Pumping air in Covid lungs

RE: Pumping air in Covid lungs

royce_jp — Sat, 18 Apr 2020 19:49:42 GMT

I assume that we are going to use a BVM (Bag valve mask) aka Ambubag, for the actual ventilation

This already has a valve for over pressure, and a oxygen inlet and reservoir.

We will require an HMI that will allow the user to set the following parameters (this could be a 4 line alpha lcd with some keys or potentiometers):

1. Breaths per minute (BPM). This will determine the interval between 2 compressions, Typically 6-10 secs.

2. The intensity of a compression (aka Tidal Volume).

This will determine the angle through which the motor moves (smaller angle = lower compression).

This setting is needed for adult vs infant lungs etc.

This could be calibrated with a pressure gauge (BVMs with pressure gauges inbuilt also exist) but in practice, adults typically need 500ml air per compression .. (Actually 7 ml x body mass in kg if there is time to calculate).

It is easy of the volume of the bag is known - If using a 1000-mL volume bag, squeeze only halfway to obtain the correct tidal volume.

In practice, you can adjust the setting to cause a bag compression just large enough to cause the chest to rise.

3. Some kind of alarm to detect abnormal conditions like leakage, blockage etc.

4. An advanced model might offer an option to route the air through a water bath at around 36*C (Temperature sensor/ADC required) to maintain humidity and temperature of the mucus inside the nasal area. However this is required ONLY in invasive ventilation where the nasal mucus is bypassed.

5. Further advancement might be processing the exhaled air to avoid aerosoling of infection and filtration at the air inlet (not the Oxygen inlet).

Both these will require modifications to the BVM.

RE: Pumping air in Covid lungs

14rhb — Fri, 03 Apr 2020 17:39:08 GMT

A simple and low-cost 'over pressure' device could be to T off the high-pressure supplied air and take via a tube 400mm below the surface of of a jar filled with water. As the pressure goes up the water in the tube would displace and excess pressure would release as bubbles from the tube. Lower max. pressure would be achieved by lowering the water level.

I get this isn't perhaps a clinical solution but it could prevent lung damage.

RE: Pumping air in Covid lungs

Fred27 — Wed, 01 Apr 2020 12:03:36 GMT

You've done some impressive stuff, but ventilators are way more complicated than just an air pump. Even a simpler CPAP is complex. I found this was a very informative article on ventilators and why trying to build one may be dangerous.

https://hackaday.com/2020/03/25/ventilators-101-what-they-do-and-how-they-work/

I'm not trying to dampen your enthusiasm and I applaud your work, but please be very careful if you get as far as testing it on a person!

RE: Pumping air in Covid lungs

dubbie — Wed, 01 Apr 2020 11:53:51 GMT

Looks like a good project. Very innovative.

Dubbie

RE: Pumping air in Covid lungs

jw0752 — Wed, 01 Apr 2020 02:32:32 GMT

This is a great use of trapped at home time. Congratulations.

John

RE: Pumping air in Covid lungs

ankur608 — Wed, 01 Apr 2020 02:18:58 GMT

Wow, a 5V respirator out of drone-parts!...that's innovative.

RE: Pumping air in Covid lungs

14rhb — Tue, 31 Mar 2020 15:53:11 GMT

You are a genius - great work.