>in times of shortage you could sanitize and sterilize multiple use metal parts in house

Got one word for you: prions. Standard sanitization procedures do not work with them, and if the hospital is not setup to decontaminate for prions, they're unlikely to be able to to it during the crisis.

see https://www.memphis.edu/ehs/pdfs/deconprions.pdf for what it takes.

That is a valid argument for neurological equipment, which has the highest liklihood of infection for prions, but during this pandemic, the likelihood of prion transmission is very remote, probably to the point that it approaches zero, and is probably zero for these valves.

Not all prions need to break skin to be an issue. Kuru, one of the more infamous prions, was transmitted orally [0]. Mad Cow is also thought to be transmitted orally, but research is on going. Though a low possibility, the absolute last thing you need is an even more complicated issue running about during a world-wide triage/crisis. To save live you are trying to eliminate variables, not add to them.

[0] Kuru is not something you want to research whilst eating, fyi. Hell, none of them are.

transmitted orally from eating neural tissues not from prions in saliva that could contaminate medical equipment such as ventilators (that's my understanding at least)

Mad Cow is still active in it's research. We cannot yet rule out that salivary contact is a transmitter of prions, though I agree that it is very unlikely.

https://www.thelancet.com/journals/laninf/article/PIIS1473-3...

It is in the eyes https://www.nih.gov/news-events/nih-research-matters/detecti...

>Autoclave at 132 C for 4.5 hours

All hospitals should have autoclaves, shouldn't they?

Not everything can go in autoclaves: https://www.denverpost.com/2019/06/16/porter-hospital-infect...

Every biology adjacent facility I've ever heard of requires them for at a minimum biohazard waste disposal. I don't know how a hospital could not have enough given that all those plastic one time use parts still get autoclaved after disposal.

In terms of overall mass, sterilizing all those parts should be equivalent to throwing them away. It would require different internal procedures though, I don't think people are used to saving and reusing things. And it would be more labor intensive. And autoclaving might destroy the parts.

Most of which seem like reasonable tradeoffs in an emergency.

I'll add Candida Auris to the list of scary things that are hard to kill in hospitals: https://en.wikipedia.org/wiki/Candida_auris

It's not to protect the patient (well also that), it's to protect the doctors. My granddad was a medical student back when they still reused syringes. That gave him a liver infection, so he could not donate blood his entire life.

One doctor can save numerous lives. Putting one out of commission is a huge blow in a crisis.

I agree with the values you're describing here, but it's still not clear to me that a re-use workflow needs to be that different from single-use. Presumably the single-use involves tossing used pieces into a biohazard disposal container to be removed later. What's the issue with tossing the same material into a biohazard container of things to be solution-rinsed autoclaved and/or UVd the hell out of, then maybe wrapped or banded so that it's clear they're clean?

Maybe it's a labor/scale issue?

Labour/scale, indeed. The facilities where these things are usually produced have the capacity to make sure they are sterile. Hospitals cannot sterilise items to the same scale.

You just need to be careless once for it to be a problem. And considering how many sterile items you need to use every day - particularly in an emergency - it is not unlikely that one item went back into the reuse cycle without being sterilised. It's to avoid the question, 'was this item sterilised?' If its wrapper is open, assume it is used. You can only do that safely with single-use items.

Except that sterilised items usually are repackaged in some way that removes this doubt.

I have seen many different techniques for this kind of workflow.

> If its wrapper is open, assume it is used. You can only do that safely with single-use items.

How about putting the re-usable item in a wrapper so that the same rule can apply.

All surgical steel is reused exactly this way. There are plenty of plastics that get autoclaved as well.

Yeah. For example, thinking about needles and syringes, they used to be disinfected by boiling water. That's certainly not enough to kill all existing pathogens especially after you used it in a person.

You probably need to autoclave the parts, and then some more to be sure.

This would be ok some decades ago. Now we know that prions can survive

Autoclaving is hard but it seems to be doable for Prions https://consteril.com/prion-sterilization-guide/

Simple boiling won't do much even for viruses

Depends on the nature of the contamination. Some pathogens are exceptionally difficult to de-contaminate, like Candida auris.

There aren't many things that survive high pressure autoclaving. Prions are the only possible concern that I'm aware of.

The cost and complexity of making parts that can survive autoclave is a big driver of single use parts.

Asteroid organic sample return missions actually face some of the same problems. Even moderately complex sample retrieve mechanisms can't be autoclaved. That's why so many are using passive sample collection bins and compressed gas.

From what I understand, there are some components that can't be put in an autoclave and/or have areas that aren't well suited to autoclaving. So it may not be a one-size fits all solution.

Good point

The defense in depth mindset response would be single use where it is superior, but with emergency protocols for reuse in emergencies where perfect becomes the enemy of good. E.g. rate disposable items for heat treatability even if nobody will try to disinfect them outside of an emergency shortage.

You could alternatively just have a couple reusable items on hand per machine instead of making every single disposable one reusable.

Yeah, that would be my recommendation. Make a supply of parts that can take the autoclave and keep them around for emergencies. If you had to use them because you messed up the supply chain (didn't order enough), big fine. If you ordered but the supplier couldn't deliver, no fine.

Even better! Seal them in a box labeled "break glass in emergency" if capitalism is the main objection.

This article could make one more concerned about that problem just by making them aware of it. But if you were previously concerned about it, this news should reassure you, since now you know that there is a solution available even in crisis conditions.

Only for parts amenable to 3D printing, which is limited at the current state of technology.

Yes the issue is the stability of the plastic at the temperature and pressures that sterilisation needs. I know that plastics have been developed for exactly this purpose but I don’t think they’re very widespread yet.

