WFHSS - World Forum for Hospital Sterile Supply

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WFHSS - World Forum for Hospital Sterile Supply

WFHSS Discussion Forum - English Version


WFHSS - World Forum for Hospital Sterile Supply :: Discussion

WFHSS Discussion Forum

Date Title/Topic Author
15/07/2005 Is globalization the future (1) Wim Renders
07/08/2003 Washer-Disinfector / Critical Process Parameters and Cleaning Efficiency (1) PEREG GmbH
20/01/2003 Which Sterilant is the Active Component in a Steam Sterilization Process? Steam? No, it's water! (1) Dr. Ulrich Kaiser
26/11/2002 Can chemical indicators replace biological ones in routine control of sterilization processes? (3) Michael Fangon
23/11/2002 Can chemical indicators replace biological ones in routine control of sterilization processes? (2) Wim Renders
27/10/2002 Can chemical indicators replace biological ones in routine control of sterilization processes? (1) Wim Renders
16/09/2002 Packaging Materials (1) N.N.
13/02/2002 Training for Sterilisation Assistants (1) Wim Renders
16/11/2001 Science or Politics? (2) Margaret Burn
15/11/2001 Science or Politics? (1) Wim Renders
24/10/2001 The Bowie-Dick Test (6) Dr. U. Kaiser
04/07/2001 The Bowie-Dick Test (5) Stuart Line
25/06/2001 The Bowie-Dick Test (4) D. Doyle
18/06/2001 The Bowie-Dick Test (3) Michele Tait
17/06/2001 The Bowie-Dick Test (2) Peter Hooper
13/06/2001 The Bowie-Dick Test (1) Wim Renders
02/02/2001 Monitoring the Performance of Washer Disinfectors (2) Peter Hooper
25/01/2001 Monitoring the Performance of Washer Disinfectors (1) Mary Deane
30/11/2000 How Far Is Too Far? (2) Yaffa Raz
28/11/2000 How Far Is Too Far? (1) Wim Renders
11/07/2000 Re-use of medical aids meant for one time use: towards a definite standpoint in Belgium (1) Wim Renders
01/05/2005 Reuse of Single-Use Devices (5) Samantha Jennen
09/05/2000 Reuse of Single-Use Devices (4) Wim Renders
07/03/2000 Reuse of Single-Use Devices (3) Pete Bobb
25/02/2000 Reuse of Single-Use Devices (2) Peter Hooper
21/01/2000 Reuse of Single-Use Devices (1) Wim Renders
Reuse of Single-Use Devices (1)

by Wim Renders
see also:
Reuse of Single-Use Devices (2) by Peter Hooper
Reuse of Single-Use Devices (3) by Pete Bobb
Reuse of Single-Use Devices (4) by Wim Renders
Reuse of Single-Use Devices (5) by Samantha Jennen


Reuse of products meant to be used only once remains a controversial issue, not only in Europe but also in the United States where the Food and Drug Administration (FDA), after carrying out a thorough market study, intends to adapt the regulations regarding disposables (Central Service 6/99).

In Europe the Medical Device Directive (93/42/CEE) has as far as the manufacturer is concerned created the necessary clarity. But the activities of the C.S.S.D. remain nebulous certainly in countries of the European Union where the government has not provided a regulatory framework in relation to reuse.

In a number of countries reuse is strictly forbidden. In others the government's attitude is ambiguous by not promulgating clear guidelines as it fears the financial consequences of a total ban.

It is evident that only the policy makers on the European level can provide an adequate answer by issuing general guidelines.

The can make a particular contribution by unanimously deciding on a minimum platform and by communicating it to the European decision makers. As a basis for discussion the proposition made by ASTER and VSZ to the Belgian authorities can be used. It is given below.

Via the you are kindly requested to comment on the proposals. Your reactions will then be incorporated into the final proposition.

In the proposition formulated below only reuse in one's own hospital is discussed. With reuse is meant the use of a previously used product.

Some remarks:

Can a general ban on the reuse of sterile medical devices meant for one-time use only be introduced?

No, because a number of medical devices meant to be used only once can be reused such as:

  • Catheters for electrophysiological examination,
  • Electromyelographic needles.

Moreover re-use is not forbidden by the Medical Device Directive as the M.D.D. does not apply to the Central Sterilization Department of a hospital. The Sterilisation Department does not put products on the market. But as the directive wants to offer the patient and the user of a medical device a quality guarantee and as it is irrelevant to the patient if a new or re-used device is used on condition that the same safety level is attained, not the letter but the spirit of the law has to be satisfied. The directive describes the "state of the art" and is therefore also applicable to the C.S.S.D. The C.S.S.D. of a hospital, which takes upon itself the responsibility of manufacturer, should satisfy the relevant essential criteria given in appendix 1. The most important ones are mentioned in clauses 8.4 and 8.5. They stipulate that when sterile devices are delivered they have to be produced and sterilised with a fitting and validated method and that they should be manufactured in adequately controlled circumstances. Only if these conditions are met can re-use within certain limits be allowed and is the focus, which was exclusively constricted to the reprocessing of re-usable instruments, widened to all devices a C.S.S.D. is responsible for. It is therefore essential that sterilization units meet the highest quality norms.

N.B. Sterilization as such is not considered as fundamentally changing the device and as a result the sterilization process does not fall within the scope of the directive.

Other elements which have to be taken into account are the following:

  • When the manufacturer attaches the symbol for one-time use only to the device, it can mean that the device concerned can only be used once but it can also mean that the manufacturer has not looked into the possible reuse of the device.
  • Is the potential damage caused by re-use covered by the insurance policy?
  • Incidents are not solely restricted to reuse. New medical devices too can have serious defects. The duty of disclosure of incidents with devices is explicitly formulated in the M.D.D.
  • The manufacturer can no longer held accountable when processing a disposable for reuse.
  • Looking for alternatives for the reuse of disposables is more efficient in terms of cost control.

The drawing up of a list of disposables which can be considered for reuse is a gargantuan task as with even the smallest change a manufacturer makes, the whole procedure has to be done all over again. The setting up of a laboratory to check the integrity of the raw resource and the functionality of the device is exorbitantly expensive.

In contrast a negative list could minimize the risk for the patient because of the consensus that the devices appearing on it are not to be considered for reuse. However, this does not mean that the reuse of all other devices is allowed. The latter fall under the guidelines given here.


Restricted reuse of certain medical devices can be allowed on condition that an appropriately supervised and adequately applied method, suitable for each device, is used in its preparation for re-use. It has to be proven, in whatever manner, that the device can be used safely after it has been adequately processed (Dutch Health Council).

Reuse of devices then becomes medically and ethically acceptable because the same quality requirements as those applied to medical instruments (of which the sterilization can also pose problems) are set. In other words it should be possible to clean the disposable material in a controllable manner. Moreover the functionality, integrity and sterility of the devices have to be guaranteed.

In practice this means:

  • the decision to reuse is an individual decision (by a hospital) which can only be taken when there is unanimity between all concerned.

The sterilization unit has to, both for the processing of the reusable instruments and for the reuse of sterile devices meant for one-time use only, meet the "state of the art" criterion (At present the quality provided differs widely and is sometimes inferior.) The quality of the sterilisation unit has to checked regularly. It is urgently required to take the necessary measures.

Reuse should be prevented as far as possible by:

  • asking the person in charge of C.S.S.D. to advise on the purchasing of medical materials,
  • considering reusable alternatives,
  • striving for realistic prices of disposables.
  • Distinguishing between non-critical, semi-critical and critical devices when working out procedures. Non-critical items carry less risk than critical ones.

It is evident that reuse can only be allowed when it is scientifically supported. For this reason we would like to ask you to bring to the attention of the forum scientific articles in which reuse is examined - either positively or negatively. We shall put them on our website in order to stimulate the debate.

