[DIYbio] Re: Ventilators

https://youtu.be/eSVbwWANqRI

"Covid 19, multiple patients on one ventilator, with interpatient compliance mismatch compensation."

quote

This is a description of a setup for ventilating multiple patiënts on one ventilator. It is a test setup, we are aware of that. 

This one is for 2 patients, but you can extrapolate the setup to 4 patients by using extra T-connectors. We modified the basic technique for multiventilating already suggested by other physicians ( https://emcrit.org/pulmcrit/split-ventilators/ ), by using a rotary valve on the inspiratory limb for each patient, that can be closed, so you can adjust the pressure and flow to each patient separately with the patient specific valve. 

So the ventilation can be titrated for each patient individually. 

These rotary valves can be purchased in a normal plumbing store or DIY store. The internal diameter of our tubes is 22mm en they fit reasonable well on these kind of valves. We think you can use any type of valve, as long as it can be closed and opened.  This way you can compensate for a compliance mismatch between the patients on your ventilator and titrate the ventilation individually in a rough manner. 

We suggest to use one-way valves on the expiratory limbs because on our ventilators the pressure is redirected from inspiratory to expiratory side trough our ventilator, thus decreasing the effect of the valves.  

To our knowledge this kind of modified system as shown, has not been tested yet in real patients but we believe that it can be a solution in a disaster situation when this is the only option left. This is not for standard situations, only in case of disasters and emergencies when there are too much patients and not enough ventilators. 

Adapting the valves to each patient and adapting the primary tidal volume needs to be done on a clinical basis, with standard monitoring, with arterial blood gases if available and with capnography if available.

This setup has been tested for more than 6 hours continously en with different settings: Volume control, pressure controle and different peep, and it seems that the peep is not lost but is kept in both systems. This needs further testing.

Our test setup has now been functioning for more than 20 hours and seems to keep functioning. 

Special thanks to Dr. Evy Voets and Dr. Luc Janssen of the anaesthesiology and critical care department, Dr. Michiel Stiers (Emergency department), Dr. Harald De cauwer (Neurology department). We would also like to thank Mr. Luc Geens from our technical staff and Ir. Philippe Caers and Ir. Dirk Wenmakers fot the technical support and advice.