Staining/residues on medical instruments are not always caused by lack of hygiene
Residue formation from the reprocessing of Ferrozell (Resin/fabric)
A further problem not adequately addressed up to now are residues that can occur because of instruments with handles made of phenol resin with fabric filler. This material is sensitive to alkalinity, acidity and the effect of heat. The brownish residues caused by Ferrozell precipitate out onto instruments and predominantly in the sterilization chamber.
It is safe to assume that these depositions pose no hygiene risk, however we have no information on their toxicology risk. Instruments with residues caused by the reprocessing of Ferrozell should be removed from circulation and repaired as quickly as possible. Because of their high sensitivity to the effective parameters of instrument reprocessing devices made of Ferrozell should be completely swapped for more durable materials where at all possible.
The most common types of corrosion found in daily practice
In addition to these there are surface alterations on medical devices that are far more critical and therefore from a hygiene point of view must be immediately removed. Here we have for example pitting corrosion, fretting corrosion, crevice corrosion and stress corrosion. Our article will concentrate on these.
Pitting corrosion is the most well-known of these. It is elicited mainly by chloride or longer contact of blood and secretions on instruments. It can be prevented for example by using fully demineralized water in the final rinse of reprocessing and by keeping the time as short as possible between using the instruments for operations and reprocessing them. In order to guarantee patient safety, the instruments showing corrosion must be of course immediately be removed from instrument circulation and overhauled by the manufacturer.
The hygiene risk here is that rust can form in the pits and that this can then be distributed as flash rust throughout the whole reprocessing process. As well as reaching all the instruments it also spreads in the WDs and sterilisers and therefore naturally also as far as a patient.
Fretting corrosion happens where metal is subjected to friction, which greatly roughens the surface and damages the protective passive layer. Then blood or other residues can be deposited and corrode the instrument. To prevent this it is essential to allow instruments to cool down to room temperature after cleaning/disinfection and sterilization and then to maintain them adequately using suitable lubricants and instruments oils. Affected instruments should be immediately sorted out and be given to the manufacturer for repairs.
For some time now crevice corrosion has been becoming more common. It is found mainly on new instruments with narrow grooves/joints necessary for the design, especially on carbide metal insertions, for example in dissection scissors and needle holders. If not treated properly rust comes out of the gap and is often falsely confused with organic residues.
Stress cracking corrosion is another common type of corrosion. It often occurs because of the way an instrument is assembled, through high tensile stress e.g. at seams of jointed instruments.
This is why it is important to clean and disinfect jointed instruments in the open position and during sterilization to make sure that at the most only one notch is closed, to prevent additional tension. Damaged instruments should be removed from instrument circulation immediately and interchanged for new ones. Repair is not possible here.
In order to appreciate adequately the risk factor it is necessary to identify inorganic deposits and rule out hygiene risks from organic residual soil using semi-quantitative or alternatively protein tests.
For further information on this and many other topics about professional instrument reprocessing please see the Red Brochure by the Working Group Instrument Reprocessing, as a free down load at www.a-k-i.org.
To conclude we would like to point out that CSSD closures due to actual hygiene risks are completely justified. But it is preferable to make a correct evaluation of the individual situation in situ and to come up with a suitable reaction.
If there really are hygiene deficits in the central sterilizing department, then the well-being and care of the patients obviously comes first and closure of the reprocessing department would be an absolutely logical consequence.