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Recommendations by the Quality Task Group
[23] Classifying Medical Devices before Processing (Part 2)

Semi-Critical Medical Devices (MDs) B
are MDs coming into contact with mucosa or pathologically altered skin and whose cleanliness cannot be assessed by visual inspection. Examples of such devices are gastroscopes and other flexible endoscopes, rigid endoscopes, hand and angle pieces, surgical motors and drilling shafts, which are not used in sterile body cavities, as well as respiratory and anaesthesia equipment, etc.
Subsequent disinfection with an agent endowed with bactericidal and virucidal activity is adequate for MDs that are not used in sterile body cavities.

Requirements of the Robert Koch Institute (RKI):
In some cases pre-cleaning of semi-critical devices of Group B is required immediately after use on patients (flexible endoscopes). They should preferably be subjected to automated cleaning and disinfection.

Conventional Processing:
As a rule, flexible endoscopes are processed in the endoscopy department. Many endoscopy departments are equipped with special endoscope washer-disinfectors. However, only neutral detergents and a temperature of up to 60 °C can be used due to the fact that the materials of endoscopes are ultra sensitive and are not heat resistant.
The manufacturers of flexible endoscopes and of endoscope washer-disinfectors recommend that endoscopes be wiped off and rinsed immediately after use; in addition, pre-cleaning with a brush is being currently recommended. No fixing agents or processes may be used. Only impeccably cleaned endoscopes can be subjected to manual or automated cleaning followed by a chemical-thermal disinfection step, while using approved aldehyde-based disinfectants with bactericidal and virucidal activity . Any residual proteins would undergo coagulation with the aldehydes and form insoluble residues.

Anaesthesia and respiratory equipment, suction tubes, and similar,
are generally cleaned and disinfected in a washer-disinfector, preferably centrally in the CSSD. But sometimes automated cleaning and disinfection is also carried out at a decentralised location, while preferably resorting to thermal disinfection. The majority of materials such as rubber, latex, silicone elastomers can tolerate mildly alkaline detergents and temperatures of 90 °C. Materials undergo premature ageing if the drying temperatures are too high. A chemical-thermal process with bactericidal and virucidal activity can be used for heat-sensitive MDs. The manufacturer’s instructions must be observed.

Checks:
The semi-critical MDs and equipment are visually inspected, as far as possible, after decontamination in the washer-disinfector. They must be optically clean. Additional checks must be carried out to ensure that all process parameters have been observed and that impeccable cleaning and disinfection can be assumed.

Critical Medical Devices (MDs) A
are MDs that are used invasively and come into contact with blood, internal tissues and organs. To a large extent, cleanliness of these MDs can be assessed by visual inspection. These MDs can be subjected to steam sterilisation.
Such devices include general surgical instruments without lumens, e.g. retractors, needle holders, clamps, forceps, etc.

RKI requirements:
No special requirements apply. Preference should be given to automated preparation with thermal disinfection including bactericidal and virucidal activity. Steam sterilisation is used here. Effective cleaning processes must be performed, because only clean MDs can be reliably sterilised. Preferably, alkaline detergents with a pH value > 10 should be used in the cleaning solution because their good cleaning action is especially tailored to the removal of protein and fat residues. It possible, alkaline-sensitive MDs should be replaced with alkaline-resistant MDs.

Conventional Processing:
The critical MDs of Group A are generally cleaned and thermally disinfected in a washer-disinfector in the CSSD. Since in general surgical instruments made of stainless steel are alkaline resistant, alkaline detergents can be used. Likewise, mildly alkaline detergents endowed with adequate anti-corrosive properties in respect of light metals can be used. The pH values of the cleaning solutions are > pH 10, or are often in the pH range 12 - 12.5. Alkaline-sensitive MDs thus call for commensurately gentler detergents. What is important is to ensure that the requisite water quality is also used for the cleaning step. The manufacturer’s instructions must be observed.
Thermal disinfection is used at 90 °C with a holding time of 5 min among the sterile supply (bactericidal and virucidal activity).

Checks:
Critical MDs are inspected after cleaning and disinfection in the washer-disinfector. They must be optically clean. Additional checks, e.g. compilation of independent temperature profiles with thermologgers, tests with typical load using suitable cleaning indicators such as TOSI, and tests for protein residues must be carried out to ensure that all process parameters have been observed and that impeccable cleaning and disinfection can be assumed.

Critical Medical Devices (MDs) B
are MDs that are used invasively and come into contact with blood, internal tissues and organs. Cleanliness of these MDs can be assessed only to an extent or not at all by visual inspection. These MDs can be subjected to steam sterilisation. Such devices include e.g. minimally invasive instruments.

RKI requirements:
Stringent requirements apply for processing. If the manufacturer prescribes pre-cleaning directly after use, this must be performed without using fixing agents. Automated cleaning is used in all cases. Due to their superior cleaning action, alkaline detergents with a pH value > 10 should be used if possible for the cleaning solution.
This is followed by thermal disinfection with bactericidal and virucidal activity followed by steam sterilisation. In addition, the person entrusted with processing must be in possession of a recognised qualification as a sterilisation assistant.

Conventional Processing:
Processing is carried out in general in the CSSD. The MDs are cleaned and thermally disinfected with bactericidal and virucidal activity (90 °C, 5 min) in a washer-disinfector. First of all, minimally invasive instruments (MIS instruments) are dismantled in accordance with the manufacturer’s instructions and placed in a special insert or MIS insert. If necessary, manual pre-cleaning is conducted using non-fixing agents and processes. The restrictions imposed by the manufacturer (e.g. that only neutral detergents be used) in view of the material properties cited in prEN 17664 or in the processing instructions must be borne in mind.
It must be possible to validate the cleaning and disinfection process in the washer-disinfector, including the MIS insert and typical load; otherwise, the latter must be subjected to appropriate performance qualification test.

Checks:
The MDs and equipment are inspected after decontamination in the washer-disinfector. They must be optically clean. By means of additional checks - e.g. compilation of independent temperature profiles with thermologgers, testing for adequate flow at all connections during a typical load using suitable cleaning indicators such as TOSI Lumcheck and testing for protein residues - it must be ensured that all process parameters have been observed and that impeccable cleaning and disinfection can be assumed.

Critical Medical Devices (MDs) C
are MDs that are used invasively, have lumens, do not permit optical checks and cannot be subjected to steam sterilisation.

RKI requirements:
Particularly stringent processing requirements must be applied. In addition to the aforementioned requirements, risk analysis must be conducted and the quality management system must be certified.

Conventional Processing:
As a rule, these MDs are not processed in a CSSD.