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Designing a Filter System for Endoscope Reprocessing

A system designed to last the longest and most cost-effectively remove bacteria is the best endoscope reprocessing filter system.  But what does that mean?  Well, that depends on a few factors, which we will discuss below and, hopefully, give you the information you need to get the best performance out of your filters.

We all know that the quality of the water used to rinse endoscopes is critical to patient safety.  Even though the water may be supplied by a municipality and treated using widely accepted methods, it could still contain organisms1-7.  Those organisms may form biofilms (as discussed in the previous blog posting) or remain on a scope and harm a patient if introduced during an endoscopic examination.

Water can also affect the aesthetics of the endoscope after reprocessing.  The water could leave visible particles or hard water deposits on scopes after drying.  Even the chlorine level n the water can affect the efficacy of the chemicals used in cleaning and disinfecting.

Filters can treat water with high particulate counts, bacteria, high chlorine levels and water with some organic chemicals.  Other treatment methods such as softening, de-ionization or even reverse osmosis are needed for water chemistry issues like hardness or dissolved materials.

We won’t review the water quality requirements for endoscope reprocessing, that has been done in a previous post.  We will look at how to design cost-effective filter systems based on the water conditions and facility demands. For more detail, you can e-mail me at allen@filtersupply.com and ask for the “How-To Guide – Water Filter Systems for Endoscope Reprocessing”.

Flow Rates

The “normal” flow rate through the system is the most important design consideration.  A widely-adopted rule of thumb is to use a 10-inch filter element for every 3 gallons per minute of “average” flow.  If practical, the maximum flow rate per 10-inch element should be below 5 gallons per minute.  This is true no matter the filter media or pore size rating.  So, to calculate the number of filter elements required, divide the normal gallon per minute flow by 3 and round up to the next whole number.

What Has to Be Removed? In endoscope reprocessing, the final goal is to remove bacteria.  That dictates the use of a 0.22μm or 0.10μm rated, membrane-based  filter as the last in the system.  If the water were clean except for bacteria, that could be the only filter in the system.  However, virtually all water systems deliver water with a wide range of particles and organisms of various sizes.  Those particles may foul (plug, in laymen’s terms) the final filter very quickly.  So, to protect the final filter, prefilters are used.  What prefilters depends on the number, size distribution and organic or inorganic nature of the particles.

A more detailed discussion of the nature of the particles in various water systems was discussed in our blog post on filter life.  Since most endoscope reprocessing filter systems are made up of a single prefilter and the bacteria filter, the choice of prefilter is critical to the life of the bacteria filter and will have a big impact on the cost of operating the system.

Space Considerations

A fact of life in most healthcare facilities is the shortage of space.  Reprocessing rooms are sometimes no larger than a walk-in closet.  Finding space for a filter system on the wall can be challenging.

Most facilities install a separate filter system for each reprocessing machine, even though that creates overcrowding on the wall of the room.  Most systems are a series of 2 or 3 10-inch filters in plastic housings.  Combining the filters for 2 machines into a single system may be as simple as replacing the 10-inch filters in one system with 20-inch versions, and replacing the 10-inch filters with 20-inch filters.  This simple design change will allow the removal of one filter system and can save almost half the wall space taken up by the two systems.  However, you should check with your reprocessor manufacturer to make sure that their machine warranty or instructions do not require dedicated filters for each machine.

Housings

Getting Longer Filter Life

Some of you may be wondering how to increase the time between filter changes.  Some of you might also wonder how filter life might be affected by combining systems.

It is not intuitively obvious, but a single system with 20-inch elements can process more than double the water of a system with 10-inch filter elements if it is operated at the same flow rate.  If the 20-inch system is replacing two 10-inch systems for two machines, this assumes that the machines fed by the combined system are demanding water at different times.  In other words, a 20-inch filter will process more than twice what a 10-inch filter can process (at the same system flow rate).

How can that be?  Well, without using too much filter industry jargon, the end point of a filter’s life is when the pressure drop reaches a set limit, usually 20 or 30 pounds differential between the upstream pressure and downstream pressure.  The pressure drop increases as the amount of particles clogging the filter pores increases, restricting the flow and requiring more pressure to force water through the filter media.  If the flow rate AND filter area were both doubled, then the filter life would be the same because the flow rate per 10-inch filter element would be the same.  However, in most cases the flow rate per 10-inch element will be cut in half, so the pressure drop starting point is lower by about half.  That means that the amount of water that can be filtered before reaching the maximum is higher per 10-inch element, meaning that more than twice the amount of water can be filtered in a 20-inch system than a 10-inch system.8

I know.  That sounds confusing, but the phenomenon has been proven in real life applications thousands of times.

Ergonomics

The best filter system installations are positioned so the filter housings are at about chest height (4 or 5 feet off the floor) and are above drains to allow the draining of the housings without needing buckets and mops.  There should be no other equipment or materials, even storage, in front of the filter housings.

Finding a place to install a filter system that allows that kind of access can be difficult.  The space shortages mentioned above sometimes force systems into tight spaces.  In my opinion, the most important consideration is making sure that the water that is released during a filter change doesn’t fall onto any equipment or supplies.

Reaching the housings should also be easy and not require long reaches or excessive bending.

Conclusions

Filter systems for endoscope reprocessing can be optimized based on flow rate, the particle content of the water, and space available.  The systems can be designed and operated in a cost-effective manner, even if the facility water supply contains high levels of particulates.  Users can contact Filter Supply or their filter supplier for assistance in system optimization.

