Sterilization, Decontamination and Critical Instrument

 Decontamination is the removal or reduction of chemical, biologic, or radiologic agents from the patient's skin, mucosa, lungs, and gastrointestinal tract.Decontamination is an important step in decreasing the clinical effects of the agent on the patient, as well as protecting coworkers from exposure. For most agents and the vast majority of scenarios, the removal of clothing and a simple 5- to 6-minute shower with soap and water is sufficient to eliminate the risks to the patient and hospital staff. In rare circumstances, additional steps in decontamination including gastric lavage, broncho-alveolar lavage, surgical removal of wound foreign bodies, and administration of activated charcoal, polyethylene glycol electrolyte solution, and radioisotope binding agents, may be necessary.Decontamination is a series of processes that effectively remove or destroy infectious agents or other contaminants (e.g. organic matter) in order to prevent the spread of infection.

      Process of Decontamination

 There are three processes:

Cleaning

Enhanced cleaning

Disinfection

1.Cleaning:

The first stage of decontamination is cleaning – or in other words, the physical removal of dirt, dust and soil from surfaces. In most healthcare environments this process will be performed daily and will usually involve a combination of water, detergent, cloths and mops.Cleaning may be either manual or automated.How successful the cleaning is in terms of reducing microbial contamination depends on various factors including:The effectiveness of the cleaning process The amount of bioburden (soil) present.The cleaning process is generally suitable for items that are not in direct contact with the patient and medical equipment that are in contact with the patient’s skin.This process will remove organic matter on which infectious agents thrive but will not completely eliminate microorganisms from environmental surfaces.

2.Enhanced cleaning:

Enhanced cleaning refers to methods used in addition to standard cleaning, and is carried out in response to a specific infection prevention and control requirement.This process may involve increased frequency of cleaning, either for all surfaces or of those that are frequently touched, or it may involve the use of additional cleaning equipment or disinfectants.It is routinely undertaken at the point where a patient who has been known to be infected with a pathogenic microorganism is discharged or transferred. In the case of an outbreak of norovirus or diarrhoea, enhanced cleaning may be required for entire wards.

3.Disinfection:

Manual disinfection can help to reduce the number of viable infectious agents in the healthcare environment, but it isn’talways sufficient on its own to inactive certain microbes,such as viruses and spores.In some cases, the use of a specific concentration of a chemical agent may be required. For example, for blood and bodily fluid spillages, infected areas are usually disinfected using freshly prepared hypochlorite solution.

Q2.What is a washer disinfector Machine?

A washer disinfector is used for the automated cleaning and disinfection of instruments in practices, clinics, dental offices, medical centers and hospitals. The reliable monitoring and documentation of the relevant process parameters ensures standardized and reproducible decontamination procedures. The automated metering of the liquid process agents consisting of cleaning agent, neutralizer and rinse aid optimizes the cleaning and drying outcome. The instrument disinfection is, however,accomplished by hot water over a prescribed period.

process steps of a washer disinfector

1. Cleaning:

A pre-rinse phase with cold water is the first step to remove coarse soiling and proteins. The use of cold water for the pre-rinsing prevents coagulation of protein residues. The subsequent cleaning phase is performed with an alkali-enzymatic cleaning agent and warm water.

2. Neutralization:

The low pH value of a citric acid or phosphoric acid-based neutralizer equalizes the alkalinity of the previous cleaning phase. The neutralization and subsequent intermediate rinsing of the instruments in the washer disinfector remove the remaining agents and make for the best-possible cleaning outcome.

3. Disinfection:

After intermediate rinsing with clear water, the proper thermal disinfection of instruments is performed at 90 °C,including a holding time of 5 minutes. The combination of temperature and time enables achievement of the especially important A0 value of a minimum of 3.000 in the thermal disinfection. The A0 value represents a standard for the elimination of microorganisms during automated thermal instrument reprocessing.