It appears from Wikipedia that normally you sterilize things at 121° in steam for 15–20 minutes? If that's the case, common plastics like nylon and polydimethylsiloxane should be okay, although poly(lactic acid), commonly used in FDM 3-D printing, and poly(ethylene terephthalate) won't be.

A lot of plastics will deform when autoclaving. There are enough lists for autoclave compatibility that I forget the answers, but this looks like a pretty complete chart.

https://www.industrialspec.com/resources/plastics-sterilizat...

This is a really comprehensive table! It lists PLA as "Poly(L-lactide)", giving it a surprisingly good "Fair" grade for autoclaving, and polydimethylsiloxane as "Silicones", rating them "Good". It also lists polycaprolactone, which melts around 70° and can be easily molded by hand while molten, as "Fair". Surprisingly, though (to me), it lists nylon (6 and 6-6) and teflon (polytetrafluoroethylene) as only "Fair", like PLA and PCL, even though at least teflon is totally insensitive to water and commonly used with service temperatures up to 260° (among other things, in FDM printer hotends).

So I wonder if this table might have some significant errors in it? Maybe someone interchanged some plastics without intending to. It can't possibly be correct to put PTFE and PCL in the same category, can it?

Anyway, common plastics it rates as "Good" for autoclaving include acetal (Delrin), polypropylene, silicones, and (for some definitions of "common") PEEK.

Surprisingly polyimide (Kapton), the favorite high-temperature chemically-inert plastic of aerospace and electronics, isn't in the table at all.

It is totally possible that different companies will have slightly different charts but usually they're about the same. The canonical way to know if to ask the manufacturer of the actual plastic you're using, these comprehensive tables are usually put out by distributors as general guidance.

I'm not surprised that some plastics may not be based on temperature only. For instance, nylon might crack if it's a thin piece due to thermal expansion. Or some may chemically react with steam.

I agree that it's weird that PCL would be okay while Teflon isn't, but it could be a molecular weight or thermal cycling thing. Teflon is very soft already so it might simply get deformed.

I'd trust such a table to point me in the right direction but find a second independent source if the answer seems weird.

Of course in practice you just try it and see if it survives and is functional. lots of plastics can survive a cycle or three but not five.

Note that it's 121˚C (and under pressure), not a tepid water bath.

Things like needle drivers and forceps hold up fine with some care, but things with delicate moving parts are not supposed to be autoclaved. Plastics depend on the material--some are fine, some deform.

Right, I didn't mean 121° Frankenstein, and I see now that my comment could be misinterpreted as meaning that all common plastics would be fine, when actually I only meant nylon, polydimethylsiloxane, and a few others — and even for nylon I should have been more specific.

I was just trying to emphasize that it's a fairly...aggressive process.

You can pasteurize eggs at ~135˚F and they're practically uncooked. The autoclave isn't like that at all--15-20 min at full temp/pressure plus the rampup/down times can do a number on things.

I appreciate you having clarified my comment with your emphasis! It was definitely needed.

Nylon isn't generally known to be autoclavable (at least I avoid it when I want to sterilize parts in house (R&D at a medical device company).

Thank you! The plastics compatibility chart linked above also listed it (even nylon 6-6, which it called nylon 66) as only "fair", which surprised me. Does it hydrolyze?

I have no idea what happens, maybe cracking or deformation. Most things I've read is that the max service temp of nylon is close to autoclaving temps (or just below) and its not suitable for use in boiling water either.

Given the temperature constraints, I can imagine exactly those plastics are fairly unlikely to be suited to the traditional extrusion heads on common-or-garden 3d printers.

Yes I would think moulding would be the way. One of my clients is a plastics company and I saw a presentation on it a little while back. The new plastic versions of things can be non-disposable but still much cheaper and lighter than metal versions.

We use plastic for single-use because of their low price. If the parts are to be re-used, I assume we could use silicon/glass/metal.

Is it really necessary to use a sterile valve for a new patient affected by the same strain of virus. I would expect the hospital to reuse a valve, instead of letting a patient die without the ventilator.

Would there be risk of contamination from other diseases that patients may have? I agree with your general expectation that risky reuse over high-probability death seems strongly preferable. One tricky moral dilemma is what to do if you have 1 clean valve, 1 dirty valve, and 2 patients.

> One tricky moral dilemma is what to do if you have 1 clean valve, 1 dirty valve, and 2 patients.

Why would this be trickier than having 1 clean valve, 0 dirty valves, and 2 patients?

Well it's exactly the same after you make the choice/use the first valve.

> what to do if you have 1 clean valve, 1 dirty valve, and 2 patients

"Just received word from an ICU doctor at a small NY hospital: They are officially out of ventilators and are now double venting patients with COVID (using the same ventilator for 2 infected patients)."

Absolutely insane. It's barely started.

Triage as you would anyway (same prioritization), or flip a coin.

I think you'd at least want to sterilize it. Not sure if it's the case with these things, but other devices like endoscopes have enough cracks and crevices for stuff to hide so they have to go through an acid wash instead of steam, so the plastic probably wouldn't survive. Stuff like that either has to be non-corrosive metal or disposable.

Wouldn’t plunging them in a solution with high concentration of alcohol do the trick? (Not a medical professional, asking out of curiosity).

There are much better 'disinfectants': alcohol is good at killing living cells, but doesn't do a great job killing spores or penetrating into protein-rich....gunk.

You would probably want to use a "high-level disinfectant" or "sterilant" instead. Gluteraldyhde is fairly common choice or ethylene oxide gas, though both can be fairly nasty if not handled carefully (which is, of course, the whole point).

More emphatically: do not trust alcohol at any concentration to kill pathogens. (Likewise, freezing.)

The way alcohol swaps are used, they move contaminants away from the needle insertion site, and the alcohol helps to dislodge them. And, of course, it does kill some kinds of pathogen, as does soap.