Journal for Hygiene in Hospitals and Medical Practice • Edition November 2007

aseptica

www.aseptica.com

TITLE TOPIC

Clostridium difficile –

Pathogen increasingly

common worldwide

Clostridium difficile –

Pathogen increasingly

common worldwide

English Edition

Editorial

aseptica English Edition 20072

Content

The significance of washing pressure

measurements in WDs S. 3

»It all comes out in the wash!« S. 5

Validation with regard to washer-

disinfectors (WDs) from the user’s

point of view S. 8

Clostridium difficile – Another

significant nosocomial pathogen S. 11

Restructuring CSSD –

where are we going? S. 14

The International FORUM Medical

Devices and Processes

Berlin: 2006/2007:

A Review and a Preview S. 16

Checking instrument cleaning by

reflectometric measurement S. 18

Evaluation of a fully automated

decontamination processes for prion

decontamination using cell culture

and chemiluminescence tests for

surface-bound prions S. 20

Resistances from the Intestine S. 22

Dear Readers,

what was it we wanted?

The 2nd International Edition of aseptica is reaching out for the world!

This doesn’t mean to say we are "teaching the deaf", but fact is, that

there are many curious people out there, wondering how we cope with

sterile processing and associated products (not to say problems). As we

are faced with a world population that is growing and aging, a natural

growth of the international health care sectors is to be expected (cf. our

Market Study in last year's international edition).

Small but highly productive nations like Germany might have their share – if

we are there! There is an open invitation to

participate in national markets worldwide. My resumee of our visitations of

several countries within the framework of the

7th International FORUM

Medical Devices and Processes: In Mexico,

the 4th Panamerican

Congress on Sterilisation had 1200 visitors. A huge medical fair in

Zhangzhou showed China and Chinese know-how at its best. In Russia,

Georgia, Armenia there is an enormous demand for surgical and endoscopic

equipment, apart from the rush for dental implantation. There is a wide

range of interests and questions concerning details like ‘Which disinfectant

do I use to what end?’ as well as gigantic projects, e.g. hospital rebuilding.

Are we ready to play a part in all of this? Is there anybody out there to

provide support? Who will answer questions on disinfectant use, manual

or automated cleaning and such, when there are so many doing the job?

Why data loggers if I have these nice indicators? The gap between the

daily routines and our wishful thinking might be huge, but the world is

jumping at us while we are busy discussing guidelines for regulations

(or vice versa). In order to parttake in the global development, we will have

to travel as far as Marco Polo once did and get to the places, where our

expertise is needed.

By the way: The label "Made in Germany" was introduced to discriminate

German products, which partially copied English originals. What was it we

wanted?

Thomas W. Fengler

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Process validation for flexible endoscope

washer-disinfector appliances

F. Wille

Author

Dr. Frank Wille

Managing director

Geschäftsführer

HYBETA GmbH

Albrecht-Thaer-Str. 14

48147 Münster

Tel.: 0251/2851-150

A method for validating automatic

wash-disinfection processes for fle-

xible endoscopes was developed,

based on the standard prEN ISO

15883-4:2005. The aim was to make

the validation relevant to the prac-

tical situation and above all to make

it affordable, so that its acceptance

by users would be as great as possi-

ble. For a little over a year now the

process has been continuously furt-

her developed. It is acceptable to

both users as well as the monitoring

authorities. With the help of this

method, processes can be validated

from appliances already in use as

well as from new appliances.

According to § 4 paragraph 2 of the Medi-

cal Device Operator Ordinance (MDOO),

washing, disinfection and sterilisation of

medical products should be carried out

using validated processes. The requirements

of the MDOO are clear: all automatic pro-

cesses must be validated. In contrast, prac-

tical implementation is still very sluggish.

While validation of sterilisation processes is

already carried out ubiquitously, the valida-

tion of washing and disinfecting processes

is only slowly catching on. This applies

however, only to the reprocessing of ther-

mo-stable medical products. Process valida-

tion of chemo-thermal wash and disinfec-

tion processes for reprocessing of flexible

endoscopes has seldom been carried out up

to now.

The fundamental reason for this is the

lack of standardised principles and recom-

mendations from specialist bodies/associati-

ons. The requirements for washer-disinfector

appliances (WD) are laid down in the stan-

dard series DIN EN ISO 15883. Parts 1-3

were completed in December 2005 and have

been available since April 2006 in German.

Parts 4 and 5 are still at the draft stage.

Part 4 has been available as a second draft

since June 2005. It contains the require-

ments and test methods for WDs using

chemical disinfection for thermo-labile

endoscopes (WD-E). The draft standard

defines the appliance requirements and fit-

ments. In chapter 6 of the draft the various

tests are described and Appendix C defines

which tests should be carried out for opera-

tional tests and performance tests. Detailed

directions for carrying out validation are

omitted.

As well as the standards listed above,

there is a guideline for the validation and

routine monitoring of automatic

washing/disinfecting processes for thermo-

stable medical products (validation guideli-

ne) published by the DGKH (Deutsche

Gesellschaft für Krankenhaushygiene- Ger-

man Society for Hospital Hygiene), the

DGSV (Deutsche Gesellschaft für Sterilgut-

versorgung- German Society for Sterilisati-

on Services) and the AKI (Arbeitskreis

Instrumentenaufbereitung- Instrument

Reprocessing Working Group). This Gui-

deline contains concrete descriptions of

how process validation in WDs should be

carried out. For WD-E a guideline like this

is only in the planning stage. Based on the

standards, draft standards and the validati-

on guideline described above, the firm

HYBETA GmbH in cooperation with

Olympus, has developed a method for pro-

cess validation in WD-E, which fulfils the

legal requirements. More than 50 washer-

disinfector WD-E processes from various

manufacturers have already been validated

according to this method. The results were

checked by the various monitoring bodies

of several German federal states and accep-

ted without exception.

Validation

Before starting validation, the premises and

the organisational conditions should be

appraised. For appliances already in use, it

must be ensured that validation is possible.

In addition, these appliances require servicing

according to the manufacturers directions.

According to the validation guideline, the

actual validation consists in installation, ope-

rational and performance qualifications.

Installation qualification

The installation qualification (IQ) is carried

out according to the relevant checklist 4 of

the validation guideline. For the IQ, amongst

other things, the manufacturer, appliance type

and appliance number are recorded. Checks

are made to see that the appliance is correctly

connected and is in impeccable technical con-

dition. Also the relevant appliance documents

are checked for completeness.

Operational qualification

The operational qualification (OQ) also fol-

lows the validation guideline –checklists 5

and 6.

During the course of the OQ, amongst

other things, the reprocessing programmes

used are recorded and the appliance func-

tions (e.g. appliance malfunction message

system) are checked. For appliances able to

test the patency of tubes, there is not yet a

complete check of the malfunction message

system. At the moment no check is available

that is suitable for the practical situation.

The same applies to the leak tightness test-

here too, suitable test equipment is lacking.

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As well as the points listed above, the per-

formance parameters of the appliance are

also measured, for example the cleaning

pressure, the volume of water run in and

the doses of the process chemicals. In addi-

tion thermometric tests in the wash cham-

ber are carried out, as laid down in the

standard DIN EN ISO 15883-1: 2006-04.

Performance qualification

After successfully carrying out the installati-

on and operational qualification, the perfor-

mance qualification (PQ) can be started.

This comprises tests on cleaning and disin-

fection performance. Here microbiological

tests on the final rinse water are also carried

out. For the performance qualification test,

models described in chapter 6.11.3 of the

standard prEN ISO 15883-4:2005 are used.

Test model

The test model consists of a 2m length of

PTFE tubing. According to the draft stan-

dard two test models with different internal

diameters are required. The models should

have an internal diameter of one and four

millimetres respectively. Countless tests have

shown that the requirements for cleaning

and disinfection are greater for narrower

tubes. To reduce validation costs, only the

model with a one millimetre diameter is

used. Three test pieces made of 20cm lengt-

hs of tubing are integrated into the model.

The first test piece is contaminated with a

suspension of Enterococcus; the second with

a Pseudomonas aeruginosa biofilm. The

third test piece tests cleaning performance

using a test contamination of proteins, fats

and polysaccharides. The manufacture of

tubing models is carried out according to a

quality-controlled and standardised method.

When the process is finished, the test

models are taken out and first of all checked

visually for cleanliness. Then the three pie-

ces of tubing are processed further in the

laboratory. The testing of the chemothermal

disinfection performance is carried out by

determining the microbiological reduction

of the test germs used. For tube length 3

(test contamination) residual protein deter-

mination using the Biuret method is made.

Test instruments

As well as testing the tube models, the clea-

ning performance for other additional instru-

ments was recorded. During everyday use, in

addition to flexible endoscopes other instru-

ments are cleaned and disinfected in the

WD-E at the same time. Testing is carried

out as described in the validation guideline,

using Crile haemostatic clamps. For the test

contamination, heparinised sheep’s blood

rendered able to coagulate with protamine

sulphate, is used. These test instruments are

also removed at the end of the process and

checked visually for cleanliness.. Finally in

addition, residual protein determination is

carried out using the Biuret method. In order

to test the cleaning of endoscope attachments

in the attachment trolley, a test body is used

that simulates a hollow instrument. It can be

adapted to the connection on the attachment

trolley using a Luer lock connector. Inside

the test body is a stainless steel plate conta-

minated with sheep’s blood, according to the

validation guideline.

Measurements

During the tests, the relevant process para-

meters such as temperature, cleaning pres-

sure, volume of water, time and dosage of

process chemicals are recorded indepen-

dently of the appliance documentation, to

compare them with the appliance recor-

dings. Because of this, a parametric release

is made possible for routine operation.

Should the appliance not have a suitable

recording system, then the necessary routi-

ne control checks are carried out as part of

the validation report. The concentration of

disinfectant is calculated from the volume

of cleaning solution and the dosage of

disinfectant. For this the dosage of disinfec-

tant is established gravimetrically and the

cleaning solution volume is determined

using a calibrated water meter. The concen-

tration, temperature and holding time are

stipulated by the disinfectant manufacturer.

For this reason, the temperature and hol-

ding time are monitored during the entire

disinfecting stage, using a data logger. In

addition the temperature distribution in

the wash chamber is tested. The temperatu-

re and time measurements are made using

calibrated data loggers from Ebro. To ensu-

re the reproducibility of the processes, at

least three consecutive run-throughs are

tested. On each load carrier a tube model is

connected to the connection for endosco-

pes, so that 6 models in total are tested.

