DECONTAMINNATION OF UNIT AND EQUIPMENT

 

1.      DECONTAMINNATION OF UNIT AND EQUIPMENT:

         Decontamination is the process of cleaning an object or substance to remove contaminates such as micro organism or hazardous materials, including chemicals, radioactive substance and infectious diseases.

Purpose:

  The purpose of decontamination is to prevent the spread of micro-organisms and other noxious contaminants,

 Decontamination process of unit and equipment includes the following

Disinfection Techniques:

1.      Disinfection : Disinfection is process by which most micro-organisms are destroyed, with the exception of spores.

Terminal disinfection  : Is disinfection of patients unit; that I all articles including room ,furniture and linen used by patient on his discharge or release from isolation or death. disinfection is achieved by either physical or chemical means.

Disinfectant : An agent (as heat or radiation or a chemical ) that destroys microorganisms that might carry disease.

A disinfectant used for disinfection should meet following criteria:

·         Its should efficient.

·         It should be used in correct strength.

·         It should not cause any damage to the instruments.

·         The instruments or articles should fully emerge in it.

·         Should be applied for a sufficient length of time.

 

Disinfection by Chemicals  : 

·         These methods of disinfections are used to the articles which are heat sensitive articles.

·         Disinfection by chemicals is effective only when the articles are thoroughly cleaned and free of debris, blood, oil, pus and grease

The presence of organic material diminishes the efficiency of disinfectant, whenever possible instrument to be taken in pieces for disinfection by chemicals.

2.      Sterilization :  Sterilization is defined as the process by which an article, surface or medium is freed of all microorganism(pathogenic and non pathogenic)either in the vegetative or spore state.

By sterilization both the pathogenic and non pathogenic organism are destroyed . there are various methods use in the sterilization of articles the methods chosen must ensure the destruction of all micro organism including the spores.

 

Sterilization can be achieved by physical agent or by chemical agents.

(a)Physical Agent : sun light drying dry heat (flaming, incineration, and hot air), moist heat (pasteurization, boiling , steam under normal pressure),filtration (candles, Asbestos pads, membranes), radiation, ultrasonic and sonic vibrations.

(b) Chemical Agents : Alcohols(Ethyl isopropyl, Trichloro ethanol ),aldehydes  (formaldehyde, Gluta aldehyde), dyes, halogens, phenols, surface active agents metallic salts and gases(ethylene oxide, formaldehyde).

  All method of sterilization begin with thorough cleaning of the instruments, cleaning is the basis of sterilization. The most common method for sterilization of articles is heating/steaming.

Sterilization by Heat: 

1.Autoclaving (moist heart)or steam under pressure

2. Dry heat.

3. Boiling.

1. Autoclaving:

·         The principle of the autoclave or steam sterilizer is that water boils hen its vapour pressure equals that of the surrounding atmosphere.

·         Hence when pressure inside a closed vessel increase, the temperature at which after boils also increases.

·         Saturated steam has greater penetrative power.

·         When steam comes into contact with cooler surface it condense into water and gives up its latent heat to the surface and this condensed water ensures moist condition for killing micro organism.

-                    Sterilization by steam under pressure is carried out at temperature between 108°C -147°C, by                using appropriate temperature and times a variety  of materials such as dressing materials; Instruments,    laboratory articles etc. are sterilized. liquids are sterilized   between 108°-126°C

-      Autoclaving or sterilization by steam under pressure is most widely used, economical and one of the most effective methods of destroying micro organism.

-    This method uses high temperature pressure and humidity to destroy bacterial life. In an autoclave steam is present under pressure to maintain the necessary high temperature for sterilization and its allows rapid penetration of article packed in it.

-   Autoclaving is the name given to a sterilizer that utilizer saturated steam under pressure

-  the steam is used in the autoclave when steam is held in a closed container it is compressed an the temperature rise far above that of the boiling point of water.

- The another reason the steam used is-steam is able to penetrate pores material very rapidly provided that it is not impeded by unsuitable rappers or by air trapped within fabrics or hollow instrument.

