Standard disinfection and sterilization procedures for patient and equipment care are adequate
to sterilize or disinfect instruments or devices
contaminated with blood and other body uids
from persons infected with emerging pathogens.
Where there is doubt, disposable or single-use
endoscopic instruments should be used.
9 Conclusion
Endoscopic surgical equipment and instruments
are peculiar for their complexity and high cost;
the level of disinfection or sterilization is dependent on the intended use of the item. Critical items
(devices that contact sterile tissue such as surgical
hand instruments) require sterilization, while
semi-critical items (devices that contact mucus
membranes such as endoscopes) require a minimum of high-level disinfection, and non- critical
items (objects that contact intact skin such as
electrosurgical return plates, patches and cables)
require low-level disinfection. Cleaning should
always precede disinfection and sterilization.
Learning Points
• Endoscopic instruments are complex in design
and contain many articulations and crevices
where tissue debris and microorganisms can
get lodged.
• The focus of endoscopic instrument repro-
cessing includes the prevention of hospital-
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35
acquired surgical site infections and
prolongation of instrument lifespan.
• Most laparoscopic instruments can be classied as semi-critical devices and high-level
disinfection is considered appropriate.
• All the preliminary steps in endoscopic instrument processing should be followed to aid
effective sterilization or disinfection.
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The Electrosurgical Unit: Basic
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Principles forPractice
JosephIfeanyichukwuIkechebelu
andChukwuemekaO.Ezeama
1 Historical Perspective
Human beings have traditionally been dependent
on re for their very existence; unsurprisingly its
use for medicinal purposes was initiated shortly
after its discovery [1, 2]. Cautery is mentioned in
some very early medicinal texts credited to
Hippocrates [2, 3]. It was used to stop bleeding
from injuries, amputations, etc.
From the late eighteenth century up until the
late nineteenth century, the discovery of electricity and its application rose exponentially. Several
renowned scientists including Galvani,
Becquerel, Sèrè, D’Arsonval, Doyen and
Nagelschmidt were pioneers in the eld of electricity and its use in medicine.
J. I. Ikechebelu (*)
Gynaecology Endoscopy and Assisted Reproduction
Unit, Department of Obstetrics and Gynaecology,
Nnamdi Azikiwe University, Awka, Nigeria
e-mail: ji.ikechebelu@unizik.edu.ng
C. O. Ezeama
Gynaecology Endoscopy Unit, Department of
Obstetrics and Gynaecology, Nnamdi Azikiwe
University Teaching Hospital,
Nnewi, Anambra State, Nigeria
e-mail: co.ezeama@unizik.edu.ng
The basic electrosurgical unit was produced
by William Bovie. His invention was tested in
1926, while its use during surgery for a vascular
myeloma was carried out by Dr. Harvey Cushing
[4]. Since the rst ‘Bovie’ unit was used, many
modications have been introduced to make this
instrument a safe and important part of the surgeon’s armamentarium.
It works by applying the principle that passing
an alternating current through tissues generates
certain effects which the surgeon can leverage to
improve surgical precision and reduce bleeding
during procedures. Intimate knowledge of the
principles of electrosurgery is paramount for current surgical practice [5].
2 Biophysical Principles
The three main properties of electricity are current (I), voltage (V), and impedance (R).
Current is a measure of the movement of
electrons within a circuit. It is measured in
amperes.
Voltage expresses the force required to push
electrons through a tissue; this is measured in
volts.
Impedance/resistance is a measure of the difculty the current must overcome to pass through
a given substance (i.e., biological tissues); it is
measured in ohms.
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature
Switzerland AG 2022
J. E. Okohue et al. (eds.), Gynaecological Endoscopic Surgery,
https://doi.org/10.1007/978-3-030-86768-3_4
37
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J. I. Ikechebelu and C. O. Ezeama
In an electric circuit, these three properties are
expressed by Ohm’s law: I=V/R.
Power is the ability to do work per unit of
time and is measured in watts. It is mathematically expressed as the product of voltage and current W=V × I
Since I=V/R,
Then W (power)=V × V/R=V2/R
Or W=V × I=I2R
Heat/energy produced=W × T (time)=I2RT
3 Types ofCurrent
3.1 Direct Current
As seen in computer and car batteries. Here the
current is unidirectional and does not change
polarity.
3.2 Alternating Current
where the current changes direction (polarity)
periodically as seen in our home electrical
outlets.