When testing the attachment trolley, the

test bodies are arranged so that the partsFigure 1: tube model

achtung - noch deutschebezeichnung

Figure 2: tube model on load carrier

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most difficult to reach are recorded.

Validation is regarded as successful if all

the test cycles show a sufficient cleaning

and disinfection performance and if the

Figure 3: measurement of the dosage Figure 4: connected test equipment

recorded process parameters lie within the

tolerances defined by the manufacturers.

To conclude, the results are documented

in a detailed and comprehensive validation

xxx

The preparation stages of cleaning

and disinfection of medical devices

in the Central Sterile Supply Depart-

ment (CSSD) are the focus of consi-

derations for personal and patient

safety. Information published by the

regulatory authorities indicates defi-

ciencies in clinical quality manage-

ment and instrument management,

but in particular in process validati-

on of the preparation of medical

devices which can be explained by

economic constraints and a lack of

knowledge. If committed and quali-

fied hospital staff are on site they

can, after appropriate training,

undertake the performance qualifica-

tion for cleaning and disinfection

equipment (CDE) using a set of

equipment. This method, set out by

the German Society for Hygiene in

Hospitals (DGKH), not only saves

costs, it also increases the quality

Validation in a Team – Process Validation for Cleaning and

Disinfection Equipment in the CSSD [Central Sterile Supply

Department] by qualified hospital staff

B. Schlappler-Scheele, S. Krüger, N. O. Hübner

of preparation and reduces civil law

and liability risks.

The Problem

High quality preparation of medical devices

is becoming increasingly important. The

requirements placed on the professional

qualifications of those working in the

CSSD contribute to this [1], as does the

realisation that device management in a

hospital accounts for a significant proporti-

on of the budget alongside staffing costs.

Innovations in medical technology leave

their mark in the complex instrument geo-

metry with all the resultant problems for

preparation. In all cases the legislator

demands a preparation result »which does

not endanger the safety or health of pati-

ents, users or third parties« [2]. Only those

who take into account the stipulations of

the RKI [Robert Koch-Institut] for hygiene

when preparing medical devices are on safe

ground in terms of legal implications. This

Author

Dr. med. Bernhard Schappler-Scheele

Groß-Buchholzer Kirchweg 39

30655 Hannover

E-Mail: schappler-scheele@htp-tel.de

Sigrid Krüger, Leitung der Sektion

Reinigung und Desinfektion

Deutsche Gesellschaft für Kranken-

haushygiene (DGKH)

Minneweg 22

21720 Grünendeich

E-Mail: sigrid-krueger@t-online.de

Dr. med. Nils-Olaf Hübner

Beauftragter der DGKH

Ernst-Moritz-Arndt-Universität Greifswald

Institut für Hygiene und Umweltmedizin

Walter-Rathenau-Straße 49a

17487 Greifswald

E-Mail: huebner@uni-greifswald.de

report. The validation report also includes

recommendations-relevant to the particu-

lar appliance equipment- for the carrying

out of routine monitoring.

Summary

During the course of tests so far, some

appliances have showed insufficient disin-

fection performance. These results always

correlated with deviations in the determi-

ned process parameters. This shows how

important the validation is in combination

with parametric release- for patients’ and

employees’ safety. ■

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and hospitals can, however, lead to success,

despite the complex material [11].

The validation guidelines produced by

the DGKH, DGSV [German Society for

Sterile Supply] and AKI [Instrument Prepa-

ration Working Group] for C+D processes

for thermostable medical devices set out in

the annex the »Qualifications of the valida-

tor – requirements for the qualifications of

persons undertaking validation« [12]. Loo-

king at the evidence of training and valida-

tion files for external validators is sufficient

to enable technical experts to realise that

the same could be achieved at least as suc-

cessfully by their own personnel following

training in a team consisting of three spe-

cialist disciplines (technician, hygiene spe-

cialist, sterilisation assistant).

Manufacturers of cleaning and disinfec-

tion equipment often perform process vali-

dation for CDE from their own product

range and therefore have a great deal of

know-how when it comes to the use of

CDE in practice. They therefore represent a

potential know-how resource which should

always be involved, in the interests of high

quality medical device preparation.

The Solution

After inspecting 38 hospitals (35 of which

did not have validated C+D processes) it

was decided to propose that the quality

standard of the DGKH, DGSV and AKI

guidelines be met by means of a validation

team. With pressure from the authorities

owing to the prospect of huge cost savings,

hospital managers were quickly recruited

for a pilot project. Seven hospitals in the

Hanover area took part in the study, inclu-

ding the Medizinische Hochschule Hanno-

ver (Hanover Medical College, MHH).

The aim was to equip members of hospital

staff with qualifications and knowledge

such that the performance qualification for

CDE would conform to the guidelines pro-

duced by the various associations.

In December 2006 the DGKH took on

the overall leadership of the pilot project.

The first hospital to successfully complete

the final examination before the head of

the Cleaning and Disinfection Section from

the DGKH in the presence of the regula-

tory authority responsible was the team

from Hanover Medical College. The

Gewerbeaufsicht [inspectorate] deemed

Captions for figures:

Figure 1: Documentati-

on of hygiene, occupa-

tional health and

safety, quality and

instrument manage-

ment along with manu-

facturers’ information

and validation folders

at a CSSD.

is intrinsically linked to the need for full

and complete evidence demonstrating that

preparation was undertaken using suitable,

validated processes* [3].

In the field of validation of cleaning

and disinfection processes the so-called cur-

rent standard of technology is defined by

the national implementation of EC direc-

tives [4], European standards relating to the

various devices [5], guidelines [6] and an

abundance of technical-organisational

instructions [7, 8]. Many of those who

operate CSSDs find this body of legislation

so complex that they outsource the validati-

on of their preparation processes and there-

fore do not make use of their own know-

how in the area of preparation quality.

The fact that the preparation of medi-

cal devices in Germany is not necessarily

always performed in line with legal require-

ments and that not all the options are

exhausted is evidenced in information

published by the regulatory authorities [9,

10]. This is astonishing given that qualifica-

tions, commitment and a sense of responsi-

bility are often a given on site (see figure

1). Cooperation between the authorities

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aseptica English Edition 2007 7

that the validation measures were perfor-

med in line with legal requirements.

To the point of demand-oriented routi-

ne validation in the CSSD this qualificati-

on plan for hospital personnel consists of

seven steps. These are:

step 1: forming the validation team;

step 2: training course;

step 3: validation set;

step 4: gaining practical experience on site;

step 5: final examination before the

DGKH;

step 6: certification by the DGKH;

step 7: routine validations.

Because detailed information on these steps

would go beyond the scope of the publicati-

on please refer to the information platform

for validation teams. Overviews, round-ups

and all the building blocks for your own

successful validation can be found at

www.validieren-im-team.de along with

contact addresses for training providers.

Step 1: Forming the validation team

The qualification requirements for persons

performing validations in C+D processes

are set out in the annex to the DGKH,

DGSV and AKI validation guidelines (see

above). This makes it almost essential to

form a team with one representative from

each of Technology, CSSD and Hygiene.

The area of responsibility of the Tech-

nology representative includes ensuring

that the basic technical requirements for

successful operation of the equipment are

met. The installation qualification (IQ)

and the operational qualification (OQ) for

the CDE and the quality of the process

media are all relevant here. The manufac-

turers are under an obligation here, with

the involvement of the hospital’s own tech-

nical staff. For collaboration in the team to

undertake performance qualification (PQ)

technical knowledge of the equipment is

necessary, along with knowledge of instru-

mentation and control technology for

CDE.

The »CSSD« team member is particu-

larly important. As the person responsible

for preparation processes in the CSSD this

team member knows the operating proce-

dures, operational conventions and instru-

ment management, thereby ensuring prac-

tical relevance. Because this team member

has day-to-day responsibility he/she should

lead the validation team and must have at

least Fachkunde 2 [Technical Qualification

2] in accordance with the Guidelines on

Technical Training Courses from the

DGSV-SGSV.

The specialist in hygiene forms the

team’s link to the legal framework, quality

management and hygiene management in

the hospital. His/her specialist training,

concluded with a state examination, should

ensure that the validation team acts in

accordance with legal requirements.

His/her involvement in the team again

takes into account the hygiene require-

ments and is helpful in developing prepa-

ration instructions and embedding these in

the hospital’s documentation system.

Once these three people have been

identified they can register with a course

provider who is registered with the DGKH

(see website) and obtain their qualification.

For quality assurance reasons the course

provider must register with the offices of

the DGKH.

Step 2: Training course

In just two working days the training cour-

se gives the team all the basic knowledge

needed to understand how to responsibly

undertake the performance qualification of

processes with solely thermal disinfection.

This includes, but is not limited to, know-

ledge of microbiology, law and standards,

the technology of equipment and procedu-

res, media supply, measuring systems and

methods to determine the cleaning effi-

ciency as well as documentation require-

ments. The focus is on learning the infor-

mation which is important in practice,

avoiding looking at the subject matter

from too specialised a scientific perspective.

Short practical exercises in determining

residual protein using the biuret/BCA

method are included even at this early sta-

ge. Temperature, pressure, pH value and

conductivity measurements using datalog-

gers, the relevant validation software and

the significance of the data obtained are all

covered in detail. After this the team is able

to undertake the validation of a perfor-

mance qualification of a CDE in theory,

they know the legal background and the

documentation requirements and are able

to assess the performance of the cleaning

and disinfection process and sources of

errors.

The course concludes with a final

examination based on a list of questions

compiled by the DGKH. The team solves

this exercise together because the questions

deal with various subjects. If the team is

successful each team member receives a so-

called Testat 1 [Certificate 1] from the

DGKH, which only relates to the individu-

al’s specialist discipline. For reasons of

workflow management and quality assuran-

ce, course providers must notify the

DGKH of any participants in the course

with a Testat.

Step 3: The validation set

It is not possible to perform process valida-

tion without the relevant equipment. As

for external validators, the team must be

able to continuously record the process

parameter temperature. It should also be

possible to measure the parameters pressu-

re, pH value and conductivity. Analysis

software makes documentation considerab-

ly easier and technically sophisticated soft-

ware is available. The test clamps and addi-

tional test specimens described in the

validation guidelines produced by the

various associations can be obtained easily

over the internet. This also applies to sets

or kits used to assess the performance of

the cleaning process in terms of determi-

ning the residual protein using the biu-

ret/BCA method. A complete list of the

equipment necessary for validation can be

found at www.validieren-im-team.de.

