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How Clean is ‘Clean’?

Xiang Zhang at CERAM presents the debate for and against the reuse of single-use medical devices, and discusses the sterilisation requirements involved

For the past several decades the practice of reprocessing and reusing single-use medical devices (SUDs) has increased, as well as the debate surrounding them. The key question which needs to be answered is whether SUDs are still safe and effective for their intended use after reprocessing, something which is, of course, a general requirement for any medical device on the market. This article will discuss the debatable issues of this subject in terms of safety, regulation, economics and environment.

A BRIEF HISTORY

From an historic point of view, and certainly before 1970, there were no such issues regarding reprocessing and reusing single-use medical devices. Indeed, in hospitals they were considered to be reusable whenever and wherever applicable, as they were made from glass, rubber or metal. Early reprocessing of reusable medical products, such as surgical instruments, often involved little more than hand wiping, dipping and soaking in disinfection solutions, with some reusable medical devices undergoing sterilisation if applicable. There were no ‘standards’ in general on medical device reprocessing and any procedures that existed were very simple. The safety and efficacy of reprocessed medical devices were not issues that were ever dealt with because hospitals considered reprocessed devices to be as good as new ones. This was purely a matter of economics – prior to 1970, there were no single-use medical devices on the market that had been manufactured on an industrial scale and so were cheap enough to be disposable.

In the late 1970s, SUDs were born and two factors probably played a key role in this. The first was the development of new plastics, including PVC, polyethylene, polypropylene, polyester, nylon, and so on. Further developments in processing technology and machinery made it possible for plastics to be made into any form and to be manufactured on an industrial scale large enough and cheap enough to allow the resulting range of products to be disposable. The second factor was probably due to the introduction of ethylene oxide sterilisation technology.

So these two factors, plus market demand from hospitals, brought about the start of the manufacture of disposable medical devices. With more and more disposable medical devices being developed, hospitals began to see products labelled ‘single-use only’ that were similar to devices that had been formerly distributed or continued to be distributed as ‘reusable’. For economic reasons, hospitals soon began to reprocess the SUDs themselves and later contracted this job out to third parties. The practice of reprocessing and reusing SUDs obviously had an effect on the business of original medical device manufacturers with the result that they raised the question about regulations on reprocessing and reusing of medical devices labelled ‘single-use only’. There were, at the time, no such regulations specified to the reprocessing and reuse of SUDs anywhere in the world, including the FDA in the US.

DEBATES REGARDING REPROCESSING & REUSE

There are many concerns about the reprocessing and reuse of single-use medical devices, including issues around safety, economics, environments and regulations.

The Argument For
We live in an increasingly ‘disposable’ society and healthcare has followed this trend for many years. It is estimated that hospitals generate approximately 6,600 tonnes of solid waste every day. Figure 1 is a typical example of medical waste dumped into an open field. This figure of 6,600 tonnes is increasing year after year, largely due to the higher use of disposable products. Taking the US as an example, if just one or two per cent of all the disposable medical devices used in the US today were reprocessed, the healthcare industry would save one billion dollars every year.

The Argument Against
The reasons against reprocessing and reusing single-use medical devices are also robust. One famous photo, in Figure 2, provided evidence to show that EP catheters contain reddish brown contamination after reprocessing, which is, of course, potentially hazardous. SUDs were developed at the request of the medical sector to minimise the risk of infection. The re-use of a medical device labelled ‘single-use only’ is against the instructions of the original manufacturer and does not fall under any legislation. In theory, the manufacturer is the only party who takes full responsibility for the quality and the function of the medical device in its intended use. Ethically, patients should be told if a SUD is used during their treatment.

IS IT SAFE TO REUSE SUDs?

There are many reports concerning the safety of reusing SUDs. The most thorough investigation was carried out by the FDA and was reported in 2006. Based on all the available data and on the investigation itself, it concluded that SUDs can be reprocessed with a reasonable assurance of safety and effectiveness; indeed the FDA believes that reprocessed SUDs that meet its regulatory requirements are as safe and effective as a new device. The law and regulations in place are designed to protect public health by assuring that the practice of reprocessing and reusing SUDs is based on sound science. The FDA continues to monitor the performance of these devices and to assess and refine the ability to regulate these devices appropriately. In fact, since 2000, it has conducted inspections of reprocessing companies once every two years, a rate considerably higher than the one inspection in four years for original medical device manufacturers. However, there still may be some cases where the reuse of SUMs is not safe, though, it is unnecessary to list all evidence of this to date. Indeed, it is clear that the FDA’s investigation is the most comprehensive and complete one seen so far. The question is whether all medical devices labelled ‘single-use only’ can be reprocessed and reused? The answer is no.