We would like to ask the manufacturers to inform us about the reusable alternatives for disposables. We would like to draw up an inventory of these devices for the benefit of our members. You can Email us at .

Please .

Reuse of Single-Use Devices (2)

by Peter Hooper
25 February 2000
see also:
Reuse of Single-Use Devices (1) by Wim Renders
Reuse of Single-Use Devices (3) by Pete Bobb
Reuse of Single-Use Devices (4) by Wim Renders
Reuse of Single-Use Devices (5) by Samantha Jennen


Wim's article in Zentral Sterilisation is worthy of comment and I am sure will raise many comments from Europe and beyond. Clearly many recent articles in Zentral Sterilisation and other journals have displayed a generally confused approach. We in the UK have been as much to blame as anyone and a recent article from a UK CSC working party was published suggesting allowable reprocessing. This article was not reviewed by the CSC Editor and Committee and, if being re-written today would almost certainly be written differently.

The UK experience has been to discuss reprocessing of single use devices to save money. this was done via Risk Management groups to assess likely implications. We now realise that these implications are too great to bear. Whilst some suspicion may exist with respect to labelling and pricing, the practice of a hospital unilaterally deciding which process is applicable and effective is now unacceptable. I feel this practice which is the basis of the Belgian recommendations is judged in the UK against firstly the inability to define precise validation parameters as well as the legal implications of removing liability from the manufacturer to the hospital.

We may have special reasons for extending universal precautions to cover the possibility of unknown transmission of vCJD via the reprocessing of medical devices but this may only assist us to face the fact that reprocessing of single-use devices should not take place. Our recent publication, HSC 199 179, states that "Chief executives should take action to ensure that relevant staff never re-use medical devices designated as single use". Since its publication in August 1999 most Risk Management groups have re-thought their policies to respond.

The safety of working to this very precise guideline is very re-assuring. All we have to do is find the money to make it work. My guess is that finding money is a little easier than shouldering a burden that, although difficult to quantify, is potentially very expensive.

I will be interested to see if any other European and worldwide colleagues agree.

Best wishes - keep up the good work,

Peter Hooper, UK

Please .

Reuse of Single-Use Devices (3)

by Pete Bobb
7 March 2000
see also:
Reuse of Single-Use Devices (1) by Wim Renders
Reuse of Single-Use Devices (2) by Peter Hooper
Reuse of Single-Use Devices (4) by Wim Renders
Reuse of Single-Use Devices (5) by Samantha Jennen

Good day WFHSS members:

The reuse of single use items is a topic of great interest to all members of the sterilization community.

I have several comments to add to this discussion: When a "single use item" is reprocessed in the hospital setting, the reprocessor assumes all the liability as the manufacturer of the item. Lacking validation of the procedure used for each item processed, the reprocessor sets himself or herself up for legal challenges by the patient the item is used on. Without validating the procedure, the patient should sign a release stating their understanding that they are a subject in an experimental protocol. The validation of a procedure for each item can cost hundreds, if not thousands of dollars per item. I feel that before beginning any validation study, the user should consider the cost benefits to be gained as the first criteria in determining what items may be studied. Obviously, the manufacturer of medical devices have a moral obligation to perform validation studies and let the buyer know why an item is considered suitable for single use only, or the steps required to safely reprocess the medical device. Unfortunately, most manufacturers do not tell the buyer of medical devices why the item is labeled as a single use item.

Many "single use items" are made from plastic. Plastic contains volatile plasticisors that give the plastic its unique characteristics. They allow the plastic to bend, give it a smooth exterior, and keep it from shattering when the plastic is used in patient care. These plasticisors can be cooked out or leached out of the plastic even with 'low temperature' reprocessing. The validation studies need to keep this in mind when determining whether the reprocessing of an item changes the functional characteristics of the medical device. We have all heard the stories of hospitals that reprocessed single use cardiac catheters in the attempt to save money, only to have the tip of the cardiac catheter break off inside the patient!

I believe a rational way to approach the decision as to which items to study as candidates for reuse needs divide items into categories based on several criteria:

  1. Potential cost savings considerations based on:
    1. Actual cost of the item
    2. Frequency the item is used The 80/20 rule applies: 20% of the items used account for 80% of the cost. Look at items that can truly generate significant cost saving after considering the cost of validating the reprocessing procedures.
  2. Infection control considerations:
    1. Critical medical devices come in contact with sterile body cavities or the vascular system
    2. Semi-Critical medical devices come in contact with non-sterile body cavities (normally in contact with mucous membranes)
    3. Non Critical medical devices come in contact with intact skin. Items such as bedpans, crutches, and blood pressure cuffs are examples of non-critical medical devices that are not likely to cause infections in our patients if we reprocess the single use items. Critcal medical devices require a much higher level
  3. Patient risk considerations:
    1. what potential harm will come to the patient if the device fails. A cardiac catheter tip breaking off inside a patient's heart is a significant failure to provide proper care to our patients.

Only after taking all three of these considerations into account, can we rationally justify which items to study as candidates for reprocessing.

Thank you for allowing me to contribute to this discussion

Please .

Reuse of Single-Use Devices (4)

by Wim Renders
10 May 2000
see also:
Reuse of Single-Use Devices (1) by Wim Renders
Reuse of Single-Use Devices (2) by Peter Hooper
Reuse of Single-Use Devices (3) by Pete Bobb
Reuse of Single-Use Devices (5) by Samantha Jennen

Consensus proposal about the re-use of sterile medical devices meant for one-time use

In the proposal given below the minimum conditions are formulated which have to be met by a hospital and in particular by the central sterilisation unit in order to allow the limited re-use of medical devices meant for one-time use only.

  1. Summary

    Restricted re-use of certain medical devices can be allowed on condition that an appropriately supervised and adequately applied method, suitable for each device, is used in its preparation for re-use. It has to be proven, in whatever manner, that the device can be used safely after it has been adequately processed (Dutch Health Council). Re-use of disposables then becomes medically and ethically acceptable because the same quality requirements as those applied to re-usable instruments are set.

  2. Procedure

    1. A hospital which wants to re-use disposables has to apply for a license from the authorities.
    2. The sterilisation unit of this hospital has to be inspected in order to ascertain whether this unit meets the essential requirements of appendix 1 of the Medical Device Directive (93/42/CEE). The most important ones are mentioned in appendix 1 clauses 8.4 and 8.5. They stipulate that when sterile devices are delivered, they have to be produced and sterilised with a fitting and validated method and that they should be manufactured in adequately controlled circumstances. Only when these conditions are met can permission to reprocess be given. The inspection can possibly be carried out by a generally recognised advisory body or a 'notified body'. Their recommendations are binding. Before the inspection a transition period may be foreseen.
    3. A hospital which has been granted a license submits the medical devices meant for re-use to a, to be erected, national commission of experts. The submission has to be accompanied by a treatment procedure for each device. The commission deals with the submission on an item per item basis. The commission may get the assistance of a third party.
    4. Annually an inspection by the C.S.A. is carried out. It can take the form for example of an intercollegiate test or of an accreditation.

  3. Remarks

    1. Validation of the cleaning
      If a medical device can be cleaned and if the body of experts on the basis of scientific information decides that the integrity and the functionality of the device is not affected and that it can be sterilised, then a biological validation of the device suffices. There is no reason to impose stricter norms on the reprocessing of disposables than on the preparation for re-use of a device which can be re-used. For re-usables cleaning, especially when done manually, can pose the same validation problems.
    2. Legal complication
      By drafting a generally accepted code of conduct the professional bodies can influence the attitude of the judicial, lawmaking and administrative authorities. Re-use in this context should be covered by the 'civil liability' policy. The authorities have to take the necessary steps to ensure that state-of-the-art re-use is not dealt with under the criminal justice code.
    3. Vigilance
      Incidents with re-used medical devices have to be reported to the commission of experts. This commission proposes adequate rectifying measures.

