Disinfection and methods:
Disinfection is the process of killing the pathogenic or
disease producing microorganism but not usually bacterial spores.
Disinfectant is germicide an agent which kills pathogenic or
disease producing microorganisms but not usually bacterial spores. Eg . phenol
and Lysol.
A deodorant is an agent, which suppresses bad odours. Eg.
Lime , bleaching powder
Detergent
is a surface cleansing agent, which acts by lowering surface tension. Eg soap.
Antiseptic
is an agent which prevents the growth of microorganisms. Eg alcohol.
Sterilization
is a
destruction of microorganisms and their spores.
Types of Disinfection:
1.
Concurrent disinfection: This
is disinfection of infectious material
( eg stools, urine contaminated linen) through out the course of an illness .
This procedure checks or prevents the dissemination or further spread of the
disease agent.
2.
Terminal disinfection: This
is disinfection that is undertaken
at the termination of an illness. ( eg. After recovery or death of the
patient).
3.
Prohylactic disinfection: Boiling
of water, pasteurisation of milk,
washing hands with soap and water are examples.
Sterilisation :
It is
one of the methods of disinfections which is stated above.
Methods of disinfection:
1.
Natural: Sunlight
and air
2.
Physical: Dry
heat , moist heat and radiation
3.
Chemical: Liquids,
solids and gases.
Preparing articles for disinfection
(sterilization):
A convenient method often used is to prepare sets of the
instrument, swabs, sponges, dressings, towels and the surfaces needed for each
type of operation or sterile procedures.
These sets are packed into drums, bundles or on trays,
labeled and kept ready for sterilising.
The articles should be carefully arranged so that those
needed first are on top.
They must be loosely packed for steam to penetrate.
Drums or bins must have the perforations opened.
Bundles should have a double wrapper of close-woven cloth,
or of paper.
Dressings:
Swabs and sponges are usually made of
several thickness of surgical gauze. Raw edges must be folded to the desired
size to prepare gauze. Sponges used for abdominal surgery need to be large,
stitched around the edge and a piece of tape sewed to one corner. When an
artery forceps is clipped into the end of the tape, there is no risk of the
sponge being left inside the abdomen.
B.
Packing gauze:
It is made in various sizes. Use
gauze four times the width of the desired packing. Fold the edges so that they
meet in the middle and again fold down the center, and roll.
C. Cotton balls:
It is prepared in various ways.
Cotton balls of various sizes are prepared by rolling between the palms. Some
may be needed for intestinal surgery, and for this the cotton ball must be
covered with gauze and tied. This type of ball is grasped with a long handed
forceps.
D. Instruments:
After use, surgical instruments should be washed first in
cold water then in warm water with a detergent. Use a brush to clean well
especially between the teeth of artery forceps and clamps. To be properly
sterilized, there should be no dried blood or discharge. Rinse in clean water,
then boil for 5 minutes and dry well.
Sharp
instruments, knives and needles should be dealt with separately, taking care to avoid
cuts and puncture wounds.
E.
Glass syringes and metal needles:
After
use, draw up some water into the glass syringe and push enough through each
metal needle to make sure they are not blocked. Infected glass syringes (used
for withdrawing blood or pus) should be washed immediately in cold disinfectant
solution.
Next wash the syringes and needles in warm soapy water,
using a bottle brush for the barrel. Rinse in clean water. Take care not to get
barrels and plungers mixed, but keep them always paired together.
Needles should be examined carefully
for sharpness. Take care not to prick your finger as infection may be
transmitted in this way.
F. Rubber tubing
After use tubes should be cleaned with cold water, then with
hot soapy water and then rinsed. The inside must be thoroughly cleaned. Then it
is boiled, and hung over. Rubber catheters should be cleaned by running cold
water through from both ends. Wash and rinse in cold water, then dry, with a
towel or by hanging up. Autoclave the catheters before use.
Disinfecting methods (sterilisation-
physical ):
Dry heat:
Sterilizing of glassware including syringes is often done in
a hot air oven at 1600c for one hour.
Spores as well as organisms are killed. Rubber articles will
not withstand this heat.
This method is not efficient where heat has to penetrate as
in dressings, towels and gowns.
Moist heat
: Autoclaving (Steam under pressure):
1.
This is a reliable method and may be
used for most articles.
2.
The autoclave is a chamber with an
outer jacket and a lid or door, which can be firmly clamped.
3.
Steam, is generated by heating water
in a boiler or in the outer jacket.
4.
Air is evacuated from the chamber by
displacement.
5.
Then the steam is allowed to build
up pressure, usually 15 to 20 lbs per square inches, and is kept at that pressure
for 15 to 30 minutes.
6.
Then the heat is turned off and the
contents of the autoclave allowed to dry out.
7.
They should be quite dry when
removed from the autoclave.
Points to remember:
1.
All articles should be clean and dry
before packing. Any organic matter such as blood or pus prevents penetration of
steam.
2.
The holder in the drums must be open
when placing into the autoclave and closed immediately on taking them out.
3.
Bundles should be neither be too
large nor be too tightly packed. Steam should be able to penetrate to the
center.
4.
Rubber gloves cannot withstand high
temperature and long sterilising. Autoclave them separately at 15 lbs pressure
for 15 minutes.
5.
To autoclave bottles of fluid,
loosen the screw cops, evacuate the steam slowly.
Boiling:
I.
This
method is suitable
for enamel, metal, glass and rubber ware.
II.
Bowl sterilizers are used for larger
articles and instrument sterilizers for smaller articles.
Points to remember:
1.
See that the articles are quiet
clean and completely immersed in clean water.
2.
When the water boils, start timing.
If more articles are added, the sterilizing time must begin again.
3.
Boil for 5 minutes.
4.
Boiling will not kill spores
5.
Remove articles with sterile cheatle
or other lifting forceps, and place them on a sterile surface.
Chemical disinfection:
This method is used for sterilising
delicate instruments such as eye instruments.
Points to remember:
1.
The articles must be clean and free
from pus, blood or oil.
2.
They must be completely immersed in
the disinfectant.
3.
The disinfectant should be of
certain strength, and the articles must be in contact with it for a specific
period.
4.
After sterilization, articles must
be well rinsed in sterile water before use.
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