References

  1. Phillips MS, von Reyn CF. Nosocomial infections due to nontuberculous mycobacteria. Clin Infect Dis 2001; 33:1363–74.
  2. Tobin-D’Angelo MJ, Blass MA, del Rio C, Halvosa JS, Blumberg HM and Horsburgh CR Jr. Hospital Water as a Source of Mycobacterium avium Complex Isolates in Respiratory Specimens.  J. Infect. Dis. 2004 189(1): 98-104
  3. Flannery B, Gelling LB, Vugia DJ, Weintraub JM, Salerno JJ, Conroy MJ, et al. Reducing Legionella colonization of water systems with monochloramine. Emerg Infect Dis. 2006 Apr; 12(4): 588-596
  4. LeChevallier MW, Cawthon CD, Lee RG. Factors promoting survival of bacteria in chlorinated water supplies. Appl. Environ. Microbiol. 1988;54:649-54.
  5. Ribeiro CD, Burge SH, Palmer SR, Tobin JOH, Watkins ID, Legionella pneumophila in a hospital water system following a nosocomial outbreak: prevalence, monoclonal antibody subgrouping and effect of control measures.  Epidemiol Infect 1987; 98:253-62
  6. Anaissie EJ, Kuchar RT, Rex JH, Francesconi A, Kasai M, Müller FJC, Mario LC, Summerbell RC, Dignani MC, Chanock SJ, Walsh TJ,  Fusariosis Associated with Pathogenic Fusarium Species Colonization of a Hospital Water System: A New Paradigm for the Epidemiology of Opportunistic Mold Infections Clin Infect Dis. (2001) 33(11): 1871-1878.
  7. Elias Anaissie EJ, Stratton SL, Dignani MC, Summerbell RC, Rex JH, Monson TP, Spencer T, Kasai M, Francesconi A, Walsh TJ, Pathogenic Aspergillus Species Recovered from a Hospital Water System: A 3-Year Prospective Study. Clin Infect Dis. 2002; 34:780–9
  8. Repetti, RV and Ponchick, AR.  Selecting the Most Economic Cartridge Filter.  Chemical Processing Online, http://www.chemicalprocessing.com/articles/2004/149/?show=all.   Accessed 8/27/2013

Biofilms in Endoscopes – An Issue? Yes. (In My Opinion)

It has been a while since there was much discussion of biofilms in endoscopes.  There has been no conclusive evidence presented that an infection has resulted from biofilm in a properly reprocessed endoscope.  Some people take that lack of evidence as proof that biofilms are not a problem in endoscopy.  However, as we all know, proving a negative is almost impossible. 

A different question for me is – does a condition exist that MIGHT create an infection?  Well, … can biofilms be present in reprocessed endoscopes?  The answer, according to some of the studies discussed below, is “yes”.  If that is the case, can the organisms in those biofilms potentially be released into patients?  Well … as the study discussion will show, if an endoscope biopsy channel with biofilm is used as part of an examination, then “yes”.

This summarizes my concern with biofilms.  While no infections have been documented, there is evidence that there can be, and are, biofilms in endoscopes, even after they have been properly reprocessed.  To me, that means there are live organisms in some scopes that are ready for use in a patient examination.  If the organisms are pathogenic (like some water borne Pseudomonas), and they COULD be transferred to a patient, then there is the potential, at least, for infection through colonoscopies, bronchoscopies, etc.  In short, it seems logical that biofilms in endoscopes can be an issue.

I don’t believe that anyone would say that having a biofilm in a scope is OK.  On the other hand, I also think biofilms aren’t getting attention because there is no evidence of harm, YET.

Prevention and Remediation

Most of the research and work done on biofilms (and discussed below) is about finding biofilms and then performing some sort of REMEDIATION – dealing with biofilms after they are established.  The later part of this post is about PREVENTION – reducing the probability that biofilms will occur in the first place using filters and other methods.

Let me be clear, no prevention program will be 100% effective, just like no remediation program will be 100% effective.  It is the combination that may reduce the number and severity of biofilm formations.

The History of Research on Biofilms in Endoscope Reprocessing

About 10 to 12 years ago there was a great deal of discussion of biofilms in healthcare environments.  The publications of Whitely et al1 of Australia in 2001 and Donlan and Costerton of the CDC2 in 2002 introduced many in the healthcare community to biofilms as a potential source of patient infections.  Though these two papers did not specifically address endoscopes or endoscope reprocessing, their description of biofilms signaled that medical devices, including endoscopes, could be susceptible.  To add to the concern, Anaissie et al3 linked hospital water supplies to patient infections and urged action.  Finally, in 2001 Kressel and Kidd4 published a study that found biofilm contamination in the tubing of an automated endoscope reprocessing machine, though they did not mention the endoscopes.

As stated in the introduction, there was no evidence presented showing that patient infections could be linked directly to endoscopes due to biofilm, or any other source, if the endoscopes had been properly reprocessed.  That lack of evidence was taken as an indication that properly reprocessing endoscopes would protect against potential infections from biofilms.

Two years later, in 2004, Pajkos et al5 found that biofilm was accumulating in suction/biopsy channels and air/water channels of endoscopes and probably interfering with the cleaning and disinfection process, causing disinfection failures even when proper procedures were followed.  This raised concerns, even though there was still no direct evidence of endoscopes causing patient infections.  The good news is that solutions were already being developed.

Not surprisingly, the fact that biofilms had been discovered in medical devices led initially to the development of ways to remove biofilms.  Developing remediation solutions made sense because the research showed biofilms forming in medical devices like endoscopes.   A series of studies on cleaning chemistries starting in 2004.  Vickery, Pajkos and Cossart collaborated on a paper6 that evaluated cleaners for their efficacy on removing an E. coli biofilm.  They found that non-enzymatic cleaners could reduce biofilms, but not eliminate them.   Marion et al in 2006 further investigated what they called “detaching agents”7, new products introduced in Europe and elsewhere (and since introduced in the US) that they found were effective in removing biofilms under laboratory conditions.  Finally, in 2009, Vickery et al8 published a study showing that multiple cycles of reprocessing using select, non-enzymatic cleaners could remove most, though not all, of a P. aeruginosa biofilm in endoscope lumens.

There was concern within the Society of Gastroenerology Nurse and Associates (SGNA) and other organizations that biofilms were not being addressed in actual practice and could potentially cause patient infections.  Donna Girard and Joan R Gray did a presentation at the 34th Annual SGNA Course in 2007 educating members of the organization on biofilms and how they might be controlled9.  Ms Girard also mentioned biofilms in her presentation on rinse water10 at the 36th Annual SGNA Course in 2009 as did Lawrence Muscarella in his presentation11 on the risk of transmission of various infectious agents.