  4. Finally

    If these guidelines are followed, irresponsible re-use will disappear, waste will be avoided and the interests of patient (safety) and of the authorities (finances) can be reconciled.

Please .

Reuse of Single-Use Devices (5)

by Samantha Jennen
1 May 2005
see also:
Reuse of Single-Use Devices (1) by Wim Renders
Reuse of Single-Use Devices (2) by Peter Hooper
Reuse of Single-Use Devices (3) by Pete Bobb
Reuse of Single-Use Devices (4) by Wim Renders  

Our Hospital will begin sending away all single use items to be re-processed. I am concerned about how long this study has gone on. Does the reprocessor assume all the liability the manufacturer of them item being re-processed. Is the patient aware.

Samantha Jennen

Please .

Re-use of medical aids meant for one time use: towards a definite standpoint in Belgium

The Gordian knot untied.

by Wim Renders
11 July 2000

Since October 1999 a workgroup under the auspices of the Ministry of Health have been looking into the problem of the re-use of medical aids meant for one time use. This workgroup has to advise the minister on this contentious matter. The 2 regional societies for sterilisation namely ASTER and the V.S.Z (Society Sterilisation in Hospitals) were involved in the discussions.

In the course of the meetings the original standpoint that re-use is the individual decision of the hospital, has evolved via a proposal to entrust a commission of experts with the supervision of the re-use of disposables to the recommendation to a total ban on the re-use of disposables.

Although all the parties agree on the fact that a - albeit limited - number of medical aids could be considered for re-use, this did not prove to be attainable as the authorities did not want to provide the necessary legislative backing. In the present context re-use will be condemned by whatever judge in Belgium. Also the insurance policy 'civil liability' caused problems. If the due care principle is included in the contract cover is uncertain.

The authorities were not prepared to take the necessary initiatives to deal with these problem areas with the result that re-use remains the personal responsibility of the persons concerned. This was recently confirmed by the minister in reply to a parliamentary question. In these circumstances re-use is in fact impossible; there is no other way than to follow the standpoint which the Pharmaceutical Inspection (F.I.) expressed and confirmed at the last meeting of the workgroup.

The Pharmaceutical Inspection stated that medical aids have to be used and applied in accordance with their purpose and the instructions given by the manufacturer when putting the aid on the market and/or when it is used. Not without justification, the F.I. stated that the safety of the patient has to be absolutely guaranteed. The problem points are that proof has to be provided that the integrity of the material remains intact after reprocessing and that a validated cleaning has taken place. This is almost impossible in a hospital environment.

As for aids, which could qualify for re-use, the F.I. proposed to ask the manufacturer to change the labelling. The standpoint of the F.I. implies a ban on re-use. It has the advantage that finally there is clarity and that there are solutions within the framework of the M.D.D.

Both societies are very enthusiastic especially because the authorities have expressed the willingness to compensate the financial consequences of such a ban. Proposals regarding this issue are at present being discussed in another working group. A general increase in lay day price (i.e. the amount paid to the hospital per day a patient is in the hospital) On the basis of a provisional estimate an increase by 1.5 Euro per day would be sufficient to compensate for the stopping of the re-use practice. In problem areas such as the electrophysiology of the heart, some examinations in gastro-enterology, ophtamology, urology and general surgery where the compensation for the nomenclature is not high enough to pay for the devices used, a solution may lie in an increase of the funding by the authorities for these examinations. The societies urge the authorities to officially inform the hospitals as soon as possible in order to not to allow a dubious situation to continue any longer.

Finally Belgium joins the group of nations in which re-use is not allowed. The big advantage of this position is that it offers the certainty that all concerned can operate within a legal framework. This certainty should be created throughout the whole of Europe because it is ultimately beneficial to the patient.

Wim Renders

Please .

How Far Is Too Far? (1)

by Wim Renders
28 November 2000
see also:
How Far Is Too Far (2) by Yaffa Raz

After a recent trip to Africa I returned home with a wry and ambiguous feeling. The confrontation with a continent plagued by overpopulation, famine and aids, where the biggest part of the population is deprived of even the most essential first-line help remains a moral challenge. The realisation that a minimal improvement in the availability of basic medical care and drugs means a big leap forwards and for a lot of people even signifies the difference between life and death, is painful because you feel powerless to do anything about this situation.

Africa also teaches us another 'relativity theory'.

A lot of things we attach a lot of importance to, only have a value within a western frame of reference. When the frame shifts, one gets a totally different picture of the world, its realities and priorities.

The link with the CSSD is the open question which I have asked myself as a result of the confrontation with Africa and which I would like to submit to the reader: How far is too far?

I wonder how far we still can and should go in laying down more norms, in installing more controls, in tracebility, in the industrialisation of the CSSD, etc.?

Are we not at the borderline of what still is statistically relevant?

When do we reach the highest point in the efficiency graph, when does the efficiency effort become decline?

I do not think we can ignore these questions.

A critical attitude, based on knowledge, is needed to find the right answers. Plato already knew this in the fourth century B.C. In The Republic, one of his philosophical masterpieces, he states that in order to find the truth one has to think for oneself and to be prepared to make up your own mind. To accept the values imposed by others can be equated with intellectual dishonesty.

I think that Plato's ideas have lost nothing of their relevance and moreover that they can be applied to the CSSD. At the very least they should make us think.

I would like to hear your reactions.

Wim Renders

Please .

How Far Is Too Far? (2)

by Yaffa Raz
30 November 2000
see also:
How Far Is Too Far (1) by Wim Renders

Dear Wim

Africa is indeed overwhelming. It took me a few weeks to recover my thought after coming back from there two years ago.

I think there is no "too far". If you have resources the sky is the limit. If resources are not available, one should have a vision of an ideal situation.

Africa is not the only place where frames are shifted. In fact, the majority of the world lives in conditions that are non imaginable. Yet, even in situation like that, the world is a global village. Communication brings information and ideas to others. I live in Israel. It's not Africa, yet it's not Europe, but certainly it is not a developing country. Yet, up until a few years ago, sterilization standards and CSSD procedures were not considered an issue. Contacts with other countries and communication have made these subjects "hot".

I think it is a mistake thinking that if other countries are so far behind when concerned with health care etc., we should stop bringing in new ideas and more standards. You don't really consider stopping going out to the theatre or to restaurants because people are starving in another place in the world.

What you can do is contribute in the best way you can. Use your values to influence and never ignore evil.

Yaffa Raz

Please .

Monitoring the Performance of Washer Disinfectors (1)

by Mary Deane
25 January 2001
see also:
Monitoring the Performance of Washer Disinfectors (2) by Peter Hooper

Over the years there has been discussion, research and large amounts of money spent on testing sterilizer efficiency. Sterile services departments spend a considerable amount of money and time assuring sterility. Bowie Dick tests are used and many use indicators in each pack or load.

In recent years there has been considerable emphasis on the importance of decontamination to reduce bioburden prior to sterilization. Only during the past year has cleaning been increasingly regarded as an independent research subject (Central Service 6/2000).

Until now the only assurance we have of successful cleaning is visual inspection of instrument surfaces. There are various products currently on the market to test the performance of washer disinfectors. Surely these products should be used on a regular basis, at least daily, if not in every cycle?

Mary Deane

Please .

