Bernard & EchoAs many of you know, I have refrained from posting on SH to avoid any potential conflict with my professional asset management side. But given the ongoing debate between Bernard and Echo, I would like to chime in on a few things that were brought up.
Turnaround time: I think we can all agree that the best case turnaround time for EtO is next day reuse. We can argue whether VP4 can do 2 or 3 reuse a day, it is nonetheless superior to EtO. To be fair, ERCP is only done 500-600k/yr in US, so not many facilities will need to turn around their ERCP the same day. But this would be a huge VP4 advantage if terminal sterilization is spread to colonoscopes (15mm+ per year). On the topic of biological indicator, the 18hr VP4 BI is a true test that includes incubation to grow cultures in worst case scenarios, this is not comparable to the 1hr quick BIs and I don't think anyone can do this faster if they want to go down the incubation route.
Damage to Equipment: it is true that EtO by itself is much more equipment friendly than H2O2. New EtO systems by Andersen for example highlight its 100-300 cycle before a need for major rebuild, vs. the 50 for VP4. We must remember that these numbers are ERCP scopes running through sterilization cycles and do not include actual use (doctor manipulation, transports, etc.) However, there are a couple of major wrinkles in real life use. First, most hospitals use EtO in conjunction with HLD to process their ERCPs, whereas VP4 has the FDA claim to terminally sterilize by itself (i.e.: don't need HLD). Second, these scopes are used by doctors in patients in real life. So if we talk to Altru or U of Colorado, they will tell you that these ERCP scopes need repair in 20-25 uses (using HLD) due to wear-n-tear by docs. If we look at the real-life data submitted by TSO3 for its duodenoscope application, which obviously was accepted by the FDA, it highlights EtO + HLD requires inspection after 12 uses for possible repairs, whereas VP4+HLD is around 20x. HLD by itself is 112x. But like I said before, if these scopes need to be repaired due to doc use every 20-25x, so compatibility beyond that number is not beneficial. Because these scopes needs to be repaired every 20-25x anyway, almost all hospitals enroll in some type of maintenance contracts with the like of Olympus, Pentax, etc. to repair their scopes when needed, and using a 100+ cycle compatible sterilization modality is not going to change that need.
Prove EtO is more Dangerous? Given Bernard's laser focus on "good" research, I am surprised he even asked this question. Even the NIOSH report that he keeps citing clearly said that IARC (International Agency for Research on Cancer) classified EtO as a definite cancer causing agent. It is true that there is much less data on H2O2, but if we look at IARC's evaluation on animal data (where both agents have enough studies done to evaluate), EtO is listed as having sufficient evidence for cancer causing in animals, whereas H2O2 is listed as having limited evidence. Finally, Bernard keep mentioning this NIOSH study did not find an elevated risk for EtO workers. I am glad this is the case for the workers involved, but we must remember that these EtO workers are required to dress like someone in a SARS/outbreak (e.g.: with full face respirators). Just look at the Australian guideline before they ban EtO (https://www.safeworkaustralia.gov.au/system/files/documents/1702/nationalcodeofpractice_safeuseofethyleneoxideinsterilisationfumigationprocesses_nohsc2008-1992_pdf.pdf)
Finally, here is the kicker that makes this debate pointless: EtO cannot terminally sterilized complex scopes in real life, as per studies done by Alfa and others. Just look at the CDC's assessment (https://www.cdc.gov/infectioncontrol/guidelines/disinfection/sterilization/ethylene-oxide.html)
"Like all sterilization processes, the effectiveness of ETO sterilization can be altered by lumen length, lumen diameter, inorganic salts, and organic materials.469, 721, 722, 855, 856, 879 For example, although ETO is not used commonly for reprocessing endoscopes,28 several studies have shown failure of ETO in inactivating contaminating spores in endoscope channels 855or lumen test units 469, 721, 879 and residual ETO levels averaging 66.2 ppm even after the standard degassing time.456"
And what was the NIOSH study's average worker exposure again? 4.3ppm over 8hrs, vs. 66.2ppm in this CDC document...OUCH. Also so much for Bernard's spore comments, as VP4 has been shown and FDA approved to terminally sterilize complex scopes, spores or not!!!