Low-Cost Open Source Ventilator or PAPR

Johnny Lee

Last update: Dec 21, 2022

Related tags

CLI Tools ventilator

Overview

Last updated 2020/04/19

Low-Cost Open-Source Ventilator-ish Device or PAPR

NOTE: This is currently an independent project not affiliated with any commercial institution.

In the event that COVID-19 hospitalizations exhaust the availability of FDA approved ventilators. This project documents the process of converting a low-cost CPAP (Continuous Positive Airway Pressure) blower into a rudimentary non-invasive pressure support ventilator that could help with breathing during respiratory distress. It's an evolving project, but in it's current form, it most aligned with the definition of a non-invasive pressure support BiPAP ventilator.
This same project can also be used to create a reasonable low-cost Powered Air Purifying Respirator (PAPR) with filter adapter and mask. PAPRs are effective pieces of Personal Protective Equipment (PPE) that could be helpful to caregivers. PAPRs will also be in extremely short supply and are much less risky and controversial than a DIY ventilator. You may be able to save many more lives by building a PAPR that protects a caregiver than a mediocre ventilator for one patient. Unless you are able to participate in the detailed engineering and medical discussions regarding mitigating the risks of high pressure ventilation, I would highly recommend focusing on the PAPR version of this build.

WARNING/DISCLAIMER: Whenever possible, please seek professional medical care with proper equipment setup by trained individuals. Do not use random information you found on the internet. I am not a medical professional, just a random person putting information on the internet. There are significant risks associated with using a high pressure BiPAP as a DIY ventilator without medical supervision.

What are the primary risks of a DIY ventilator?

Being viewed as a viable alternative to available professional care or delaying seeking professional care. This should be viewed as an educational resource or a last resort option only. Community driven engineering efforts like this run the risk of making it "too easy to be harmful" which would be a bad outcome.
Using non-invasive interfaces (such as masks and mouth pieces) can create aerosolized virus infecting many others in clean environments. Infecing yourself or other healthy individuals multiplies the problem. Usage should be restricted to places where aerosolized viruses are already abundant (lots of unmasked symptomatic individuals), COVID wards, or in isolation. NOTE: Self-quarantine in an apartment or multi-unit residence is NOT proper isolation due to potential shared ventilation and sewage.
Giving too high a pressure (such as 20cmh2o and up) without observing lung compliance can cause rupture of infected lung tissue. This design currently lacks several features that provide enough feedback to a caregiver to monitor that risk.
See more detailed discussion of these risks and potential engineering/administrative controls to address them.

Too risky? Build a low-cost PAPR!

One more time, a low-cost Powered Air Purifying Respirator (PAPR) is highly valuable for caregivers, and may have much more positive impact than bulding a mediocre ventilator.

Want to build something without electronics? Consider building PPE

There are many efforts making DIY face shields
There are many efforts making face masks from home materials. We've also posted some of our results of testing filter performance of different materials.

Hardware Requirements and Medical/Government Request for proposals:

Requirements doc from Code Life Ventilator Challenge - Montreal General Hospital Foundation (Canada)
Requirements from Gov.UK - Rapidly Manufactured Ventilator System (UK)

Current Hardware Capabilities

This rudimentary design can have a programmable breathing rate (ex: 10-16/min)
It can have a programmed Positive End-Expiratory Pressure (PEEP)
The blower is physicially able to hit a peak airway pressure of up to 45cmh2o. However, going above 20cmh2o can be DANGEROUS.
It cannot yet hit a target tidal volume. What level of accuracy in volume would be sufficient? 100mL? 10mL?
It does not regulate fractional oxygen (FiO2). But, a down stream connection to an O2 tank is possible to boost O2 concentration with manual flow adjustment. I could use a pointer to a low cost O2 sensor.
It is lacking in many other ways, but it is possible that this limited functionality could be helpful when better care is not available. It is also a starting point for making progress. Critical features can be added over time.

Here's a youtube video walking through the components as of 2020/03/17:

There are also many other efforts in this direction. Here's a short list of them Thanks! discussion

To Do's - aka Things I could use help with

I've moved the To Do's to a Wiki so it is easier to update. Please check there if you are interested in helping. Thanks to those that already have!