Recently there have been studies that found a continued threat from biofilms.  The most extensive studies were done in the Netherlands by a group including Julia Kovaleva and others12,13,14.  All of these studies, and a doctoral thesis published in 2013 by Ms Kovaleva15, agreed that the proper use of chemical cleaners and high level disinfection will control biofilm and prevent transmission, as long as the endoscopes are free from defects or damage.  Any small defects or damage to lumens can cause incomplete cleaning and disinfection and make the formation of biofilms possible.  Even then, a literature review by Muscarella still found no published evidence that properly reprocessed endoscopes were a risk factor for transmission of biofilm organisms16.

How Can Biofilms Still Grow in Endoscopes After Reprocessing?

In general, organisms capable of forming biofilms are present almost everywhere in the environment.  Biofilms are formed in endoscopes when water remains in the device channels after reprocessing.  Muscarella17 emphasized how important drying is to the prevention of biofilms in 2006 as he was making a case for including drying in all reprocessing standards (which has since happened).  However, the studies noted above found that small defects or damage to the endoscope lumens could create traps for water, no matter how well the reprocessing and drying protocols are followed.  Even the small amounts of water in lumen surface defects can allow biofilms to grow12,13,14.

Since airborne bacteria are not likely to enter lumens (since the air used to purge channels is almost always filtered to remove bacteria) the most likely source of biofilm organisms is the water used for rinsing the scopes.  Several studies18-22 have found bacteria in hospital water supplies and traced that bacterial contamination to outbreaks of disease.  Many of the organisms named in the studies, such as Pseudomonas, are known to create biofilms.

endoscope reprocessing filter

The Importance of Using Bacteria Retentive Filters as One Part of Biofilm Prevention

Reprocessing an endoscope as soon after use as possible will help prevent organisms already inside the lumens from establishing a biofilm23.  But preventing organisms from being introduced into the endoscope during reprocessing is also critical.

One step in the prevention process is keeping the water supply system free of bacteria and biofilms using water treatment (ie. chlorine, chloramine, peracetic acid, hydrogen peroxide, ozone, UV light, heat).  This is remediation for the water system, but for purposes of this discussion we will consider the water system as outside the reprocessing system.

Creating a barrier between the exterior water supply and endoscope reprocessing machines is an effective form of prevention.  Filters are a proven physical barrier24-30 that can block bacteria from reaching critical hospital and healthcare environments.  The biggest question is then – what filter to use as the barrier?

The bacteria filters provided by machine OEMs or third parties can be manufactured with a whole range of performance levels.  Almost all filters can claim that they remove “some” bacteria.  Even initial prefilters can, theoretically, remove larger bacteria (bacteria can be as large as 5 microns).  Knowing whether or not the bacteria filter you are using removes “all” bacteria may be critical to you.  Your OEM or filter supplier should be able to provide documentation showing that the filters pass the industry standard test for bacteria retention, also called sterilizing filtration31.  Using filters with this level of performance will prevent organisms that may be living in your water supply system from reaching your endoscopes.  Depending on the filter system configuration, you may also protect your automated endoscope reprocessing machine itself from contamination.

Conclusion

Biofilms are found frequently in water systems and are an effective survival system for organisms that may be pathogenic.  Following current reprocessing standards and using the latest available cleaning and disinfection chemistries serves as a remediation step to limit the development of biofilms in devices that are free of defects or damage.  However, even these remediation steps are not completely effective if a device has small defects or damaged lumens.

Prevention steps are also needed to reduce the likelihood of biofilm development and improve the effectiveness of any remediation that may be required.  Chemical and other water treatments in the water supply will remove at least some bacteria.  An effective prevention method will also include the use of documented bacteria retention filters as a barrier to block biofilm organisms from reaching endoscopes.

References

 1.     Whiteley, R.K., Pajkos, A., Vickery, K., “Biofilms and their importance in infection control,” Journal of Gastroenterological Nurses College of Australia, 2001; 11 (3): 18-22

2.     Donlan, R., Costerton, J., “Biofilms: Survival Mechanisms of Clinically Relevant Microorganisms,” Clinical Microbiology Reviews, April 2002; 15(2): 167–193.

3.     Anaissie EJ, et al., “The hospital water supply as a source of nosocomial infections: a plea for action“, Arch Intern Med, 162:1483-1492, 2002

4.     Kressel AB, Kidd F. “Pseudo-outbreak of Mycobacterium chelonae and Methylobacterium mesophilicum caused by contamination of an automated endoscopy washer.”  Infect Control Hosp Epidemiol 2001;22:414-8.

5.     Pajkos A, Vickery K, Cossart Y. “Is biofilm accumulation on endoscope tubing a contributor to the failure of cleaning and decontamination?” J Hosp Infect. November 2004; 58(3):224-9.

6.     Vickery K, Pajkos A, Cossart Y. “Removal of biofilm from endoscopes: evaluation of detergent efficiency.”  Am J Infect Control. 2004 May;32(3):170-6.

7.     Marion K, Freney J, James G, Bergeron E, Renaud FN, Costerton JW  “Using an efficient biofilm detaching agent: an essential step for the improvement of endoscope reprocessing protocols”. J Hosp Infect. 2006 Oct; 64(2):136-42. Epub 2006 Aug 21

8.     Vickery K, Ngo QD, Zou J, Cossart YE.  “The effect of multiple cycles of contamination, detergent washing, and disinfection on the development of biofilm in endoscope tubing.”  Am J Infect Control. 2009 Aug;37(6):470-5. doi: 10.1016/j.ajic.2008.09.016. Epub 2009 Jan 19

9.     Girard, Donna BSN, RN, CGRN and Gray, Joan R, RN.  “Biofilm Within Endoscopy: The Cause and the Cure” Presentation at SGNA 34th Annual Course, Baltimore, MD, May 2007

10.  Girard, Donna BSN, RN, CGRN.  “How Clean Is Your Rinse Water?” Presentation at SGNA 36th Annual Course, St Louis, MO. May 2009

11.  Muscarella, Lawrence F, PhD.  “An Infection Control Update: Gastrointestinal Endoscopes and the Risk of Transmission of Biofilms, C. difficile, and Other Epidemiologically Important Infectious Agents”.  Presentation at SGNA 36th Annual Course, St Louis, MO. May 2009

12.  Kovaleva J, Meessen NEL, Peters FTM, et al. “Bacteriologic safety in endoscope reprocessing: stringent enough?”  Endoscopy 2009;41:913e916.