Monitoring the Performance of Washer Disinfectors (2)

by Peter Hooper
2 February 2001
see also:
Monitoring the Performance of Washer Disinfectors (1) by Mary Deane


Your comments on regular testing of washer-disinfectors raise an interesting problem. In the UK we are beginning to introduce the testing requirements of HTM 2030. The validation will ensure that a machine is handed over with the parameters for successful cleaning and disinfection available. On a process-by-process basis these cycle parameters should be checked against the relevant validation values to confirm continuing acceptance. This, of course, assumes that ALL parameters are recorded at each cycle. These parameters will include not only time and temperature (ie disinfection) but also water pressure, water volume, water quality, additive delivery (ie cleaning). Just as steam sterilizers are monitored parametrically, the washer-disinfector routine tests for soil removal and protein residuals need only be carried out routinely - quarterly and weekly respectively. This relies on each process being subject to a full parametric product release and the availability of all critical parameter data. Few machines have this at present and it is sometimes difficult for the resources to be made available for the product release to be done, let alone all the instrumentation and testing. Nevertheless the content of HTM 2030 is generating much discussion, aided of course by our many Circulars on vCJD and the need for vigilance. My own preference is for the protein residual test to be done weekly by the Users - it does, after all, measure the important facility to remove possibly-contaminated protein and the User will receive immediate feedback.

Most machines I have tested are able to meet the quarterly soil test when testing both the instruments and the chamber for cleanliness. Some people find all this a little "over the top" but without this information we are lacking in our ability to validate the safety of the product. As someone asked me two weeks ago, would you choose (if forced to do so) instruments that have been properly cleaned but poorly sterilized or instruments that have been poorly cleaned but properly sterilized. A silly hypothetical question, I know, as they are both unacceptable, but the answer that most people would give would indicate why a full knowledge of the washer-disinfector process is essential. I wonder what others will think?

Peter Hooper

Please .

The Bowie-Dick Test (1)

by Wim Renders
13 June 2001
see also:
The Bowie-Dick Test (2) by Peter Hooper
The Bowie-Dick Test (3) by Michele Tait
The Bowie-Dick Test (4) by D. Doyle
The Bowie-Dick Test (5) by Stuart Line
The Bowie-Dick Test (6) by Dr. U. Kaiser

Will there be a palace revolution?

For years the Bowie-Dick test (B-D) has been the standard to test, on a daily basis, the performance of the steam autoclave by checking steam penetration and air removal.

The classic towel pack has long been replaced by reproducible single-use packs. Very recently even an electronic B-D test was introduced. But as the B-D test is correlated with the sterilisation of linen, which does not happen anymore or in any case much less than previously, the question is asked by some whether it is useful to carry out this test in sterilisers in which only instruments are sterilised? Are the helixtest and the use of dataloggers not better suited to the new generation of autoclaves and to the loads which have to be sterilised? What is the added value of the Bowie-Dick test?

Please .

Wim Renders


The Bowie-Dick Test (2)

by Peter Hooper
17 June 2001
see also:
The Bowie-Dick Test (1) by Wim Renders
The Bowie-Dick Test (3) by Michele Tait
The Bowie-Dick Test (4) by D. Doyle
The Bowie-Dick Test (5) by Stuart Line
The Bowie-Dick Test (6) by Dr. U. Kaiser


your comments on the Bowie and Dick test make interesting reading. I also have felt that the use of a test based upon textile loads is not relevant to the loads we process every day. I feel that the test - or the test equipment - needs to be changed to reflect the variety of mixed loads processed. The advent of electronic devices suggests to me that they may be tuned to reflect loads in a hopsital-by-hospital basis. It may be that the daily test then becomes a type of process challenge and will reflect performance qualification loads rather than an assumed - and not relevant - test load. I also hope that the daily test done by the User will remain but I also feel that a properly defined (and possibly more rigorous) product release procedure needs to be defined. This is, after all, all part of proper parametric release.

I hope I am provoking !
Best Wishes.

Peter Hooper, UK


The Bowie-Dick Test (3)

by Michele Tait
18 June 2001
see also:
The Bowie-Dick Test (1) by Wim Renders
The Bowie-Dick Test (2) by Peter Hooper
The Bowie-Dick Test (4) by D. Doyle
The Bowie-Dick Test (5) by Stuart Line
The Bowie-Dick Test (6) by Dr. U. Kaiser

Hi Peter

You are quite right in what you have said and I do agree with your comments. I have been using the electronic test (ETS) in my department over the last few months and apart from the actual technical advantages of using it in terms of accuracy etc. it has raised the question of what exactly doing the linen test achieves. I have felt for quite some time now that the linen test whilst being a good reference point does not represent for example the vast amount of loosely packed items we sterilise here in the Dental School (70,000 per week). I am sure it will only be a matter of time before we begin routinely testing electronically and as you say fine tuning it to the activities of different hospitals and their specific loads sterilised.There is a lot to be learned about the steriliser from the ETS results when the test is used and as a teaching tool here it has introduced the operators to aspects of the Bowie & Dick test not obvious from a standard test pack. There is only so much information you can interpret from the test sheet in the pack but a great deal of information can be gained from the results generated on computer from the ETS. It is in itself an insight into the process more so than the test pack.

Are other Hospitals using this also??

Michele Tait

Please .

The Bowie-Dick Test (4)

by D. Doyle
25 June 2001
see also:
The Bowie-Dick Test (1) by Wim Renders
The Bowie-Dick Test (2) by Peter Hooper
The Bowie-Dick Test (3) by Michele Tait
The Bowie-Dick Test (5) by Stuart Line
The Bowie-Dick Test (6) by Dr. U. Kaiser

I fully agree as a Qualified Test Person that the B&D in its present form is outdated. It is only an indicator on the day and is not a record. I agree that an electronic test, is, if the calibration is correct and a testing of calibration is completed on a regular basis, is the way to go and the results can be saved on PC files, thus forming a permanent record. One of my concerns that I currently have is that, one of the companies promoting the electronic test is making a claim that their equipment results are sufficient for a Quarterly Test. It is still important to do Quarterly Testing using independently calibrated and validated test equipment. The other concern is the initial, and replacement cost, which makes the daily test expensive. I wonder if there are any moves afoot by any manufacture to create a device that would be permanently attached to the autocalve, and would assure the user as to the performance of the machine?

Please .

The Bowie-Dick Test (5)

by Stuart Line
4 July 2001
see also:
The Bowie-Dick Test (1) by Wim Renders
The Bowie-Dick Test (2) by Peter Hooper
The Bowie-Dick Test (3) by Michele Tait
The Bowie-Dick Test (4) by D. Doyle
The Bowie-Dick Test (6) by Dr. U. Kaiser

Although the linen B-D test was developed many years ago it does have the ability to detect a number of sterilizer faults that ETS and helix test may not detect. It is important that the linen used for the B-D test is correctly conditioned before use. The helix test also suffers from abuse if it used without thorough drying between uses. In addition the type of the helix head used will affect the result. At present there are several versions of then gke helix, and the prEN13060 is not yet complete, so the test may change again!

The ETS is designed for certain sterilization cycles. It is based on an electronic helix test as it uses a tube and temperature sensors to detect the presence of air. Therefore the ETS and helix may not detect NCG that enters the chamber via the steam supply during sterilization, as the tube has already been filled with steam. The linen B-D test has a more dynamic test area in the centre of the pack, so late arriving air could affect the colour change of the indicator. The ETS does give more information to someone that can interpret the data, but care is needed as the test is limited in what it can detect in a sterilizer chamber. As the ETS is an electronic based system calibration is an issue. It is not possible to recalibrate the ETS during its 400 cycle life. Therefore a secondary temperature and pressure measurement is required to check the ETS remains accurate.

I do not think the use of different test systems to suit the load being processed is the way to go. The B-D test was developed as a worst case system. As the B-D test does not rely on electronics it does not require calibration. As long as the indicator is from a reliable source, stored correctly and the towels are conditioned, the test is reproducible. Sterile services have enough to concern them selves without having to work out the type and design of test systems for their sterilizers. It is likely that the easiest design to pass would be in common use, as the sterilizer would fail less frequently, saving time and money.

The B-D test in all its forms does provide a permanent record that is not influenced by any data handling system. Therefore the test does provide long term data on a sterilizer that can be kept in a log book. For the user it provides a simple method of control.

