Comment on the risk assessment in the RKI Guideline: "Hygiene requirements for processing medical devices" (section 1.2.1 Processing of medical devices (MDs) entails as a rule:
- Appropriate preparatory tasks (possibly pre-treatment, pre-cleaning, dismantling, opening of jointed instruments, arrangement and transportation)
- Manual or automated initial rinse, cleaning, disinfection, final rinse and drying
- Inspection for cleanliness, corrosion, impeccable maintenance, functional test, labelling, packing
- Sterilisation if required.
Safe and effective disinfection and sterilisation are possible only for CLEAN MDs. Therefore effective cleaning processes must be used. Preference should be given to automated processes in suitably equipped washer-disinfectors because they assure better standardisation and occupational safety. Alkaline cleaning with a pH value > 10 in the use solution is highly effective for dissolving protein and fat residues.
DISINFECTION should preferably be conducted in a washer-disinfector, using thermal processes. For spectrum of action AB, with efficacy against hepatitis B, 90 °C and a holding time of 5 min are needed for the items to be disinfected. Non-critical MDs can be cleaned and disinfected manually.
For STERILISATION preference should be given to steam sterilisation at 134 8C using a holding time of 5 min provided that more stringent requirements do not apply (e.g. CJD prophylaxis). Based on the RKI Guideline, modular systems should not be dismantled for sterilisation. The MD manufacturer must furnish proof that this can be accomplished without any problems.
The PROCESSES IN WASHER-DISINFECTORS must be validated and subjected to regular checks. The QUALITY ASSURANCE CONCEPT for the washer-disinfectors can entail parametric inprocess checks, e.g. a check of the temperature and holding time in the thermal disinfection step, of dosage quantities as well as independent physical, chemical and microbiological tests and suitable cleaning indicators. Regular maintenance of all equipment constitutes a good basis for safe processing. The operator is responsible for formulating a quality assurance concept and for conducting the relevant tests.
The MDs to be processed are classified into RISK GROUPS, while taking account of the preceding and subsequent use, constructional features and material properties. Preference should be given to automated processing, involving an adequate cleaning step and thermal disinfection as well as steam sterilisation at 134 °C. Whether sterilisation is required or not also depends on special types of applications or on transportation channels also in the case of non-critical and semi-critical MDs.
INSPECTION FOR CLEANLINESS is carried out by inspecting MDs, using optical aids if necessary. In addition to this and if it is not possible to conduct adequate visual inspection, e.g. in lumened MDs, impeccable functioning of the washer-disinfector must be ensured by means of further additional tests. Such supplementary tests could involve for instance compiling independent temperature profiles with thermologgers, using cleaning indicators, e.g. TOSI, and conducting spot checks for protein with the biuret, ninhydrin or OPA methods.
All medical devices (MDs) undergoing processing must first of all be classified by the operator in accordance with the specifications of the Robert Koch Institute into the given groups. In doing so, device groups can be formed. If non-critical MDs are being used together with critical MDs, the non-critical MDs must be assigned to the critical group. (Example: a set with general surgical instruments and kidney dish.)
- Semi-critical A
- Semi-critical B
- Critical A
- Critical B
- Critical C
Non-critical medical devices (MDs)
are MDs that do not come into contact with the patient or only come into contact with the patient's intact skin. These include e.g. kidney dishes, containers, ECG electrodes, HF generators, stethoscopes, etc.
No special requirements
The devices are processed as a rule in the CSSD: utensils made of stainless steel, e.g. dishes etc. are as a rule processed in a washer-disinfector together with the semi-critical A and critical A groups and then subjected to thermal disinfection. If necessary, they are subjected to steam sterilisation together with the sets to which they belong. Storage dishes for wound care must for example be sterile, but disinfection would suffice for dishes used for example for storage of an oral hygiene set. Manual cleaning and disinfection are also possible.
Containers for the transport of used MDs made of stainless steel, aluminium or plastic are if possible cleaned in a washer-disinfector and then subjected to thermal disinfection. If enough machine capacity is not available, the containers can be subjected to a wipe disinfection using a disinfectant from the approved list of disinfectants. Steam sterilisation may be required depending on the transportation channels used within the specific establishment.
The non-critical MDs and utensils are inspected after cleaning and disinfection. They must be optically clean.
Semi-critical medical devices (MDs) A
are MDs coming into contact with mucosa or pathologically altered skin and whose cleanliness can be judged by means of visual inspection. These include speculas, impression plates, stomatoscopes, etc.
Semi-critical MDs belonging to Group A can be cleaned and disinfected without having to observe any special requirements. Approved disinfectants or processes endowed with spectrum of action AB must be used.
The devices are processed as a rule in the CSSD. All heat-resistant MDs are preferably processed in a washer-disinfector and subjected to thermal disinfection with spectrum of action AB (90 °C, hold time 5 min). Manual processing is also possible.
For any pre-treatment or pre-cleaning measures required only non-fixing agents and methods may be used. Cleaning should be carried out before disinfection, e.g. in an ultrasonic bath. Approved disinfectants should be used for subsequent disinfection of the clean MDs, with additional proof of efficacy against hepatitis B. The ultrasonic baths should be replenished on time, while taking account of the contamination as well as on the stability of the substances being used.
The semi-critical MDs and utensils are inspected after cleaning and disinfection. They must be optically clean.
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The different processing steps
CLEAN MDs are required for effective disinfection and sterilisation
DISINFECTION should preferably be carried out in a washer-disinfector, using thermal processes
FOR STERILISATION preference should be given to steam sterilisation at 134 °C
PROCESSES IN WASHER-DISINFECTORS must be validated
A QUALITY ASSURANCE CONCEPT entails e.g. parametric inprocess checks and regular maintenance of all equipment
RISK GROUPS serve as a basis for classification of MDs, while taking account of different characteristics
AN INSPECTION FOR CLEANLINESS is carried out by inspecting MDs, possibly using optical aids and by means of other test procedures.
The Risk Groups
Requirements for processing non-critical MDs
Requirements for processing semi-critical MDs (A)