To provide comments/feedback/offer help, create a new issue on the project. Thanks!

Useful References/Docs about the supply shortages, and guidance around unapproved devices:

There is a growing list of useful documents around guidance for use of unapproved equipment, and information around estimated shortages of both ventilators and personal protective equipment. We have moved them to References Wiki to enable better updates to make it easier to maintain.

Materials

Continuous Positive Airway Pressure (CPAP) devices are commonly used by individuals to treat sleep apnea. As a result, CPAP blower components are fairly abundant. Used ones are available on eBay and new ones on Alibaba. In many of these devices, the blower is a simple BLDC motor that can be driven with an Electronics Speed Controller (ESC) used by quadrotors and RC cars. The one I used is pulled from a Respironics REMStar. In volume, these blower components can be under $20.

Alternative: test a 12v inflator pump which is even more abundant.
Alternative: print a blower [discussion]

Arduino Compatible Nano/Clone to control the motor speed, breathing cycles, and handle user input. Download the Arduino IDE to program the microcontroller software.
Brushless DC Motor Electronic Speed Controller capable of at least 10A.
Button or switch for input control. The code cycles through 5 levels of pressure. Double click to switch between CPAP and BiPAP/Fixed PEEP mode.
12v DC power supply that can handle at least 5A. The blower works pretty hard, and the breathing cycles can create voltage drops which will reset the Arduino if the supply is not strong enough.
Tubing and face mask. If you search for CPAP face mask, you'll find many options/suppliers. A full face mask that covers both the mouth and nose will enable pressure buildup in the lungs. As an alternative, see below for draft 3D printable parts.
Optional inline 12v battery backup.

Building

This is the full system with mask, tubing, pump, 12v battery, and switch for input. However, I would strongly recommend running this with a DC power supply since the battery will only last about 3-4 hours. Wearing the mask with a dead battery could cause dangerous CO2 build up. This particular battery can charge and supply power at the same time, acting as an inline battery backup to wall power.

Below is a close up of the extracted blower. It is simply a BLDC motor driving a blower fan. A small ESC and Arduino are attached (technically a Teensy2.0++, but the code has now been changed to an Arduino Nano). It has a 3d printed tapered hose adpater on it to fit in the hose. The microcontroller software can be programmed with the Arduino IDE. The software goes through a short initialization sequence to configure the ESC; it then starts at the lowest CPAP setting. You can use the switch to cycle through pressure levels, and double click to cycle through operating modes.

Here is the schematic for the electronics. As you can see, it is very simple with only a few parts. A slightly modifed version that is able to sense the blower current is here.

Face mask / Tube Adapter

Since I have a CPAP, I happen to have a Resmed AitFit F20 mask that I can use. This is quite comfortable and covers both the nose and mouth to make a good seal. However, if you can't get a mask, below is a prototype mouthguard that fits in the category of not-so-great-but-usable-if-you-have-a-lot-of-tape. I am using some elastic straps as head gear. However, in order to get a good air seal to get enough positive pressure, this would require some tape. A little bit of leakage is actually desirable to allow CO2 to escape near the mouth and nose to flush out the air over time; this prevents CO2 from being stuck in the tube. WARNING: wearing this sealed to the mouth with tape without power may cause dangerous CO2 build up.

Download the [3D model] [Fusion 360 link].

Pressure Testing

This is a picture of my test rig to measure the output pressure. It is a U-shaped tube with an attached measuring tape to check displacement of water. The actual liquid displacement is 2x the measured line since liquid is being pushed downwards an equal amount on the other side of the U, doubling the displacement. (I think this is the correct way to measure). At full blast at 12v, it is achieving 45cmh2o. WARNING: Going above 20cmh2o can be DANGEROUS. So, these blowers are plently powerful.

Here are some images showing the dislacement of the liquid at different speeds. I happen to have Diet Dr. Pepper on hand which makes it easier to see the liquid level rather than just plain water.

Here's a video of the blower pushing a breathing cycle of 16 cycles/min oscilating between 12 and 22cmh2o.