A permanent device that is attached to the sterilizer to monitor the presence of air is called the 'air detector' and has been used in the UK for many years. No data is displayed about the operation of the air detector unless a failed cycle is detected. Unfortunately even an air detector can not indicate all the possible failures that may occur on a porous load sterilizer. Therefore at present I consider the use of a daily B-D pack to be a good compromise test system.

I would be interested in the experience of others.

Stuart Line

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The Bowie-Dick Test (6)

by Dr. U. Kaiser
24 October 2001
see also:
The Bowie-Dick Test (1) by Wim Renders
The Bowie-Dick Test (2) by Peter Hooper
The Bowie-Dick Test (3) by Michele Tait
The Bowie-Dick Test (4) by D. Doyle
The Bowie-Dick Test (5) by Stuart Line

Remarks on: Renders W, Hooper, P, Tait M, Doyle D, Line S:
The Bowie & Dick Test - Still a useful Standard? Zentr Steril 2001;9 (4): 228 - 229.

We welcome the critical comments from Mr. Renders and Mr. Hooper, who correctly ask whether the 40-year-old Bowie-Dick test still complies with the state of the art, in view of the fact that essentially more complex instruments are meantime being processed in the central sterilization department.

Mr. Tait asks whether, using electronic test systems (ETS) sterilization monitoring can be improved and automated at the same time. While it is true that the ETS can provide essentially more information on process data than the standard pressure-temperature-time-information, we know that unfortunately no homogeneous conditions prevail within the sterilization chamber and that the datalogger records only information pertinent to the locations at which its sensors are placed. However, since the most difficult to sterilize areas are to be found inside hollow devices and packs, it cannot be established with certainty whether the dataloggers at all carry out, and then correctly interpret, measurements in these problem areas.

Mr. Doyle correctly poses the critical question as to whether a datalogger system can act as a substitute for validation. Indeed the point just referred to above is of major importance for risk analysis during validation and can by no means be replaced by a datalogger.

Mr. Line in the next letter states, with reference to the ETS, that during its 400-cycles' life recalibration is not possible and hence the prescribed redundant monitoring is lacking. Mr. Line states correctly that on using reusable challenge device systems, such as the original Bowie-Dick test laundry pack, reusable paper piles or a helix, preconditioning must be carried out properly as otherwise incorrect interpretations can ensue. Furthermore we agree with Mr. Line that, depending on the items to be sterilized, different test systems should be used. It must always be more difficult for steam to penetrate into the challenge device than into the most difficult to sterilize instruments of the load.

Mr. Line goes on to remark that the original Bowie-Dick test was developed as a "worst case system. But that was 40 years ago at a time when there were no surgical instruments with the complexity of their modern counterparts. In an article (Central Service 2001; 9 (3): 177?186) we have demonstrated on comparing porous and hollow test systems that the original porous BD test under certain process conditions is easier to sterilize than hollow challenge devices. Hence there is increasing doubt as to whether the original BD test pack continues to be representative of "the object that is most difficult to sterilize".

Mr. Line correctly states that inert gas detectors, depending on their design and interpretation software, by all means provide more information on the sterilization process. But whether this information is also relevant for the internet volumes of minimally invasive surgical (MIS) instruments has not been proven to date. Here one is faced with the same problem as in the case of ETS, because the inert gas detector can measure only those sterilization properties relevant to its own location and not the "worst case" situation in the load.

Mr. Line comments on the behaviour evinced by the helix test, as per EN 867-5, in a manner that unfortunately does not stand up to the test of objective scrutiny. First of all, it must be stated that European Standard EN 867-5, in which the helix Hollow A is described, has been completed as a standard, as announced by Mr. Dennhöfer, head of the Standardization Committee TC 102, on page 225 of issue 4/2001 of Central Service. Therefore there will be no further changes to the test.

Nor do we agree with the statement that the helix test does not detect inert gas. Mr. Line states that the hollow device system (tube) was already filled with steam and that due to this - as dictated by the principle involved - no further inert gases could be detected. In our laboratories we have conducted measurements on this subject over the past 5 years and have indeed noted that helix test systems are well able to detect inadequate air removal, entry of air into the sterilizer due to leaks and the presence of inert gases in the steam. European Standard EN 867-4 is a test method for checking alternative test systems for these three faults. The Bowie-Dick simulation test from gke, which is based on a helix challenge device, meets these requirements for sub-atmospheric vacuum cycles. Due to the principle involved, trans-atmospheric or super-atmospheric air-removal cycles may not be able to remove air - at a justifiable investment - from complex hollow systems, as outlined in the aforementioned paper.

The reason that helix systems also detect inert gases resides in the fact that helix systems during the heating phase likewise consume steam due to condensation and if any inert gases are present they will also be picked up by the helix system but - and in this respect Mr. Line is absolutely right - the consumed quantities of steam are essentially smaller than is the case in a Bowie-Dick test system. But the quantities of inert gas needed for error detection in a standard Bowie-Dick test are in the range 200 -300 ml injected air, whereas a suitably designed helix test system is capable of detecting even less than 0.1 ml air, i.e. the sensitivity ratio is 200 : 0.1 or 2,000 : 1. A properly designed helix system needs only around a two-thousandth part of the inert gas quantity to show the same fault.

This enormous increase in sensitivity compensates for the essentially lower steam consumption and thus renders both systems comparable in respect of inert gas sensitivity. But the sensitivity of helix systems to inert gases greatly depends on the terminal challenge device used and on the indicator, because the reaction shown by indicators to the relative atmospheric humidity differs greatly. Under no circumstances should indicators intended for checking packs or for the Bowie-Dick test pack be used in the helix test.

Since very small quantities of inert gas fill relatively large lengths of thin pipes (a 10-cm pipe with 2 mm inner diameter is filled with 0.314 ml), sterilization of thin challenge devices is so vulnerable to the proportions of inert gases in the steam, irrespective of whether they come from inadequate air removal, leaks or arise during the steam generation.

We look forward to continue a lively discussion of this subject on the WFHSS website and in Central Service.

Dr. U. Kaiser

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Science or Politics? (1)

by Wim Renders
15 November 2001
see also:
Science or Politics (2) by Margaret Burn

At first sight the CSSD seems to be free from political interference. It looks as if decisions are only made on a sound scientific basis. However, on closer analysis a different picture emerges. A case in point is the French decision to have all instruments sterilised for 18 minutes at 134 degrees. The same is true for the English measure to use disposable instruments for tonsil resections. The approach of the anthrax affair does also frown many eyebrows. These examples raise a number of questions. However, despite their poor scientific underpinning, they have the advantage of creating a transparent situation.

This is not always the case. A large number of authorities for example have failed to work out a policy regarding the re-use of disposable products and/or remain silent about the quality or lack thereof of the CSSD. Is it out of fear for the financial consequences? Unfortunately the link between the quality of the CSSD and of the prevention of postoperative wound infections is difficult if not impossible to prove. But is this necessary? It is glaringly obvious that a patient can only benefit from the lowest possible presence of germs. How many anonymous victims do there have to be before action is taken and before the implementation throughout Europe of the European norms is accepted and imposed by the authorities concerned?

To quote Cicero: "Quousque tandem Catilina aboutere patientia nostra?" or "For how much longer Catilina are you going to test our patience?"

Please .

Science or Politics? (2)

by Margaret Burn
16 November 2001
see also:
Science or Politics (1) by Wim Renders

At first glance I wasn't sure if Wem Renders was for or against the reuse of single use products. At last I worked it out. Definitely against (I think).

While it is certainly true that it can only benefit the patient if the products used for treatment are free from germs, it ignores some of the other issues. In some cases the manufacturers are afraid of being taken "to the cleaners" in terms of litigation and therefore mark the goods "Single Use" leaving the Sterile Services manager with the problem. Not to mention the manufacturers that enjoy banking their not inconsiderable profits at the expense of the public. Call me a cynic if you like.