4. Drying:

Active exterior and interior drying protects the instruments against corrosion and damage. A HEPA filter is installed to remove microorganisms from the ambient air drawn into the washer disinfector for the drying of instruments. The instruments are thus dry and hand warm after the cleaning and disinfection procedure. The complexity of hollow body instruments with narrow lumen such as handpieces, turbines, endoscopes or ophthalmological instruments require additional manual drying in accordance with manufacturer's specifications.

Q3.Eplain fully on the following:

Critical Instruments

Semi critical intsruments

Non critical instruments

1) Critical instruments are those used to penetrate soft tissue or bone and should be sterilized after each use.Sterilization is achieved by steam under pressure (autoclaving), dry heat, or heat/chemical vapor. Critical instruments include forceps, scalpels, bone chisels,scalers, and burs.Critical instruments are  those that come in contact with sterile body cavities. Common examples include surgical instruments, needles, syringes, and surgical implants. These items require sterilization.Critical items confer a high risk for infection if they are contaminated with any microorganism. Thus, objectsthat enter sterile tissue or the vascular system must be sterile because any microbial contamination could transmit disease. This category includes surgical instruments, cardiac and urinary catheters, implants, and ultrasound probes used in sterile body cavities. Most of the items in this category should be purchased as sterile or be sterilized with steam if possible. Heat-sensitiveobjects can be treated with  EtO, hydrogen peroxide gas plasma; or if other methods are unsuitable, by liquid chemical sterilants. Germicides categorized as chemical sterilants include≥2.4% glutaraldehyde-based formulations, 0.95% glutaraldehyde with 1.64% phenol/phenate, 7.5% stabilized hydrogen peroxide,7.35% hydrogen peroxide with 0.23% peracetic acid, 0.2% peracetic acid, and 0.08% peracetic acid with 1.0% hydrogen peroxide. Liquid chemical sterilants reliably produce sterility only if cleaning precedes treatment and if proper guidelines are followed regarding concentration, contact time, temperature, and pH.

2) Semicritical instruments:. are those that do not penetrate soft tissues or bone but contact oral tissues, such as mirrors and amalgam condensers. These devices should also be sterilized after each use. In some cases,however, sterilization is not feasible and, therefore,high-level disinfection is appropriate.Semicritical instruments are those that come in contact with mucous membranes, but not sterile body cavities. Common examples of semi-critical items include endoscopes, speculums, and ear/nose/throat instruments used for office procedures. These items require high level disinfection process. This was based on a study that showed that mouthpieces and spirometry tubing become contaminated with microorganisms but there was no bacterial contamination of the surfaces inside the spirometers.

3).Non critical Instruments: are those that come into contact only with intact skin such as external components of X-ray heads. Such devices have a relatively low risk of transmitting infection and, therefore, may be reprocessed between patients by intermediate-level or low-level disinfection.Noncritical instrunents are those that come in contact only with intact skin and do not enter sterile body cavities or mucous membranes. Common examples of noncritical instruments include blood glucose meters, stethoscopes, and blood pressure cuffs. These items require a minimum of a low level disinfection process.Noncritical items are those that come in contact with intact skin but not mucous membranes. Intact skin acts as an effective barrier to most microorganisms;therefore, the sterility of items coming in contact with intact skin is “not critical.” In this guideline,noncritical items are divided into noncritical patient care items and noncritical environmental surfaces.Examples of noncritical patient-care items are bedpans, blood pressure cuffs, crutches and computers . In contrast to critical and some semicritical items, most noncritical reusable items may be decontaminated where they are used and do not need to be transported to a central processing area. Virtually no risk has been documented for transmission of infectious agents to patients through noncritical items when they are used as noncritical items and do not contact non-intact skin and/or mucous membranes. 

       References

https://inivoscom/blog/decontamination-process-infection-control/

https://www.researchgate.net/publication/7596007_Decontamination

https://wwwcdcgov/infectioncontrol/guidelines/disinfection/rational-approach.html#

https://blog.pentaxmedical.com/disinfection-and-sterilization

https://www.melag.com/en/products/washer-disinfector