Air Filtration - PAPR Option

An open air blower into someone's airway isn't great. If possible, some filtration is preferred. These parts were originally used for a DIY Powered Air Purifying Respriator (PAPR). However, adding a filter will definitely affect the output pressure. It will depend on the blower you have if the motor can handle the additional load. Given the headroom of the blower I tested, these CPAP blowers can probably handle the filter and still hit the target pressure. However, I haven't done long term thermal testing at high pressure and with a strong filter. These adapter plates can be attached with liberal amounts of hot glue and wrapping the unit in vinyl tape to get a reasonably airtight seal. My blower's enclosure was not air-tight, so it is difficult to guarantee that 100% of the air is coming only through the filter. Setting the blower to a low CPAP pressure, and leaving the face mask vent holes open will allow it to function reasonably as a PAPR.

This is an adapter plate for a 3M P100 or N95 face mask filter cartridge. Download [3D model] [Fusion 360 link]

This is an adapter plate for a NATO 40mm gas mask filter cartridge. These fitlers are available with CBRN ratings which are needed for viral and bacterial defense similar to those approved by the CDC/NIOSH. Download [3D model] [Fusion 360 link]

This is an option for an inline filter [discussion] that looks easy to install, and would be helpful for non-CPAP blowers.

Update Log

Click here to see updates.

Comments

EUREKA! We discovered the at-home treatment for coronavirus that works! PLEASE READ CAREFULLY AND WATCH THE VIDEO
How to Kill the Virus With Hot Air.zip

I have recommended for decades that anyone feeling the first sign of a cold or flu, to take an immediate hot bath to kill the virus and many of the symptoms diminish much more rapidly. This has proven to be very effective in many research studies.

The problem is that the coronavirus can withstand temperatures that are too hot for the normal person's body. The coronavirus dies at a temperature of 130F to 133 F (56C). At hot bath, will not get the body to that temperature inside.

It turns out that the coronavirus lodges in the sinus cavities before the pneumonia starts. This is why the test for the coronavirus is done by sticking a swab up your nose and you can be without symptoms for up to five days after infection. Once it infects your lungs, you are likely to get extremely ill.

HOT AIR will kill the coronavirus. We can safely breathe in hot air that is a temperature of 130F (56C). People who live in desert environments, where it gets really hot, do this all the time. People who sit in a dry sauna regularly breathe in air that is 140F+. If you have a dry sauna at home you can use it. If you do not have a dry sauna, you can use a simple hairdryer, IF you use it carefully.

I heard about using a hairdryer to make hot air, but my concern was that people would burn their faces. Now, we have a SAFE technique that can be done at home with just water, a clean water spray bottle, and a hairdryer.

Use the water spray to moisten the face.

Then, use the hairdryer on the lowest setting and use one hand to block some, not all, of the air coming in the back of the hairdryer to reduce the volume of air.

Wave the hairdryer in front of your face but do not let it blow directly in one place to burn you. You can feel the air get hot.

Breathe in the dry, hot air for five minutes through the nose with the mouth closed.

Close your eyes as much as possible during the procedure (peeking only if you need to) to keep them from drying out. Use eye drops afterward, if your eyes become dry.

Attached is a video showing the safe technique. Please watch it carefully, to the end, to learn how to do this properly.

If you experience fever, headache, dry cough, or shortness of breath, these are the signs of the coronavirus infection. Fever is usually the first sign. Take your temperature regularly, and take the temperature of the ones at home with you as well. If you do not have a thermometer, use your hand to touch your forehead. You can easily feel a strong fever this way.

Use this breathing dry hot air technique the moment you notice a fever beginning. Continue to use it as described in the video.

You will not kill all the virus and you will still be infected, and you still may get sick. However, you will lower the viral load as it enters the body through the nose. This will help your immune system withstand the viral attack.

I have verified the information in this video by reading the scientific research papers (published and peer-reviewed) and it is 100% accurate.

Precautions:

If you are sick, always consult with a health practitioner over the telephone. This is not a substitute for receiving adequate medical care and not medical advice, only a healthy defensive technique that you must do properly, to do it safely. YOU CAN BURN YOUR FACE IF YOU DO THIS INCORRECTLY! Use caution and follow the instructions in the video. If you feel discomfort STOP! Wave the hairdryer to have it create hot air in front of your nose that you can breathe in. Do NOT hold the hairdryer still, while it is pointed at your face. Elderly people and children need assistance to perform this technique correctly.