I have often thought that as a healthcare professional I should be able to judge certain things for myself. The application of the use of some single use products is one such area. An example would be the use of Yankeur Suckers. It would be more relevant to say 'Single Patient Use' rather than 'Single Use'. Where the sucker is being used in Ward setting in the patients mouth and water is used to flush it through, I can see no harm in using it more than once. Of course if the same sucker was being used for suction in Theatre during an abdominal operation for example it should be discarded.

In the UK healthcare has been something of a political football since the NHS was first established. It is accepted that we spend less of our GNP on healthcare than most industrialised nations. Much time and deliberation is spent on discussing the politics of healthcare. A lot of that discussion centers around the law of diminishing returns. I like to think of this as bartering. It goes something like this, you can get four hip replacements for the cost of one heart transplant. With odds like this, is it surprising that single use products are sometimes reused?

Margaret Burn

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Training for Sterilisation Assistants (1)

by Wim Renders
13 February 2002

September 2002 sees in Flanders (Belgium) the start of a new edition of the training course for sterilisation assistants. In the past this course was organised by the VSZ (Flemish Sterilisation in Hospitals society). The course provides basic information about the sterilisation department and is specifically aimed at the shop floor worker.

In the coming academic year the training programme will be integrated in the regular educational circuit. Is this our big leap forward? We, in any case, assume that the recognition by the authorities of our profession has come a little bit closer. Ultimately it should lead to the official recognition of the professional title of 'sterilisation assistant'. This is a necessary and unavoidable step in the process to guarantee the quality of our collaborators and hence of the CSSD.

Within the VSZ there has been a lot of debate about the minimal qualifications a candidate should have before being allowed to follow the training. I would very much like to know what your opinion is on the following two questions:

  1. Is the minimal eductional level required by the VSZ, namely to be 18 years of age and to have finished general technical education sufficient?
  2. The training course takes 60 hours and is followed by a 5 day internship. Do you think this is enough?

The training course 'advanced central sterilisation' will also be programmed in the same educational circuit. It takes in total 120 hours and a 10 day internship in a CSSD. The minimum requirements are:

  1. either to have taken and successfully completed the sterilisation assistant training course;
  2. or to have a degree of higher education, e.g. nurse, pharmacist etc.

Do you agree with these criteria?

I look forward to receiving your reactions.
Wim Renders

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Packaging Materials (1)

by N.N.
16 September 2002

Dear Colleagues,

We are running through the evolution of sterilization technology. And I find we sometimes loose a realistic view on the scene.

In Dutch, we say "we don't see the wood through the trees anymore".

Specially I would like to open the discussion about packaging materials.

I don't think they are really that bad. Take a look at your sterile storage, if it is as bad as mine, I think containers are the best solution. They are the strongest, and with an inner paper wrap they do assure sterility.

2 Step in 1 Method:
I rather have my people make a double wrap in the old way. If it is not perfectly done, you still have a second one. If I see people working with the 2 in 1 Method, taking a small sheet, to save money, then I really think we are using our sense of reality.

I think we all let us press too much from the industry, we all want to have the latest evolutions, in an attempt to follow the run of the technical evolution but we are loosing our common sense.

Please .

Can chemical indicators replace biological ones in routine control of sterilization processes? (1)

by Wim Renders
27 October 2002
see also:
Can chemical indicators replace biological ones in routine control of sterilization processes? (2) by Wim Renders
Can chemical indicators replace biological ones in routine control of sterilization processes? (3) by Michael Fangon

Monitoring and routine control of the different sterilization processes applied in a hospital, sterilization with steam, ethyleneoxide and gasplasma still raise a number of questions. This is evident from the questions and answers page of the WFHSS website. There is also a great need in the sterilization department of clearly formulated guidelines and procedures so that sterile medical instuments and devices can be confidently delivered.

Parametric release on the basis of the control of the temperature, pressure and time, does not pose any problems for steam sterilization processes. A condition is that validated processes are used in a controlled environment. The physical parameters can easily be monitored and the reproductibility of the process can be controlled. EN 554 exhaustively describes the requirements for validation and routine control of sterilization with steam. However, there are a number of processes and circumstances such as the carrying out of non validated processes, the lack of a quality system in the CSSD, the use of devices which do not display all parameters, which make a parametric release impossible. These cycles therefore need more controls in order to allow the release of sterile loads with absolute confidence. Apart from the necessary controls of the physical parameters prEN ISO 14161 states that: "BI may not be required and may provide little value in routine monitoring of some sterilization processes (e.g. moist heat sterilization, cf. ISO 11134 and ISO 13683). For processes where parametric release is not achievable biological indicators will provide the best available alternative for demonstrating microbial lethality in the sterilization process." But also the use of BI is hampered by quite a number of practical problems. For example the long response time, in other words the waiting for the result of the incubation of the BI is a big obstacle (which can only be removed by the use of rapid read out tests). As a result of the high turnover of the instruments the putting into place of a recall procedure, in the case of a positive result, is only a theoretical possibility. And what to do in when the BI test fails? Do we need to incubate and identify to determine wether test organism or contaminating organism is present? Also the positioning of the BI in the sterilisator and the number of tests which need to be carried out per cycle remains very often arbitrary. Answers to these questions should be given through validation. But what if no validation took place? Another nettlesome aspect of the BI is the Sterility Assurance Level. EN 556 requires "For a terminally-sterilised medical device to be labelled "sterile", the theoretical probability of there being a viable micro-organism present on the device shall be equal to or less than one in 1 x 1.000.000." The BI carry at least 100.000 micro-organisms for moist heat sterilization (EN 866-3) and 1.000.000 micro-organisms for Ethylene oxide and formaldehyde sterilization (EN 866-2 and -5). Can they guarantee that a production is sterile with a certainty of 1/1 millon? BI only show that there are no survivors but they are not really a gauge for the necessary SAL? Could in case of steam sterilization the use of chemical indicators (CI) group D (EN 867) provide a better solution? Of integrators and emulators at the very least the equivalence with BI (if not the surplus value) and the reproductibility of the results can be demonstrated. These CI moreover have the enormous advantage of direct readability and thus offer certainty to the patient and the sterilization department.

In the EN 550 Sterilization of Medical Devices - validation and routine control of ethylene oxide sterilization - control of each process with BI, as far as conventional release is concerned, is taken up. Parametric release is only possible after a physical and microbiological validation but requires standard loading which is out of the question in a hospital. As fewer processes are performed and aeration takes a long time the waiting for the results of the culture of the BI is less critical (The use of rapid read out tests can allow an almost preventive intervention). Here too most considerations mentioned above are applicable. The use of CI could therefore provide a solution.

Processes with gasplasma have to comply with ISO 14937: "Sterilization of healthcare products: General requirements for characterization of a sterilizing agent and the development, validation, and routine control of a sterilization process for medical devices." This new standard describes requirements for the development and validation of novel and unique sterilization processes. Comment is soon to follow on the discussion page.

When we insist on using BI do we not stick to rituals and beliefs which give us a false sense of security and juridical certainty? The patient however has to ward off real microbes and not fake specimens.

Wim Renders
Bruges, 06/10/2002

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Can chemical indicators replace biological ones in routine control of sterilization processes? (2)

by Wim Renders
23 November 2002
see also:
Can chemical indicators replace biological ones in routine control of sterilization processes? (1) by Wim Renders
Can chemical indicators replace biological ones in routine control of sterilization processes? (3) by Michael Fangon

Processes with gasplasma have to meet the requirements of EN ISO 14937 "Sterilization of health care products - General requirements for characterization of a sterilizing agent and the development, validation and routine control of a sterilization process for medical devices (ISO 14937: 2000)."
This international standard has to be applied e.g.:

  • for manufacturers and users of sterilization systems in health care settings for which a specific international standard does not exist.

