One-way ('check') valves

One-way valves ensure there is no backflow between the patient’s circuits. 

Add a one-way valve (or ‘check’ valve) on the inspiratory and expiratory limb of each patient. 

These one-way valves are crucial to prevent backflow in the circuits. If they are not inserted on the correct limbs, any pressure difference between patients will yield a flow from regions with higher pressure to regions with lower pressure. This backflow could take place in both inspiratory and expiratory circuits without one-way valves: for example, a difference in individual PEEP could yield a backflow from higher PEEP to lower PEEP through an inspiratory circuit without one-way valves. 

 

Advice and comments from our contributors

Naturally, it is very important to insert the one-way valves in the correct direction. To avoid errors in urgent situations, it is therefore advisable to use one-way valves that come with a visual indicator of direction, or to mark the correct direction on all the valves beforehand. 

In case there is an extreme shortage of one-way valves, one could use a smaller number of valves in the following situations: 

  • if one patient (out of two) will need a higher PIP and PEEP than the other patient for a considerable time, the one-way valve on the expiratory limb of the patient with highest pressure could be left out, and the one-way valve on the inspiratory limb of the patient with lower PIP and PEEP could be left out as well. 
  • In principle, a reliable in-line PEEP valve could replace a one-way valve in an expiratory limb. 

Current Status

We’re working on a unified test protocol.

Important properties

    • Unidirectionality:  ideally, the valve should let 100% of flow pass in one direction and 0% in the other 
    • Safe materials: all used materials should be safe for breathing purposes and for use with high oxygen concentrations
    • Possible to disinfect: should at least have the possibility to be disinfected with ethanol. 3D printed components should be printed with professional equipment to reduce the chances of bacterial hotbeds forming in filaments and pores.
    • airtight: no air leakage to the room, even if the valve is placed behind filters 
    • low resistance: added resistance to the circuit should be as low as possible
    • durability: should reliably function for at least 2 weeks, at max. 30 breaths per minute
    • flow range: should function in flow range 150ml/s to 1500 ml/s

List of one-way valves

We’re currently still working on a unified test protocol to compare all the different proposed one-way valves. The information given below is thus so far collected ad hoc.

Medical one-way valve

3D printed one-way valve, project open air (cameradactyl)

3D printed one-way valve, Rabbitcreek

3D printed one-way valve, Stephen Gordon

Medical one-way valve

Advantages

  • Already present in hospitals.

Drawbacks

None, unless no visual indication of direction.

Materials

Depends on brand.

First test

n/a

Independent test

n/a

Additional Resources

Example image of how to insert one-way valves by Dr. Mergeay, hospital Geel:

3D printed one-way valve, project open air (cameradactyl)

Advantages

Open source.

Drawbacks

To be determined.

Materials

See general guidelines on 3D printing and preferable materials.

First test

No information on testing.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

3D printed one-way valve, Rabbitcreek

Advantages

Open source.

Drawbacks

Very shallow cavity for the membrane to open into, might restrict the flow.

Materials

See general guidelines on 3D printing and preferable materials.

First test

No information on testing.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

3D printed one-way valve, Stephen Gordon

Advantages

Open source.

Drawbacks

To be determined.

Materials

See general guidelines on 3D printing and preferable materials. The centerpiece can possibly be printed from elastic material, but preferably a 3D printed mold would be made and Silicone would be injected in.

First test

Testing in progress.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

The International Workgroup on Differential Multiventilation

Disclaimer

None of the contributors, or any other person connected with this international working group, can be held responsible for the information provided on these webpages. The content provided on this website might be incomplete or incorrect. The use of the described methods or any other reliance on the information provided by us is solely on your own risk.