Open source and DIY PPE, Facemasks, 3D printing, etc. master list for this blog.

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University of Florida

UF researchers lead the way in rapidly designing, building low-cost, open-source ventilator

https://ufhealth.org/news/2020/uf-researchers-lead-way-rapidly-designing-building-low-cost-open-source-ventilator

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https://www.newyorker.com/magazine/2020/04/06/the-macgyvers-taking-on-the-ventilator-shortage

Let’s say we build twenty thousand ventilators in a World War II-style effort,” he said. “It could come down to, O.K., who is physically at the hospital to take delivery?” Or, “How does a doctor know that it’s O.K. to use these ventilators? Do you print a piece of paper saying ‘This has emergency F.D.A. approval’ and stamp it on each one?” He went on, “Can a doctor train up on this equipment in an hour?” And what if there are enough ventilators, but not enough doctors to operate them? What will we do then? ♦

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MIT-based team works on rapid deployment of open-source, low-cost ventilator

http://news.mit.edu/2020/ventilator-covid-deployment-open-source-low-cost-0326

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A friend going into Crit Care recommended this after I said I’d have to manage an open ICU next yr as a hospitalist. My program only lets fellows and attendings touch the vents and doesn’t do all that much vent teaching.

I read this over three times in 2 weeks (short read) and can now explain vents to my co-residents. While you obviously still need the hands on, this book will give you all the tools you need to manage the vast majority of vent cases. It’s explained as simply as I can imagine, and really takes the mystery out of vents making you think “ Eh, vents aren’t that difficult.” Highly recommended for anyone who needs to know how to manage vents.

Here are some standard settings used with a hospital ventilator when a patient is intubated:
INITIAL SETTINGS
* Volume per Breath = no less than 6 ml/kg of predicted body weight; no more than 8 ml/kg of predicted body weight
Predicted body weight is based on a patients height.
This is the chart to calculate predicted body weight:
http://www.ardsnet.org/files/pbwtables_2005-02-02.pdf
Volume per breath must be configurable by health care provider; increments of 100 ml is probably acceptable as long as volume per breath falls within 6-8 ml/kg
* Breaths per minute = 10 - 20 breaths/ minute
The must be configurable by health care provider. Increments of 1 breath per minute is required
Note: practioner’s goal is to deliver a total volume per minute (volume per breath x breaths per minute).
If the volume per breath is on the high end, the breaths per minute can be dropped to achieve the target volume per minute objective.
In other words there is some wiggle room that’s acceptable in both these settings for a particular patient because the other setting can compensate for it.
* Minimum air pressure provided to patient at trough of breathing (exhalation): 0 - 25 cmH2O (most common setting for Covid 19 appears to be starting at 5 cm H2O working up to 15 cm h2O)
Must be medical provider configurable, ideal would be in 1 cm H20 increments, 2.5 cm H2O would be the largest acceptable increment.
(This setting keeps “lungs” from “collapsing” during exhalation)
* need an oxygen intake port that can handle 40 - 60L oxygen at 100% concentration which is usually delivered from the hospital wall.
Oxygen at the source is always 100%.
100% oxygen can be mixed with atmospheric air, which is 21% oxygen, in ratio to get desired level of oxygen that the patient needs.
Oxygen concentration that the patient receives usually starts at 100% and dropped to the lowest level possible that provides adequate oxygen in the blood and adequate carbon dioxide range in the blood. A medical provider will draw blood approximately every 30 minutes when tweaking ventilator settings to get the settings right for the patient.
Hospital ventilators have two modes:
Mode 1: Dr sets the desired volume per breath, ventilator uses as much pressure as needed to deliver the volume. (A compromised lung will require more pressure to “inflate” than a healthy one). This is known as “volume mode”
Mode 2: Dr sets target pressure for ventilator to reach, regardless of volume per breath. This is known as “pressure mode”
volume based mode is used more often than pressure based mode.
A ventilator that delivers a fixed volume of air per breath must also have a sensor to indicated how much pressure was needed to deliver the breath.
This is important as both a safety and diagnostic tool.
This peak pressure used to deliver the inhalation breath if too high for too long can damage the lungs. If pressure needed to deliver a set volume is increasing this has diagnostic relevance to the doctor and is key to monitoring the patient
In volume based mode, the pressure needed to deliver the inhalation is a reporting feature.
In pressure based mode, the pressure level is a user configurable setting.
Safe level of peak pressure is general less than 35 cm H2O.
When pressure exceeds this level, it’s a sign to the practitioner that patient has too much volume per minute; and prompts practioner to verify this by X-ray and usually to reduce volume per breath, or breaths per minute.
Finally it is useful for practioner to know how much pressure the system has when the system is on hold. A system pause button is useful to pause the ventilator and to determine the pressure at the end of exhalation coming from the patient. This is a nice to have feature. The other features are more important.

PPE info and plans for 3D printing, ventilator, button masks and more.HERE

Button mask info here.

These are comments and links about materials. I am constantly organizing and editing all of these, and the organization is improving, slowly.

