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HFNO (High Flow Nasal Oxygen) splitter

This page contains an overview and history of the development. All final design files and all documentation is available at If your system does not exactly match the current drawings, please contact us and we could look into local adaptions.

Treatment with HFNO (High Flow Nasal Oxygen) is a critical treatment in COVID-19 and if timely and correctly used may prevent need for respirator treatment. The supply for such system is limited. In Sweden the most common HFNO is called “Airvo 2” (or popularily called “Optiflow”). Current guidelines for COVID-19 indicates treatment at 30L/min wheras the system is capable of delivering 60 L/min. The system could therefore be used to treat two patients if there are not enough systems.

This project aims to develop a splitter and perform proper risk analysis.

Overall design

The Airvo system connects to the patient with a proprietary electrically heated tube. This tube is still used, but instead of directly attaching the nasal mask tube, a T-splitter is inserted and the flow can be split the flow to two patients. The two patients needs to be reasonably well matched to each other such as body size and lung resistance.

The T-splitter design is shown below.

Below the splitter two bottles are attached to collect potential condense water. The splitter is intended to be placed on the holder to the Airvo 2 system and to be a lowest point to ensure condense water is collected in the two bottles.

Flow simulations have been made to show flow distributions and to ensure that there is minimal risk for cross contamination between patients.

3D printed prototype

Project timeline

  • 2020-04-11 All documentation in place and system ready for use.
  • 2020-04-07 Ready for testing
  • 2020-04-05 Documentation work
  • 2020-04-03 First full risk analysis finished
  • 2020-04-02 Second 3D print, documentation work
  • 2020-04-01 Second design iteration
  • 2020-03-31 First 3D print prototype
  • 2020-03-30 First draft medical description
  • 2020-03-28 Flow simulations ready
  • 2020-03-28 Risk analysis starts
  • 2020-03-28 3Dverkstan makes a 3d scan of the propriety connectors
  • 2020-03-27 Dimensions established
  • 2020-03-26 Project initiated

Involved personal

Jesper Fogestam Hessius, Region Västmanland (Västerås) Project initiator and MD in internal medicine and cardiology
Per Nordqvist, MT, SUS, Region Skåne Engineer, regulatory, documentation, risk analysis
Einar Heiberg, Klinfys, Lund Engineer, 3D printing, regulatory, all-in-all
Petter Frieberg, Klinfys, Lund MD, Engineer, Flow simulations
Erik Cederberg, 3DverkstanCAD and design
Erik Ekbom, BFT, SUS3D printing
highflowsplitter.txt · Last modified: 2020/04/28 14:47 by