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Medicine

Hospital Autoclaves May Allow Safe Reuse of N95 Masks (www.cbc.ca) 71

Posted by BeauHD from the ready-to-go dept.
Freshly Exhumed shares a report from CBC.ca: "[Autoclaving] is like a pressure cooker -- basically you enclose items into a chamber, you lock down the chamber, you heat it up and actually increase the pressure inside the chamber," Dr. Anand Kumar, a professor of medicine at the University of Manitoba, said. The machines heat up to about 121 C for 15 minutes, killing bacteria and viruses. "It'll sterilize anything." The assumption has been that if you tried this on an N95 mask they would degrade rapidly. We thought we'd give it a try anyway," Kumar said. "And actually what we found is while it does degrade some [types of] masks, there's a certain group of masks that are made of kind of a fabric-type material, rather than being moulded closely to the face they're called pleated [masks]," he said. Kumar said the pleated fabric masks can be cycled through an autoclaving machine 10 times and come out as good as before.

"The reason this is really important is that autoclaves are available at literally every established hospital in the world. There is probably no hospital in the world that doesn't have an autoclave machine," Kumar said. "So everybody can use this for these particular types of masks and these particular types of masks are probably the most common type of N95 mask, so we're really pleased." Kumar said the technique could be put into use at any hospital at any time. "It's a technology that's available and ready to go right now."
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Hospital Autoclaves May Allow Safe Reuse of N95 Masks More

Hospital Autoclaves May Allow Safe Reuse of N95 Masks

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  • Leave it to Canada to come up with such a simple idea...

    • It is kind of an obvious idea. I have been thinking about sterilising masks in a pressure cooker a couple of weeks ago, but since I am a nobody and the masks are sold out anyway...

    • Leave it to Canada to come up with such a simple idea...

      ...along with social-distancing by imagining a hockey stick held at arms-length.

    • Re:Unblame Canada! (Score:4, Informative)

      by Dunbal ( 464142 ) * on Thursday April 02, 2020 @08:34PM (#59903236)
      In Latin America many operating theaters use face masks, caps and surgical gowns made of linen. They get washed and thrown in the autoclave after every surgery, because it's cheaper in the long run that buying disposable stuff. This is not a new concept at all.

      • Re: (Score:2, Interesting)

        by Mashiki ( 184564 )

        It was the norm in the west prior to the 1990s as well. It fell out of fashion because 'new and sterilized' was faster, cheaper, and reduced transfers from drug resistant diseases. Every 30 years or so, it seems we simply repeat the same thing and go back to "tried, true, and tested" methods after trying something new because either MBA's/pencil pushers or idiots manage to convince people that xyz way is better.

        • Re: (Score:1)

          by Anonymous Coward

          Your post is contradictory. The reasons you stated for giving up reusable equipment are perfectly valid and sensible, especially the issue of drug resistant superbugs. We're only going back to them because we're experiencing a clusterfuck of a pandemic and we can't get hold of enough disposable masks and whatever, not because the "tried, true and tested" solutions are actually better.

        • "It fell out of fashion because 'new and sterilized' was faster, cheaper, and reduced transfers from drug resistant diseases."

          This seems to be common sense; not the domain of MBAs.

    • It is simple in concept, but the difficult thing is proving that it works and the masks remain effective following the autoclave process. Great science to prove the result!

    • Leave it to Canada to come up with such a simple idea...

      They remembered a simple idea. That idea has always been around.

      There are a couple of issues here. I get jitters when I see people reusing anything in an environment which relies on DNA/RNA PCR tests. While the infections can be stopped, there will be lots of rather idiotic false positive test results. We have already been there. The utterly moronic claim about "this test is fake because it has male dna in a female sample" in the McLaren doping report most likely was caused by this: https://www.fagain.co. [fagain.co.uk]

    • This may be true of the corona virus, but that is not the only viruses found in a hospital. The only sure fire way to be safe, is to kill everything.
      • So don't do this unless you're treating Covid-19 patients. One can assume that medical personnel knows what patients they're dealing with.
        • Corona patients often die to other infections. They can enter the blood due to the lung damage, and overwhelm the immune system.
          • They may die of lots of things, but I don't think infection in the blood stream is something you wear a mask against.
            • Ok true. I was thinking of creating a completely sterile environment, but I guess that would be luxury if it went that far.
            • On the other side, in such a medical environment it is standard to try to kill all germs. They certainly would not use such a partially disinfected mask for surgeries. I would guess intensive care is similar.
              But maybe it's ok in other places.
              • If you're talking about respirators, those don't protect patients. The air going out is simply vented. So the physician's health is the prime consideration here.
                • Yes. For surgeries the outer layer of what they wear is properly sterilized. That's what I had in mind, and there this method might not be sufficient.
                  But it should probably be ok in normal hospital work, that must be a large part of where the masks are needed. How sterile they work in intensive care I don't know.
                  • If you're working specifically with intubated and ventilated patients unable to breathe on their own, as opposed to surgeries, chances are that the risk of the patient catching something additional from the physician is minuscule: the patient's air is already unlikely to be affected by what the physician exhales. From what I understand, the ventilators already have fairly beefy filters of their own, if they outright don't use piped air from outside the room, or both.

        • Re: (Score:2)

          by Dunbal ( 464142 ) *
          No, this is healthcare. You don't create a situation where you put patients at risk. Not spreading nosocomial infections is far more important than "not degrading the material".
          • Exactly. You put patients at risk by destroying their physicians' protective equipment. So, don't destroy their protective equipment. Otherwise there won't be physicians to take care of patients.

      • And the only sure fire way to kill everything is to nuke it from orbit.