Sources: Elevated body temperature helps certain types of immune cells to work better, evidence suggests
https://www.sciencedaily.com/releases/2011/11/111101130200.htm

Heat at 56°C kills the SARS coronavirus at around 10000 units per 15 min https://www.who.int/csr/sars/survival_2003_05_04/en/

Thanks to Robert in Romania for finding this video for us.

PLEASE PASS THIS INFORMATION ON TO OTHERS We can defeat this virus with accurate information.
opened by willivision 19
Motor controller wire identification.

The motor controller shown in the link has on the input side a large red and back wire (presumably supply and ground) and three smaller wires ending in a plug which are not identified. They are brown red and yellow. It appears from the circuit diagram only two are used sig-esc and v-esc. Can anyone identify which these are, or how to discover? Thanks

opened by lebothan 4
FYI: Washington Hospital version of improvised PAPR

I'm trying to get a hold of you about your PAPR designs. Specifically, I'm organizing a group of (loosely vetted) people who are seriously working on improvised PPE.

Halo design video, and 3-d print files Specifically, these doctors/HCP solved a lot of the PPR issues: https://www.youtube.com/watch?v=JMXP8jAmDKA&feature=youtu.be

Innovations: existing inline viral filters (widely available in hospitals) and use of disposable plastic bag for hood.

I'm hocho on this discord server: https://discord.gg/H3jUmar (all welcome, and expect to be vetted lightly) or [email protected] or 607-279-3623 (text/phone)

In it to make an impact and move the needle. Working 12hr days 7 days a week. Mainly, i'm organizing and connecting people.

opened by chonghorizons 3
Over pressurization

I don't think that 20cm h2o is very high, nor would cause any lung trauma. My personal NIV mask setup tops out at 25cm and isn't even fully inflating my lungs. Cough assist machines go into the 60s-70s of pressure, even if it is for brief periods.

All this to say, we likely will have problems getting high enough pressures, don't need to really worry about over pressurization. As a FYI, I'm from Washington State where Covid-19 is out of control. My pulmonologist is one of the top in the nation (Dr. Joshua Benditt) and we talked about too high of pressures on my ventilator. He wasn't concerned.

opened by fireb0lt 3
Link to colab notebook with data visualization

Made a Colab notebook for visualization of the data: https://colab.research.google.com/drive/1iFMmMMrg_3OeifzJikT75fy4ev84W235

Upside of using Colab: instantly usable by anyone with an internet connection, no setup required.

Downside is it's not tracked in git, but I think should be OK as long as the data paths don't change. (Instead strictly add data paths.)

opened by peteflorence 3
Use Decathlon or similar diving mask as C-PAP mask

Hi,

In Europ, we have a project to mod a diving mask to a C-PAP mask --- It's tested and in use now in Italy ---

See link https://www.isinnova.it/easy-covid19-eng/

Video https://youtu.be/w4Csqdxkrfw

By https://www.isinnova.it/

opened by PaulStefaan 2
First draft of README.md

I think it's a good time to capture real-life references and other things related to model development. @jcl5m1 can you think of any other points to be added?

opened by RomanTheLegend 1
Helping out with Todos

Hi @jcl5m1 @nasocializes , I'm an EE undergrad at UCLA, with some knowledge of PCB design, matlab, python, and programming arduinos. I was looking over your documentation, and would like to help out with some of the to dos. Having limited resources and no med background, I'm not sure if I can recreate and test aspects of your todos in ways useful. But I'm available if you'd like to offload any busy work in modeling and design especially with electronics, because I'd like to make this as easy for you as possible. Any chance we could briefly talk through github or email ([email protected]) would be awesome. Thanks in advance and great work.

opened by kenryhou2 1
Jupyter notebook for visualize.py

HI @jcl5m1

I see that you are already have ventilator_data_analysis.ipynb But perhaps, to keep track of changes in the same repository of visualize.py, a Jupyter notebook might be helpful. Will later put a PR for that :-)

opened by mxochicale 1
Offering help with the TO-DOs

Hello Johnny,

Very inspiring what you are doing, myself and a team of Biomedical Engineering Senior year Students would like to help with the TO-DOs, we have a pretty good background with both the Medical and the Engineering aspects of the electro-mechanical ventilation systems and would gladly invest our times in such project.