Equipment to enable continuous measure-

ment of pH values and conductivity is now

on the market and again improves the

assessment of CDE performance in run-

ning equipment cycles.

Because dataloggers can capture rele-

vant CDE process parameters as often as

every second and the validation software

can represent these on-screen by curves of

various colours the result is a visual repre-

sentation of the relevant processes against

time. Malfunctions in the equipment, loa-

ding errors and areas which are not cleaned

as a result of these are immediately appa-

rent, as is any drop below the necessary A0

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protocol, preparing the validation folder

and having a team discussion. With a view

to the success of the team it is sensible to

start including the content of the DGKH

final examination during the practical stage

(please refer to the website). As a primary

benefit the practical stage also includes

training and instruction in using the

equipment. After this the team should be

ready to register for the final examination.

To conclude the practical experience stage

the external trainer awards the members of

the team DGKH Testat 2.

Step 5: The final examination

In this stage the team performs a standard

performance qualification with thermal

disinfection using CDE in front of a repre-

sentative from the Cleaning and Disinfec-

tion Section of the DGKH, thereby sho-

wing their ability. The CSSD member of

the team leads the demonstration in accor-

dance with his/her responsibility for the

preparation of medical devices. The con-

tent of the examination includes, for exam-

ple, the selection of reference loading, test

instruments, using the dataloggers, stan-

dard positioning of the test specimens

along with monitoring, analysis and docu-

mentation of the parameters obtained.

Finally there is a team discussion in which

the reasons for the choices made are pre-

sented in order to examine the team’s

understanding of the process.

In addition, the validation folder is

reviewed. At this stage this folder should

contain the protocols for the sampling and

maintenance measures, the team’s qualifica-

tion certificates [Testate], calibration certi-

ficates for the dataloggers, collected infor-

mation on the measuring system used and

all the documentation of the process para-

meters obtained together with an asses-

sment of these.

Step 6: Certification

The certificate awarded by the DGKH

recognises the team’s ability to perform

validations using CDE with the restriction

that it is only valid for performance quali-

fication and for processes using thermal

disinfection. This confirms at a high level

that the measurements taken by the valida-

tion team are correct in terms of methodo-

logy, complete and reproducible. On the

basis of these high quality findings, a con-

clusive microbiological-medical risk asses-

sment and interpretation by the Specialist in

Hygiene are also possible. The certificate is

related to each individual in the team but is

awarded as an integrated award covering all

three disciplines. Because it does not contain

any local limitation team members can be

recruited at will if a team member leaves.

The registration process with the DGKH’s

offices validates selective top-up training for

new team members. Because the manage-

ment of the team is linked to the CSSD spe-

cialist, the main know-how remains within

the individual hospital in accordance with

the responsibility.

In order for the team to have freedom

from instructions an appropriate letter […].

Step 7: Revalidation and

Routine Monitoring

The validation team is now familiar with

the process. They validate the cleaning and

disinfection equipment processes whenever

any parameters change in the preparation

processes. Routine monitoring is now

easier because the hospital has the neces-

sary measuring equipment. When perfor-

med periodically, systematically or just in

case this strengthens the assumption that

preparation is being performed correctly.

The understanding of the functions of the

equipment and the processes increases and

leads to regulatory measures whenever this

is seen to be needed.

Summary

The German Society for Hygiene in Hos-

pitals (DGKH) is supporting a model

which has already successfully completed

the pilot phase. Because of the nationwide

significance, complete drafts of all the

DGKH documents are already available on

the internet at www.validieren-im-team.de

in the form of an information platform for

future validation teams. The seven steps

outlined represent an appropriate method

for validating CDE processes in a CSSD in

a way which conforms with the standards

within the legal framework. It allows hospi-

tal staff to cut costs, increase the quality of

preparation and reduce the risk of infec-

tion. ■

values. Improved loading configurations or

optimised process management can be eva-

luated during operation to make sure the

operation is worthwhile.

As a matter of principle every hospital

with a validation team should have a com-

plete validation set at all times so that re-

validation is possible at short notice, for

example if new instruments are introduced.

This also supports regular routine monito-

ring in terms of organisational and techni-

cal factors. Equipment sets which are loca-

ted in associated hospitals are

counterproductive here.

Dataloggers and validation software are

expensive initially but this is quickly and

certainly balanced by the cost savings. Not

complying with legal regulations can

quickly become more expensive if it is not

possible to demonstrate evidence of valida-

ted preparation during liability proceedings

or if requirements stipulated by the regula-

tory authorities have to be fulfilled. For

smaller hospitals it can be feasible and

expedient to join together to form so-cal-

led »machine pools«. Buying equipment in

bulk can also give significant savings with

each hospital involved still receiving its

own set with a full guarantee. It is neces-

sary for those responsible for purchasing to

come to an agreement in order for this to

happen, and this could be organised by the

Hospital Federations [Krankenhausgesell-

schaften] in the individual German states.

Step 4: Gaining practical experience

The validation team must »grasp« their

process, i.e. in a very literal sense the team

must have picked up the equipment set in

their own hospital. External validators regi-

stered with the DGKH can help here and

can be found on the internet. Before trai-

ning starts the trainer must register the

team and the date of training with the

DGKH. Under the instruction of the trai-

ner the validation team practices the neces-

sary steps using its own, complete validati-

on set within the context of a sample

validation process. The manufacturers of

the equipment should be involved in this

because they can provide valuable informa-

tion on the functions of the equipment

and the processes running. The practical

training also includes using the validation

xxx

aseptica English Edition 2007 9

vered the Mycobacterium

tuberculosis, for which he

received the Nobel Prize

for Medicine in 1905.

This made it possible to

differentiate tuberculosis

on the basis of certain

symptoms and differing

organic effects, to diagno-

se it and to treat it.

The development of

public healthcare systems

along with improved

hygiene and nutritional

conditions made it possi-

ble to drastically reduce

the number of fatalities

resulting from TB in

Europe over the course of the century from

1850 to 1950. Although there was a tem-

porary increase in the number of cases of

the disease after each of the world wars, the

discovery of the antibiotic streptomycin in

1946 and the introduction of the tubercu-

losis drug isoniazid in 1952 led to a conti-

nued reduction in the number of cases.

Epidemiology since 1980

Since the late 1970s and early 1980s there

has been a revival of the infectious disease

TB in Europe and the rest of the world.

The reasons for this are the high mobility

of the population, along with immigration

into all areas of Europe by people from

countries with a high prevalence of TB.

The global increase in the immunodefi-

ciency AIDS and the development of resi-

stance to the established standard treatment

by the tuberculosis bacteria also play an

important role in this epidemiological

development. A large proportion of those

infected with HIV are also carriers of non-

specific tuberculosis, thereby forming a

reservoir for the spread of the pathogens

into the population at large. Both latent

and fresh tuberculosis develop quickly and

in an uncontrolled way into open TB in

persons with an immune deficiency. This

again increases both the risk of spread and

the development of resistant strains of the

bacteria.

Alongside the historical developments

there has also been a change in public per-

ceptions of TB – from a romantic con-

sumption until the 19th century, to the

disease of the proletariat until the early

20th century, through to a marginal disease

nowadays. This has consequences in terms

of the assessment of the risks which are still

associated with tuberculosis today, not only

for doctors in hospitals and general practice

but also for all other nursing staff and for

the patients affected.

Globally 8 to 9 million people become infec-

ted with TB each year. Around 4 million of

these have the highly infectious »open tuber-

culosis« where the bacteria can be detected

microscopically in the sputum. Sub-Saharan

Africa, south and east Asia, some Latin Ame-

Author

Dr Berhard Meyer,

Ecolab GmbH & Co OHG

Ms Marlis Potempa,

FAI Healthcare Germany

Correspondence: Dr Bernhard Meyer

Since the global spread of the immu-

nodeficiency AIDS there has been an

unprecedented spread of tuberculo-

sis on a global scale but in particu-

lar in eastern Europe – the time has

come to address how we can keep

this in check.

Renaissance of an ancient disease

Traces of tuberculosis (TB) have been found

on prehistoric human remains dating from

as early as the year 4000 BC. In around 450

BC Hippocrates described the disease as

Phthysis, which means »wasting« in Greek.

Even at that time it was known as the most

widespread of all diseases, it was almost

always fatal and was for a long time treated

with little success using a »hygienic dietary«

principle with »good food, plenty of rest,

regular changes of temperature«.

Fostered as it was by poverty, poor nutriti-

on and a lack of hygiene, tuberculosis clai-

med over 100,000 lives a year in the Ger-

man empire alone during the industrial

revolution. Despite the fact that the effects

and symptoms of the disease had been

identified and described, for a long time

doctors remained in the dark as to the

aetiology and treatment of the illness –

uneven distribution of body fluids, malign

effluvia from the ground, a general decline

in moral standards and hereditary factors

were all discussed as possible causes.

In Italy it was believed as early as the

beginning of the 18th century that the

disease was communicable. As a result it

was made compulsory to report cases of the

disease in Italy in the mid 18th century and

measures were introduced which served to

reduce the risk of infection. In England as

well the theory of hereditary transmission

held sway for a long time. This first chan-

ged in 1720 with the publication of Benja-

min Marten’s »A new theory of consumpti-

ons«, in which he presented the theory that

the disease was the result of infection by an

infectious agent.«

On 24 March 1882 Robert Koch disco-

Tuberculosis – the current situation

B. Meyer, M. Potempa

In einem medizinisch-diagnostischen Laboratorium werden nach

einer Tuberkulose- Testmethode mittels Venenblut Kontrolltests

durchgeführt.

achtung - BU nochübersetzen

xxx

aseptica English Edition 200710

rican countries and the countries belonging

to the former Soviet Union are worst affec-

ted. And despite the fact that tuberculosis is

treatable, 2 million people die as a result of

the disease every year; more than any other

treatable infectious disease.

The role of tuberculosis in 21st

century Europe

As mentioned above a global reduction in

cases was seen initially. A 10-year trend

from the early 90s showed a continuous

drop or stagnation in the number of cases

of TB in many western European countries.

