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Avoiding medical packaging material failures
Overview
As the last line of defense between bacteria and the medical device, sterile barrier packaging plays an important role in patient safety. As such, failures in medical packaging materials present serious issues for the Medical Device Manufacturer (MDM); measures can and should be taken to avoid them. If a failure is observed in the field, the result could be as costly as a product recall.
This paper will examine how device design, material choice, package design, sealing process, and package distribution and handling can impact the potential for package material failures, as well as the measures that can be taken to avoid them.
For purposes of this paper, 'materials' refer to film or lidstock, and 'components' refer to pre-made pouches, die cut lids, or thermoformed trays.
Device design
Because many medical device components are formed by an injection molding process, it is important to ensure that mold flash is minimized. A part exhibiting excessive flash can easily puncture the film of a pouch or TFFS package, causing a breach in sterility. When designing new device components, sharp edges should be avoided by making radii as large as possible. This will create ease and reduce future expense when packaging materials are chosen and validated. If a device is designed with minimal sharp components, lower-cost films can be used, thus lowering costs for the MDM on an annualized basis.
Materials/components
Choosing the right supplier is just as important as choosing the right packaging material. Ensure the supplier has a strong quality system in place. Material defects such as gels, thin spots, and seal failures often originate in the supplier's manufacturing process. Make certain the supplier has robust process validations in place to support the production of defect-free materials. Pay attention to how the supplier handles materials internally and how they are shipped to the MDM. Is adequate protection provided during transit to prevent damaged rolls of film (e.g., the use of core protectors, protective bags, corrugated shipper)? Are pre-made pouches packed in bags to protect against particulate, and in appropriate sized cartons to prevent the folding or bending that can result in delamination or flex cracking?
Package design
When designing a sterile barrier package for a medical device, take into account the size, shape, and weight of the device. If the device is exerting pressure on the seal of a pouch, seal creep can occur during EtO sterilization. If the device size is pushing the limits of the TFFS cavity, the tubing or other components of the device can end up in the seal as the machine is indexed. Both scenarios can result in a breach of the sterile barrier and often are not detected until the end user attempts to use the device.
Be sure to design pouches, trays, and TFFS packages with sufficient seal widths. Narrow seal widths can be less forgiving in a rigorous sterilization and distribution environment. When choosing films and lidding for the unit package, consider materials that are acceptable for the application. For instance, sharp bulky products may require nylon film. Leverage your packaging suppliers' expertise in selecting materials for your application.
Sealing process
Defects in the seal can often be traced back to problems in the sealing process. When troubleshooting a seal defect, it is important to consider the state of the sealing equipment. Are gauges calibrated? Are preventative maintenance procedures in place and followed to ensure seal gaskets and tooling are in good working order? Are the key parameters of temperature, pressure and dwell in control? Under-sealing, which produces weak or light seals and potential channels, is typically caused by having too little heat or dwell time when creating the seal. Over-sealing, which produces transparent-looking seals and/or tearing and delamination when peeling open the package, is typically caused by too much heat, pressure and dwell time. Care needs to be taken to ensure that minimum seal strength requirements can withstand sterilization and distribution environments.
Distribution and handling
Product distribution and handling environments are commonly overlooked, but are responsible for a large number of the medical packaging defects seen in the field. When reviewing package handling inside the MDM facility, it is important to consider how the unit package is transferred from the sealing operation to its final shipping carton. Belted conveyor systems and transfer chutes should not put the unit package in contact with sharp objects such as staples and bolt heads. Additionally, the conveying system should not expose the package to large free-fall drops that can create blunt force punctures in the sterile barrier. When human interaction is required to handle packages, operators should be trained to minimize the potential for damage that can be created by dragging packages across rough or abraded surfaces.
When reviewing package handling external to the MDM facility, it is important to consider how the master shipping cartons are distributed to the end user. The method of packing and shipping—by pallet load or individual case—will impact the level of shock and vibration the package will endure. Individually shipped cartons are more likely to see extremes in shock and vibration; this should be taken into account when designing the packaging system in order to avoid defects. Will the package be exposed to altitude via air shipment or truck shipment in mountainous regions? If so, package materials must be porous or incorporate high seal strength to avoid prematurely opened seals caused by pressure differentials. Will the product be exposed to high temperature and humidity? Seals must be able to withstand the heat they will be exposed to in the distribution cycle.
Conclusion
Sterile barrier packaging plays a critical role in patient safety by keeping bacteria from the medical device. By taking appropriate measures, MDMs and their suppliers can avoid medical packaging material failures.
About the author
Kevin Zacharias manages Oliver OnSite package engineering services and oversees project management of new product development.
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