Email me if possible at [email protected]

opened by MostafaAbdelmegeed 1
AG Inductries Generic CPAP outlet filter CAD model draft

Based on this model: https://www.cpap.com/productpage/generic-bacteria-filter-cpap-machines-10-pack

As far as I've seen all of these parts have same "ports", that is Male Connector End Outer Diameter: 15mm Female Connector End Interior Diameter: 22mm

Submitting as draft because I do not have filters themselves to check the dimensions (waiting for delivery) Also because I set wall thickness to 2.5 it will somehow affect the volume of airflow, so it might require a bit of an extra pressure to produce same throughput.

Recommend to print it with transparent PTE-G

Additionally attaching Fusion360 project in case if somebody could test and do the adjustments sooner

opened by RomanTheLegend 1
I got inspired from your ventilator

Johnny I got inspired from your ventilator and I built my own. Let me know what you think of this one: http://magicventilator.com/

Here is some information on how it works: http://magicventilator.com/2020/07/12/how-the-magic-ventilator-works/

Let me know what you think?!

opened by magicventilator 4
Add issue and pull request template

I strongly believe adding pull request and issue templates is a good change for this project, as this would standardize and encourage new contributions.

opened by breno-helf 0
Create a CODE_OF_COUNDUCT.md and a CONTRIBUTING.md

I strongly believe you guys should create a CODE_OF_CONDUCT.md and a CONTRIBUTING.md. Those files would encourage new people to collaborate on the project, and will make it more aligned with open source guidelines. I can help to create those files and give examples if needed.

opened by breno-helf 3
Project Updates
Hi Johnny,

Congratulations on your swift and proactive response to the Coronavirus crisis that is gripping the world. I couldn't find a public email so I hope this is a suitable place to post this message. I work with the Technology Exchange Lab (www.techxlab.org) and I have followed your progress with great interest. We are a nonprofit based in Boston and host a database of sustainable, cost-effective technology that can change the lives of people living in poverty.

The new COVID-dedicated section of TEL's website collates and curates up-to-date information on products, prototypes, and design specifications of ventilators and other equipment. The data are, as always, free to all, in a user-friendly yet information-packed format. As a new initiative that meets our criteria, your project has its own dedicated entry on our site (it is listed as both a ventilator project and a PPE project due to its potential use as a PAPR)

https://www.techxlab.org/solutions/low-cost-open-source-ventilator-ish-device-or-papr

I have looked through your published specs and I am looking for any updates to the following questions. Any additional information that you can supply will assist other projects around the world who hope to work quickly and efficiently to solve the ventilator shortage problem.

Is this a Volume Control Ventilation, (VCV), Pressure Control Ventilation, (PCV), or Pressure Regulated Volume Control (PRVC) device?

What is the plateau pressure range?

What are the I/E ratio settings?

What is the Tidal Volume Range?

What is the respiratory rate range?

How long can it run without interruption?

The solution page for your project on our site has an update form, please feel free to add any updates there or contact me directly.

I look forward to hearing from you soon,

Éadaoin Ilten Operations Manager www.techxlab.org
opened by eadilten 0
Cpap ventilator

Consider adding my HC-05 and Android Phone Bluetooth Control Interface to your Project

Adds CPAP, BiPAP, and pressure sensor sync modes. High and low pressure and High and Low delays are all adjustable thru sliders.

Link Address to public repository .... https://github.com/CDtice/Ventilator-Bluetooth-Control-Interface

opened by CDtice 0

Low-Cost Open Source Ventilator or PAPR

Related tags

Overview

Low-Cost Open-Source Ventilator-ish Device or PAPR

What are the primary risks of a DIY ventilator?

Too risky? Build a low-cost PAPR!

Want to build something without electronics? Consider building PPE

Hardware Requirements and Medical/Government Request for proposals:

Current Hardware Capabilities

To Do's - aka Things I could use help with

Useful References/Docs about the supply shortages, and guidance around unapproved devices:

Materials

Building

Face mask / Tube Adapter

Pressure Testing

Air Filtration - PAPR Option

Update Log

Comments

Owner

Johnny Lee

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