Subsequently the number of cases of the

disease continued to fall and reached a very

low level in the last few years. The Baltic

states on the other hand saw a steady increa-

se in the number of cases in the late 90s.

This trend only turned around in 2001.

In total 59,497 cases of TB were registered

in the 25 EU states and in Norway and Ice-

land in 2005, with an average of 12.8 cases

per 100,000 inhabitants. It is noticeable

that there was a particularly high proporti-

on of TB cases among immigrants in

western European countries, e.g. Luxem-

burg (68%), the Netherlands (66%), Swe-

den (73%) and Great Britain (64%). In

eastern Europe on the other hand the pro-

portion occurring in immigrants is extre-

mely low – e.g. in Lithuania the rate of the

disease is very high at 75.0 cases per

100,000 inhabitants, but only 3% of cases

in Lithuania occur in immigrants.

In the countries of eastern Europe, the

so-called new independent states (NIS) of

the former Soviet Union, the collapse of

the healthcare systems means that it has not

been and is not possible to provide ongoing

treatment for many TB suffers. This makes

the risk of resistant strains of bacteria deve-

loping particularly high in this patient

group because irregular treatment results in

the pathogen having contact with the the-

rapeutic agent without being completely

eradicated. The geographical proximity of

these areas of eastern Europe and the

migration from them means that the deve-

lopment of TB is significant for Germany

and the other EU countries as well.

Wider involvement of the EU countries

in terms of checking and documenting resi-

stance to medications is urgently needed in

order to enable this health problem to be

more closely monitored.

Tuberculosis treatment today – deve-

lopment of resistance is the greatest

challenge

TB is transmitted by Mycobacterium

tuberculosis which is released when patients

cough or sneeze and which can remain in

room air for a long time. Carriers are

always those who have infectious or »open«

tuberculosis where the focus of the disease

has a connection to the respiratory tract.

In open TB the pathogens can be detected

microscopically in the sputum and bronchi-

al secretion as well as in the gastric juice or

aspiration biopsies. If there is microscopic

evidence of mycobacteria a culture should

always be taken and resistance testing car-

ried out to confirm the findings. X-ray

investigations also play an important role in

the detection and prognosis of pulmonary

tuberculosis.

The incubation period can range from

weeks to many months but the disease

generally develops around six months after

infection. From this point infection can be

detected by means of a tuberculin test even

if there is no actual illness. Only around 5-

10% of people infected with TB actually

become ill; the pathogens often lie dormant

in the body for months or even decades but

can become active and lead to the onset of

the disease if the body’s immune system

become weak – e.g. as a result of old age,

malnutrition or HIV infection.

In line with the course of TB infection we

differentiate between:

■ TB exposure – contact with open TB,

tuberculin test still outstanding

■ TB infection – tuberculin test positive,

no symptoms of the disease

■ TB illness – positive tuberculin test and

symptoms of the disease

■ Primary TB illness – onset of the disea-

se within one month of infection

■ Post-primary TB illness – infection hea-

led, renewed onset after years or decades

In around 80% of people suffering from

tuberculosis the disease manifests as pulmo-

nary tuberculosis but in theory it can affect

any organ.

Standard treatment with antibiotics

Once a diagnosis has been confirmed, or if

TB is strongly suspected, patients are treated

with combination treatment consisting of

several antibiotics which are specifically

effective against Mycobacterium tuberculo-

sis, also called antituberculosis drugs, as

standard. At the beginning of treatment, i.e.

in the initial phase, isoniazid (INH), rifam-

picin (RMP), pyrazinamide (PZA) and

ethambutol (EMB) or streptomycin (SM)

are given for a period of two months. This is

followed by the stabilisation phase, during

which patients have to take a combination

of INH and RMP for at least four months.

Resistance to treatment

Mycobacterium tuberculosis is a bacterium

which grows very slowly and which tends by

its very nature to become resistant because it

is frequently inactive for a long time. For

this reason treatment of open tuberculosis

must last for six months, or considerably

longer in complicated cases where there is

still evidence of bacteria after three months

of treatment.

It is this long duration of treatment

which presents the greatest problem in the

fight against tuberculosis: if treatment is

stopped too soon – either because of poor

compliance or because sufficient, adequate

medicines are not available – it can lead to

the development of dangerous resistance of

strains of the bacteria to the antibiotics used.

Some experts even believe that antibiotic

treatment which is carried out incorrectly

and inadequately is worse than no treatment

at all.

If the bacteria are resistant to more than

two of the antibiotics available it is called

multi-drug-resistant tuberculosis (MDR-TB).

According to the most recent WHO report,

in eastern Europe and central Asia around

15% of new TB infections are now caused by

multi-resistant tuberculosis pathogens and in

Germany the proportion of MDR tuberculo-

sis cases has increased from 2.5% to 2.7%

over the course of just one year.

Another phenomenon which was first obser-

ved in the South African province of Kwazu-

lu Natal in March 2006 is even more worry-

ing. In Kwazulu Natal a strain of TB

bacteria was discovered which is resistant to

almost all second-line medicines. Extensive-

xxx

aseptica English Edition 2007 11

an investigation of the outbreak is neces-sary, coordinated by the health authorityand comprising the following elements:

■ Immediate identification of the pathogen

including culture and resistance testing

■ Establishment and assessment of the

contact history, tuberculin tests, if appro-

priate X-ray examinations and laboratory

testing of the contact persons

■ Physical isolation of the patient if there is

open tuberculosis, even if on a general

hospital ward

■ Good ventilation of the patient’s room

must be ensured

■ The patient should be instructed to cover

his/her mouth with a tissue when coug-

hing, laughing or sneezing.

■ Wearing of protective gowns, masks cover-

ing the nose and mouth (FFP2 masks for

particular exposure, FFP3 masks for

MDR-TB), protective gloves and appro-

priate hand hygiene if there is contact

with material containing the pathogen

■ Complete or partial lifting of isolation is

only recommended after the patient has

been classed as not infectious or, if there is

any doubt, after the patient has been sup-

plied with a mask tightly covering the

nose and mouth.

The implementation of effective disinfection

processes is particularly significant in con-

trolling tuberculosis. Tuberculosis pathogens

have a higher resistance than normal patho-

gens and cannot necessarily be reached by all

disinfectants. In order to ensure that the cor-

rect disinfectant is used to treat surfaces and

instruments and to disinfect the hands, it is

advisable to read the label of the disinfectant

concerned carefully. For everyday use suita-

ble substances are primarily those given in

the list produced by the VAH. Some active

substances are particularly suitable in terms

of how they are handled, their efficacy and

the method of application. This includes the

active substance glucoprotamin.

Although tuberculosis represents a threat

which should be taken extremely seriously,

particularly its highly treatment-resistant

strains, with suitable disinfection measures

and measures to prevent exposure there are

still effective weapons available in the fight

against this disease. ■

Bildtafel aus den 30-er Jahren: Wie schützt

man sich und andere vor Tuberkulose?

ly-drug-resistant strains of TB of this kind

(XDR-TB) have now been diagnosed in 37

countries – with increasing frequency and

alarmingly low chances of recovery.4

Resistance to treatment does not

mean resistance to disinfection

Preventative measures such as actively looking

for cases in persons who have had direct

contact with patients with confirmed open

TB, increased attention to members of special

target groups, for example asylum seekers,

refugees, Ethnic German resettlers [Aussied-

ler], migrants, homeless people, drug users,

and prison inmates, are a requirement if there

are to be high detection rates and a reduction

in the number of cases and the development

of resistance.

Thorough disinfection of surfaces and

medical devices in hospitals, doctors’ practices

and other medical institutes is a particularly

effective and controllable measure to prevent

tuberculosis infections. Special disinfectants are

used for this and these are listed with the

Robert Koch-Institut (RKI) or the Association

for Applied Hygiene (VAH), depending on the

requirements of the situation.

However, the term »development of resi-

stance« is often associated with the idea that

there may also be resistance to disinfectants.

This concern is, however, unfounded because

the effect of biocides on bacteria outside the

human body is different to the effect of syste-

mic antibiotics.

Treatment and disinfection –

different mechanisms

Antibiotics and disinfectants work against

bacteria in different ways. Antibiotics attack

specific cell structures or interact with spe-

cific metabolic/synthesis processes. The

effect of biocides, on the other hand, is

non-specific: they destroy biological mem-

branes and/or react non-specifically with

functional groups of proteins or genetic

material. For example, it has been shown

that at concentrations below the minimal

inhibitory concentration some biocides

initially destroy the functional integrity of

cell membranes and at higher concentrati-

ons then lead to »leakage« of intracellular

material. The possibility of resistance deve-

loping to these non-specific mechanisms is

highly unlikely, in particular because bioci-

dal active agents are used in microbicidal

concentrations far above the minimal inhi-

bitory concentration in disinfectants.

Preventing nosocomial transmission

In view of the fact that only around 10% of

people infected with TB will actually beco-

me ill and that this will normally only hap-

pen in the first two years of having become

infected or even later it is extremely diffi-

cult to identify nosocomial transmission of

TB. Nevertheless cases of nosocomial trans-

mission are described in the literature and

studies reveal that the tuberculin test is

positive more often for those working in

the health service than for the general

population.

In terms of measures to prevent nosoco-

mial TB infections in hospitals and doctors’

practices the public health authorities’ regu-

lations and of course the special guidelines

for the avoidance of hospital infections app-

ly. The guidelines from the German Central

Committee to Combat Tuberculosis (DZK)

in particular should be noted here. If tuber-

culosis is suspected doctors and nursing

staff should complete a risk assessment,

taking into account the epidemiology, the

reservoir and the release of the pathogen,

the infectiousness of the pathogen, the

infection routes and the disposition of the

person exposed.

If there are more than 2 cases of the illnesswith an epidemiologically confirmed link

achtung - BU nochübersetzen

xxx

aseptica English Edition 200712

ebro Electronic, Ingolstadt, has develo-

ped a new software solution

Winlog.med specially for the routine

monitoring/validation of cleaning and

sterilisation processes using datalog-

gers in the CSSD. For CDMs analysis

with the new software is carried out in

accordance with the standards as per

DIN EN 15883-1,2,3 and as per the

draft guideline of the DGKH and DGSV,

for steam sterilisers in accordance

with DIN EN 285, DIN EN 554, DIN

58946-6 and DIN EN13060.

