Ventilator

[chipenter]

As the NHS in the UK is short of ventilator's and I have a oxy acetylene welding set , I made my own purchased some 6mm fish tank silicone air line  , turned a connector from stainless punched a hole in a dust mask , and its there if needed , total spent £1 30 just hope it wont be needed .

[Joules]

That would also be handy for having a pint down the pub, if they were open 

[JHovel]

What you made is an oxygen mask connector. Nice try.

A ventilator is a sophisticated machine that forces air or oxygen enriched air into someone's lungs through a tight respirator mask or an endotracheal tube - at the right rate, pressure, volume and cadence based on blood carbon dioxide levels.....

Lastly, industrial oxygen is fine for a short period of resuscitation. But it contains impurities (including gas traces which are NOT from the atmosphere and metal molecules from the compressors). Medical oxygen is MUCH cleaner, as it is often used for many hours or days continuously. That would deposit the impurities in ever growing quantities in the lungs. So welding oxygen is not a good idea for long-term use.....

[AdeV]

...So welding oxygen is not a good idea for long-term use.....

It works better than Argon! Damn mig/tig welders....

[chipenter]

It was such a simple idea that took less than 15 minuets to make , I checked the B.O.C. web site and welding oxygen is 99.5% pure but unstable for humans whereas medical oxygen is also 99.5% pure and for medical use only , possibly how clean the connections are when filling  I don't know , there is no mention of impurities .

[nrml]

Old style anaesthesia ventilators like the Manley can quite easily be built in an average home workshop, but these have long become obsolete. Modern ventilators are an entirely a different kettle of fish. They allow tight control of gas flow patterns controlled electronically and are equipped with several sensors to measure parameters like volume, pressure, flow, temperature, leaks, compliance of the circuit, compliance of the patient's lungs,oxygen concentrations etc etc etc

Aside from the complexity, they must be designed and tested to work flawlessly 24 hours a day for months on end continuously without any break. Failure is quite literally the difference between life and death. Things like lubrication, friction management and wear need special solutions as the machine is directly connected to the patient's lungs as do fail safe and back up modes for every subsystem on the machine.

They are amazing works of engineering probably on par with the complexity of modern aerospace engineering and its not really a surprise that there are only a handful of companies that design and manufacture them these days.

[mattinker]

I have a respirator for sleep Apnoea, how do theses compare?

[edward]

CPAP machines are a mild positive pressure of unoxygenated air so not really the same. I guess it might hold your alveoli open a bit but I don't think it'll see you through acute respiratory failure :-)

[Will_D]

CPAP machines are a mild positive pressure of unoxygenated air so not really the same. I guess it might hold your alveoli open a bit but I don't think it'll see you through acute respiratory failure :-)

They can also administer (blend in) oxygen at the required level if neded.

[nrml]

CPAP machines for sleep apnoea are very simple devices. They are basically a tight fitting mask with a pressure release valve that pops open at a fixed pressure. It's supplied with pressurised air or oxygen either from a piped gas supply, cylinder or small pump. As mentioned earlier, all it does is splint your lungs open like a partially blown balloon. It doesn't take over the work of breathing which a mechanical ventilator does.

Noninvasive ventilators are in some ways a halfway house between CPAP and a full mechanical ventilator. They help reduce the work of breathing and offer some support but can't takeover the work of breathing completely. We have one UK based manufacturer of these devices. All the talk of large technology companies stepping in to manufacture ventilators on a war footing to support the corona effort is pure fantasy. At best  they might be able to manufacture a very simple noninvasive ventilator under licence. While such devices would have a role in supporting people without severe respiratory failure, they wouldn't be a substitute for an intensive care or anaesthesia ventilator. A badly designed or manufactured machine or even one that is capable but not intuitive to use would be lethal as cascading training would be very difficult in the current environment.