13.  Kovaleva J, Degener JE, van der Mei HC. “Mimicking disinfection and drying of biofilms in contaminated endoscopes”.  J Hosp Infect. December 2010; 76(4):345-50

14.  Kovaleva J, Peters FT, van der Mei HC, Degener JE. “Transmission of infection by flexible gastrointestinal endoscopy and bronchoscopy.”  Clin Microbiol Rev. 2013 Apr;26(2):231-54.

15.  Kovaleva JS. “Microbiological safety in endoscope reprocessing”. Doctoral Dissertation.  University of Groningen Library (host), 2013, http://irs.ub.rug.nl/ppn/355083086

16.  Muscarella LF. “Evaluation of the risk of transmission of bacterial biofilms and Clostridium difficile during gastrointestinal endoscopy.”  Gastroenterol Nurs. 2010 Jan-Feb;33(1):28-35.

17.  Muscarella LF. “Inconsistencies in endoscope-reprocessing and infection-control guidelines: the importance of endoscope drying.”  Am J Gastroenterol. 2006 Sep;101(9):2147-54. Review.

18.  Winiecka-Krusnell J & Linder E, “Free living amoeba protecting Legionella in water: The tip of an iceberg?”, Scand J Infect Dis, 31:383-385, 1999

19.  Reuter S et al., “Analysis of transmission pathways of Pseudomonas aeruginosa between patients and tap water outlets”, Crit Care Med, 10:2222-2228, 2002

20.  Blanc DS et al., “Faucets as a reservoir of endemic Pseudomonas aeruginosa colonization/infections in intensive care units”, Intensive Care Med, 30: 1964-1968, 2004

21.  Trautmann, M., H. Royer, E. Helm, W. May, and M. Haller. “Pseudomonas aeruginosa: new insights into transmission pathways between hospital water and patients”. Filtration. 2004;1(Supplement 1): 63-70

22.  Rogues, A-M, H. Boulestreau,, A. Lashe´ras, A. Boyer, D. Gruson , C. Merle, Y. Castaing, C.M. Be´bear, J.-P. Gachie. “Contribution of tap water to patient colonization with Pseudomonas aeruginosa in a medical intensive care unit.” J Hosp Infect. 2007; 67:72-78.

23.  Roberts CG. “The role of biofilms in reprocessing medical devices.”  Am J Infect Control. 2013 May;41(5 Suppl):S77-80.

24.  Sheffer, P., J. Stout, M. Wagener, and R. Muder. “Efficacy of new point-of-use water filter for preventing exposure to Legionella and waterborne bacteria.”  Amer. J. Infect. Cont. 2005;33(5) Supplement 1:S20-S25.

25.  Vonberg, R.P., T. Eckmanns, J. Bruderek, H. Ruden, and P. Gastmeier. “Use of terminal tap water filter systems for prevention of nosocomial legionellosis.”  J. Hosp. Infect. 2005;60:159-162.

26.  Van der Mee-Marquet, N et al. “Water microfiltration: a procedure to prevent Pseudomonas aeruginosa infection.”  XVI Congres Nat. Soc. Franc. D’Hyg. Hospitaliere, Water and Hospital Symposium.2005;Reims, France. Abstract S.137.

27.  LaFerriere, C. “Infection control measures vs. waterborne microbes in the NICU.” SHEA Annual Meeting Poster Session. 2006;Chicago.

28.  Vianelli, N. et al.  “Resolution of a Pseudomonas aeruginosa outbreak in a hematology unit with the use of disposable sterile water filters.” Haematologica.2006;91(7):983-985.

29.  Cervia J.S., Farber B., Armellino D., Klocke J., Bayer R.L., McAlister M., Stanchfield I., Canonica F.P., Ortolano G.A. “Point-of-use water filtration reduces healthcare-associated infections in bone marrow transplant recipients.” Transpl Infect Dis. 2010 Jun;12(3):238-41

30.  Holmes C., Cervia J.S., Ortolano G.A., Canonica F.P. Preventive efficacy and cost-effectiveness of point-of-use water filtration in a subacute care unit. Am J Infect Control. 2010 Feb;38(1):69-71.

31.  ASTM International. ASTM F838 – 05(2013) “Standard Test Method for Determining Bacterial Retention of Membrane Filters Utilized for Liquid Filtration”,  2013

Endoscope Reprocessing Filters – What Do You Need, and Are You Getting It? – Part 3

This is the last of 3 postings that should help you make educated choices about your endoscope reprocessing filters.  The first posting reviewed the requirements for filtration – from both standard setting organizations and endoscope manufacturers.  The second post took a look at the practices widely adopted for filtration in scope reprocessing.  This final post in the series will give you questions to ask your filter supplier so you know what kind of performance you are getting from your filters.  After reading all of the posts in the series, you will be able to understand what level of filtration you want and, perhaps most important, whether the filters you now use actually deliver the performance you want.

endoscope reprocessing filter

Review – What Are the Requirements for Endoscope Reprocessing Filters?

There is some confusion about the water quality and filtration requirements for endoscope reprocessing. Almost all information on water quality in endoscope reprocessing is focused on the final rinse water for the devices. The confusion comes from conflicting statements from standard setting organizations that allow a range of water quality and water treatment options and more specific requirements from some endoscope manufacturers.

The recurring message in both the guidelines and instructions seems to be that “bacteria-free” rinse water is most desirable.  However, the instructions from the manufacturer(s) of your endoscopes should be followed, at a minimum.

Review – Current Practices in Endoscope Reprocessing Filters

Filter systems in most facilities are either installed by AER makers or recommended by them.  They generally comply with the regulatory and endoscope manufacturer requirements for filtration performance.  These systems will remove particles and bacteria from the water.  The final filter in these systems is almost always called a “bacteria retention” or “bacteria removal” filter.

The most common systems use two filters in series (Figure 1). The two filters are a prefilter and bacteria removal filter.

Figure 1 – Common Endoscope Reprocessing Filter System

Endoscope Reprocessing Filter System

Other filter system configurations are also used. Some use two prefilters configured as shown in Figure 1, but with a final bacteria filter inside the reprocessing machine or mounted on the wall downstream of the two prefilters.