Application of direct current during surgery
would lead to an electrolytic effect causing generation of sodium hydroxide and hydrogen chloride. These would have a seriously deleterious
effect on the cells leading to necrosis. The use of
low-frequency alternating currents (under
10,000Hz), apart from causing similar problems,
also predisposes to stimulation of nerves and
muscles (Faraday effect) [6]. Due to these
unwanted effects, the current used in electrosurgery is high-frequency alternating current (over
300kHz).
From the above, it can be surmised that the
human body, when inserted into an incomplete
circuit, completes the circuit and conducts
electricity. When voltage is applied across the
human body, its electrons are forced to move.
The tissues of the body resist the ow of these
electrons and in doing so cause a local rise in
temperature. The thermal energy occurring in
these areas of the body causes local tissue damage and destruction.
The biophysical principle equations above
show clearly that the voltage is directly proportional to the power produced and also the tissue
destruction it produces. Also, the time the electrode is applied is directly proportional to the
thermal effects generated. The surface area of the
electrode used or the tissue in contact is inversely
proportional to the heat produced at the site of
application per unit time.
3.3 Thermal Eects onTissue
Electrical currents when passed through tissues
particularly those with a high uid content cause
movement of molecules and subsequent heat
generation. The tissue effect of this heat varies at
different temperatures.
4 The Electrosurgical Generator
(Electrosurgical Unit [ESU])
In the earlier section on the type of current, the
alternating high-frequency current was recommended as most appropriate for electrosurgery.
To generate this current, special equipment called
electrosurgical generators are used. They ramp
up the normal current frequency seen in house/
theatre outlets from 50–60 Hz to 500,000–
3,000,000Hz [7]. This very high frequency does
not allow the faradic effect.
The tissue effect of this current depends on
several factors, but the thermal damage on tissue
is generally directly proportional to the volume
of current passing through it. This thermal effect
is a function of current density.
The size/cross-sectional area of the electrodes determines the density of the current at
its tip. Smaller electrodes have a larger current
density than larger-sized electrodes. Various tissue types have different electrical resistance,
which affects the rate of heating. Adipose tissue
and bones have high resistance and are poor
conductors of electricity, whereas muscle and
skin are good conductors of electricity and have
low resistance.
The Electrosurgical Unit: Basic Principles forPractice
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39
Fig. 1 ESU output
modes
Cutting mode
Blend mode
Coagulation
mode
Fulguration
mode
The output from the generators can be modied to produce specic tissue effects. The various outputs are determined by the shape of the
waveform and the duration of the specic duty
cycle (the term duty cycle is used to describe the
percentage of time that the ESU is producing a
waveform—if it is 80% of the time, it is referred
to as an 80% duty cycle).
Output modes include cutting, coagulation,
blend, and fulguration modes (see Fig.1).
4.1 Cutting Mode
Peak
Voltage
Average
Voltage
Watts [9]. The coagulation mode can be used for
desiccation or fulguration depending on the
active electrode positioning to the target tissue.
4.3 Desiccation
Using the coagulation mode, the surgeon can
desiccate (loss of water from the tissue cells but
no signicant protein damage). The end result is
deeper necrosis and greater thermal spread. For
desiccation, direct contact of the electrode with
the target tissue is necessary.
This mode has a continuously high current and
low-voltage waveform, causing a very rapid rise
in temperature of up to 100°C.As earlier noted,
this causes vaporization of cell uid and disruption of their membranes, thus resulting in cutting
with no coagulation. The duty cycle in this mode
is 100%. A power setting between 40 and 80
Watts is ideal for this mode [8].
4.2 Coagulation Mode
This is a high-voltage mode with the waves
dampened and produced in bursts. The duty cycle
in this mode is typically 6%. The pulsed nature of
the current delivery allows for cooling of the tissues in between pulses and minimizes the cutting
effect while allowing for the production of coagulum due to dehydration and denaturing of the
tissue proteins. This coagulum is very effective
for haemostasis. The coagulation current is operated with a power setting between 30 and 50
4.4 Fulguration
This is coagulation in a non-contact position. The
electrode is held 2–4 mm away from the target
tissue. An arc of current is formed which nds its
way to the tissue in a spray-like effect, hence the
name ‘spray coagulation’. This is due to the rapid
rise in temperature and subsequent rapid cooling
resulting in supercial coagulation, typically to a
depth of about 0.5 mm. It covers a wider area
than the surface area of the electrode alone. Its
benet is seen in small arteriolar and capillary
bleeding.
4.5 Blended Current (Cut/
Coagulation)
Blended currents are actually modulated lowvoltage waveforms. It produces different tissue
effects by modulating the duration of the duty
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