Application in CSSD

Two versions of Winlog.med are available:

■ Standard version Winlog.med: for daily

routine monitoring. It is easy to use,

meaning that even untrained staff can

easily learn how to use it.

■ Winlog.med Validation: this software has

been developed for annual validation.

Winlog.med and Winlog.med Validation

perform fully automated analysis of the

dataloggers used in daily routine monito-

ring and annual validation of cleaning

disinfection machines, bedpan washers and

steam sterilisers. The software independent-

ly identifies and checks the relevant phases

of cleaning/sterilisation, automatically per-

forms all necessary analyses and produces a

quick and accurate assessment of the pro-

cess (pass/fail).

Routine Monitoring

For the daily routine monitoring of CDMs

and bedpan washers the disinfection para-

meters A0-value 60, 600, 3000 and the

temperature-time response are particularly

significant.

For the routine monitoring of steam

sterilisers the pressure-time response and

temperature-time response are documented.

The values are automatically calculated and

represented graphically with the help of the

standard version Winlog.med.

Validation

Winlog.med Validation is suitable for the

validation of CDMs, bedpan washers and

steam sterilisers.

In addition to the features of the stan-

dard version the software also offers »map-

ping«, i.e. the number and position of the

dataloggers is defined in three dimensions

in the software. This means that the exact

position of the loggers inside the equipment

is entered into a three dimensional model of

the CDM or steam steriliser, recording the

serial number, channel and position. The

equipment to be checked is first selected

from a database.

As an automatic result of the CDM

validation using dataloggers Winlog.med

Validation provides a protocol containing

the following information:

■ CDM data: Model, inventory number,

equipment number, program, datalogger

batch, last check

■ Name of the person carrying out the

check (established on the basis of the

electronic signature of the operator,

which must be entered prior to using

the equipment)

■ Positions of sensors, type and serial num-

ber of sensors

■ Program selected

■ calculated and specified A0 value

■ Batch release (yes/no) Automatic reports

are generated for steam sterilisation in

exactly the same way as for CDMs but dif-

ferent information is important for steam

sterilisers:

■ Steam steriliser data: Model,

inventory number, equipment number,

program, datalogger batch,

last check

■ Name of the person carrying out the check

(established on the basis of the electronic

signature of the operator, which must be

entered prior to using the equipment)

■ Positions of sensors, type and serial num-

ber of sensors

■ Program selected

■ Residual air

■ Minimum pressure during vacuum

■ Compensation time, hold time

Author

Susanne Neumann, Marketing

Iven Kruse, Vertriebsleiter

ebro Electronic GmbH & Co. KG,

Peringerstr. 10, D-85055 Ingolstadt

Tel. 08 41/9 54 78-0, Fax 08 41/9 54 78-80

E-Mail info@ebro.de, Web: www.ebro.de

S. Neumann, I. Kruse

New datalogger software for routine

monitoring and validation Winlog.med and Winlog.med Validation

xxx

xxx

aseptica English Edition 2007 13

Interview: on the transmission risk of the

variants of CJD and the decontamination

of surgical instruments(translated from the journal »medical special«

published by the Ith Publishing house)

For patients undergoing operations,

contaminated instruments pose a

certain amount of risk of contracting

the new form of Creutzfeld-Jakob

disease (vCJD). The infectious pro-

teins called prions, which can trans-

mit the disease, adhere well to stain-

less steel surgical instruments and

can only be rendered innocuous with

enormous effort.

British researchers consider it theoretically

possible that in Great Britain iatrogenic

transmission has occurred during operations,

via surgical instruments. Though up to now,

after 160 people have died of vCJD, experts

cannot say exactly how great the risk of con-

traction of infection was and now is. Further

studies will now follow, grounded on the first

data from extrapolations.

In Germany there has not yet been a single

known case of vCJD.We spoke to the post-

graduate Andreas Schmitt at the Centre for

Neuropathology and Prion Research of the

LMU (Ludwig Maximilian University)

Munich, about how medical materials and

diagnostic surgical instrument sets can be

reliably decontaminated, in order to prevent

an iatrogenic transmission of prions.

1. Prion diseases, including amongst

others the different variants of the

Creutzfeld-Jacob disease (CJD), are

really quite rare diseases. Herr

Schmitt- are the risks of iatrogenic

transmission of prions at all relevant

for federal German clinics?

Is iatrogenic transmission possibly relevant

only to certain clinic departments or specia-

list operating sectors?

Although prion diseases may be rare, pre-

vention is of the utmost importance, as the-

re are no available therapies and the disease

is always lethal. The new variant of CJD

(vCJD) caused by BSE is particularly rele-

vant here. Indeed, in Great Britain only

160 people have so far died of vCJD. But

prevalence studies carried out on appendec-

tomy biopsies indicate however a not insi-

gnificant number of infected persons there.

vCJD can be distinguished from the

other human prion diseases by its lym-

photrophism i.e. its potent ability to accu-

mulate infectious prion protein (PrPSc) in

the lymph tissue of infected persons.

Author

Dr Berhard Meyer,

Ecolab GmbH & Co OHG

Ms Marlis Potempa,

FAI Healthcare Germany

Correspondence: Dr Bernhard Meyer

■ Sterilisation temperature reached

■ Temperature range

■ Theoretical temperature

■ F0 value

■ Batch release (yes/no) Each of these values

is assigned an OK/Not OK value by the

software. The relevant value or curve can

be displayed at the click of a mouse but-

ton. The protocol is initially displayed on

screen. However, it can be saved and/or

printed.

Result

The new software Winlog.med and Win-

log.med Validation produced by ebro Elec-

tronic enables the user in the CSSD to

automate routine procedures using a data-

logger and thereby to simplify them. Becau-

se Winlog.med/Winlog.med Validation

have been developed specifically for the

cleaning and sterilisation process in the

CSSD they contain precisely those features

which are needed in this area. ■

achtung - der Autor fehlt noch

xxx

aseptica English Edition 200714

Whereas for the other human prion

diseases PrSc is probably present only in the

CNS and in the eye in quantities relevant

for transmission, vCJD patients also show

large amounts of PrPSc in lymph tissue,

where it is accessible during many surgical

and diagnostic interventions. Because cases

of BSE in cattle in Germany are detected

every now and then, one must presume that

also in this country, the population is expo-

sed alimentarily to the BSE pathogen that

causes vCJD. Even though a case of vCJD

has not yet been detected in Germany,

because of the long incubation time of

vCJD, it is not clear whether any, or how

many people are infected with vCJD, who

could then pose a risk for the transmission

of this disease. In contrast to the other

human prion diseases, where the risk of

iatrogenic transmission is posed first and

foremost by ophthalmic and neurosurgical

operations, vCJD, because of its marked

lymphotrophism, poses a high risk for

transmission of the disease for a large num-

ber of surgical and diagnostic interventions.

Particularly for frequently carried out opera-

tions such as for example, appendectomy or

tonsillectomy, there is direct contact with

the high-risk tissues.

2. Does this have consequences for

the requirements for sterilisation of

materials or for the reprocessing and

disinfection of instruments?

In 2002, because of the background danger

of iatrogenic transmission of vCJD, the

Robert Koch Institute (RKI) extended its

earlier recommendations for instrument

reprocessing. Here they recommend that

instruments that have come into contact

with patients, who are clinically likely to be

suffering from vCJD, should not be repro-

cessed and used again. These instruments

should be disposed of by incineration.

Instruments that cannot be disposed of

because of their high price, should, after

special reprocessing, only be used on pati-

ents with vCJD. If a patient is perhaps suf-

fering from vCJD, then if possible only dis-

posable instruments should be used on him.

These are then disposed of as intended.

Reprocessable medical products should not

be reused until the diagnosis of the patient

is certain. If the diagnosis of vCJD is confir-

med, the instruments can be disposed of; if

vCJD can be ruled out, they can be repro-

cessed.

The RKI also delineates a different pro-

cedure compared to the earlier recommen-

dations for instruments coming into contact

with all other patients who show no sign of

the existence of vCJD. Using a combination

of two at least partially prion-decontamina-

ting procedures, an iatrogenic transmission

of unrecognised vCJD should be prevented.

According to the RKI, the following proce-

dures are at least partially effective against

prions: a thorough alkaline wash; steam ste-

rilisation (preferably at 134°C); or chemical

decontamination with NaOH (1M for at

least an hour), NaOCl (2.5- 5% for at least

an hour, with at least 20,000ppm chlorine

content) or GdnSCN (? 4M for at least 30

minutes).

At any rate, pre-treatment with alcohol

or aldehyde detergents and disinfectants

should be avoided at all costs, as these fix

the infectious prion protein and therefore

can prevent successful decontamination.

3. Are there special diagnostic or sur-

gical instruments or sets of instru-

ments for which the requirements for

cleaning, disinfecting and sterilising

procedures are particularly high?

Instruments that are not readily accessible to

chemical decontamination and cleaning are

especially critical for reprocessing. These

include for example, appliances with narrow

lumina, hollow spaces with only one ope-

ning, or with complex or not readily accessi-

ble surfaces. In addition, for such appliances

the overall optical check of cleaning success

is often not possible.

Because generally physical decontamina-

tion is seen as more reliable than chemical,

this should always be given priority.. Against

this background, the reprocessing of thermo

labile instruments is always critical, because

here the only effective physical procedure

for prion decontamination is steam sterilisa-

tion - which cannot be used.

4. Why are the established cleaning,

disinfecting and sterilising procedu-

res not sufficient for a prion-contami-

nated instrument set?

The inefficacy of many established deconta-

mination procedures lies in the nature of the

prion pathogen. Unlike all the other known

infectious pathogens, prions (PrPSc) consist

only of protein. They do not have other

components such as a lipid envelope or

nucleic acid genome that many of the

decontamination procedures would attack.

In addition, as proteins go, prions have

an unusually high resistance to environ-

mental influences because of their tertiary

structure. So for example, unlike most pro-

teins, prions are partially resistant to enzy-

matic degradation by proteases, and possess

a remarkable resistance to thermal denatura-

tion. Various studies have shown that PrPSc

can partly survive sterilisation in saturated

steam at 134°C and can even maintain its

infectiousness after treatment with dry heat,

possibly even at 600°C.

5. Can one use expensive thermo

labile instrument sets for diagnostic

or therapeutic interventions on CJD

patients?

Certain interventions for CJD patients

require expensive instruments, which due to

their price are not intended to be disposable.