The bacteria filters provided by machine OEMs or third parties could be made to provide a whole range of performance levels.  I won’t define all of the terms used by filter suppliers, but the only term that assures you that a filter will remove ALL bacteria is “sterilizing filter”.  Other filters may be promoted as removing bacteria, and there can be some truth to the claim, but sterilizing filters cannot be called such unless they are able to remove all bacteria according to standardized tests, and have the supporting documentation to prove their performance.

Almost all filters can claim that they remove “some” bacteria.  Even initial prefilters can, theoretically, remove larger bacteria (bacteria can be as large as 5 microns).  Knowing whether or not the bacteria filter you are using removes “all” bacteria, including small, water borne bacteria like Pseudomonas species, may be critical to you.  To determine how much of the bacterial load your current filter removes, and the quality of the filter, You should ask your filter supplier some questions.

Q&A for Filter Suppliers

What questions should you ask?  More important, what should you get for answers? Below is a short list of questions paired with answers you should expect.  With these answers, you can make an informed decision about your endoscope reprocessing filters and any other water filter applications in your facility.

Q 1. Will your filter remove all bacteria, or only some?

A. This is the most critical answer.  If the supplier says they will remove all bacteria, then move on to the second question. If they only say that the filter will remove bacteria, ask again if that means “all” bacteria. If they cannot answer that question with a simple yes or no, or if your supplier isn’t sure, ask them to get documentation from the manufacturer and forward it to you.

Q 2. Can I integrity test your filters?

A. If the supplier is offering a true sterilizing filter, then this information should be readily available. It may be in the form of a full “Validation Guide” as used in the pharmaceutical industry. It may be more useful in the form of a short data sheet accompanied by a letter confirming that supporting data is available.  Depending on how strictly you interpret CMS regulations regarding fraudulent representation, providing you false data can be seen as anything from an unethical to a criminal act.

Q 3. Are your filters made of materials that comply with FDA food contact standards?

A. Most filter manufacturers use materials that meet the FDA standards for indirect food contact. They should be able to provide a letter or certificate saying that the filters are made using materials that comply with 21 CFR Parts 177-182.

Q 4. Are your filters shipped with documentation of quality?

A. Any filters made to the sterile filtration standards of the pharmaceutical industry will be shipped with documentation showing that the filters have been tested and passed an integrity test for sterile filtration performance. Prefilters and other filters not intended for use as sterilizing filters may still have package inserts indicating the performance of the filter. Ask your supplier for examples of the documentation that is shipped with each filter so you can see what level of performance is documented.

Q 5. What additional services or expertise do you offer to help me protect my final filters from premature plugging and reduce my overall filter cost?

A. The answers here should show experience in filter applications and knowledge of how to solve problems with filtering tap water.  Specific examples of problems encountered and solved may be helpful.  Ideally, the supplier should demonstrate familiarity with your particular water filtration issues, and how to solve them.

Please add your own questions or experiences with filter suppliers in the comments.  We’ll be happy to facilitate any discussion.

For a complete document with the content of all three of these posts, contact me at allen@filtersupply.com.  I will send you the complete paper “Endoscope Reprocessing Filters – What Do You Need, and Are You Getting It?”

Of course, if you have any questions on filtration or are experiencing issues with filter performance, we will be happy to help.  Just send an e-mail or call us at (800) 232-4221.

 

Endoscope Reprocessing Filters – What Do You Need, and Are You Getting It? – Part 2

This is the second of 3 postings you will see in the next week that should help you make educated choices about your endoscope reprocessing filters.  The first posting reviewed the requirements for filtration – from both standard setting organizations and endoscope manufacturers.  This second post takes a look at the filtration practices that have been widely adopted for endoscope reprocessing.  The third and final post in the series will review the sometimes confusing terminology used by filter suppliers, and give you questions to ask your supplier so you know what kind of performance you are getting from their filters.  At the end of this series you will have the tools to know the filter performance you want and, perhaps most important, whether the endoscope reprocessing filters you now use actually deliver that performance.

Review – What Are the Requirements for Endoscope Reprocessing Filters?

There is some confusion about water quality and requirements for endoscope reprocessing filters. Almost all information on water quality in endoscope reprocessing is focused on the final rinse water for the devices. The confusion comes from conflicting statements from standard setting organizations that allow a range of water quality and water treatment options and more specific requirements from some endoscope manufacturers.

The recurring message in CDC, SGNA and other guidelines and manufacturer instructions seems to be that “bacteria-free” rinse water is most desirable.  However, the instructions from endoscope manufacturers should be followed, at a minimum.

Endoscope Reprocessing Filters

 

What Are Facilities Actually Using?  Current Practices with Endoscope Reprocessing Filters

Most facilities that use automated endoscope reprocessing (AER) machines install a filter system provided by or recommended by the AER manufacturer.  In virtually all cases, both the AER manufacturer and the endoscope maker certify that the AER, including the recommended filter system, is capable of reprocessing the endoscope model you use.

All filter systems from AER makers will remove particles and bacteria from the water.  In general, the final filter in the system is called a “bacteria retention” or “bacteria removal” filter.  While not explicitly stated in most AER machine marketing literature, filter systems are often presented in a way that implies that “bacteria-free” water will be supplied for at least the final rinse in the reprocessing machines.  Some machines filter all water entering the machine, which implies that the water used for cleaning and/or high level disinfectant mixing will also be bacteria-free.

The most common systems use two filters in series (Figure 1). The two filters are a prefilter and bacteria removal filter. The prefilter, most often rated at 1 micron or 5 microns, removes larger particles and protects the bacteria filter from being overloaded. The bacteria filter, intended to remove all bacteria, is made using a membrane, usually rated at 0.22 or 0.10 micron, depending on the system that was installed with the reprocessing machines.

 Figure 1 – Common Endoscope Reprocessing Filter System

Endoscope Reprocessing Filter System

Other filter system configurations may also be used. Some systems have two prefilters configured as shown in Figure 1, but with a final bacteria filter inside the reprocessing machine or mounted on the wall downstream of the two prefilters.

Measurements of system performance are most often based on two factors, how much bacterial contamination is removed, and how long the system operates between filter changes. 

Do current endoscope reprocessing filter systems remove bacteria and operate long enough to meet user expectations?  Do they comply with the requirements for endoscope reprocessing?  The short answer is to both questions is “Yes”, but with some reservations.