[Joules]

Realistically there is untapped production from engineers workshop across the country.  It seems a shame we can’t organise the production of maybe none essential none critical components, freeing up production elsewhere.   This would give alot of people something to do and make them feel involved in the efforts to combat this virus.   Many older people will be isolated and despite best efforts may not be able to concentrate on their own projects as much as something that might make a difference to others.

I had thought about how anyone with access to a laser cutter could be making paper masks.  Store them for 72hrs to hopefully let any possible viral contamination expire.  Other disposable parts that could be used in hospital enviroment, many of us have 3D printers at our disposal now.

Just how to get the word out.

[AdeV]

All the talk of large technology companies stepping in to manufacture ventilators on a war footing to support the corona effort is pure fantasy.

I don't see why. There are hundreds, perhaps thousands, of CNC-equipped factories and workshops all over the UK - and I don't mean little home shops like ours, proper professional setups producing professionally priced goods - which could turn out ventilator parts by the millions, if needed. For sure, assembly, testing and certification of the end products might be more specialist, but again, on a "war footing", with money more-or-less no object, suitable training could be rolled out in days.

[awemawson]

The underground tunnels beneath the car factories in the Midlands, that were used as shadow factories in the war are still in existence - perhaps we should open them up? They are a bit wet in places but still in remarkably good condition:

 

[nrml]

All the talk of large technology companies stepping in to manufacture ventilators on a war footing to support the corona effort is pure fantasy.

I don't see why. There are hundreds, perhaps thousands, of CNC-equipped factories and workshops all over the UK - and I don't mean little home shops like ours, proper professional setups producing professionally priced goods - which could turn out ventilator parts by the millions, if needed. For sure, assembly, testing and certification of the end products might be more specialist, but again, on a "war footing", with money more-or-less no object, suitable training could be rolled out in days.

Designing a new ITU ventilator from scratch needs a lot of knowledge of pulmonary physiology in normal and diseased states besides engineering and testing. They are not simple devices. There is awful lot of custom electronics and software control which has to be completely bug free before being used on people.
The easiest route to mass manufacture would be to produce an existing device under licence and perhaps pare it down to simplify the build. The custom electronics would again be a rate limiting step rather than the mechanical bits. It's doable given enough time, but that is something we don't have a lot of.


The experience from China and Italy seems to suggest that a large proportion of patients with respiratory failure need ventilation for  2-3 weeks. An expensive ventilator with limited capability and questionable reliability is of limited value clinically for supporting a patient for this long.  It would have to be reliable enough to work non-stop without any malfunction for several weeks at a time. It is probably safer to stick with anaesthetic machines for extra capacity as most UK hospitals are doing and wait for existing manufacturers to deliver. China, Germany and America have put their efforts into ramping up production within existing manufacturers facilities.

Our hospital has been able to order extra ITU ventilators from one of the smaller German manufacturers and we have commandeered ventilators and anaesthetic machines from private hospitals in the region. We are likely to face a shortage of skilled manpower to manage these ventilated patients before lack of devices becomes the major limiting factor.

[Will_D]

One Irish example of re-purposing:

2 clothing factories in Donegal and NI have stopped producing existing clothing and sports wear lines and are no producing hospital "scrubs".

Un-fekkin-believeably in this here republic is that health care workers

[Will_D]

Oops: Posted too soon!

One Irish example of re-purposing:

2 clothing factories in Donegal and NI have stopped producing existing clothing and sports wear lines and are now producing hospital "scrubs".

Un-fekkin-believeably in this here republic is that health care workers HAVE TO BUT THEIR OWN SCRUBS!!

There is now a "go fund a scrub" cloud funding scheme

[nrml]

Scrubs are becoming uniforms for some groups of healthcare workers, so it's no different from uniforms in any other job I guess.  Operating theatre scrubs are always provided by the hospital because they need to be clean.

[Joules]

..... Borderline rant, not helpful at these times......

Post redacted.

[Kjelle]

There are loads of stuff that is needed, that can be produced without too much problems, like holders for face sheilds. Yes, we need ventilators, but those are, as has been noted, complex and difficult to produce.
I know, it isn't as glamorous to make holders or some little widget for some less-than-unknown gadget that is needed but not covered by the news...

