Homemade Medical Ventilator

#homemademedicalventilator

In the time of COVID-19 pandemic (Coronavirus) there is the lack of Medical Ventilators all around the world. Currently there are many virus outbreaks and cities and countries have broken supply chain to buy any material. Professional Medical Ventilators have a high price and it is not easy to buy hundreds of them.

Goal for this project is to create a Homemade Medical Ventilator from the material we have it available all around for low price so that we can reproduce it anywhere fast.

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Legal notice: I do not accept any responsibility. Make it and use it on your own risk. This project is not finished yet, I do not have a working prototype yet, I do not know if it will help or not (it may even kill a healthy men when not created/used properly). But I am publishing the idea anyway if someone will see it in place with coronavirus outbreak and will be able to create it successfully and will save any life with it...

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Few citations from wikipedia:

"using an automotive wiper motor to drive the bellows used to inflate the lungs"

"While modern ventilators are computerized machines, patients can be ventilated with a simple, hand-operated bag valve mask."

Source: https://en.wikipedia.org/wiki/Medical_ventilator

"An endotracheal tube (ET) can be inserted by an advanced practitioner and can substitute for the mask portion of the manual resuscitator. This provides more secure air passage between the resuscitator and the patient"

"When using a self-inflatable bag, even experienced anesthesiologists in our study may have performed ventilation with too short inspiratory times and/or too large tidal volumes, which resulted in stomach inflation in some cases." The study goes on to state that "Stomach inflation is a complex problem that may cause regurgitation, [gastric acid] aspiration, and, possibly, death."

Source: https://en.wikipedia.org/wiki/Bag_valve_mask

• Bag valve mask (it is already made of materials that are human friendly, it has all the valves and it has a plug for oxygen)
• ET endotracheal tube (optional)
• Automotive windscreen wipers motor (it is designed to long run)
• Windscreen wipers mechanism (you can unmount it from your car)
• 12V power supply
• Wooden panels
• Hinges
• Angle bracket (to mount a motor on it)
• Foam (with the right hardness to limit max pressure)
• A controller to have the right beat (simple R/C circuit OR NE555 timer OR Arduino + transistor/optocoupler + relay)

It is convenient to use medical Bag valve mask because it already includes:

• valves (we user medical ventilator to push air into lungs only, but not to vacuum it out. patient breaths out by him self ant breath out air goes out of this bag, so that it is filled with air and oxygen againt for next breath)
• connection to oxygen (there is a tube and additional small bag to connect it to oxygen supply)
• it is made of materials, that do not irritate the patient (for some potential allergy or something)
• not hard to get it: any ambulance, health center, hospital or local medical supply store should have it

In this project we use automotive windscreen wipers motor and mechanism. It is easy to get it anywhere on the world. You can even unmount it from your car.

Some useful characteristics:

• it has a gear for slower speed
• integrated end-switch to control the end position
• it already has a mechanism that goes up and down

How to control this device:

• to control the volume of air that should be pushed, you can mount the motor higher up or lower down
• to control the pressure of air you can wire automotive windscreen wipers motor to pin for fast or slow speed (for fine-tune you can change the voltage of the power supply)
• to control max pressure you can add some foam on mechanism pressing to the BVM (you can not expect that every breath out will have exactly the same volume. so the volume needed to push into lungs will not be exactly the same every time. professional machines use precise pressure sensors and complex circuits to control that. however the most simplified way to control the max pressure it can be used some foam pressing on the bag. when the pressure will grow, foam will start squeezing and stop pressing the bag)

We have to control the beat with the respiratory rate of 10-12 respirations per minute.

To control the motor we have to generate a pulse on 5 seconds. When pulse will be generated the motor will start rotating. Then it has to rotate till the end position. There is the end switch already integrated in the motor. We use this switch to rotate the motor to the end position and then it stop. It will start again with next pulse received.