How often should the movable parts of intruments, e.g. hinges, be lubricated?
Ideally, cleaning performance is such that all residues including the care products are removed during the cleaning process. All instruments with metal sliding surfaces should therefore be lubricated after each cleaning process as recommended by the manufacturer.
Is it correct that pitting on surgical instruments is locally confined and therefore cannot be transfered to other instruments via reprocessing products?
No, active pitting can cause extraneous corrosion deposited on other items. Depending on the cause, severity and extent of pitting, affected instruments concerned should be removed from the reprocessing cycle. Such instruments should be returned to the manufacturer or a qualified repair service for reconditioning. For further information, cf. the Red Brochure, 8th Edition, Pages 55-56.
Are welds on surgical instruments made from stainless steel less corrosion-resistant and are welds prone to increased corrosion after frequent processing?
Products from well-known instrument manufacturers do not show any difference in corrosion resistance. This is assured by appropriate welding methods, welding parameters, and, where applicable, by the use of additives and subsequent heat treatment to improve the homogenisation of the material.
Why should instruments for eye operations be reprocessed in a washer-disinfector/steriliser and not manually as in the past?
This refers to the debate concerning manual reprocessing and machine reprocessing of instruments for eye operations. In principle, the method of choice should be reprocessing in washer-disinfectors/sterilisers. In many recommendations, leaflets and brochures, thermal disinfection methods are advocated as being superior to chemo-thermal or chemical methods. Machine washing and disinfection in a closed system also serves a key function by protecting members of staff. Another factor is that only machine processes can be reproduced in a sufficiently precise and validated manner that meets the requirements of the operator's regulations. The concerns of doctors and nurses relating to the sensitivity of instruments are no longer justified. Particularly in the case of instruments used in eye operations, baskets and perforated trays with holders ensure secure storage. Rinsing nozzles and the alignment of the rack for holding baskets and perforated trays must be such that instruments are not released from their holders. This would be the case if standard rinsing technology for surgical instruments were used. Provided rinsing procedures and rinsing technology are used correctly, machine cleaning is gentler than manual cleaning. Aseptica 7 (3); 2001: 18-19 reports on a practical example of the reprocessing of microsurgical instruments.
Are there specific directives or guidelines on reprocessing surgical needles? Should surgical needles be reprocessed in washer-disinfectors and do specific regulations apply?
As far as we know, manufacturers use different materials for reusable needles. A rough distinction is made between needles made from corrosion-resistant high-alloy steel and needles made from electroplated low-alloy (i.e. non-corrosion resistant) steel. In principle, both types can be reprocessed in washer-disinfectors/sterilisers using programmes certified for surgical instruments made from stainless steel. pH-neutral or mildly alkaline reprocessing is particularly suitable for chrome-plated needles and other chrome-plated instruments. The needles must be held in suitable containers during reprocessing so they are not lost in the washer-disinfector or steriliser chamber. Needle boxes provided by manufacturers are particularly suitable for this purpose and they also ensure adequate cleaning. As well as checking whether the instruments have been cleaned sufficiently, chrome-plated/nickel-plated needles in particular require thorough checking for surface damage. This is best done using a magnifying glass. If the needle is chrome-plated or nickel-plated, the chrome or nickel forms a protective coating on the substrate designed mainly to make the instrument corrosion-resistant. This layer, however, will always contain micro-fissures. Extended cracks will form over time as a result of mechanical strain. Such parts with prior damage are exposed to additional attack during reprocessing because of chemical ingress and a reaction which induces corrosion. Needles damaged in this way must be taken out of circulation and discarded in order to protect other instruments. There is a risk of transfer to other uncorroded instruments (secondary corrosion). The number of reprocessing cycles is therefore determined by surface integrity. Needle boxes can be used for cleaning, sterilisation and storage of needles at the point of use. During routine use, rubber-coated magnetic plates have proved effective for passing needles to the surgeon at the point of use. After cleaning in a washer-disinfector, the needles are arranged on these plates when instrument sets are reassembled.
Are the following specifications on reprocessing ophthalmic instruments (used in laser surgery) given by manufacturers sufficient, or is the disinfection stage missing? "Clean all instruments in filtered and softened water enriched with Palmolive (1:100)
Reprocessing steps are defined for reprocessing surgical instruments and hence for ophthalmic instruments. A rough distinction is made between manual and machine cleaning in the disinfection and cleaning process. As this question is based on a manual procedure, we only propose to comment on the manual approach. If manual cleaning is specified, the instruments used are subject to wet disposal. This involves immersion in a disinfection bath. This treatment is required to protect staff health (see occupational safety regulations). The disinfectant used for this purpose must be certified for surgical instruments. An approved disinfecting detergent can also be used. Blends of detergent and disinfectant made up in-house are not permissible as this may impair the effectiveness of disinfection. A product designed to remove typical residues (tissues, body fluids, blood, proteins, etc.) must be used to clean surgical instruments. Domestic detergents are not suitable for reprocessing surgical instruments. Tap water can be used for cleaning. Toothbrushes are ideal for cleaning purposes. Fully demineralised water is recommended for final rinsing (the term "filtered" is not specific enough). Fully demineralised water does not contain lime (hardness) or other salts or ingredients. Rinsing must ensure that any residues, both organic and from detergents and disinfectants, are removed. Instruments must be dry prior to sterilisation. Drying with compressed air is particularly gentle and effective.
