In-line, Adjustable PEEP Valves

In-Line, adjustable PEEP valves will allow to set individual PEEP values for each patient.

Add an in-line, adjustable PEEP valve on the expiratory limb of each patient. 

An in-line, adjustable PEEP valve is also a good candidate for a flow restrictor on the inspiratory limb, see our flow restrictor page >>

An in-line PEEP valve is a PEEP valve for which the vented air is collected—as opposed to vented to the room—such that the vented volume can be passed on to the ventilator through the remaining parts of the expiratory circuit. For almost all ventilators the individual PEEP valves will have to be placed in-line: most ventilators rely on a comparison between outgoing and incoming volumes to detect leaks, and some ventilators, especially anesthesia ventilators, will not even work when they don’t receive back all of the volume that has flowed out into the patient’s circuits initially. 

However, most commercially available, adjustable PEEP valves we encountered are not in-line. We did find some adjustable (magnetic) inline PEEP valves, but they are not for sale everywhere in the world, and they did not perform well in our initial tests. We have therefore designed several options to convert adjustable PEEP valves to in-line valves. We are currently also testing a completely printable in-line, adjustable PEEP valve. 

 

Advice and comments from our contributors

Please note that the obtained individual PEEP will be the sum of the ventilator PEEP and the PEEP set by the individual PEEP valve. For example, to set a PEEP equal to 12cmH20 for patient A and 16cmH20 for patient B, with an adjustable PEEP valve with minimal value 2cmH20 PEEP, one could set up the ventilator and in-line PEEP valves as follows:

  • ventilator setting at PEEP = 10cmH20
  • individual PEEP valve for patient A at 2cmH20, resulting in individual effective PEEP = 12 cmH20
  • individual PEEP valve for patient B at 6cmH20, resulting in individual effective PEEP = 16 cmH20

Alternatively, one could set the PEEP on the ventilator to zero, and use only the individual PEEP valves at, e.g., 12 cmH20 and 16 cmH20. In that case, please note that some ventilators always provide a minimal PEEP, even when they are set to zero.

The effective PEEP is additive because air can only flow through the PEEP valve if the pressure before the valve is larger than the pressure behind the valve, plus the added pressure threshold resulting from the spring in the valve. Since the pressure behind the valve equals the PEEP set by the ventilator, the effective individual PEEP value thus equals the sum of the PEEP on the ventilator and the PEEP set on the individual valve. 

A reliable in-line PEEP valve could in principle replace the one-way (‘check’) valve on the expiratory limb.

Important properties

  • adjustable: should be adjustable without having to disassemble the circuit
  • safe materials: all 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 
  • durability: should reliably function for at least 2 weeks

Current Status

We’re working on a unified test protocol.

List of in-line, adjustable PEEP valves

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

Commercial in-line adjustable PEEP valve

3D printable conversion to in-line valve by Nate Surls

3D printable conversion to in-line valve by Arun Agrawal and James O’Neal

3D printable Conversion to in-line valve by Tom Vrysen

3D Printable Conversion to in-line valve by Dominik Textor and Stefan Stahl

Fully 3D printable in-line PEEP by Dominik Textor and Stefan Stahl

Conversion to in-line valve by Leonard Bunting

Conversion to in-line valve by Steven Roy

Fully 3D printable in-line PEEP valve by Simran Kaur Matta and Peter West

Commercial in-line (magnetic) adjustable PEEP valve

Advantages

Commercially available product.

Drawbacks

  • Might be only for sale in US.
  • Introduces “noise” into the pressure waveform which makes it much more difficult to interpret.

Materials

Depends on brand.

First test

Tested by Dr. Greensweig, MD.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

3D Printable conversion to in-line valve by Nate Surls

Advantages

  • Open source

Drawbacks

To be determined.

Materials

See general guidelines on 3D printing and preferable materials

First test

Dr. Greensweig, MD.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

3D printable conversion to in-line valve by Arun Agrawal and James O’Neal

Advantages

Open source

Drawbacks

To be determined

Materials

See general guidelines on 3D printing and preferable materials

First test

Dr. Agrawal, MD.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

3D printable conversion to in-line valve by Tom Vrysen

Advantages

Open source

Drawbacks

To be determined

Materials

See general guidelines on 3D printing and preferable materials

First test

Dr. Mergeay, MD.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

3D printable conversion to in-line valve by Dominik Textor and Stefan Stahl

Advantages

  • Open source.
  • Transparent enclosure (PEEP valve visible).
  • 3 parts only, 1 printed, 2 commercial (O-ring, drink bottle) / no glue.
  • Tight seal with commercial O-ring.
  • ISO 5356 conical connections.
  • Printable with FDM printers, no supports.
  • Valve can be adjusted without opening the containment
  • Enclosure can be reused/PEEP valve can be exchanged if needed.
  • Both 30 mm female and 22 mm male valve versions can be used on the same enclosure.
  • Introduces no twist into the tubing system.
  • SLA printable.

Drawbacks

  • 3D-printed file has to be adjusted to other bottle models

Materials

See general guidelines on 3D printing and preferable materials.

First test

Test results and protocol available soon.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

Fully 3D printable in-line PEEP by Dominik Textor and Stefan Stahl

Advantages

Advantages:
  • Open source
  • Fully printable inline PEEP valve
  • Several spring options: printable spring, bike hub spring (international near-standard), laser cut flat spring
  • Several seal options: Flat rubber seal (best option), 3d-printed TPU
  • Optimized for 3d-printing with all printers, no supports, easily adjustable to meet tolerances
  • Similar behavior to commercial PEEP valves
  • Tight seal to outside with commercial O-ring and ISO 5356 conical connections 22mm
  • Also usable as flow restrictor and check valve

Drawbacks

No FDA-approved medical product.

Materials

See general guidelines on 3D printing and preferable materials.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

Conversion to in-line valve by Leonard Bunting

Advantages

  • Open source.

Drawbacks

To be determined.

Materials

PVC

First test

Dr. Bunting, MD.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

Instructional video by Dr. Bunting

Conversion to in-line valve by Steven Roy

Advantages

  • Open source.

Drawbacks

To be determined.

Materials

  • 1 x 2″ diameter central vacuum pipe (transparent preferred)
  • 2 x 2″ diameter central vacuum cap fitting
  • 1 x AMBU PEEP valve with 22mm adapter
  • 1 x 10-32 machine bolt (2″ length)
  • 1 x rubber washer (1/4″)
  • 1 x 10-32 nut
  • 1 x convenient 22mm adapter
  • 1 x low grit sandpaper
  • 1 x epoxy (or other inert-when-dry glue appropriate for plastics)

First test

Dr. Roy, MD.

Independent test

No information about independent test yet.

Send us your test report.

Additional Resources

MATTA-WEST fully 3D printable in-line PEEP valve by Simran Kaur Matta and Peter West

Advantages

  • Open source.
  • Printable.

Drawbacks

To be determined.

Materials

Five 3D printed parts:

  • Valve Body
  • Flapper Valve Plate
  • Adjustment Screw Plate
  • Cover
  • Knob

Can be PLA, PETG or Polypropylene.

Three readily available parts:

  • GE part number 0211-1454-100, Free breathing flapper valve
  • Tractor Supply spring kit #2, compression spring
  • 10-32 x 1in Philips head screw and nut

First test

Dr. Simran Kaur Matta, MD.

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.