Infection Control Today - 02/2004: Making the Best Case for Medical Equipment

Making the Best Case for Medical Equipment

By Ed Sullivan

When it comes to cases, trays and other enclosures for medical devices and instruments, off-the-shelf products and those made from plastics may not be the best solution. Before ordering or designing your next medical case or system, it could pay major dividends to consider the questions that many experts ask themselves.

Providing unfailing protection for medical devices and equipment a function often performed by cases and other enclosures is not to be taken for granted. While there is no shortage of medical case fabricators and other suppliers, selecting the right case whether carrying case, instrument housing, sterilization container or other equipment enclosure can be vital to the successful care of patients.

Because medical cases are often subjected to the stresses of harsh environments, such as chemical or autoclave sterilization, rugged use and atmospheric pressure, or carry devices that will benefit from special design features, it behooves medical equipment suppliers and practitioners to be highly selective when specifying case-application requirements.

Many people in the medical community feel that cases, trays and other equipment enclosures are more or less standard items, says Don Saak, business development director for Zero Manufacturing. The fact is that custom cases are not only practical, but are often critical for the protection, performance and efficient use of the equipment they contain.

What criteria should manufacturers and users of medical equipment consider in the specification of cases for their products? While that depends on specific applications and the sensitivity of case contents, Saak identifies five guidelines for specifying medical cases:

1. Choose appropriate case materials

The materials from which cases are fabricated have a direct bearing on protection of the case contents and durability of the case itself. Essentially, the choice of case materials is between metal and plastic. Metal cases are usually constructed of aluminum or aluminum alloys, and are typically either deep-drawn or welded. Plastics, ranging from standard compositions to space-age composites, are commonly vacuum formed, thermoformed, rotationally molded, blow molded or injection molded.

Metal cases are well known for their protective attributes, as they offer high resistance to impact, can be sealed tightly, can withstand extreme temperatures and can be made fireproof.

If an aluminum case is subjected to high impact, the shock will be absorbed by the entire case, explains Saak. Weve received letters from customers that told how their metal cases withstood the impact of auto accidents and buildings collapsing. These cases may be dented, but they will take a beating or go through a fire and still protect the contents.

Plastic cases can also offer a good seal and, depending on composition, substantial resistance to impact. When plastic cases give, they tend to crush or crack. While metal cases are not crush-proof or crack-proof, they will usually sustain a wider range of extreme heat or cold. Aluminum becomes harder in extreme cold, whereas plastic becomes brittle. Aluminum dissipates heat, whereas plastics can deform or melt when subjected to extreme heat, exposing contents to shock and perhaps functional damage.

Sometimes overlooked, case materials can affect the hygiene of contents that undergo sterilization. The materials that make up the plastic case could out-gas during some chemical sterilization processes, Saak explains. While this is not a common problem, it is one that could cause contamination of items such as surgical instruments or implants that are being sterilized. Also, many plastics are weakened during autoclave sterilization, and may have a much shorter lifespan than their metal counterparts. One-piece deep-drawn metal cases also offer the advantage of having no seams or welds, so there are fewer hiding places for bacteria and other foreign matter.

In some cases, applications require shielding from EMI/RF (electromagnetic interference/radio frequency interference), which will affect choice of materials. We have a lot of experience in this with aerospace and military cases, Saak says. We know that aluminum provides a natural EMI/RFI shield, which will prevent stray emissions from affecting instruments inside or even outside one of our cases. Plastic must be coated or impregnated with shielding materials.

Case inserts, such as plastic, metal and foam that are typically used to hold and protect contents, should also be considered. The abilities to absorb impact, withstand extreme temperatures and facilitate access will be important to many applications. Quality suppliers should be able to offer a selection and assist with evaluating choices.

2. Consider short-term and future costs

While the choice of case materials has a definite impact on cost, the true economics depend primarily on the manufacturing process involved. To a certain extent, costs will depend on economies of scale. However, total cost is the inevitable concern, and it is here that some customers are in for a surprise.

Aluminum cases fabricated from the deep-drawing process can be far more affordable than many people realize. Deep drawing is a process used to form metal without seams, rivets or welds. Essentially, a sheet of aluminum, pre-cut to the correct size, is formed around a die in the shape of the case required.

Using the deep-draw process, modifications can easily be made according to customer specifications without creating new tooling. So, if the thickness or alloy of the metal needs to be changed to accommodate changes to the case contents, those alterations can be made without starting from scratch, says Saak. Metal cases fabricated using the deep-draw process provide an economy of scale, because once a die has been set up production goes very quickly.