Is it sufficient to immerse the surgical instruments in a disinfectant solution specified by the manufacturer in order to use these instruments on other patients? Isn't it necessary to sterilize these instruments each time?
Instruments used in invasive surgery must be sterilized after reprocessing. A steam sterilization procedure in accordance with EN285 must be used for steam-sterilizable instruments to achieve this. Thermally unstable instruments must be subjected to a low-temperature sterilization procedure in conformity with the manufacturer's instructions. Make sure you also observe the RKI (Robert Koch Institute) recommendations on reprocessing medical devices published in November 2001. These instructions can be downloaded under www.rki.de.
Is there a risk that instruments made from stainless steel loose their properties in use as a result of reprocessing?
Is there any literature or other information on the corrosion of laser lettering on instruments?
Laser labelling is a procedure used for identifying medical instruments. Etching is the conventional method of marking and identifying instruments and laser labelling must also be clearly visible and resistant to standard conditions of use and (re)processing. Provided correct procedures are used for laser labelling, none of the letters will corrode. Corrosion of laser labelling is usually due to insufficient guidelines or faulty procedures in the labelling process. We are not aware of any literature on this issue. At this point, however, we should also like to point out that any factor triggering or promoting corrosion such as contact with water containing high amounts of minerals or salts should be excluded during reprocessing.
Can the hardness of a surgical instrument (surface layer and core) change after repeated sterilization cycles?
Is the hardness of a surgical instrument the same throughout the instrument?
That depends on the heat treatment during the hardening process. The hardness of high-quality instruments is the same throughout.
Can instruments made from stainless steel lose their useful properties through reprocessing?
Established cleaning, disinfection and sterilisation processes do not have any negative effect on the original usage properties of stainless steel instruments. This also applies, for example, to wear on cutting surgical and microsurgical instruments. As a result, the steam sterilisation process, which has been discussed repeatedly in this context, should be given preference over other sterilisation methods as it is most effective from a hygienic point of view.
Are there any studies on the cleaning of instruments with knurled handles (cross knurl)?
Investigations on the cleaning of instruments or stainless steel test challenge devices with the design features of instruments have focused mainly on joints, not knurled handles.
The exposure times to disinfectants depend on the application concentration. Is it therefore possible to work with a reduced concentration if instruments are exposed overnight or over a weekend?
It is correct that the assessment of disinfectants result in combination of concentration/exposure times. In the case of instrument disinfection according to the test method issued by the German Society for Hygiene and Microbiology (DGHM), the exposure times tested are 15 mins., 30 mins. and 1 hour. Longer exposure times, where the test method would lead to more dilute concentrations, are not tested. The reason for this is that dilute concentrations promote the resistance of microorganisms and, in addition, the risk of corrosion is increased because the concentration of corrosion inhibitors in the solution is too low.
Is it possible to leave instruments to stand overnight or over the weekend, or is wet disposal through immersion overnight or over the weekend possible?
Practical experience shows that soiled instruments can be stored untreated for up to 6 hours after use without influencing cleaning performance in the machine. If stored overnight or over the weekend, adequate cleaning cannot be guaranteed. In addition, there is a risk of corrosion due to blood or physiological salts adhering to instruments over a prolonged period. If soiled instruments are stored overnight or over the weekend, corrosion must be expected.
Can surgical instruments be reprocessed in a bedpan washer?
In our opinion, a bedpan washer is not suitable for reprocessing surgical instruments as the processes on these devices are not designed for this purpose. This applies to cleaning performance, rinse quality as well as thermal disinfection parameters. In the case of the latter, HBV effectiveness may also have to be ensured. Keywords: Treatment in bedpan washers.
Is the anodised layer on instruments degraded when instruments made from anodised aluminium are machine-washed and disinfected at high pH values (pH 10-11) to prevent the spread of CJD?
Indeed, the anodised layer on aluminium instruments may suffer under these conditions. However, it should be noted that there are hardly any aluminium instruments or instrument components made from aluminium. Furthermore, there are chemical suppliers who sell alkaline detergents offering 100% material compatibility even at the pH values specified, at least for products which are not colour anodised. In this context, however, the water quality, especially in the last rinse water used for thermal disinfection, must also be taken into account. Whereas softened water can severely damage anodised coatings, fully demineralised water protects anodised coatings by making them denser.
Is there a general risk of redeposition of material released from anodised coatings on other stainless-steel instruments during mechanical reprocessing? Does this pose a risk of cross-contamination?
