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| Pharmaceutical companies Guide
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Procedure for Decontamination of medical equipment
Decontamination equipment, medical equipment, decontamination of medical equipment
Introduction
Medical equipment decontamination involves the total eradication of any
organism that is present to avoid infection to other patients or the staff
of hospital.
If the equipment is shared between 2 persons without being decontaminated,
the Microbes(bacteria & viruses) can infect the other person, therefore
equipment needs to be decontaminated after every use. While examining
patients they can also be present on the surface of the skin, so washing
hands after examining each patient is important. Microbes enter the body
through wounds that are open, by inhaling infected secretions or by having
close contact with the membrane of he mucous. When microbes pass from
one infected person to another , the process is known as ‘cross infection’.
Decontamination process involves Cleaning, disinfecting and sterilizing.
Chances of cross infection can be reduced if equipment is Decontaminated
after every use also it enhances the useful life of equipment.
Some Definitions
Cleaning is the process of removal of micro-organisms,
organic matter like vomit, blood etc and contaminants like dust particles.
Organic matter on which micro organisms thrive is also removed through
cleaning.
Disinfection is a process wherein micro- organisms are
not killed or removed but their no is reduced to a level which does not
harm an individual’s health.
Sterilisation is a process where there is removal or
killing all forms of microbial life which includes bacterial spores also.
Any instrument or any medical equipment that comes in contact with a patient
is a source of infection. These infection can be categorized under 3 kinds
of risks:
• high
• intermediate
• low
Items of High risk are which come in close contact with
any opening in the skin or mucous membranes or introduced to a normal
sterile area of the body e.g. instruments used in surgery, all types of
catheters & needles. This group require Sterilisation.
Items of Intermediate risk which are in close contact
with mucous membrane or items contaminated with virulent or readily transmissible
organisms. e.g. respiratory equipment Items which includes laryngoscope
blades, endotracheal and tracheostomy tubes, oropharyngeal and nasal airways.
This group requires Disinfection
Items of low risk are which come in contact with body
e.g. stethoscopes or washing bowls. This group requires only adequate
cleaning.
Disinfection and sterilization Techniques
An equipment should be properly cleaned before it is to be disinfected or
sterilized. Simple washing with water and soap is fine. Body should be protected
by covering with apron, facemask and gloves.
Moist heat such as boiling water upto 100°C for 10-15 mins kills all organisms
except for some bacterial spores. It is the best way of Disinfecting. One
important thing to remember that temperature at which water starts boiling
decreases as we go above in altitude and boiling time has to be longer for
e.g at 3000m above sea level where boiling occurs at 90°C a minimum of 15
-20 mins is required for disinfection. For sterilization of medical equipment
boiling is not an effective technique.
Chemicals are another way of Disinfection, which may be toxic when in direct
contact with skin or if inhaled. Chemicals can also have corrosive or flammable
nature so one needs to protect the body with proper cover like apron, gloves
and facemask. There are two types of Chemical disinfectants , one which
are ready to use and other which require dilution to give an adequate solution.
Disinfectants can also decay and lose activity. High temperatures lead to
rapid decay and presence of impurities can accelerate the decay. Disinfectants
need time to work. tpf tpf
Arena of activity of disinfectants
Gram positive bacteria e.g. Staphylococci, is relatively
sensitive than gram negative bacteria e.g. Pseudomonas. More resistant are
Mycobacteria and spores. Enveloped viruses e.g. HIV are destroyed by most
disinfectants but non-enveloped viruses e.g. Coxsackie are relatively more
resistant .
Spores. Disinfectants easily kill fungal spores. Bacterial
spores like Clostridia has developed resistant to most disinfectants in
general use.
More resistant to chemical disinfectants are Tubercle bacteria than other
bacteria.
Viruses. HBV and HIV are inactivated by Cidex in 2 -3 minutes,
to ensure adequate penetration, soiled items should be kept in a 2% glutaraldehyde
solution for nearly 30 minutes. Exposure to 70% alcohol solution for 10
minutes is also very effective. Viruses causing Rabies, Lassa fever and
other haemorrhagic fevers are also destroyed by Cidex. tpf tpf
Chemical disinfectant Solutions
Soluble Phenolics like Stercol & Hycolin are very effective
for destroying most bacteria including TB.
There activity is limited against viruses.
Hypochlorites like Presept & Milton has a wide range
of activity against bacteria, fungi, viruses and bacterial spores.
Any area with blood spillage can be decontaminated with these solutions.
Correct concentration should applied as they are corrosive in nature. They
decay on storage and get inactivated by organic matter.
Alcohols like methanol, ethanol & isopropanolol are
very effective against bacteria & viruses. Alcohols should be used only
after thorough cleaning of the area to be disinfected .
Aldehydes like glutaraldehyde & formaldehyde are effective
against bacteria, viruses and fungi. Their action against tubercle bacilli
is slow and are irritating to skin and eyes.
Sterilisation
Sterilisation can be achieved by steam, steam & formaldehyde, hot air,
ethylene oxide or irradiation.
The commonest method is Autoclaving. Steam is used under pressure and is
the most effective method to sterilise instruments. Recommended a temperature
of 134°C for 3 minutes or 121°C for 15 minutes.
Formaldehyde is harmful to the eyes, respiratory tract and skin. Hot air
method of sterilisation takes longer time and items should withstand temperatures
of at min 160°C for duration of 2 hours or above.
The colourless gas Ethylene oxide is toxic to inhale. It is very effective
towards all organisms and equipment is not damaged.
Irradiation method of Sterilisation is an industrial process and is suited
to the sterilisation of big batches of products. It can create serious deterioration
of materials and that is why not a suitable method for the sterilization.
Decontamination Procedures Summary
Respiratory equipment
Hazards of Infection can be lessened by lowering the amount of condensation
in the circuit by way of heat-moisture exchangers, moisture traps and by
the constant cleaning and drying of valves and circuits.
Many hospitals do not have disposable ventilator circuits and that is why
with mechanical ventilators, internal circuit can occasionally be autoclaved.
The circuits which are external (or patient) humidifiers can be disinfected
in a washing machine. The external circuit s required to be changed after
a span of 48hr or between patients. Heated water humidifiers needs to be
cleaned, dried and filled with sterile water after every 48-72hr. Incase
of use of nebulisers , they should be rinsed in alcohol after cleaning every
48 hours.
After each use Anaesthetic face masks should be cleaned & washed.
Laryngoscope blades also needs to be washed and disinfected after every
use by either chemical process or thermal means(boiling).
Endotracheal tubes are supposed to be used once but they can be used again
if properly cleaned and disinfected.
Medical Instruments
After use Needles and cannulae (including spinal and epidural needles).
must be sterilised. Autoclaving is the most appropriate technique .
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