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Designing In Green

A medical product designed for reuse can eliminate the need to stock disposables and reduce the amount of medical waste. A medical product designed for reuse can also require space, manpower, and time for the process of cleaning and sterilization, including the safe storage of the item between medical procedures. So, which is greener? The reusable item that must be washed, sterilized, packaged, and stored, or the single-use item that must be discarded after each use?

For a well-designed medical product to be successful, the ‘sterilization or single-use?’ decision must be made early in the design process. If the device is small and simple and can be manufactured inexpensively, single-use design may make sense. Sometimes, a disposable is easier to use, cleaner, and has a smaller carbon footprint.

But if the product is large, complex, costly, or requires a high material strength, a design for a reusable product may be the only option.

In any case, the product development process must begin with consideration of the entire life cycle of the device within the system. Ethnographic research performed at the beginning of the design process can create important design inputs by answering important questions such as: What is a ‘day in the life’ of this instrument or piece of equipment? How is it used, and who interfaces with it? Physicians, nurses, technicians, and patients will experience the device in their own, often different ways.

A doctor in surgery may only care that an instrument, no matter how well designed, is sterile and ready for use. But in his own office, a doctor is also an entrepreneur running a business and may take an additional view: not only must the instrument be sterile and ready for use, it must be affordable - in terms of efficiency, space and time required for cleaning, sterilizing, and storage. He or she must also consider how the entire process affects the staff members in the office.

The sterilization of a medical device includes a time factor as well as the costs associated with the dedication of space, equipment, and staff. In a physician's office, the time required for cleaning and sterilization may even become a bottleneck for a practice. The process takes a specific amount of time for cleaning, drying, bagging, sterilizing as well as tracking reusable items. In answer, the practice has to increase its investment in sterilization equipment, maybe with additional dedication of office space and resources.

A whole system approach takes account of the way people will use the product, including the cleaning, sanitizing, and sterilizing after use. Over the last few years, sterilization requirements have become more stringent in response to concerns about hoof-and-mouth disease, Creutzfeldt-Jakob disease, HIV, hepatitis, and MRSA (methicillin-resistant Staphylococcus aureus) infections. There are many types of germicides, wipes, solvents, and cleaners that may affect device design and material selection. And if the product will be sold in markets outside the United States, the design has to take into considerations the general practices, standards, and regulations of those markets.

As a result of increasingly stringent regulations, including increased autoclaving temperatures and much more aggressive media used for cleaning, sanitizing, and disinfecting, newer and potentially more costly materials must be used or else a shorter product life has to be anticipated.

For example a stainless steel instrument that once had a useful life of about 10 years, now has an expected life of only about seven years because of the way the material (especially chromium) reacts to the more aggressive chemicals. Plastic products that were designed for autoclaving temperatures of 121° C might not survive temperatures of 134° C, as now required in the EU.

Another aspect of disposable vs. sterilized is what happens when an instrument gets packaged for sterile storage. For example, emergency room decisions about which instrument to use require proper instrument identification without breaking the sterile seal. To be able to identify, open the sterile package, and quickly deliver the instrument to the doctor, the instrument ID must be visible through the package or the package must be labeled appropriately. This is an example of how a design feature — in this case the I.D. number or graphic on an instrument — can be affected by an in-place process and how proper design of such an ID can reduce the necessary human interaction, in this case the labeling of the sterile package by hand.

Additionally, it is nearly as important for a medical instrument to be perceived as clean and sterile as it is for the device to actually be sterile. Even if the sterilization process is entirely satisfactory and safe, the surgeon and the rest of the surgical staff may be ill at ease with the surgical tool if discoloration gives the appearance of contamination. Also, textures, crevices, and contours can be perceived as potential harbors of bacterial growth.

A design that fulfills the requirements of the entire system, taking into account all users, processes, potential hazards, and demands, may be a design that combines the benefits of sterilization with disposability. Large devices, motors, moving parts, electromechanical systems, are often too costly for single use. Still, the process of design may discover natural separations. The design may place the mechanicals in one area that can be draped, shrouded, or bagged for sterility. Other elements of the system may be detachable for disposal or for sterilization between uses. And visual cues, such as those for directing fastening of the shrouding material without obstructing vital elements like displays and controls, may take into account how users interact with the equipment during use.

The matter of visibility of critical areas, something so seemingly simple, is a good example of the way that design must reflect a whole system analysis.

Good design for healthcare environments, whether the setting is a hospital, the physician's office, or the home, will be determined by the conditions and the environment in which it is used, from the interaction with the healthcare professionals and patients, the pace of the surgery center, and the systems for sterilization and protection between uses.

In the end, the strategic decision between a disposable and a reusable solution has a huge impact on the final direction of the development process.