Before COVID-19 put most airline travel on hold, I traveled quite a bit for my job. I enjoy visiting our customers, attending trade shows and industry conferences, and giving educational seminars in person. When I sit on a commercial aircraft, climbing to altitude and experiencing the physical aspects of pressure changes, I sometimes think about the impact that pressure differentials can have on sterile barrier systems (SBS).
The SBS can experience shifts in pressure during transportation via air and road & rail systems that traverse the globe at higher altitudes. Gas sterilization modes include vacuum cycles that expose the SBS to fairly extreme changes in pressure. Even shifts in temperatures will cause the air inside a package to expand and contract and create pressure changes.
In my career, I’ve seen SBS’s fail as a result of exposure to pressure changes associated with transportation at high altitude. This typically relates to packages that are not breathable or packages that have very limited breathability. A classic example I’ve seen a few times involves a medical device that is gamma irradiation sterilized and the legacy packaging that was chosen included a breathable substrate such as DuPont Tyvek. As a value improvement project, lower cost non-breathable substates are chosen for the SBS. Depending on the amount of head space in the package, the risk in this scenario can vary. A large amount of headspace equates to higher risk as there is more air available to create pressure and ultimately stress on the seals of the SBS. It is very important to include altitude testing as part of your approach with any non-breathable SBS. The pressure differentials can cause seal failure and thus compromise sterility. Watch these examples of a tray/lid or pouch that failed altitude testing. As the non-breathable SBS’s expand due to the change in pressure, there needs to be enough available space inside cartons and shippers. Otherwise they can expand to the point of causing cartons and shippers to tear or flaps to open.
If you’re struggling with or concerned about seal failures caused by altitude and pressure changes in general, you’re not alone. In fact, in a recent webinar, when we polled our audience, a majority of respondents said “vacuum” was the most challenging parameter in EO sterilization. Partner with your packaging supplier to learn how others have overcome these types of risks.
Safe travels! (post Covid)
Kevin