-An autoclave consists of an outer chamber and an inner chamber which can tightly closed by a safety lock.

-First the steam is introduced in the outer chamber

-unit the design temperature is reached at this point steam is turned into the inner chamber

-The articles are then sterilized.

-As the steam enter the inner chamber, the air is forced through the valves. The steam is kept flowing into the inner chamber until the Desir temperature is reached. 

   The removal of air from autoclave during the sterilization process is important for two reasons.

1.      Air left in the centre a pack or in the cannula of a catheter will prevent the steam from coming into the direct contact with the centre of the pack or to the lumen of the catheter. Failure to contact means failure to sterilize.

2.      Air mixed with steam reduces temperature of the steam. At the end of the period the steam supply  is shut off but the door is not opened until the pressure gauge is zero.

 

GENERAL INSTRUCTION :

1.      The articles being sterilized are exposed to high temperature, pressure and moisture.

2.      The wrapper and the container should allow penetration of the steam into the article.

3.      The inner chamber must be too full nor the contents arranged too compactly. Bundles and drums must be packed loose. Cans or jars must be opened and turned on their sides so that steam can easily penetrate the contents.

4.      The temperature and pressure of the steam should be high enough to kill all the micro-organism including spores. The usual temperature is 121°C and the pressure is 1.05kg/cm².

5.      The destruction of a bacteria depends upon the length of time the articles are exposed to steam under pressure. The minimum time can be minutes. If pressure is increase the exposure time can be reduced.

6.      In opening an autoclave , it is important to remember that all the air in the inner chamber must be driven out and entirely replaced by steam. Otherwise although the gauge may show a pressure of 151bs. This pressure would be caused by a mixture would be lower than that of the steam alone.

7.      The articles should be left in the autoclave for a short time after the procedure is over in order to dry the materials.

 

2.DRY HEAT:

   Dry heat kills microorganism by oxidation provided that the articles to be sterilized are exposed to a temperature of 160°C for one hour, all organism and there spore will be destroyed.

·         High temperature & comparatively long exposure time are required.

·         It is not a suitable sterilizing agent for fabrics and dressing which are poor and uneven conductors and are ruined by excessive heat.

It is however the method of choice for fine metal cannula ( eg. L .P. Needles) and for glass syringes since these can be sterilized with a stylet in or the piston in position.

·         Heating by conduction ensures sterilization of the inside

   

  The articles which are damaged by the moisture are sterilized by the method.

 

3.      Boiling  

 All pathogenic organisms are in the vegetative  form and many spore form are killed by 5 minutes immersion in boiling water.

 Temperature at 100°C –boiling :

Boiling for 5 to 10 minutes kills most of the vegetative forms of bacteria but few spores survive.

Articles to be sterilized must be totally immersed in water.

When the boiling period is over, the articles are removed with a sterile forceps and placed directly into a sterile kidney tray and should be covered by a sterile towel.

Total immersion in boiling water (100°C) for 10 minutes will kill most of the pathogenic organisms as is the common and reliable method of disinfection (not sterilizing) instruments.

 Advantages :

Boiling can be used in the homes environments and other situations when other methods are not available it is one of  the economic way of sterilizing articles.

Disadvantages

Some bacteria and virus and all spores are resistance to boiling . this boiling becomes ineffective in sterilizing articles . boiling method cannot be used for the articles which are destroyed by moisture and heat.

Flaming

 The material selected should have a high melting point and capacity to get heated up within few seconds and also to become cool, within few seconds.

 Ultra – violet rays:  

·         Ultraviolet rays can kill micro organisms by breaking the bonds in DNA of the nucleus.

·         Articles are sterilized, without being heated up; hence this method is also called “cold sterilization”

·         The most useful is gamma rays , which are the penetrating rays from atomic energy source such as cobalt-60

·         Machines such as linear accelerator are used to produces high speed electrons

·         Commonly used for commercial sterilization of pre-packed singles use (disposable) articles in bulk. Articles like, needles , plastic syringes, catheters , IV lines etc