This standard requires, for routine monitoring and control, that there shall be evidence through measurements, supplemented as necessary by biological indicators or chemical indicators that the sterilization process was delivered within the defined tolerances. During performance qualification data shall be generated to demonstrate the attainment of the defined physical and/or chemical conditions within specified tolerances, throughout the sterilization load. The relationship(s) between the conditions occurring at positions used routinely to monitor the sterilization process and those conditions occurring throughout the sterilization load shall be established. This is achieved by determining the attainment of the specified condition(s) at predetermined positons throughout the sterilization load.

In principle the use of biological indicators is therefore no longer obliged for routine monitoring of sterilization processes with gasplasma contrary to the obligations put on us by EN 550 for conventional release of ethylene oxide processes (see part 1). The necessity to dispose over reliable chemical indicators is therefore present.

Wim Renders

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Can chemical indicators replace biological ones in routine control of sterilization processes? (3)

by Michael Fangon
26 November 2002
see also:
Can chemical indicators replace biological ones in routine control of sterilization processes? (1) by Wim Renders
Can chemical indicators replace biological ones in routine control of sterilization processes? (2) by Wim Renders

Routine validation: Chemical Indicator, Biological or parametric release?

I would like to say that I am happy to speak about this famous ISO 14937 standard, unfortunately not known as the EN 554 or EN 550 & 556.
This standard is the only international one that explains clearly how to proceed to validate the sterilization process in routine (including. Chapter 10.2 says: "there shall be evidence through measurement supplemented as necessary by chemical or biological indicators that the sterilization process was delivered within the defined tolerances".
It means of course biological indicators are not an obligation but it is also true for the chemical indicators. As written in this standard, only the measurement is an obligation. In this case, the printout af any validated autoclave and / or the use of independent data loggers as a parametric release for each load is acceptable. It is also a more efficient method to prove that the sterilization process has been done in the defined tolerances.

Michael Fangon
Amcor Flexibles SPS

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Which Sterilant is the Active Component in a Steam Sterilization Process? Steam? No, it’s water! (1)
(Published in Central Sterilization 6/02)

by Dr. Ulrich Kaiser
20 Januray 2003

This provocative title is, to begin with, a hypothesis that must be proven. To that effect, the following 3 sterilants will be discussed.

1. Steam

It is well known that overheated steam, while it is in the gas phase at an unchanging temperature, is endowed with sterilization properties that are only on a par with those of air. Likewise, the saturated steam that streams into a completely dry textile pack made of cellulose fibres, such as e.g. linen or cotton, generates an intrinsic heat due to hydroscopic condensation on the cellulose fibres on absorbing steam. It does not, however, moisten the fibres, hence inside these textile packs temperatures are measured that are higher than the saturated steam temperature. Therefore steam condensation cannot occur in the inside region of the textile packs. Any standard biological indicators placed within the pack in accordance with EN 866-3 will not be killed at these sites on using standard steam sterilization processes at 121°C for 15 min. Of course, overheated steam can cool down and condense when further cooled, on coming into contact with cold surfaces.

2. Condensing Saturated Steam

At saturated steam temperature steam condenses on objects that are colder than the saturated steam temperature. In doing so, the steam transfers its condensation heat very quickly and effectively. Once the objects in question have reached the temperature of the saturated steam no further condensation or heat transfer takes place. During the heat-up phase water condenses on the objects to be sterilized, whereas during the sterilization phase no further steam consumption and hence no condensation takes place. Many authors claim that it is the condensing steam that acts as the sterilant without ever having provided proof of this. If one observes how biological indicators are inactivated in steam sterilization processes, one sees that on illustrating a logarithmic plot of the surviving microbes against a linear plot of the time one gets a straight line. This means that during the condensation phase at the beginning of sterilization there is no "kink"; rather in this diagram we see linear inactivation, during which no further steam condensation takes place. This thus proves that condensing steam does not give rise to inactivation.

3. Water

Liquids can be sterilized in closed vessels without supplying steam. Here one can observe that the microbial kill kinetics evidenced in distilled water at an unchanging temperature is equal to the kill kinetics that would be manifest if the same micro-organisms were killed in a steam sterilization process under otherwise similar conditions. From this observation one can unequivocally conclude that it is only the water that can act as the sterilant.


The belief, which on occasion is still being propagated at specialist training courses, that wet sterilized articles are not sterile at the end of the sterilization process is thus ill founded. This belief also runs counter to the fact that in following sterilization processes that do not include a drying cycle at the end, such as flash sterilizers, the wet articles are likewise not sterile. Even today sterilization processes that do not include drying are being used - provided that the articles are immediately put to use. Wet articles at the end of the sterilization process are thus sterile provided - that the sterilization process has been properly conducted. Hence wet articles can be released for immediate use without any reservation. But wet articles should not be stored because microbes can penetrate though wet soft packaging or growth conditions can be fostered within wet packaging, giving rise to a situation in which one sole surviving microbe would be enough to engage in multiple reproductions and thus re-contaminate the respective article during storage.

To reliably sterilize all surfaces of an article it is not only the requisite temperature effect that is important but additionally it must be ensured that all surfaces to be sterilized are covered with a water condensate film, even if it is very thin. The articles may not be sterile at all sites where condensation on the surfaces to be sterilized is impeded, e.g.:

  1. Sealed surfaces using elastic sealing materials.
  2. Lubricant or biofilms that prevent water from gaining access to the surface.
  3. Narrow gaps such as those found in the plugs of cocks which are lubricated and prevent condensation between the sealed surfaces.
  4. Non-condensable gases that accumulate in porous textile packs or hollow cavities, thus preventing steam condensation.
  5. Sealing materials such as rubber seals for sealing glass bottles or metal containers.

It is well known that microbial inactivation is a function of the carrier on/ or in which the microbes are to be found. For example, additives in the feeding water supplying steam generators affect the pH-value of the water as do the additives in fluids used for infusion solution. Compared with distilled water at a pH-value of 7, the sterilization time needed for e.g. 1 % saline must be increased by around 30 % to kill the same number of micro-organisms under otherwise similar conditions.

The porosity and material of surfaces too exert a strong influence on microbial inactivation. In our laboratories we have demonstrated that rubber plugs contaminated with B. stearothermophilus, at an unchanging temperature, will need around 50% longer sterilization time than when killing the same micro-organism under saturated steam conditions in water or on filter paper.

It is therefore paramount that care products can be mixed with water or contain water themselves. They should not be allowed to prevent water condensation on the surfaces to be sterilized.

I would be delighted if this paper would lead to animated and possibly controversial discussion in this journal.

Dr. Ulrich Kaiser
Application Laboratory
Auf der Lind 10
D-65529 Waldems-Esch

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Washer-Disinfector / Critical Process Parameters and Cleaning Efficiency (1)

7 August 2003

Washer-Disinfector / Critical Process Parameters and Cleaning Efficiency
2nd Round robin test
PEREG GmbH / 84478 Waldkraiburg / Germany


The cleaning step is known to be the base of the whole reprocessing cycle and mandatory for a safe sterilisation of instruments. Regulations like the European Medical Device Directive require that the function of a washer-disinfector is tested and reconfirmed prior to use. A first round robin test in 1999 was performed in Germany, Switzerland and Austria indicated that parameters used for the cleaning step are non standardised resulting in problems for cleaning efficiency in more than half of the results. End of 2002 a second round robin test was initiated in 15 countries to highlight these problems again on an more on a worldwide base.