COMPLIANCE TO REGULATIONS RELEVANT TO REPROCESSING SUDs

As for any medical device manufacturer, a reprocessor (hospital or third party) of an SUD is required to ensure compliance to quality system regulations (QSR), at least to national level. For those companies who have little or no experience in compliance to worldwide regulations of medical devices, the reference article A Primer on Quality System Regulation, which is being prepared for publication, can help to start the process. The basic requirement for reprocessing of a SUD is design control, and a flowchart is illustrated in Figure 3. It does not cover all of the elements of design control but is sufficient to explain the steps that are critical for QSR compliance.

Design control is a systematic process with a range of activities, including the following key elements:

• Design and development planning
• Input
• Output
• Review
• Verification
• Validation
• Transfer
• Design changes

In general, design control of SUD reprocessing is about planning, design execution, testing against specifications (inputs) and requirements (SUD function needs), and uncovering and fixing problems during the process (risk reduction). It is important that a company gets used to planning and organising team action and documentation for the activities listed above. The goal is to make reprocessed SUDs as safe and effective as new ones.
 
There may be other special regulation requirements applied to reprocessing SUDs, which may vary from country to country. Design control should be good enough at the start to ensure that these requirements are met. The latest EU regulations (2007/47/EC) also cover SUDs, and all reprocessors of SUDs should comply with the regulations set by each country.

EVALUATING THE CLEANLINESS OF REPROCESSED SUDs

To date, arguments against reprocessing and reusing SUDs are based on evidence that shows ‘dirt’ remaining on an area after reprocessing. This is an issue of cleanliness, one area that has not been (or may be difficult to be) clarified by all regulations seen to date. The problem is often that the ‘dirt’ is too small to be seen by the eye without assistance of special instruments and knowledge of surface science. Most reprocessors (hospitals or companies) often lack the basic resources (experts and facilities) to evaluate cleanliness. To make the reprocessed SUDs as safe, effective and ‘clean’ as new ones, it is advisable for all SUD reprocessors not only to follow the design control but also to add cleanliness as a requirement and document this in the list of activities. This, plus sterilisation, which is required for most medical devices, will make reprocessing and reusing SUDs more acceptable.

Here it is also worth noticing the difference between sterilisation and cleaning. The misunderstanding is that most reprocessors of SUDs think sterilisation is all they need to do, wherever applicable. Compliance to the regulatory requirement of sterilisation is simple because there are well documented standards to follow. However, it does not mean that the SUD is ‘cleaned’ through this process. Cleaning is the removal of foreign material, an essential prerequisite, as organic material such as dried mucus, tears, skin or make-up may harbour infective organisms in dangerous concentrations and prevent adequate disinfection or sterilisation. It is not a question of lower or higher extent but rather compliance to certain regulations and, more importantly, the device must be safe for the intended use as claimed by the manufacturers. The difficulty is determining cleanliness – how clean is ‘clean’?

Good methods for surface analysis include x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectrometry (Tof-SIMS). Figure 4 is an example of how ToF-SIMS works. The image shows a surgical knife after cleaning. It appears that part of the knife has been ‘contaminated’ because there are foreign materials (protein mapping in red in the figure) left on the knife. This is actually not correct because all the protein materials on the handle of the knife are caused by holding the knife. What is left are the materials which have been transferred from the hand to the handle of the knife. In fact, the effective area of the knife for surgical application is clean. This example does show the powerfulness of surface science technology such as ToF-SIMS. It can see ‘dirt’ that is impossible to see with the eye. ToF-SIMS is one of the surface science instruments that can analyse top level surface materials to a depth between three and five nanometres.

CONCLUSION

The practice of reprocessing devices that are intended for single-use began in hospitals in the late 1970s. Since that time, the practice of reprocessing and reusing SUDs has become widespread. The debate around reprocessing and reusing SUDs has been around for a while and will continue to be for the sake of safety, regulatory, economics and environmental reasons, and also because of the benefits to interested parties. Like all other medical devices, existing quality system regulations (QSRs) are applicable to SUDs in a way that is applicable and practical. The methodology in design control of QSRs should be essential for all reprocessors of SUDs to follow. It is also recommended that cleanliness requirements and specifications are included in the planning of design control, as this matter has caused the most concerns regarding reprocessing and reusing SUDs to date. The key is to safeguard public health to make sure that reprocessed SUDs are safe and effective for intended use and comply with national and/or worldwide medical device regulations.


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Xiang Zhang is Principal Consultant, Medical Devices at CERAM, an independent global expert in materials testing, analysis and consultancy. Xiang’s PhD and postdoctoral research covered micro-mechanics and micro-fracture mechanics of toughening plastics. After spending a further four years on polymer research for industrial applications, Xiang was awarded an industrial fellowship at the University of Cambridge in 1995. At CERAM, Xiang works with clients throughout the healthcare industry, supporting their R&D and manufacturing programmes and helping them to solve problems with materials, products and processes.

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