Before the opening of the EFHSS congress on 5 May the firms
Advanced Sterilization Products (ASP), Johnson & Johnson had issued invitations to attend a seminar on the topic of "Progress in Clinical Instrument Processing". This event was well attended since apparently many delegates had arrived already one day earlier, not only to enjoy the touristic highlights of the surrounding area but also to attend this seminar.
After an opening speech by Wim Renders, in which he also referred to the important role of industry as a partner for central sterilisation - because it was only thanks to sponsor donations that the congress fees could be kept at a low level, enabling the CSSD personnel to attend - Dr. Martin Favero (ASP) gave an overview of the latest developments in sterilisation technology. He described how after the 1960s heat- and humidity-sensitive medical devices conquered the market. As a parallel approach, new sterilisation techniques had to be devised to keep abreast of this situation. To begin with, heat-sensitive instruments were sterilised with ethylene oxide. This process had, however, certain drawbacks - e.g. a long process duration and high toxicity. Favero formulated the requirements to be met by an ideal sterilisation process. A short process duration was becoming increasingly more important at present in view of rising cost pressures. Likewise, developments as far as materials were concerned had not yet exhausted all their potential; material compatibility in respect of as broad a spectrum of diverse instruments was thus accorded top priority. Favero stated that in general the trend was towards increasingly more technology-based processes and products; the aim was to achieve increasingly shorter sterilisation times, while keeping sterilisation temperatures as low as possible. At a chemical level, this development was borne out in the introduction of oxidising chemicals (hydrogen peroxide, H2O2 plasma, peracetic acid, etc.) which had been in use since around 1990 compared with the alkalising EO and formaldehyde agents which had held sway up till then. Favero went on to say that "real" low temperature methods could be developed only for the former agents because they were effective already at temperatures below 60 °C.
Favero then elaborated on the special characteristics of the Sterrad system, outlining the advantages of this system - short cycle duration, no toxicity and a good material compatibility profile thanks to low temperatures - as well as the new series of equipment designed in recent years and based on the original Sterrad 100 from 1994. In a few sentences he went on to describe the newly developed ozone-sterilisation system which had recently been licensed in Canada and granted an FDA release in the USA (see Central Service 2/2004).
In a second talk Favero focused on the role of cleaning in instrument processing. He demonstrated the weak points in verification of the cleaning results, such as e.g. the fact that that this continued to be largely confined to visual inspection; he stressed the need for a validated method for checking cleaning. He expressed hope that a quick method of doing so would be found shortly; an automated system should rule out as far as possible the 'human factor' as a source of error. Favero described a few studies on residual contamination of endoscopes and stressed that, for example, salt crystals could enclose microorganisms, thus shielding them against the effects of disinfection and sterilisation. Hence removal as far as possible of all residues was the most important prerequisite for successful sterilisation. In this context, removal of all detergent residues was also of paramount importance.
Favero then outlined the various detergents available, citing their advantages and disadvantages, and emphasised that the pH value should be tailored to the respective type of contaminant. He finished his talk with a few words on the topic of bioburden, pointing out that the bioburden on surgical instruments was on average lower than that assumed in general and reached a maximum level of around 103 cfu. But the microbial load on endoscopes was considerably higher, in the region of between 107 and 1010 cfu.
Marsha Miller (ASP) gave a talk on the topic of "New Challenges in Instrument Processing". She, too, concentrated largely on the issue of flexible endoscopes, which gave rise to a plethora of processing problems ranging from the intricacies of the device itself (narrow lumens, high bioburden, delicate design) to the processing difficulties calling for several steps, some of which could not be automated yet. This situation was further compounded by time pressures and often cramped conditions in the departments, rendering specialist processing even more difficult. Attesting to this situation, Miller stated that so far 281 infections from gastrointestinal endoscopes and 96 from bronchoscopes had been reported in the literature, including some with HBV, HCV and mycobacteria. Studies conducted by health establishments in the USA on the condition of endoscopes after processing had demonstrated that these were still contaminated in around 20% of cases.
Miller emphasised when processing endoscopes it had to be assumed that each patient was infectious. Adapting practices to the putative infectious status of the patient - i.e. less meticulous processing in the cases where the patient appeared free of infectious diseases - had to be avoided at all costs. Miller pointed to the valid recommendations and guidelines, summarising the processing mistakes frequently made. What was also important was to reflect on the expected processing difficulties before purchasing instruments. A useful approach here would be to have personnel from different departments take a look at working practices in other departments, for example by having OR staff undergo training in the CSSD too. This would also help in controlling costs, on which Miller proceeded to give a few tips.
Ronald Wassenburg (Wassenburg Medical Devices) spoke in the next talk about the progress made in automated endoscope processing. Beginning with the design of a flexible endoscope, he pointed out what had to be borne in mind for the different processing steps, as stipulated in standard prEN ISO 15883 Part 4 "Washer-disinfectors for flexible endoscopes". One difficulty was that some washer-disinfectors were not able to execute all processing steps, thus making it necessary to resort to manual procedures. Wassenberg stressed the importance of separating the individual channels during processing. Only if these could be connected separately in the washer-disinfector was reliable cleaning possible. To round off, he pointed to the critical aspects and possible sources of mistakes in endoscope processing which could jeopardise the ultimate goal of devising a safe, reproducible, verifiable, traceable and standardised processing procedure for flexible endoscopes.
Klaus Roth (SMP GmbH) reported on studies of vCJD and described the particular requirements imposed by the emergence of this disease on processing.
Pieces of wire that had been contaminated with scrapie 263 K and processed using diverse procedures were implanted into the thalamus of hamsters used as animal experimental models. The survival period of the hamsters compared with those animals into which contaminated pieces of wire that had not been first processed were implanted permitted inferences to be drawn on the effectiveness of the respective processing method. Good results were obtained with alkaline detergents with a pH value of at least 11 as well as with highly concentrated H2O2 (59%). Roth pointed out that the most effective methods were also very aggressive and thus not suitable for processing in general.
A combination of measures, for example enzymatic cleaning in conjunction with steam sterilisation did not produce better results - indeed, these were worse in some cases. Roth and colleagues obtained good results with a combination of alkaline cleaning and a modified Sterrad cycle operating on the basis of 4 injections. The majority of animals from this group have survived up till now (579 days).
In an amusing talk given at the end of the seminar Joost van Doornmalen (KW2) described validation of sterilisation processes based on ISO 14937. He outlined the various validation steps and stressed that the responsibility for proper validation was borne by the operators of the washer-disinfectors and not, for instance, by the manufacturer. The operators of such equipment could also conduct validation themselves, but, to cite van Doornmalen, there was a tendency to have validation conducted by independent firms. In any case, the most important thing was being able to produce documentary evidence that all validation steps had been properly and reproducibly executed.
Compliance with the standard conferred various advantages in this respect: operators and manufacturers communicated at the same level, provision was made for better comparison of procedures and, not least, it was easier to furnish proof that the machines were functioning properly.
Following this seminar, a visit was organised in the afternoon to nearby Izmir during which the delegates were able to get acquainted with the Turkish history and culture and, unfettered by the confines of any standards, were able to convince themselves of the high quality of life in this beautiful city.
Dr. Gudrun Westermann