We believe the sharing of a single ventilator between multiple patients can be done safer, and with more control and monitoring for each patient individually.

The Differential Multiventilation International Working Group is an international collaboration effort consisting of more than 30 medical specialists and engineers from hospitals and universities in Belgium, the USA, UK, Norway, Switzerland, Australia and Canada.

We compiled this open source differential multiventilation guide to rapidly share our discussions and tests on so-called shared, multi or split ventilation with any healthcare specialist facing an extreme ventilator shortage during the SARS-CoV-2 pandemic.

Splitter More info >
One-Way Valve More info >
Flow Restrictor More info >
Pressure & Volume Measurements More info >
Filters More info >
PEEP Valve More info >
Ventilator More info >
Bias Flow More info >

The General Idea

Introduction

In an ideal world, no one treating patients with Acute Respiratory Distress Syndrome (ARDS) would have to connect multiple patients to a single ventilator. However, the current SARS-CoV-2 pandemic leaves us in a far from ideal world, and healthcare professionals in hard-hit regions will have to strike a balance between the resources available and the resources their patients need. In the most extreme case, they might thus have to consider the unseemly solution of connecting multiple patients to a single ventilator.

Enter the Differential Multiventilation International Working Group. What started as a test setup built by Dr. Mergeay, Dr. Stiers, and Dr. Janssen in the hospital of Geel, Belgium, has grown into an international collaboration of more than 30 medical doctors and engineers from Belgium, the USA, UK, Norway, Switzerland, Australia and Canada. Several of our contributors had built their own test setups before deciding to join forces. Now the whole team is working together to describe and test the safest way to share or split a ventilator between multiple patients. This website is a means to rapidly share our work with health care professionals who unfortunately might find themselves in the extreme circumstances of a ventilator shortage.

We would like to stress the fact that this setup has not been used in a clinical setting, and that we do not consider the testing complete. It is by no means anything else than a last resort solution. But given the short time and extreme circumstances, we would like to share this setup here with everyone interested to replicate and test it.

Our Goal

A robust and straightforward ‘differential multiventilation’ setup, meaning a safer setup to share a ventilator between multiple patients where

  • all the proposed components are readily available in hospitals, can be bought in medical supply or plumbing stores, and can be 3D printed as a back up plan,
  • the setup contains no added electronics or software and should be easy to understand and implement for experienced caretakers,
  • still, the setup allows the caretaker to monitor and finetune the pressure and volume for each patient individually, including differential PEEP.
Full List Of Components
Information on all the open source and commercial components we tested are available on our different component pages.

  • 2 splitters for 2 patients, 6 splitters for 4 patients.
  • 2 one-way valves per patient. These can be left out if in-line PEEP valves are present on inspiratory and expiratory limbs, but in that case the PEEP valves would have to be very reliable.
  • 1 adjustable, in-line PEEP valve per patient.
  • 1 flow restrictor per patient. This can be an in-line PEEP valve as well.
  • 1 pressure transducer and/or volume meter per patient.
  • 1 HMEF filter per patient.
  • 1 HEPA filter per patient.
  • Optional: a bypass circuit consisting of two splitters, two one-way valves and a short connecting tube.
  • Optional: 1 capnogram per patient.
  • Optional: connectors with Luer ports, if additional ports are needed.

Instruction video by our contributor Dr. Roy, MD, University of Calary, Canada, of our differential multiventilation setup using in-line, adjustable PEEP valves both to set individual inspiratory pressure  and to set individual PEEP.

Advantages
  • The pressure can be adjusted for each patient. Patients do not have to be matched in compliance (but they do have to share some parameters such as BPM, oxygen enrichment and I:E ratio).
  • In-line, adjustable PEEP valves allow to set a differential PEEP for each patient.
  • The pressure and/or volume curve for each patient can be monitored.
  • No deleterious interactions between patient’s circuits are possible if the alarms are carefully set.
  • The system retains the high-pressure alarms of the ventilator.
  • A disconnection signal can be ensured if carefully setting the low minute ventilation alarm.
  • Consists of relatively cheap, easy to obtain or produce components.
  • Does not contain electronics (apart from connection to monitor) or components that are difficult to install.
Disadvantages
  • Only possible/safe in pressure control mode.
  • Patients should not be able to trigger (each other’s) breaths. Modern ventilators lacking this option can be locked out, i.e., the trigger threshold should be put beyond achievable values. Since this is uncomfortable, patients would likely have to be paralysed.
  • Parameters such as BPM, I:E ratio, FIO2 can only be shared.
  • In case an alarm goes off at the ventilator, it might not be immediately clear which patient triggered it.
  • O2 and CO2 measurements at the ventilator are not reliable. But individual capnograms can be connected on the filters proximal to the patients.
  • Possible auto-PEEP.
  • Possible hypercapnea.
  • Increased dead space through possible longer length of cables, splitters etc. This might induce auto-PEEP and hypercapnea as mentioned above, but it could also change the temperature of the airflow etc.
  • Possible need to reconfigure the complete network when a patient with compliance lower than the current lowest compliance is added (since set pressure or PIP should then be increased).
  • Still contains one component that is not commonly found in a hospital, namely the flow control restrictor.

Status

We’re currently developing protocols to test and compare all the component alternatives we encountered.

Contributors

The Differential Multiventilation International Working Group is an international collaboration effort consisting of more than 30 medical specialists and engineers from hospitals and universities in Belgium, the USA, UK, Norway, Switzerland, Australia and Canada.

Differential Multiventilation International Working Group

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.