Conversely, metal cases that undergo the welding process do not enjoy economies of scale. These must be fabricated one at a time, regardless of quantity. Also, welded cases must undergo grinding of the weld seams to provide a smooth appearance. This process can create voids in the welds that could permit the inward or outward penetration of liquid or gas. While deep-drawn aluminum cases can be anodized in the color of choice, welded metal cases must be painted after the grinding operation if the welds are to be disguised.

Various types of plastic-formed cases all require costly tooling, but none so expensive as injection molding, which can be prohibitive to customers exploring a non-standard size. Because injection molding is a high-volume process, many case manufacturers offer thermoform- (with relatively inexpensive mold costs, compared to injection molds), rotational- or blow-molded cases that are tailored to a customers specifications. However, if these specifications change, new tooling or modifications to the exiting tooling will be required. Injection- and blow-molding processes permit latches and hinges to be molded into the case, reducing labor costs because only the hinge pins and seals need be installed. But if a latch breaks, the case cannot be repaired.

3. Look for a turnkey solution

Relative to cost, material selection, quality and many other considerations, it is often wise to choose a supplier that offers turnkey products.

There are many quasi-manufacturers who, because of their size or limited capacity, job-out various case making operations, Saak explains. They might make the basic case at their shop, but job-out other tasks such as painting, attaching hardware, or producing foam inserts. There are responsibility and quality issues with this approach, and it creates extra work that will likely affect costs.

Saak explains that when shops outsource secondary operations they give up a certain amount of quality control while creating additional paperwork. Multiple vendors must be selected; multiple purchase orders issued and invoices paid, and subsequent inspections must be made. If cases are damaged while undergoing operations outside the manufacturers plant, the acceptable quantity delivered will be affected.

This is a difficult position to be in, Saak says. With a turnkey supplier you can be sure that when you order 24 cases youll get 24. But if the cases are sent out for secondary work, you really cant be sure theyll all come back and pass inspection

There are other important reasons for single-sourcing a medical case supplier. Flexibility and experience can be crucial factors. There are many types of medical cases needed, from rack-mounted storage systems to trays and small enclosures. A highly experienced and flexible supplier can partner with customers and give them the benefit of cross-pollinating application experience.

Ultimately, the ideal single-source supplier of cases will be able to provide multiple solutions in both metal and plastic cases. This not only provides the sophistication to offer a choice, but also ensures that the supplier will not be motivated by conflict of interest.

Compliance with industry standards may also be important in the choice of a supplier. For example, manufacturers who are members of the National Institute of Packaging Handling & Logistics Engineers (NIPHLE) or the Armed Forces Communications & Electronics Association (AFCEA) may apply the highest operational and quality standards including ethics, guidelines and equipment that adheres to very high military specifications to all their products. Suppliers who are ISO- (International Standards Organization) certified must comply with manufacturing, documentation and transactional procedures that are often beneficial to product quality as well as customers relationships.

4. Appearance actually matters

Appearance can be important in any industry, and the medical field is certainly no exception. Physicians, paramedics, hospitals and other organizations have different preferences when it comes to medical cases. Specific colors, logos, warnings and other body graphics may be required on the case exterior, and specific case handles, feet and other attachments may require aesthetic as well as functional consideration.

For those who specify drawn aluminum cases, the opportunities to create a stylish, custom look are many. For example, manufacturers of pharmaceuticals may have their sales team carry demo cases that have been anodized or painted in the companys colors. Their logo can be affixed with a label, silk-screened or embossed on the side to readily identify who the salesman represents. The seamless construction and high-tech look of these cases can make a powerful statement.

Typical applications for aluminum medical cases include optical and medical scopes, housings for instruments, defibrillators, aspirators, wound and IV care, blood analyzers, and surgical instrument cases.

Form and functionality can also be gracefully combined in plastic cases, which can be produced in special colors, with silk-screened or embossed graphics and a wide choice of handles and attaching hardware.

5. Weigh after-sale support needs

You may need a supplier who offers engineering support that continues after the initial sale, Saak advises. Medical instruments and other devices change over time, as do kits and systems that are transported or stored in cases. So it is often beneficial to have a supplier who can reconfigure or even re-engineer your case without having to go back to square one.

In some instances, customers may have problems due to product changes that affect case performance. If a customer is experiencing recurring performance problems with their medical case, its important that the supplier have troubleshooting capabilities and the test facilities necessary to correct the problem, Saak says. Its also important to have a relationship with a supplier who has the ability to meet changing FDA requirements and has the necessary awareness of changing materials and compliances that will keep you up to date with industry standards.

Other important after-sale supports include case repair, hardware replacement, redesign or replacement of foam and other case inserts.

Ed Sullivan is a technical writer based in Hermosa Beach, Calif.

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