So for example to lay a PEG (percutaneous

endoscopic gastrostomy) for a CJD patient

requires an expensive endoscope. Because

such instruments, even after special repro-

cessing, can only be further used for CJD

patients, some appliance pools for endosco-

pes have been set up, for example at the

University of Göttingen. Here, instruments

especially for the treatment of CJD patients

can be loaned. After use, the loan centre

reprocesses the endoscopes using special

techniques, or disposes of them if necessary.

6. Is there already a standardised,

anti-prion effective approach or

method for cleaning and disinfecting

the various instrument sets?

As mentioned before, the RKI recommends

combining two at least partially effective anti-

prion methods for preventive instrument

reprocessing. On no account may pre-treat-

ments with alcohol or aldehyde detergents or

disinfectants be carried out before the decon-

taminating procedure, because this would

only lead to a stabilisation of the PrPSc.

The simplest attainable approach is the

procedure recommended by the RKI for

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thermo stable instruments. Here, first alka-

line cleaning in a washer-disinfector appli-

ance is carried out, then steam sterilisation

follows at 134°C for 5-18 Min.

For thermo labile objects one must

resort to other, chemical methods for pri-

on decontamination, rather than using

steam sterilisation. If necessary, after prion

decontamination a low temperature sterili-

sation procedure can be used.

The RKI-recommended procedure is

simply a combination of partially effective

anti-prion methods. These cause a strong

depletion of the adhesive infectivity, but do

not definitely completely eliminate it. In

order to be able to carry out an effective

prevention regarding the iatrogenic trans-

mission of vCJD, new, more effective anti-

prion decontamination procedures for a

wide routine use in instrument reproces-

sing must be developed.

7. Isn’t it true that automatic pro-

cedures are safer than manual pro-

cedures? Is it possible that automa-

tic wash-disinfection procedures are

already being researched?

Of course, normally it is true that automa-

tic procedures produce more steady results

than manual procedures, and therefore

they ensure greater safety in instrument

reprocessing. Also, manual methods can be

problematical regarding the work safety of

the personnel carrying out the procedures.

According to the RKI, from amongst

the at least partially effective automatic

anti-prion procedures- two- alkaline clea-

ning, and sterilisation are established as

automatic procedures. At the moment the-

re is a new, fully automatic procedure,

especially developed for prion decontami-

nation, being tested at our institute. It is a

combined alkaline/oxidative procedure,

which runs in a standard washer-disinfec-

tor appliance. Due to the good material

tolerance and ease of use, it should be

deployable in the general routine reproces-

sing of medical products. During in vitro

experiments we were able to show a reduc-

tion of the infectious prion titre for this

method by as much as 4 log units. At the

moment the method is being tested in ani-

mal experiments. We are expecting the final

results on the anti-prion effectivity of the

new decontamination procedure in August

of this year.

9. With what methods can the

decontamination results be tested?

For the evaluation of new decontamination

procedures, the decontamination result was

checked in quite different ways in separate

studies, which makes a comparison of the

results difficult. So for example, Western

blot-, cell culture-, microscopy- and animal

test-based methods were used to detect pri-

ons. Up to now, from amongst all these

procedures, animal experiments still repre-

sent the gold standard when evaluating new

decontamination procedures.

Herr Schmitt, thank you very much for the

informative discussion!

The interview was conducted by Dr. Win-

fried Michels, Gütersloh. ■

Recent announcement from the Institute ofNeuropathology: in the meantime the in vivoexperiments have been completed, with verypositive results for the Oxivario Plus Process.The results are being prepared for publication.

Recently a manufacturer asked us

what should be included in an

instruction manual for medical devi-

ces. I then realised that the EN ISO

17664 - even three years after com-

pletion- hasn’t found its way into the

instruction manuals proposed by the

legislator, which the user should be

Medical devices require an instruction

manual – is the 17664 helpful?

A manual facilitates handling.

Th. W. Fengler

able to consult (»Manuals«) if he has

a question. Since 2001 in the Euro-

pean Union, the DIN 62079 exists

for authorised devices (EC registrati-

on mark) giving many tips for

assembling appropriate manuals.

The font size must be at least 9, and

a simply formulated description of

Author

Dr. med. Dipl.-Ing. Thomas W. Fengler

CLEANICAL GmbH

Genthiner Str. 11

10785 Berlin

E-Mail: fengler@cleanical.de

xxx

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man Medical Device Act and its Operator

Ordinance (amongst other things compul-

sory registration) should be followed as

conscientiously as is the case for obligation

to quality management and quality assuran-

ce, according to the Social Security Code

and further compulsory recording, standar-

dising and registration obligations from the

Infection Protection Act.

Guidelines and recommendations have

the character of an anticipated expert’s

report (bear in mind here § 4 of the Medi-

cal Device Operator Ordinance).

Furthermore, necessary care should be

taken during everyday use, to avoid legal

liability and possible fateful and unavoida-

ble complications according to § 276 BGB.

In Germany the KHEntg G (Kranken-

hausentgeltgesetzes- German Hospital

Remuneration Act) (it replaced the Bundes-

pflegesatzverordnung- National Ordinance

on Hospital Rates) is valid and facilitates

across the board retrospective curtailment

of the agreed remuneration (§8 Section 4-

is subject to the WD reimbursement

system according to § 17b KHG) for a pro-

ven deficit in quality management (see

Social Security Code 5th edition).

17664- Part of an extensive body of

rules and regulations

This preview should make it clear that

the handling of medical devices is subject

to an extensive body of rules and regulati-

ons, which the current level of training in

the specialist departments can hardly do

justice to. Manufacturers must also take

this into account when putting medical

devices on the market.

»The Standard applies to medical devi-

ces intended for multiple use and requiring

reprocessing after single use, which returns

them to a sterile state ready for renewed

use.« (Quote : EN ISO 17664).

The Standard does not actually apply

to the clinical use of semi-critical applicati-

ons such as (usually) in the case of (flexible)

endoscopes, but »the principles of this

Standard can be followed for medical devi-

ces only requiring final disinfection before

reuse, if the information made available for

these medical devices is taken into account.«

If the responsible parties require sterili-

sation of devices because of the scope of the

therapeutic intervention, then sterilisation

becomes mandatory, for example the use of

a flexible bronchoscope for active tubercu-

losis. This is why we recommend a suitable

formulation in the manual or instructions

for use.

Furthermore: »This Standard specifies

information that must be provided by the

manufacturer about the reprocessing of

medical devices if these are claimed to be

resterilisable, or if they should be sterilised

by the reprocessor.«

»This Standard specifies requirements

for the information provided by the manu-

facturer of the medical devices, that serve

safe reprocessing and maintenance of the

required performance capability of the

medical devices.«

This includes prearrangement at the

place of use, the preparation, washing and

disinfection in the reprocessing depart-

ment, drying, monitoring, servicing and

checking, packing and sterilisation also in

the reprocessing department, as well as sui-

table storage.

Particularly interesting is the relativising

remark about concrete reprocessing conditi-

ons! »For preparing instructions/direc-

tions… the manufacturer…is urged to take

into account training, process knowledge

and the provisions for reprocessing that

persons likely to carry out reprocessing

have available to them. Some of the repro-

cessing methods are probably of a general

nature...in this case the instructions need

only give a suitable reference.«

As well as the field of application (sec-

tion 1), it makes sense to put in the terms

(section 2) used in the Standard so as not

to bewilder the user. Here, in our opinion a

corresponding discussion of technical terms

should be added for each block of text in

the manual. Using a washer-disinfector

appliance is obviously rather different to

using a laundry washing machine or dish-

washer, which by definition are not medical

devices, but nevertheless are used variously

in reprocessing.

Section 3 stipulates as mandatory a

validated reprocessing method, which

should be cited, giving a specification for

this statement in the informative annex A.

Here manual cleaning- by the way quite

the intended use of the device must

be given, with relevant warnings

where necessary.

For medical devices, as well as a description

of function, how to reprocess them is

described as a sort of »maintenance measu-

re«. The instruction manual is therefore an

indispensable part of quality-ensuring

management and describes intelligibly the

function and care of a medical device. In

the case of a reprocessable medical device it

also includes information on manual and

automatic reprocessing.

By mentioning the RKI guideline on

hygiene (2001), the Medical Device Act

and its Operator Ordinance strongly

recommend risk group categorisation accor-

ding to design (C, B, A) and field of appli-

cation (critical, semi-critical, non-critical).

Each and every correspondingly autho-

rised medical device is intended for use

on/in patients and must correspond to spe-

cial European (EC registration mark, Gui-

deline 93/42/ EWG) and national legislati-

on (the Medical Device Act, its Operator

Ordinance, as well as directives about elec-

trical safety, the Regulation of Biological

Substances Act and general liability).

Thus for resterilisable medical devices,

there is the EN ISO 17664, containing a

framework for reprocessing. A correspon-

ding (descriptive) standard for disinfectable

medical devices does not exist; the one

mentioned here can however definitely be

applied appropriately. For the process stages

of automatic cleaning and disinfection of

medical devices, the CEN ISO 15883 is

now valid. For the process stage of sterilisa-

tion, the DIN EN 285 is valid among

others.

The EN ISO 15883 1-5 contains infor-

mation on the processing step cleaning and

disinfection. One manual should take into

account the total cycle of use of a medical

device, from preparation for use to disposal

and reprocessing for reuse on the next (or

the same) patient.

Disposable instruments are by definiti-

on manufactured only for single use (only)

on one patient.

Acts and statutes are granted absolute

binding character in German law. The pro-

visions of the European directives, the Ger-

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realistically- is explicitly not excluded.

What such a »validated« method should be

like is however not explained. The possibili-

ty of limiting the number of cycles is also

mentioned- without description of a tech-

nique- if the life expectancy of the medical

device is limited by wear and tear. Finally

the process stages are described one by one.

A suitable comparison with already existing

text blocks from existing manuals is recom-

mended and should be applied gradually to

new manuals.

Section 4 describes the presentation of

information (see also appendix B).

A cross reference of contents for the

body of rules and regulations should be

provided in the relevant text blocks. » The

information specified in section 3 (»Infor-

mation to be provided by the manufactu-

rer«) should take into account the pro-

perties and condition of the medical

devices, the intended use, as well as the

training and level of knowledge of the per-

sons responsible for the reprocessing«. In

particular it is pointed out that cross refe-

rences to standards and manufacturers’

information is also permitted in the form

of symbols (such as »EN ISO 15883«).