The amount of time that a filter will operate effectively depends on a number of factors.  Two previous blog posts discussed a couple of factors.  Click on either construction or source water quality to learn more about making filters last longer when there are more particles in your water than “normal”.

The bacteria filters provided by the machine OEMs or by third parties can perform at a number of different levels, and still be presented as removing bacteria.  In fact, almost all filters can claim that they remove “some” bacteria.  Even the initial prefilters can, theoretically, remove larger bacteria (bacteria can be as large as 5 microns).  Knowing whether or not the bacteria filter you are using removes “all” or “some” bacteria may not be critical to you.  But, if it is, you should ask your filter supplier some questions.

The next blog post, the final one in this series, will provide you with the questions you should ask your filter supplier to determine the true level of performance of the filters they provide.  Before giving you the questions, there is a brief explanation of the terms used by filter suppliers, some of which are confusing and even misleading.  Armed with the knowledge of what terms are used, and the list of questions to help clarify what your supplier is saying, you can soon know a lot more about what your endoscope reprocessing filters actually do for you and your patients.

For a complete document with the content of all three of these posts, contact me at allen@filtersupply.com.  I will send you the complete paper “Endoscope Reprocessing Filters – What Do You Need, and Are You Getting It?”

Please comment on what you have read here – and add your own experiences with determining your filter performance needs and evaluating filters and filter suppliers.  I look forward to learning more from you!

Endoscope Reprocessing Filters – What Do You Need, and Are You Getting It? – Part 1

This is the first of 3 postings you will see in the next week that should help you make educated choices about your endoscope reprocessing filters.  This first posting reviews the requirements for filtration – from both standard setting organizations and endoscope manufacturers.  The second post will take a look at the filtration practices that have been widely adopted for endoscope reprocessing.  The third and final post in the series will give you questions to ask your filter supplier so you know what kind of performance you are getting from the filters you use now.  At the end of this series you will have the tools to know the filter performance you want and, perhaps most important, whether the endoscope reprocessing filters you now use actually deliver that performance.

Endoscope Reprocessing Filters

What Are the Requirements for Endoscope Reprocessing Filters?

There is some confusion about both the filtration technology requirements and water quality requirements for endoscope reprocessing. Almost all information on water quality in endoscope reprocessing is focused on the final rinse water for the devices. The confusion comes from conflicting statements from standard setting organizations that allow a range of water quality and water treatment options and more specific requirements from some endoscope manufacturers.

The CDC made recommendations in their guidelines on disinfection and sterilization published in 20081. Two in particular apply to endoscopy.  They are:

–       Process endoscopes (e.g., arthroscopes, cystoscope, laparoscopes) that pass through normally sterile tissues using a sterilization procedure before each use; if this is not feasible, provide at least high-level disinfection. High-level disinfection of arthroscopes, laparoscopes, and cytoscopes should be followed by a sterile water rinse. Category IB.

–       After high-level disinfection, rinse endoscopes and flush channels with sterile water, filtered water, or tapwater to prevent adverse effects on patients associated with disinfectant retained in the endoscope (e.g., disinfectant induced colitis). Follow this water rinse with a rinse with 70% – 90% ethyl or isopropyl alcohol. Category IB.

The CDC (HICPAC) also made recommendations in an earlier document, the 2003 “Guidelines for Environmental Infection Control in Health-Care Facilities2.

–       To rinse disinfected endoscopes and bronchoscopes, use water of the highest quality practical for the system’s engineering and design (e.g., sterile water or bacteriologically filtered water [water filtered through 0.1–0.2-µm filters]. Category IB CDC logo

The SGNA in their 2012 “Standards of Infection Control in Reprocessing of Flexible Gastrointestinal Endoscopes” draw from the ASGE Quality Assurance in Endoscopy Committee and state that “Tap water and/or water that has been filtered by passage through a 0.2 micron filter or water of equivalent quality (i.e., suitable for drinking) should be available.”3

The 2011 “Multisociety Guideline on Reprocessing Flexible Gastrointestinal Endoscopes” states that endoscopes should be rinsed after high level disinfection “with sterile, filtered or tap water to remove the disinfectant solution.” 4

The standards seem to allow a wide range of water quality, with the base being tap water.  However, regardless of the statements on water quality from standard setting organizations, there is an overriding instruction in the standards to follow the directions of the endoscope manufacturer when reprocessing the device.  Therefore, your device maker’s statements on required water quality should govern your decisions on water treatment and endoscope reprocessing filters.

Endoscope manufacturers have different water quality requirements written into their reprocessing directions. Olympus states in a 2010 letter that deionized water is not required, but “… other water qualities are acceptable for reprocessing and/or rinsing the endoscopes …” The water qualities listed state a preference for “sterile water”, but allow “… fresh, potable tap water or water that has been processed (e.g., filtered, deionized or purified) to improve its chemical and/or microbiological quality …” if sterile water is unavailable.5

Pentax is quite specific about water quality in their instructions for manual reprocessing.  They state “…purge ALL channels with air, then RINSE all internal channels with sterile water.”6

FujiFilm Medical Systems (formerly Fujinon) calls for “… microbiologically clean drinking water or sterile water” in their instructions on final rinsing.7

All of the standards organizations and endoscope makers at least recommend (and some require) a final rinse of all endoscope channels with 70% alcohol and an air purge to dry the channels1-7. This is done to enhance the drying process and reduce the chance that waterborne organisms will grow in the devices, regardless of the endoscope reprocessing filters used.

There is a long standing belief among some healthcare professionals that alcohol will kill anything. For those who believe that, the 70% alcohol rinse at the end of the reprocessing cycle is seen as a reliable way to reduce or eliminate any bacterial contamination in the scopes. But alcohol is not sporicidal2, so it will not kill bacterial spores like those from Bacillus and Clostridium species. Alcohol also does not kill cysts, such as the waterborne Cryptosporidium oocysts that caused an outbreak of illness in Milwaukee in 1993. Filtering is a cost-effective way to remove these organisms and prevent their possible introduction into patients.

Conclusion

The recurring message in these guidelines and instructions seems to be that “bacteria-free” rinse water is most desirable.  However, the instructions from the manufacturer of your endoscopes should be followed, at a minimum.