Material and Method

The washer disinfectors tested were tunnel types and batch washers running an instrument cleaning program. Participants from the hospitals were asked to complete a form about the critical process parameters (time and temperature of pre-rinse and wash / detergent, dosing and water quality used for the wash cycle) and carry out a functional test of the cleaning efficiency. Information received was only used to indicate differences in program parameters and was not verified. The functional test was performed by placing 3 cleaning indicators (twoTOSIs in outer corners and one TOSI in the middle) on each level in one side of the washer-disinfector. Visibly clean TOSIs indicated a passed result, visible residues indicated a fail result. To avoid the effects of non standardised instrument-loads, the functional test was done in an unloaded machine.


Critical process parameters and the cleaning efficiency results are shown in the table below. Information about the Method shows the parameters time and temperature for pre-rinse and wash. Material shows information about the dosage and type of detergent. Declaration in ml/l was recalculated into %, all other information was kept as given by the participants. The water quality shown under Milieu is representative for the water used for the wash cycle only. This information was given by the participants without further analysis. A “?” is indicating no information given by the participants.

Cleaning efficiency is shown by the TOSI results on each level (bottom level = level 1 / highest level = level 5). All 3 indicators needed to be visually clean on one level to achieve a “pass”.

No Method Material Milieu TOSI cleaning efficiency
  Pre-rinse Wash Detergent Dosing Water quality Level 1 Level 2 Level 3 Level 4 Level 5
  Time/min Temp
Time/min Temp.
1. 3 cold 5 70 alkaline 0.75% ? fail fail pass pass N/A
2. 3 cold 3 70 alkaline 0.6% ? fail pass pass fail N/A
3. 2 cold 4 70 alkaline 0.6% ? pass pass pass pass N/A
4. 4 37 6 57 enzymatic 50ml/cycle purified fail fail fail N/A N/A
5. 5 45 10 45 alkaline 40ml/cycle purified fail fail fail fail N/A
6. 2 24 10 57 alkaline 60ml/cycle soft fail pass pass N/A N/A
7. 2 20 3 27 alkaline ? tap fail pass pass N/A N/A
8. 2 cold 5 40 alkaline 0.5% RO fail fail fail N/A N/A
9. 13 17 20 65 alkaline ? tap fail pass N/A N/A N/A
10. 3 R/T 5 70 alkaline 1.0% ? pass pass pass N/A N/A
11. 2 R/T 4 45 neutral ? ? fail fail fail N/A N/A
12. 2 R/T 4 65 alkaline 0.2% ? fail fail fail N/A N/A
13. 5 55 10 55 neutral 0.7% demin. pass pass pass pass N/A
14. 5.5 cold 5.5 45 neutral 0.5% soft fail fail fail N/A N/A
15. 5.5 45 5.5 47 neutral 0.5% soft pass pass pass N/A N/A
16. 4 13 4 65 enzymatic 0.4% ? pass fail fail pass N/A
17. 8 17 8 57 enzymatic ? ? fail fail fail fail N/A
18. 4 22 11 62 alkaline 1.0% RO fail fail fail fail N/A
19. 2 15 10 51 enzymatic 180ml/cycle ? fail fail fail fail N/A
20. ? ? ? ? alkaline 2 scoops ? fail fail fail N/A N/A
21. 2 cold 5 55 neutral 48ml/cycle ? fail pass pass fail N/A
22. N/A N/A 5 40 alkaline ? ? pass pass fail N/A N/A
23. 10 cold 3 60 alkaline 24ml/cycle demin. fail fail fail fail fail
24. 10 cold 8 65 neutral 24ml/cycle demin. fail fail fail fail fail
25. 10 cold 15 42 enzymatic 0.3% ? fail fail fail fail N/A
26. N/A N/A 10 93 alkaline 93 ml/cycle ? pass pass pass pass N/A
27. 5 10 7 60 enzymatic 0.3% ? pass pass N/A N/A N/A
28. 2 26 10 70 alkaline 80ml/cycle? ? fail pass pass pass N/A
29. 6 25 ? 58 alkaline 42ml/cycle ? fail fail fail N/A N/A
30. 1 16 10 44 enzymatic 180ml/cycle ? fail fail fail fail N/A
31. 3 18 20 64 alkaline 30ml/cycle ? fail pass fail pass N/A
32. 3 42 16 67 alkaline ? ? fail fail N/A N/A N/A
33. 4 20 7 60 alkaline 0.4% ? pass fail N/A N/A N/A
34. 2x2 cold 5 60 alkaline 0.3% ? fail fail N/A N/A N/A
35. 4x2 32 12 70 alkaline 65ml/cycle ? fail fail fail fail N/A
36. 2 cold 4 55 neutral 0.7% demin. fail fail fail N/A N/A
37. 5 20 5 65 alkaline ? tap fail fail fail N/A N/A
38. 2 42 10 65 enzymatic ? tap pass fail fail N/A N/A


The results are showing that the washing steps in washer-disinfectors are less standardised than sterilisation or disinfectioning processes. Even if the same types of detergents are used completely different parameters can be found resulting in possible critical variation in cleaning efficiency. Also as long as the efficiency of a detergent is not known and tested as done for disinfecting agents the efficiency of the whole process is in question. Another common problem is that not enough attention is directed on the importance of the cleaning time and cleaning temperature or parameters like dosage, or the water quality are not even known. When critical process parameters are not known validation is not possible. This situation is still very disappointing due to the fact that cleaning is nowadays known as the base for reprocessing of medical devices and is as important as sterilisation. Still our standards are only informing about the need for cleaning efficiency but not telling us exactly how to do it. More work needs to be done to create standardised parameters for different types of detergents to obtain processes with sufficient cleaning efficiency.

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Is globalization the future? (1)
(Published in Central Sterilization 4/05)

by Wim Renders
17 July 2005

At the end of March, the beginning of April 2005 more than 500 participants from 44 countries gathered for the DSc congress. The objectives of the congress were to provide an overview of the current state of affairs in the area of sterilization in the broad sense of the word, to discuss sterilization problems with colleagues and to gain an insight into future developments.

The unique collaboration between the societies which organised the congress namely the IFSS, the IDSc and the EFHSS, the worldwide interest and the international orientation of the papers demonstrate that globalization has also invaded our domain. It is an irreversible process. This is perhaps the most important conclusion which can be drawn after this very successful happening. I am indeed convinced that globalisation is here to stay and that it will make its presence felt. And certainly in Europe this should provide a lot of food for thought.

Coincidentally, I listened to a radio interview with Tom Lanoye, a Belgian writer about his latest theatre production. What he said contained a message we should take to heart. He wondered whether Europeans had not hidden inside fortress Europe for all too long. And he added that we should beware of (pretentiously) thinking that culture, philosophy and science were monopolies of the western world. He was of the opinion that we had wallowed in the security of short sighted provincialism. It was, according to Lanoye, time for a new, more outward looking Europe. A Europe which not only talks about lofty principles but which also puts them into practice. Such a "Europe" could be established anywhere.

Perhaps is it also necessary for European sterilization to reorient itself and to make a concerted effort to lower the drawbridge. This should be possible now that we have reached a certain level of maturity concerning sterilization and have gained enough self confidence to engage in an open dialogue with other, especially non-European partners.

Would it not be better if our departments no longer used the European framework as the ultimate yardstick but repositioned themselves within an intercontinental framework? From various contacts in London it became clear that the approach to sterilization in Australia and New Zealand was definitely not lagging Europe’s if it was not more advanced. And in South America too, as Helga Sagar de Agostini’s paper made abundantly clear, is not a backwater. In some of South American sterilization departments daily checks are made which for most of us, including myself, is only a pipedream. EFHSS has understood the need for reaching out to other continents and has decided to open its doors to non-European partners.

I trust we can succeed in establishing an intercontinental forum for sterilization. From this global platform we can set up an integrated sterilization approach which is adapted to the needs and possibilities of the countries and societies concerned.

Wim Renders

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WFHSS - World Forum for Hospital Sterile Supply :: Discussion

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