Section 5 requires the validation of

each and every method used in a process;

this can also be carried out as group valida-

tion.

Thus it can be differentiated between

dismantleable and rinseable instruments.

Regarding the risk analysis in Section 6

based on the nature of and intended appli-

cation of the medical device in question,

one is referred to the training level and

technical provisions of the reprocessor (per-

son). The EN ISO 14937 is named as a

guideline.

In Appendix A process classification of

methods A-J can be undertaken. In Appen-

dix B there is a form for reprocessing

instructions. Both are informative, rather

than normative appendices. Here the Stan-

dard supports in parts the Guideline

93/42/EWG and has a literature appendix

containing those standards thought to be

relevant- (general and specific information

about sterilisation, validation, packing and

symbols for registration marks).

In our opinion this Standard EN ISO

17664 should be made available to the

customer in its entirety. This does not

mean that the manufacturer has to have his

own reprocessing manual available on

request- on the contrary: the 17664 was

written precisely so that it could be referred

to in the stipulated instruction manual.

Thus it is not necessary to describe in detail

for every new manual what is actually pre-

sented in the Standard. A reference to the

relevant group suffices. It should be possi-

ble for this Standard to gain international

acceptance, because manual cleaning is

deliberately not excluded.

Chapter 3 explicitly requires »a valida-

ted (!) non-automatic disinfection method«.

However it can be presumed that the Stan-

dard is not (yet) very well known and the-

refore national regulations play a more

important role, as far as they exist in each

exporting country.

In particular the criteria for classificati-

on of what should be sterilised are not con-

gruent between America, Asia and Europe.

The user, called the »reprocessor« in the

Standard, usually follows local norms/stan-

dards, which are now being amended and

being rendered more precise through this

global standard.

In the past much of the information

mentioned and required in the Standard

has not been gathered and documented, so

that a substantial adaptation phase is requi-

red. Precisely because of this, it is vital that

the phrasing of the manual should be clear

and conform to the body of rules and regu-

lations. In particular the terms for (process-

) validation (Installation validation, Opera-

tional validation, Performance validation)

are shown over and over again to be

unwieldy.

The scope of the process parameters to

be specified will continue to grow because

of continuing improvements in the specifi-

cation of reprocessing steps. This is accom-

modated better during customer service

than in the manual itself.

Nevertheless the contents of CEN ISO

17664 can be designated as generally spea-

king practicable. Here some phrases signal

a certain leeway - such as »The following

information should be cited if it is critical

to maintain the intended function of the

medical device and to ensure the safety of

the user and patient« or »if necessary« or »if

applicable« (Section 3).

»Thresholds...of chemical residues

remaining on the device« need only be

cited by the manufacturer »if and when it is

necessary«.

The manufacturer can provide infor-

mation here, nevertheless the reprocessor

decides whether his specifically chosen (or

simply long-established) methods could

cause damage to instruments.

The patient is expected to have few

problems with »maximally residue-free«

instrument surfaces, and only in exceptio-

nal cases could proof of damage be used as

a reason for a liability case. This is why the

legislator emphasises the utter necessity of

validated reprocessing processes - that must

also be attestable (compulsory documenta-

tion – for one’s own benefit). Process safety

leads to more legal safety!

A different situation applies to disinfec-

tant concentration and contact time, which

must be specified for the process - first as

evidence of proper functioning and second-

ly with regard to patients. The disinfectant

must then be removed from the medical

device –another requirement that is also

not described in detail or verifiable. Here

too one must be able to substantiate the

customary methods, such as rinsing with

fully demineralised water (documentation).

To summarise, the realisation lingers

that the contents of this Standard are not

nearly sufficiently familiar, nationally or

internationally. It offers the user something

useful, because categories and their criteria

are named, which can facilitate validated

reprocessing.

Only measurable processes can be suffi-

ciently documented and offer, in the event

of a liability claim, the necessary proof that

work was done according to the latest

scientific and technical knowledge. ■

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Experience gathered from automatic

instrument reprocessing in an ophthalmic

clinic

U. Roider

Ophthalmic surgical operations in an

ophthalmic clinic take place primari-

ly as outpatient procedures and con-

cern the anterior and posterior

chambers of the eye. Interventions

include cataract and glaucoma sur-

gery, corneal transplantation (kera-

toplasty), vitrectomy, as well as

every type of refractive surgery.

Until 2003, instruments were exclusively

reprocessed manually, using ultrasound tre-

atment. After successfully completing the

training course Technical Qualification 1, I

started to plan the adaptation of reproces-

sing to fit the requirements of the relevant

specialist guidelines and recommendations.

The processes should be validated through-

out and the reprocessing must be recon-

structable from the documentation to aim

at the best possible legal certainty. We have

always endeavoured to offer our patients

the best possible quality and the results of

innovation, which is expressed by our

achievement of the ISO certificate. The

changeover from manual to automatic

reprocessing involved quite a few challen-

ges. First the small reprocessing area had to

be adapted structurally to accommodate the

necessary appliances, while taking into

account the hygienic aspects of the organi-

sational and spatial layout. Within this fra-

mework, the entire reprocessing equip-

ment- the washer-disinfector appliance (WD), the steam steriliser, right through to

the (Durchlaufsiegelgerät) sealing machine-

was brought up to date technically. The

choice of WD was restricted to a one door

appliance i.e. front-loading, because of spa-

tial considerations. The instruments and

the six already available sieve baskets were

tested for their automatic reprocessability,

according to the information provided by

the manufacturers. They were augmented

with 24 sieve baskets. We were unsure in

particular about whether diamond blades

could be reprocessed automatically in a

WD. Before buying new blades we made

sure that automatic reprocessing is suitable

here.

For cleaning in the WD we chose to

use an alkaline process chemical recom-

mended by the RKI Task Force vCJK,

which according to manufacturer’s informa-

Author

Ulrike Roider

Augenklinik am Marienplatz

Marienplatz 18

80331 München

Tel.: 089/23 24 10-0

Figure 1: WD with loading trolley for ophthalmic operation instruments

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tion realises a pH of almost 12. This is

added after an intensive pre-rinse, in the

cleaning phase at 55°C, with a holding

time of 10 minutes. Neutralisation then

followed, an intensive mid-wash rinse, ther-

mal disinfection with an Ao value of more

than 3000 and finally drying. The WD is

equipped with the corresponding loading

trolley for ophthalmic surgical instruments,

which can be loaded with up to 8 sieve bas-

kets. Thus we have the capacity for dealing

with days where as many as 40 operations

take place. We have found our own soluti-

on with regard to instrument sieve baskets,

customising them for use with ophthalmic

instruments. We obtained sieve baskets

designed for instrument reprocessing in the

dental area, and had them fitted with stora-

ge racks made of knobbed mats. These

were also punched with holes so that the

instruments could be wetted more effec-

tively and so that water could run off easily.

We have come to regard suction- rinse

handles as disposable, as they are quite

cheap and we don’t think the constructio-

nal »cul-de-sac« at the tip can be properly

cleaned automatically. In the same way, the

narrow internal diameters of Sautter cannu-

lae have been replaced with disposable pro-

ducts, after initial reprocessing of the can-

nulae without water filtration often led to

blockages. Other hollow instruments such

as ultrasound handles and Klöti strippers

with magnetic drives are always carefully

Figure 2: Instrument sieve baskets with integrated storage racks

connected to the wash adaptor and there

have never been any problems here. Hollow

instruments are checked for tubal patency

before being washed. After the wash process

the connections are checked to make sure

they are still correctly attached. In the very

rare case of a wash connector becoming dis-

connected, the relevant instrument is put

back to undergo another reprocessing cycle.

Every day as a spot check, a Phako handle

is tested for residual alkalinity. Here some

residual water from the instrument is drop-

ped onto pH paper and the colouration is

compared to the table? Over the last 4 years

we have never had a result that gave cause

for concern.

In the last few years no instrument

damage has been caused by automatic

reprocessing. Wear and tear has been great-

ly reduced due to the greater number of

instrument sieve baskets. The two or three

instruments per month that are sent to be

repaired are primarily damaged through

inappropriate use or an accident. Because

the fully demineralised water for the final

rinse is prepared using an ion-exchange car-

tridge, there was initially a discolouration

problem due to silicate accumulation and

escape, which was solved by putting two

cartridges in series.

The wash-disinfection process was

meanwhile re-validated for the fourth time.

This took place according to the DGKH,

DGSV and AKI guidelines. The WD is run

through a series of checks during the mor-

ning of each working day. Here checks are

made to ensure the patency of the nozzles,

that the spray-arms are free to move, that

the connection of the loading trolley to the

wash/rinse water is correct, that sufficient

process chemicals are available etc. After

each load has been reprocessed, the clea-

ning result is optically checked. The quality

of hollow cavity washing is checked weekly

using a test object and once a month the

WD is put through thermal checks using a

temperature logger. For some time now we

have had the WD connected to a personal

computer for process documentation so

that we can monitor the process during the

cycle. At the end of the cycle the protocol

is checked and the load is then released by

the data processing programme if all para-

meters have been attained. ■

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Maintaining the function of surgical

instruments using sterilisable oil

Some basic considerations should

be taken into account in regards to

wear and corrosion protection when

using sterilisable oil for instrument

maintenance. This report shall iden-

tify the need to use sterilisable oils

to ensure the functional, long-term

use of surgical instruments.

Surgical instruments generally consist of

various components, whose surfaces are

exposed to a relative motion when using

the instrument.

Poor conditions can then lead to instru-

ment damage. The science of tribology

describes the interactions of solid bodies in

relative motion.

2 Tribology

The term »tribology« originates from Gre-

ek and is made up of the words »tribein« =

to rub and »logia« = sayings, words or dis-

W. Fuchs and M.Gaißer

courses (translated literally »friction tea-

chings«).

The elementary keywords of tribology

are friction, wear and lubrication. To deve-

lop an understanding of the processes of

friction, wear and lubrication, some basic

knowledge and definitions are required,

which are presented in the following.

2.1. The tribological system

A tribological system (see Figure 1) consists

of a basic part and an opposing contacting

part, e.g. the case part and insertion part of

a clamp, the upper and lower part of scis-

sors or the rigid or movable part of a

punch. The basic part and opposing

contacting part are in relative motion to

each other (see Figure 2). An interfacial

medium (e.g. lubricants, wear debris, oxide

layers) can in turn be introduced between

the surfaces of the basic part and opposing

contacting part. All three components find

themselves in a surrounding medium such

as air, water, etc.