You may wish to review your endoscope reprocessing filters and filtration practices to see if they were/are designed to meet the level of performance called for by your endoscope provider.

References

1.     Rutala, W., Weber, D., & Healthcare Infection Control Practices Advisory Committe ( HICPAC), (2008). Guideline for disinfection and sterilization in healthcare facilities. Retrieved October 18, 2012 from http://www.cdc.gov/hicpac/pdf/guidelines/Disinfection_Nov_2008.pdf

2.     Centers for Disease Control. Guidelines for Environmental Infection Control in Health-Care Facilities, 2003. MMWR 2003;52 (No. RR-10):1-44.

3.     Society of Gastroenterology Nurses and Associates, Inc. (2012). Standards of Infection Control in Reprocessing of Flexible Gastrointestinal Endoscopes [Practice standard]. Chicago, IL: Author.

4.     American Society for Gastrointestinal Endoscopy and the Society for Healthcare Epidemiology of America (2011).  Multisociety guideline on reprocessing flexible gastrointestinal endoscopes. Gastrointestinal Endoscopy Volume 73, No. 6

5.     Olympus Letter – Water for rinsing Olympus endoscopes (Models: ENF-VQ, ENF-VT2, LTF-VH, LTF-VP, LTF-VP-S, and CHF-P60) and associated accessories, December 14, 2010, pdf file, Accessed on Olympus America website November 19, 2012.

6.     Pentax Manual Cleaning and Reprocessing Charts, pdf files, accessed on Pentax Medical website November 19, 2012

7.     Fujinon – FujiFilm Manual, “Reprocessing of flexible endoscopes and endoscopic accessories.”  Scanned pdf document accessed November 27, 2012

Is Your Filter Life As Long As You Want?

I recently posted some information on the effects of construction on facility feed water quality and filter life (click here to see the post).  Today I’ll try to answer a broader question – what “normal” water conditions will affect filter life?

As with the post on construction, the following is based on a section of the Filter Supply “How-To Guide – Water Filter Systems for Endoscope Reprocessing”.  (To get a copy of the complete guide, contact me at allen@filtersupply.com and I will e-mail you a copy).

All filter systems are designed around what is being removed from the fluid being filtered.  We all see water in rivers and streams that carries a large amount of material (like the “Muddy Mississippi”).  But water will also dissolve almost anything, because it is nearly a universal solvent.  Most materials contacted by the water will be partially dissolved until the water reaches its holding capacity.  That is why tap water supplied by municipalities can have particles, bacteria and/or high amounts of dissolved organic, inorganic and ionic material.  That content varies considerably with the water source, the distribution system, local geography and time of year.

The particle content of the water is the biggest factor in filter life.  The largest determinant of particle content, and filter life, is whether the water originates as surface water (river, stream, reservoir, etc) or groundwater (well or spring).

Groundwater Content

Groundwater from deep wells or springs is “cleaner” to the eye of most observers because it has already been filtered by the earth for many years.  However, during that time in the ground it has dissolved many elements like the minerals that cause “hardness” (calcium and magnesium) and other elements like manganese, iron, and aluminum.  The amount depends on your location.

Surface Water Content

Water from surface sources is usually from precipitation which is, effectively, distilled water.  It usually has little mineral content, though it will have more organic and inorganic particles.  The content of surface water varies by region.  Arid areas may have little organic content in rivers, but the sediment content may rise dramatically during rainfall or spring snowmelt.  In higher rainfall areas the leaves and other organic matter in and around water sources break down and contribute organic particles and organic compounds that could affect the water’s taste and odor.

The biggest concern for healthcare facilities is the organisms that enter surface water.  There are many waterborne bacteria.  Most people are familiar with Legionella and Pseudomonas strains, but there are many others.  E coli or Salmonella bacteria and cysts such as Giardia or Cryptosporidium can also enter surface water through direct or indirect contact with wild or domesticated animals.

Municipal Water Treatment

Municipalities will treat filter all water, regardless of its source.  Treatment usually includes coarse filtration (sand filters) and chemical treatment (chlorination or other treatment).  Most municipal systems do an excellent job of removing particles larger than 2 microns (about 1/25 the width of a human hair).  But no matter how well run it is, a municipal water distribution system will contribute particulates larger than 2 microns and even bacteria to the water stream.  No system is sterile, and the wear of system components and even dust and sand left from system construction are pushed through the system as particles.

What does all this mean?  Well … the more particles in the water the more the filters have to hold.  Filters have a limited amount of “dirt holding capacity” before they become fouled (plugged in laymen’s terms).  So if the water for your facility has a lot of particles, the filters may plug faster than the time estimated by your equipment manufacturer.  That could mean that your expensive bacteria filters have to be replaced more often than you would like.

Is there something you can do about it?  Maybe.  As discussed in the post on the effects of construction, you might be able to “spread the load”.

There are 2 ways to spread the dirt content of water.  The first is to increase the dirt-holding capacity of the system.  That is usually done by increasing the amount of media in the system, which automatically increases the amount of dirt it can hold.  The second is to change the media used.  Using media designed to capture portions of the dirt load in a series of filters saves the final filter from having to carry most or all of the load.

Increasing the Amount of Filter Media

The most common way to increase the amount of filter media is to install larger filter elements.  That usually means installing a 20-inch filter in the place of a 10-inch filter that is plugging too quickly.  Doubling the filter media available usually increases filter life by more than 2x.  That phenomenon is explained in the How-To Guide.

Changing the Media

Changing the media is slightly more complex,.  The first step is to understand what is in your water and plugging the filters.  A particle size analysis on a sample of your incoming water can show how many particles of each size are in your water at the time of the sample.  Assuming that the particle content of the water is consistent (which may be an heroic assumption, as explainged in the How-To Guide), A knowledgeable filter consultant can make suggestions on the types of media to use to maximize filter performance and, most importantly, minimize filter expense.

You can read the previous post for more details than are presented above, or get the How-To Guide by e-mailing me at allen@filtersupply.com

It is important to remember that each facility, feed water and filter system design is different.  The nature of the particles in the water can also significantly change the way that the filters are used.  Call Filter Supply or e-mail me at allen@filtersupply.com to get suggestions on how your facility might be able to reduce get better performance from your filters.