The best thing we all can do now, is to stay healthy, or at least keep out of the way from this bastard bug. Who knows when this is over, but us "old duffers" might be needed, when the young 'uns are too traumatized to do anything but drink decaffinated latte and moan!

Take care out there, stay safe.

Kjelle (from planet Sweden)

[AdeV]

..... Borderline rant, not helpful at these times......

Post redacted.

Joules - unless I'm mis-remembering, didn't your "borderline rant" include a link to a project for people with 3D printers to help print face shields (or holders, at least)? If so - do you fancy putting the link back in, I did visit it, I'm prepared to set up my 3D printer to help the cause (once I've made an acrylic enclosure for it); but now I can't find the link...

[AdeV]

The easiest route to mass manufacture would be to produce an existing device under licence and perhaps pare it down to simplify the build. The custom electronics would again be a rate limiting step rather than the mechanical bits. It's doable given enough time, but that is something we don't have a lot of.

That's exactly the approach I was assuming - and not even "pared down". As today's news that Rolls Royce and BAE Systems are going to start manufacturing a device ("Project Oyster" - why Oyster? Oysters don't breathe....). I don't think the "complex electronics" would be a limiting factor either; these companies all deal with complex electronics (avionics, etc.) every day, a little ventilator control board or three, which have already been designed and tested, wouldn't overly tax them I don't suppose.

One model, understood to be government clinicians’ first choice, goes by the codename Project Oyster and involves slight tweaks to an existing design by a little-known Oxfordshire firm called Penlon.

There's another design ("Project Penguin"????!) which is increasing production of an existing design; and Dyson's contract is to produce a brand new design - so they reckon it'll be at least a couple of weeks in the making, then getting regulatory approval before that one is available.

Link to article in the Graun.

[Joules]

Sorry Ade, not on that post.   Don’t think I posted a link elsewhere, but a quick search should bring something up.

[Ozwelder]

Hi Guys,

Just my 2c worth on using industrial oxygen for breathing issue.

The contaminants can come from the remnants of compressed oil that is used to lube the compressors.

Pure medical oxygen is made using compressors using vegetable oils which are harmless to human breathing in the compressed form.

Kudos to the OP for having a go ,but one must fully understand. In this case results could have been fatal as compressed oil ( the the compressed oxygen) is mixed in with the oxygen and its compression cycle.Other gases like nitrogen and argon are present in tiny amounts in the industrial oxygen mix.

So, now you know.

I had to wear a breathing rig while operating on some  some toxic material while working in the industry many,many years ago.

Oddly enough they called it a respirator then.

Ozwelder

[chipenter]

A friend of a friend worked for British Oxygen Company who said that all oxygen in the uk was compressed on the same machines , but the bottles were filled in separate rooms and a sterile environment for medical use .

[nrml]

Most of the larger consumers of oxygen in the health care sector use Vacuum insulated evaporators for the main supply and cylinders for back up and during patient transfers within and between hospitals. VIEs are built to allow a certain maximum flow rate and are sized according to requirement of the hospital. Oversizing them results in wastage of liquid oxygen to keep it cool not to mention the additional cost.

A few weeks back at Watford General hospital, they had a bit of a supply issue when they exceeded  their maximum flow and the pressure reducing valves in the VIE froze as a result. Following this, the MHRA issued a list of essential criteria for all new ventilator and CPAP device developers. This along with ''flattening the peak'' and better understanding of the Covid illness rapidly quelled the initial demand for ventilators.

Our hospital was offered a trial of a CPAP device developed by a Formula 1 team. I believe our engineering department had to turn them down because the oxygen consumption was so high that there was a risk of some of our VIEs failing if we had a number of these devices running simultaneously. Thankfully, we never were stretched for ventilator capacity despite having to use our Anaesthetic machines for a few weeks.