As already mentioned, friction and

wear processes take place on the surfaces of

the affected system components. Therefore,

more specific attention is paid to the surfa-

ce structure and surface topography.

2.1.2 Structure and topography

of a technical surface

Technical surfaces can be afflicted with

impurities in areas near the surface. These

can involve, for example, surgical residues

in the case of used surgical instruments.

Metallic materials usually have a ultra-thin

oxide layer, which in the case of stainless

steel works to protect against corrosion. In

front of the base material, technical surfaces

have an area of malleable deformations cau-

sed by e.g. grinding, pressing or rolling

processes. (see Figure 3)

A technical surface appears level and

smooth when viewed macroscopically.

However, this perception is incorrect. Vie-

wed microscopically, the surface appears as

a highly fissured »andscape« with rough

peaks and valleys (see Figure 4).

2.1.3 Friction

If two technical surfaces find themselves in

relative motion to each other, the respective

peaks catch (see Figure 5), which in turn

causes resistance to the relative motion.

This resistance is described as friction.

The friction causes the rough peaks to she-

ar off, which over the course of time leads

to surface wear. Depending on the type of

tribological system, i.e. the material combi-

Author

Wolfgang Fuchs

Marco Gaißer

Aesculap AG & Co. KG

Am Aesculap Platz

78532 Tuttlingen

E-Mail : Wolfgang.Fuchs@aesculap.de

Figure 2: Model of relative motion transferred to punches, scissors and clamps

Figure 1: Tribological system

Figure 3: Structure of a technical surface

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nation of the basic part and opposing

contacting part and the type of interfacial

and surrounding medium (see Figure 1),

various wear patterns are observed. The

types of wear and their mechanisms which

affect surgical instruments, e.g. sponge for-

ceps according to Förster, shall be introdu-

ced in the following. The mechanisms and

manifestations can be applied to all other

multi-component instruments, whose indi-

vidual components are in relative motion to

each other.

2.2 Wear

2.2.1 Sponge forceps according to

Förster

Figure 6 shows the sponge forceps accor-

ding to Förster BF122R, which are used to

explain the types of wear and their mecha-

nisms.

The sponge forceps according to För-

ster were prepared once, where a special

cleaning method was used. For this

method, a substance with an oxidising

effect (H2O2) is added to the cleaning

agent. This supports the cleaning/degrea-

sing of heavily contaminated instruments

or burned-in surgical residues in HF sur-

gery, which is the primary goal of cleaning.

A widely-used preparation process of this

type is the Oxivario process from Miele (see

Figure 7). Our research showed a residue-

and oil-free surface.

Even after a single use and preparation,

a functional check shows that the instru-

ment becomes difficult to to open and clo-

se. The contact surfaces exhibit mechanical

damage (see Figure 8). This damage can be

attributed to 2 wear mechanisms:

2.2.2 Abrasive wear

Abrasive wear leads to micro chipping on

the basic part and opposing contacting part

due to friction. Abrasive wear is revealed on

the surfaces of the contacting parts and is

usually clearly identifiable wear debris (see

Figures 9, 10, 11).

Abrassive wear is promoted when the

basic part and opposing contacting part

have differing hardnesses or there is an

additional hard phase between the basic

part and opposing contacting part. This is

particularly evident with orthopaedic or

bone surgical instruments, whereby bone

residue not removed can lead to a so-called

»three-body wear« (see Figure 12).

Contamination (see Figure 3) such as

encrusted blood

can also induce

increased abrasive

wear within the

contact surfaces.

Three-body wear

Remedial action

■ Lubrication to separate basic part and

opposing contacting part

2.2.3 Adhesive wear

With adhesive wear, the rough peaks are

first malleably deformed. In the case of

stainless steels, which are used for surgical

instruments, the corrosion-resistant oxide

layer is destroyed. It then leads to an inter-

facial connection of the basic part and

opposing contacting part (see Figure 1).

This connection leads to a stop of the

relative motion colloquially described as

»seizing«. If the force of the relative motion

is large enough, it can lead to the breakout

of the connected contact areas. Material is

transferred from one contacting part to the

other. Adhesive wear is revealed by material

transfer or breakout (see Figures 13, 14, 15).

Remedial action:

■ Lubrication to separate basic part and

opposing contacting part

Figure 4: Macroscopic and microscopic representation of a technical surface

Figure 5: Development of friction

Figure 8: Mechanical damage

Figure 6: Sponge forceps according to Förster Figure 7: Oxivario process [source: Miele]

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xxx

3 Cause of signs of wear

The cause of signs of wear and the associated failu-

re of the instrument can be attributed to the non-

lubrication or insufficient lubrication of the instru-

ment after the preparation process.

Precision-fitting, high-quality instruments are

particularly susceptible to an increased risk of wear.

Therefore, the long-term use of an instrument can

only ben ensured by the regular and purposeful

lubrication of the contact surfaces (see Figure 16).

The lubricant minimises the contact of the rough

peaks and thus reduces the effect of friction. The

lower the effect of friction, the lower the risk of wear.

Conclusion:

When using special cleaning methods in particular,

instruments that are not maintained can wear very

quickly. Only regular, purposeful lubrication ensu-

res the conservation of value and the long-term use

of high-quality and expensive instruments. ■Figure 9: Traces of abrasive wear

Figure 10: Light microscopic representation of wear debris

Figure 11: Electron microscopic representation of wear debris

Figure 12: Bone residue in a punch and thus

induced three-body wear

Figure 13: Light microscopic representation

of a material transfer

achtung - bezeichnungennoch deutsch

achtung - bezeichnungennoch deutsch

aseptica English Edition 2007 23

xxx

Scientific Advisors:D. Bremer, Harderberg; U. Junghannß, Köthen;Th. W. Fengler, Berlin; T. Miorini, Graz; M. Pietsch, Mainz; B. Schmidt-Rades, Gütersloh;E. Schott, Essen; B. Wilbrandt, Berlin

Published by:medienfabrik Gütersloh GmbHCarl-Bertelsmann-Str. 3333311 GüterslohTelefon: 0 52 41/2 34 80-50Fax: 0 52 41/2 34 80-61ISDN: 0 52 41/2 34 80-64E-Mail: info@aseptica.comInternet: www.aseptica.com

In cooperation with:Ecolab GmbH & Co OHGEuropean Headquarters, P.O. Box 13 04 0640554 Düsseldorf;Miele & Cie. KG, 33325 Gütersloh;OLYMPUS Medical Systems Europa GmbHP.O. Box 10 49 08, 20034 Hamburg;ebro Electronic GmbH & Co. KGPeringerstraße 10, 85055 IngolstadtCLEANICAL®, Kranoldstraße 24, 12051 Berlin

Responsible for contents:Reinhild PortmannPublic Relations OfficeMiele & Cie. KGCarl-Miele-Straße 2933332 GüterslohTelefon: 0 52 41/89 19 52Fax: 0 52 41/89 19 50

Editors:Klaus-Peter Becker, Ecolab, Dr. Klaus-PeterBansemir, Ecolab, Dr. Winfried Michels, Miele,Thomas Brümmer, Olympus, Iven Kruse, ebro,Helmut Pahlke, Cleanical

Implementing, layout and printing:medienfabrik Gütersloh GmbHGuido Klinker, Sebastian Borgmeier

Edition: 4.000

Title topic:mauritiusimages

Frequency:Printed quarterlyPrinted on paper processed chlorinefree

Reproduction only with editor’s permission. Indi-vidual contributions may deviate from the opinionsof the publishers. No liability is taken for unsolicit-ed manuscripts and photos. The editors reserve theright to shorten readers’ letters.

ISSN 1439-9016

Imprint

[1] Weißbach W., Werkstoffkunde und

Werkstoffprüfung, 14. Auflage, Vieweg &

Sohn Verlagsgesellschaft, Braunschweig /

Wiesbaden 2001

[2] Heine B., Werkstoffprüfung Ermittlung

von Werkstoffeigenschaften, Fachbuchverlag

Leipzig im Carl Hanser

Verlag 2003

[3] Schatt W., Worch H., Werkstoffwissen-

schaften, Wiley-VCH Verlag Weinheim 2003

[4] Merstallinger A., Tribologie und Werk-

stoff, Anwendungsorientierte Optimierung

des Reib- und Verschleißverhaltens von

Werkstoffen, IT’S T.I.M.E. / 02/02

[5] Czichos H., Habig K.H., Tribologie,

Handbuch Reibung und Verschleiß,

Vieweg & Sohn Verlagsgesellschaft, Braun-

schweig / Wiesbaden 1992

[6] Fleischer G., Gröger H., Thum H., V

erschleiß und Zuverlässigkeit, Berlin: Verlag

Technik 1980

[7] Zum Gahr, K.H., Microstructure and

wear of materials, Niederlande Elsevier 1987

[8] Arbeitskreis Instrumentenaufbereitung,

Instrumentenaufbereitung richtig gemacht,

8. Ausgabe 2004

[9] Wissenschaftliche Information, Sterilität

unter Ölfilmen bei Instrumenten und

Handstücken, Wissenschaftliche Informati-

on im Selbstverlag der Aesculap AG & Co.

KG, Aesculap C- 511-01 798/2, 3. Aufla-

ge, 1990

[10] Michels W., Pieper M., Optimierte

Figure 14: Electron microscopic representa-

tion of a material transfer

Figure 15: Side view of material breakout on

the insertion part

INCORRECT CORRECT

large-area coating of targeted oils of the contact areas

insufficient lubricating effect

Obstruction of the recleaning and sterilisation

unnecessary high consumptionof oil (avoidable costs)

unnecessary burden on space/air

Abbildung 16: Schmierung richtig gemacht

maschinelle Reinigung mit oxidativer Ver-

fahrensstufe, Aseptica 9. Jahrgang 2003,

Heft 4 S. 6,7

[11] Geibel U., Sommer N., Erste Anwen-

dungserfahrungen mit dem Reinigungs- /

Desinfektionsverfahren OxiVario Plus,

Aseptica 9. Jahrgang 2003 Heft 4 S.8,9

Literature

achtung - bezeichnungennoch deutsch