References

  1. Peeters J E, Ares Mazás E, Masschelein W J, Villacorta Martinez de Maturana I, Debacker E. Effect of disinfection of drinking water with ozone or chlorine dioxide on survival of Cryptosporidium parvum oocysts. Appl Environ Microbiol. 1989;55:1519–1522.
  2. Carpenter C, Fayer R, Trout J, Beach M J. Chlorine disinfection of recreational water for Cryptosporidium parvum. Emerg Infect Dis. 1999;5:579–584.
  3. US Environmental Protection Agency (EPA) website – National Primary Drinking Water Regulations – List of Contaminants& their MCLs – http://water.epa.gov/drink/contaminants/index.cfm#3 – accessed 11-16-2012
  4. US Environmental Protection Agency (EPA) website – Water: Long Term 2 Enhanced Surface Water Treatment Rule – Quick Reference Guides for Schedule 1 through 4 Systems – http://water.epa.gov/lawsregs/rulesregs/sdwa/lt2/compliance.cfm#quickguides – accessed 11-16-2012

My Filter Life Was Good …. Until They Started Construction …

I’ve spoken with many people in healthcare about the effects of construction projects on their water quality.  Healthcare is a growth industry, so it is no surprise that many healthcare facilities are expanding or building totally new facilities.  But that construction activity effects the quality of the water entering surrounding facilities, and filtration managers may have to deal with reduced filter life.

Construction disrupts the water lines feeding facilities as they are rebuilt, relocated or at least subjected to vibration.  The result is often feed water that is heavily loaded with silt and sediment – and that extra dirt load can require filters to hold more dirt, and have shorter filter life. 

Most of us that get our residential water from cities and towns have seen “brown water” in our homes when our municipality has “flushed” the water lines.  If we are unfortunate enough to be doing our laundry when this happens, we can end up with our clothes stained and ruined.  This is also what happens during construction in and around healthcare facilities.  The good news is that the filtration systems in place will almost always remove the increased amount of silt and sediment, so equipment will be protected.  The bad news is that the increased dirt load will plug filters much faster than under “normal” circumstances.  If not managed properly, this can result in much higher filtration costs and an increase in “low flow” alarms and reprocessor shutdowns.

So … if you are using more of the expensive filters than you would like, how do you reduce filter usage and cost during times of increased dirt load?  In a phrase – “spread the load”.

The following is adapted from a section of the Filter Supply “How-To Guide – Water Filter Systems for Endoscope Reprocessing”.  (To get a copy of the complete guide, contact me at allen@filtersupply.com and I will send you a copy)  The section in the guide is about how to design a system when the normal dirt load in the water supply is high.  But the principles are also valid for “temporary” situations like construction.

There are 2 ways to make filter systems last longer.  They are, a) increase the amount of media to increase the amount of dirt it can hold, or b) reduce the amount of dirt that the final filter has to hold.

Increasing the Amount of Filter Media

The most common way to increase the amount of filter media is to install larger filter elements.  That usually means installing a 20-inch filter in the place of a 10-inch filter that is plugging too quickly.  Doubling the filter media available usually increases filter life by more than 2x [discussed more in the How-To guide].

If installing a 20-inch element doesn’t work, or your system already has 20-inch filters, your filter supplier can provide 30-inch elements or, in extreme cases, multiple filters in a single housing (usually a stainless steel housing).  This can be expensive and may be considered a capital investment.  Filter Supply can help you evaluate filter configuration options.

Reducing the Amount of Contamination a Filter Must Hold

Reducing the amount of contamination that any given filter has to remove is slightly more complex,.  The first step is to understand what is in your water and plugging the filters.  A particle size analysis on a sample of your incoming water should be conducted using a particle size analyzer.  Filter Supply can have a particle size analysis performed using a standard analyzer.  The result will show how many particles of each size are in the water from your source.  A “typical” analysis of water from a municipality having a river as its source is represented in the figure below.

Water Sample Particle Size Analysis Graph

Particle Size Distribution in Water Sample

In this case, a “typical” filter sequence of 5 micron prefilter and 0.2 micron final filter will see the bulk of the dirt load pass through the 5 micron filter and overwhelm the (expensive) 0.22 micron final filter.  To remove more particles before the final filter, changing the micron pore size rating of the prefilter to 1 micron or below may help.  The new filter will capture more particles in the prefilter, and improve final filter life.  Using a filter with a smaller micron rating may increase the cost of the prefiltration step, but the reduced usage of expensive final filters will almost always reduce total costs.

Each facility, feed water and filter system design is different, and the nature of the particles can significantly change the way that the filters are used.  Call Filter Supply or e-mail me at allen@filtersupply.com to get suggestions on how your facility might be able to improve filter life and reduce your filter cost.

Welcome to Filter Supply – A New Source for Replacement Medical Filters

Welcome to Filter Supply and our blog!  Filter Supply provides replacement medical filters at competitive prices.  But, more importantly, we offer people in the healthcare field our expertise in solving filtration problems.  We have decades of experience in filtration for healthcare facilities, pharmaceutical manufacturing, and other filtration processes.  We’ve solved a wide variety of issues from filters plugging too quickly to systems that don’t remove what they are supposed to.  We offer you our expertise to solve your tough filtration challenges.

Our first goal is patient safety.  Our high performing filters that remove bacteria, sediment, sand and even chlorine help assure that safety.  But we also strive to improve your bottom line by optimizing filter system designs.  We want to make your filters perform at or above required levels AND reduce your overall filter costs.  Making your filter system easier to manage might give you more time to do what you want, serve your patients.

This blog is a unique opportunity to access decades of filtration experience in medical and other critical filtration applications with the click of a button.  We ask that you share your filtration frustrations, and maybe some successes.  The more people join the discussion, the more people we hope we can help.  With help from this community, we can contribute to better outcomes from filtration processes in endoscope reprocessing, dialysis water system management and sterile processing water management.

To get discussions started, we will post information here in various subject areas.  A few of those are “Filter System Design and Operation”, “Complying with CDC, FDA, AAMI and Others”, and “Filtration Best Practices”.  Of course, some company news and subjects that are suggested by other participants will also be posted here.

Check back soon to see our next post on solving a common filtration challenge if you have construction in or near your hospital or other medical facility.  We look forward to lively and helpful discussions!