Every day fabrics that you likely have at home:

You can use fine men’s shirting or high thread count sheets for fabric. You can use a third layer of cotton fabric in center if you can’t access HEPA quality fabric. Also you could use a non woven interfacing for that interior layer. The idea is that the three layers of woven fabric are offset from one another causing air when it migrates in or droplets when they migrate out to not have a straight path. If you use non woven interfacing even better because it is a complex matrix. The entering particulates collide so to speak with the fibers and are captured. Also you can consider a synthetic fabric for the middle layer since many polyesters and nylon are charged and can better capture charged cells. Instead of the pony holders I’ve used fold over elastic about 28 inches long to bind each short side of the mask. This leaves stretchy tails for tying (makes it easier to fit) as you just zig zag across folded over elastic from one end to the other. Many have also used garbage bag wires and plastic floral stems for the nose piece, you can sandwich it in duct tape so it stays waterproof. I suggest inserting it into a 4” casing made with fold over elastic sewn to the lining side of the mask. This way you can reinsert new wire as needed. Lastly after you turn it consider top stitching around to increase durability. Good work guys!

Filter materials/Materials found in hospitals

 https://m.ufhealth.org/news/2020/uf-health-anesthesiology-team-devises-respirator-mask-made-existing-hospital-materials

https://smartairfilters.com/en/blog/best-materials-make-diy-face-mask-virus

In Gainsville FL, nurses have been using the surgical fabric that is used under tools in surgery. It is 99% non permeable and we have a group that is promoting use of that fabric as opposed to cotton for homemade masks. For sewing groups in our MN area we are supplying the fabric to keep our front line workers safer. Anyone can buy the fabric, resources are on the site. maskarmy4heroes.weebly.com

Commercially available medical fabrics and filters

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It was shared with me that the product called Halyard H600 2 ply spun polypropylene is being made into masks with the support of the University of Florida. Dr. Bruce Spears a professor for anesthesiology the U of F College of Medicine recommeded the use of this product based on the manufacturer's recommendations. He stated that the masks are 4% more effective than the N95. This information is on the University of Florida website. I am a University of Iowa RN and have a BSN. I have been sewing many years also.

A study into the effectiveness of home made face masks done by I think it was Cambridge University in the UK showed that any more than 2 layers of fabric made negligible effects on the effectiveness of the mask. On particles the size of SARS2 nCoV, no matter the number of layers, woven cotton rarely blocked more than about 50-60% of the air born particles. This style of mask only really shows it's effectiveness when everyone wears them and uses them as a method of slowing the spread rather than a method of protecting the wearer from infection. But as the aforementioned study left in it's foot notes "A mask is better than no mask".

Thank you for posting this. On a related note, existing face masks can be treated with polyethelyneamine and or catechin, an African plant, to create an effective viral blocking mask; Here are some selected citations; "Studies published by Tiliket et al. and Catel-Ferreira et al. in 2015 demonstrated a cellulose based material for airborne virus filtration in which a low-cost non-woven cellulose material (Kimwipes) were chemically modified by coating them with polyethylenimine (PEI) or grafting in an antiviral agent; catechin." "The filtration efficiency of the modified filter media was first tested on aerosolized T4D viruses (Enterobacteria phage T4, Doermann’s strain T4D). Then the treated filter was inserted inside a commercial medical mask in place of its cellulose layer and the reconstructed mask was challenged with TD4 aerosols to evaluate its virus removal efficiency." "Both treatments significantly improved the virus capture factor (ratio of upstream to downstream PFU contents) of KW cellulose wipes and of reconstructed commercial masks when compared to original masks and to masks reconstructed with untreated wipes." Tiliket, Ghania & Ladam, Guy & Nguyen, Trong & Lebrun, Laurent. (2016) published "Polyethylenimine surface layer for enhanced virus immobilization on cellulose." Search for that article online. Polyethylenimine (PEI) is a polycation, which is readily adsorbed by the cellulose matrix from a 0.1% w/v solution in NaCl 0.2 M (ca. 100 ng cm−2). Further PEI adsorption steps at higher PEI concentrations induce a linear growth of the PEI films, suggesting that free adsorption sites still exist after the initial adsorption. The adsorbed PEI chains are resistant to variations of the ionic strength up to NaCl 1 M. "Promisingly, the adsorption of T4D bacteriophages are 15-fold more efficient onto the PEI-treated fabric, compared to the native regenerated cellulose films, as measured by QCM-D. This confirms the strong affinity between the negatively charged viruses and PEI, even at low PEI concentration, probably governed by strong electrostatic attractive interactions. This result explains the remarkable improvement of the affinity of medical masks for virus droplets when one of their cellulose layers was changed by two-PEI-functionalized cellulose-based filters." Polyethylenimine is commercially available. This should be of interest to DIY mask makers.1REPLY

I will add more to this post as soon as I can. Please add comments and suggestions. The source for these posts is the Open Source COVID19 Medical Supplies of Facebook.

This post is part of a series of posts about DIY/Open Source PPE.

Updated April 3 12:01 AM

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This is not related to the post above.