Back in the 1980s and 1990s, several studies were conducted testing the efficacy of using pressure cookers to sterilize medical equipment, syringes, and bottles when autoclaves were not available, primarily as a way for residents of impoverished rural communities to sterilize their medical supplies.[i] [ii] [iii] [iv] Pressure cookers are relatively inexpensive and easy to use, and training several community members in their operation didn’t take much time. They were an ideal solution, and they still work today. And they possess two distinct advantages over instant pots: they can be used even if the electricity is out and they can accommodate larger items.
In 2023, instant pots, or Instapots as they are often referred to, are a common kitchen appliance. They’re incredibly easy to use, and as a 2018 study demonstrated, all appliances tested eliminated all common pathogens. However, only the Instant Pot was able to eliminate Geobacillus stearothermophilus spores, which survive higher temperatures than most other medically relevant microbes, due to its higher operating temperature, which reaches 115-118°C. (The researchers also noted that the other brands they tested were less expensive in the summer than around the winter holidays.[v])
Before using substitute autoclave, the items to be sterilized must be cleaned and disinfected, and then they must be wrapped properly. (Links to pertinent articles are posted below.) Otherwise, when you open the sterilization device, items will no longer be sterile. Proper wrapping is accomplished with official sterilization pouches. They are easy to use and nice to have because then everyone in your family/group will be amazed at the extent to which you prepped. (We all like to have that happen once in a while, right?) But you can totally make do with clean towels and aluminum foil. (And everyone in the group will be amazed at your ability to improvise.)
Now on to using a pressure cooker/canner or instant pot to sterilize medical items.
Pressure canner: You’ll have to follow the direction that came with your particular cooker. They all vary in the amount of water that must be placed in the pot as well as in the times required for venting before you beginning pressurizing the cooker. You’ll also need a basket for suspending the items to be sterilized above the water. The pressure cooker must be held at 15 PSI and 121°C for at least 15 minutes if using sterilization pouches or autoclave paper.[vi] If you’re improvising with towels and aluminum foil, the 15 PSI and 121°C must be maintained for 40 minutes.
Instant pot: Add 0.5 liter of water to the pot and place instruments in a basket suspended above the water. The 2018 study cited above demonstrated that all of the instant pot devices tested inactivated microbes and sterilized medical instruments at 15 PSI for 30 minutes if using sterilization pouches. Improvising with towels and aluminum foil was not tested in this study.
Sterilization pouches already have indicator strips on them to show that the correct temperature was reached. If improvising with towels and foil, sterilization indicator strips/tape though not absolutely essential if your equipment is working properly, will provide a measure of confidence that correct temperatures for sterilization were attained. Unfortunately, there is no foolproof way to make sure that the correct temperature was maintained for the requisite amount of time, so the pressure canner will have to be monitored for the duration of sterilization.
[i] Using a pressure cooker as an autoclave, EPI Newsletter, December 1984, Vol 6 No 6, https://pubmed.ncbi.nlm.nih.gov/12267939/ (accessed 14 June 2023).
[ii] V Balraj, et al., Sterilization of syringes and needles for immunization programmes using a pressure cooker, Journal of Tropical Medicine and Hygiene, April 1990, Vol 93 No 2, https://pubmed.ncbi.nlm.nih.gov/2325192/ (accessed 14 June 2023).
[iii] MH Monson, The pressure cooker as a steam sterilizer, Tropical Doctor, October 1988, Vol 18 No 4, https://pubmed.ncbi.nlm.nih.gov/3194946/ (accessed 14 June 2023).
[iv] R Kamiyama, [A trial with using a pressure cooker for sterilization], Kango, October 1977, Vol 29 No 10, https://pubmed.ncbi.nlm.nih.gov/243643/ (accessed 14 June 2023).
[v] VA Swenson, et al., Assessment and verification of commercially available pressure cookers for laboratory sterilization, PLoS One, 11 December 2018, Vol 13 No 12, https://pubmed.ncbi.nlm.nih.gov/30533061/ (accessed 14 June 2023).
[vi] RJ Baez, Use of pressure cookers for sterilization of clinical instruments, https://cdn.ymaws.com/www.adint.org/resource/collection/F51AF970-F89B-4FCF-879B-C20844B31E90/Use_of_pressure_cookers_for_.pdf (accessed 14 June 2023).
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