To date, we are not aware of a single case in which dissolution products from aluminium instruments have resulted in an increase in the susceptibility of stainless-steel instruments to corrosion. In addition, if sufficient final rinsing is carried out in the washer-disinfector, all dissolved aluminium corrosion products are rinsed off stainless steel instrument surfaces.
Surgical instruments are protected by a passive layer which forms over time. Can the formation of this passive layer be accelerated by the use of chemicals?
The chemical passivation of stainless steel is carried out industrially preferably with citric acid, but also with nitric acid. In use, all acidic process chemicals, such as citric or phosphoric acid used as neutralising agents, have a passivating effect.
Is it possible that, for example, Mayo Silence scissors cut well once or twice and then suddenly stop cutting? This results in a frayed cut.
With intensive use according to the intended purpose and reprocessing according to the current state of technology, a cutting life of about 6 months can be expected for high-quality products. With normal wear and tear, the cutting properties gradually decrease. In the event of a sudden loss in performance, it may be concluded that the above criteria have not been applied either individually or in total. In this case, we recommend that the affected product be sent to a qualified repair service or to the manufacturer for repair.
How are instruments steam-sterilised in hospitals?
Steam sterilisation is usually performed with saturated steam at 134°C. For items with limited thermal resistance, a temperature of 121°C can be used for a correspondingly longer period of time. Sterilisation must be carried out using a procedure that conforms to standards and is suitable for the items to be sterilised. The packaging of the items to be sterilised must also meet the applicable standards with regard to the quality and use of the packaging materials and must also be suitable for the sterilisation process selected.
Is the use of a sterile compress impregnated with physiological NaCl solution on the sterile instrument table recommended for coarse cleaning of the most frequently used instruments during surgery with regard to pitting corrosion?
Pitting means that the passive layer on instruments is degraded by halides, especially chlorides (e.g. in physiological saline solutions). The risk of chloride-induced pitting increases with increasing chloride concentrations due to drying and prolonged exposure. Placing the instruments in physiological saline solution to allow residues to dry therefore leads to pitting. Wiping of instruments with a soaked compress can be tolerated according to previous experience. At least high-quality instruments must be able to withstand this treatment!
Do instruments have to be completely reprocessed, i.e. also sterilised, before repair, or is mechanical cleaning / thermal disinfection sufficient? Is repair staff at risk from non-sterile instruments?
Proper cleaning and disinfection according to the manufacturer's instructions is sufficient. Further information on this topic can be found in the current issue of the Red Brochure in Section 4 "Recommended action for returned goods / returns". Repair staff is not endangered by non-sterile instruments.
May instruments used by physicians in research and pathology be used again in the operating theatre on patients after proper reprocessing? In the Netherlands this is regulated by law.
In the Netherlands, the procedure is cpvered by the so-called "Veeldnorm". Without confirmation, they may not be used on patients - not even after proper reprocessing. In Germany, this is now increasingly being discussed by the relevant bodies such as the DGSV (German Society for Sterile Supplies) and is already being demanded by various hygiene officers. A legal or normative requirement does not yet exist.
What are the reasons when surgical instruments come out of a washer-disinfector still contaminated with blood? Could prior immersion in a disinfectant solution be the cause of this?
In the case described here, the prior disinfection of instruments is the reason why reprocessing in a washer-disinfector has no effect. When exposed to chemical disinfectants, blood residues can bond and adher to surfaces like a varnish coating. For this reason, the Red Brochure published by the AKI recommends the dry disposal of instruments and immediate transfer to a washer-disinfector.
Do mouth mirrors have to be sterilised or is disinfection sufficient as they are used in non-sterile areas of the body? In addition, they are stored openly as table instruments in the examination room until next used.
The decision whether or not to sterilise mouth mirrors in your hospital/department is ultimately subject to internal hygiene regulations. Hygiene guidelines (see www.rki.de) stipulate that non-invasive instruments and instruments which do not come into contact with wounds do not need to be sterile when used. At the same time, however, it is pointed out that special hygienic requirements may apply to dental surgical procedures. Mouth mirrors can be steam-sterilised from a material point of view. However, these are consumables which become blind due to moisture ingress (due to different thermal expansion coefficients). The same applies to mechanical reprocessing / thermal disinfection.
Can aluminium instruments be cleaned/disinfected by ultrasound?
Aluminium instruments are suitable for ultrasonic cleaning, provided the instrument manufacturer's approval for ultrasonic cleaning has been obtained. The detergents or disinfectants used for this purpose should be recommended by the chemical manufacturer for aluminium.
Will cutting instruments (e.g. scissors, bone punches, scalpels, etc.) made from stainless steel become blunt more quickly during steam sterilisation than during plasma or gas sterilisation?
No. Steam and the temperatures prevailing during steam sterilisation (up to 143°C) are completely uncritical with respect to the performance characteristics of instruments, regardless of the duration of the holding time. This means that neither the hardness nor the metal structure is changed by steam sterilisation. Consequently, the cutting and wear properties do not suffer either. It should also be noted that, as in the present case, thermally resistant medical devices should preferably be steam sterilised from a hygienic point of view.