      • Re: (Score:2)

        by whit3 ( 318913 )
        Since 70 C heat makes coronavirus non-infectious, I've got a few vegetable steamers
        that can make my personal mask more-or-less safely reusable. It's unlikely anything
        a COVID-19 victim exhales has other pathogens. The shortage of masks completely
        changes the usual (disposables are best) hospital economics argument.

        Autoclaves are pressure cookers, need some upkeep and suck lots of power. And, they're not DRY
        heaters, which is encouraging for my veggie steamers since the 70C test was for dry condit

    • You need to have enough time to run hundreds if not thousands of masks through autoclaves every day. Extending the time from 15 minutes to 30 minutes halves the rate at which you can sterilize things. What method is most effective will depend on number of used masks, number of people needing them, number of new masks available to substitute in for ruined masks, and number (capacity) of autoclaves.

      • Re:Time is a factor as well (Score:5, Informative)

        by demonlapin ( 527802 ) on Thursday April 02, 2020 @07:31PM (#59903064) Homepage Journal
        We have a lot of autoclaves. It used to be fairly standard procedure for instruments to be flash-sterilized in autoclaves located in the OR after basic cleaning - where I trained, there was one in almost every OR. A typical one is about 2/3 the size of a home oven, and you know how small one of those masks is. Thousands a day per hospital would not be a stretch.
      • What use is it to halve the time at the cost of destroying most masks? If you think that 30 minutes is too much, there's still the 100 C steam for 10 minutes option. Although 70 C still should be less damaging to the equipment.

    • Re: (Score:3)

      by ecotax ( 303198 )
      The linked article doesn't actually test for this virus but for E. Coli instead, so whether that should be enough is not completely sure. According to this article (in Dutch) [www.mumc.nl] using an autoclave at 60 C in combination with using hydrogen peroxide should be enough though.
      • There doesn't seem to be any reason at this point to assume that SARS-Cov-2, unlike other coronaviruses, survives what E. Coli doesn't.

    • 70 C dry heat for 30 minutes has been shown as sufficient, and it's less likely to damage protective equipment. [theisn.org]

      But autoclaves don't do 70C, they're much hotter. And hospitals don't have a whole bunch of machines lying around that happen to heat their contents to 70C, but do have a whole bunch of autoclaves. Hence it makes sense to look into whether the available devices, which are known to kill all bacteria and viruses, can be used on masks without destroying them.

      • Hospitals should have hot air ovens available. Hell, worst case, you buy one. Around where I live, it seems definitely easier to get one's hands on a hot air oven than on an autoclave.

  • Since washing your hands is a solution... I can also see why this would be a terrible idea if badly implemented

    Someone with actual knowledge please let us know

    • Re: (Score:3)

      by sjames ( 1099 )

      I have no idea if it'll work or not. The concern would be if the treatment widens the pores in the filter material of not, If not, it's OK, otherwise they will let through more potential pathogens than they should.

    • Re:Sounds reasonable? (Score:5, Funny)

      by EvilSS ( 557649 ) on Thursday April 02, 2020 @09:55PM (#59903444)
      Yes, autoclaving your hands is a very bad idea.
      • Unless perhaps if badly implemented, without closing the autoclave, temperature only at 45 degrees C, running water and a bit of soap. But at that point, you're just washing your hands, so you might as well leave the autoclave to those who need it...
  • Comment removed based on user account deletion

  • expediency (Score:3)

    by hdyoung ( 5182939 ) on Thursday April 02, 2020 @07:10PM (#59902968)
    That's the way these things work. Nearly everything is disposable when times are good. Hard times is when we actually push the limits of stuff like this. 10 times..... I bet someone will make the masks last 20 or 30.

  • Kumar said the pleated fabric masks can be cycled through an autoclaving machine 10 times and come out as good as before.

    What happens if you try 11 times? Do the masks turn into gremlins? Have they tried doing it before midnight? And what does Harold have to say about it?

    • How do you know how many times any particular mask has gone thru cleaning/autoclave ?? Could contaminate them by making a mark (roman 1) each time they are cleaned. But would you trust that each time it was marked and didn't wear off, or something else?

    • Re: (Score:2)

      by sjames ( 1099 )

      Presumably the filter material degrades such that it no longer meets the standards for an N95 mask when it goes through the process too many times.

      Of course, it will be a statistical likelihood rather than an absolute threshold.

    • I tried washing my N95 mask and it made it too hard to breathe through. It was like it closed off some of the pores in the fabric. When I inhale the mask actually deforms.

  • I read a study that steamed the N95 masks for 10 minutes (like vegetables). Killed everything and didn't damage the masks.

    • same thing. THis is a pressure cooker, which steams them at a higher temp.
      And simple steam will kill many things, but not all. Not sure that I want to true with this bug.

  • I hope they have a serial number or some other distinguishing feature otherwise they will end up in the wash a few more than 10 times. Also I have never been a big fan of the science behind a round number why not 9 times or 11 times?

  • Actually, some bugs have been found that actually CAN survive the typical autoclave cycle. However, I doubt that includes SARS-CoV-2.

  • A company I'm a little familiar with was using concentrated peroxide and radiation to clean them. Some SPD staff I know were hesitant with the high peroxide. Think these N95s are only good for like an hour tops with removal, breath, and inevitable seal failure.

  • "It'll sterilize anything."

    Prions laugh at it.

  • I do laundry with an autoclave...
  • I've read a study that shows 170F-degree heat for 30 minutes will kill coronavir, and maintain the integrity and effectiveness of a n95 mask. Every commercial kitchen I've worked in has what are called cook-n-hold type electric ovens for holding large batches of cooked food. (Cres-cor, Altoshaam and other brands) Most will plug into a normal wall receptacle. They hold a consistant low temp (120-250 degrees) without large swings of temp. (Regular ovens will not maintain such a low temp, and have swings in

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