Medical device susceptibility to shipping conditions also fluctuates widely. Typically, the medical device creators need to design the custom packaging. For example, an instrument with delicate sensors may require lots of impact-padding but very little humidity control, whereas a medical paper product is essentially impervious to impact but may be destroyed in the presence of humidity. The impact of damage runs the gamut—a one-dollar paper insert getting ruined may be no big deal, but a complex piece of medical equipment may require an expensive service visit to diagnose and fix, or may fail in a way that harms patients. The medical designer must consider and address the types and methods of damage that may be caused during shipping.
(Packaging is even more integral to the device when shipped sterile, but will not be discussed here.)
Whether a new or seasoned packaging designer for medical devices, this article will help to meet ASTM D4169, resulting in fewer failures in shipping and ensuring successful and safe delivery of a medical device.
1. Design for Shipping
The most successful packaging systems often work when a device has been designed with shipping considerations from the start. This means two things: first, consider how the device will be packaged. You may want to include anchoring or strapping points for shipping in crates, or load-bearing points for shipping in boxes in the design itself. Second, consider all shipping stresses during the beginning of the detailed design phase. For example, if your medical device is sensitive to temperature (especially freezing and boiling) but you haven’t considered the potential effects of shipping, that may be very difficult to account for later. Overall, ask yourself if the medical device may require design features or architectures to support effective shipping as early as possible.
2. How Many Walls Do You Need?
The more walls, the better—at least in the eyes of the standard. Certain tests under ASTM D4169, such as impact tests, are not required for any double walled packaging—this is a great way to reduce testing. A single box without double thick cardboard walls, or a box-in-box design (which allows you to keep the inner box undamaged) both work. Double thick walls can also help reduce the amount of padding you may need and the overall package size. However, double walls are also more expensive and may be unnecessary. It really comes down to the medical device—the more rugged the device, the less padding you need. More rugged designs may be perfectly fine without a double wall or box-in-box approach.
3. Correlate Regulatory and Verification Testing to Packaging
There may be significant overlap between device testing and the ASTM D4169 standard, which is handy to save time and money on testing. For example, IEC 60601-1 may require temperature and/or humidity cycling, which is also something the ASTM standard suggests. Though ranges can vary for shipping and normal use, it’s important to consider both when setting those specifications. The more overlap that’s possible, the more efficient the testing.
Overlap can also occur in areas like rough handling testing—if you’re following IEC 60601 guidelines on rough handling and have maximum force and impact parameters, you may want to use those as requirements for a packaged device to ensure the impact translated to the device doesn’t exceed the impacts tested in 60601. In other words, when running normal-condition drop tests on a device, you can design packaging to ensure those forces aren’t exceeded under shipping conditions (as detailed in the ASTM standard) and expect the device to survive.
Take the time to read the standard and the individual referenced test methods. You might find many tests can be omitted from your scope based on packaging size, weight, form factor, and choice of materials. Compare that to 60601 and you’ll get a better picture of possible overlap.
4. Carts Are a Little Special
Carts are larger and therefore have different risks: tilting being the big one. As crates can be tilted quite a bit when being moved from place to place, the standard recommends they be tilt-ready for up to 22 degrees. If not, the effects of overbalancing can be tested. If no damage occurs, the packaging may be acceptable, though it’s a good idea to flag the carton as potentially dangerous to handlers.
Wheels are another key consideration with carts. Wheels or casters are not typically designed for sudden downward force. Depending on the weight of the cart, the wheels may need to be protected. This can be accomplished by separating the wheels off the skid (if there is a more suitable point on the chassis to transfer force), adding impact dampening or vibration isolation elements to the skid, or using angled blocks to spread some force away from the casters. Note that when tying down the cart, you’re already applying some preload that must be considered.
5. Analyze Vibration Pathways
The ASTM standard includes a comprehensive vibration scheme for each mode of transportation. Consider which modes apply, then connect the dots between various components and the bottom of the skid. Consider that screws may back out, solder joints may shatter, rigid components may hit harmonics, and other sensitive components may be damaged. If the pathway from the skid to any component of concern is overly rigid (i.e., will transfer lots of energy), ensure the design is very strong or consider adding more isolation between the device and the transport vehicle.
6. Stacking Is AlwaysWorst Case
You may have a nice, lightweight device in a padded box with foam, and be fairly confident the device is protected from dropping, vibrations, and other factors. But you may not have thought about the same truck shipping your medical equipment may also be shipping a dozen 40-pound boxes of hamburger patties. If the driver decides to stack these on top of your device all the way to the ceiling of the container, that’s a huge load. ASTM D4169 gives a simple equation to calculate the worst-case scenario for this based on the dimensions of your package (i.e., how much can be stacked on top) and how dense someone else’s packages can be. Long story short, it’s a lot (often hundreds of pounds), so be sure to design for the burden of stacking.
Bonus: Tips Not Directly Related to the ASTM Standard
That’s about it for the standard, but following are a few other factors key for overall success:
- Consider recycling: Can the box and padding can be recycled or disposed of properly?
- Consider usability: Is the package easy and quick to use by the shippers and the receivers, with available tools, and can they can lift it?
- Local regulations: Does the area you’re shipping to have laws about material type and treatment?
- Returns and storage: Will the end-user keep the package or toss it out immediately, and if so, how do they return it?
Shipping is often one of the harshest environments the device will ever be subjected to, so designing for shipping and packaging early is essential. It’s also important to test effectively without over-testing unnecessarily. Standards like ASTM D4169 are helpful to put numbers to this, though the reality is what actually happens between the factory and the user is difficult to predict. The goal is always to maintain the safety and efficacy of the medical device throughout its lifetime. At the end of the day, it’s up to the medical device designer to ensure the risks are understood and mitigated as much as possible through effective packaging design.
Nigel Syrotuck is a mechanical engineer team lead at StarFish Medical. His background includes a diverse project development portfolio including sustainable power solutions, assisted living devices, and nano-satellite design.