How did HEPIA respond to a HUG request to produce respirators in record time? By pooling its multidisciplinary engineering expertise to automate a manual resuscitator, commonly used by emergency physicians, as a potential means of ventilation in the longer term.
The current health crisis is having an extremely disruptive and rapid impact on hospitals, and the availability of staff and equipment may well become a major problem, particularly with regard to invasive ventilators, which are used for respiratory assistance.
However, the intensive care staff are confident and well-prepared, and according to the latest figures, the number of respirators available should cover current needs. However, it cannot be ruled out, according to some scenarios, that there might be a serious shortage of them in a few weeks. This situation is unfortunately not specific to Switzerland on 6 April 2020, but concerns all countries.
To this end, a doctor from the HUG (University Hospitals of Geneva) contacted HEPIA to study the possibility of building very simple invasive ventilators, intended for respiratory assistance of intubated patients, in order to meet local needs in case of extreme emergency.
The HUG’s request was precise: to be able to produce 50 devices, within 2 to 3 weeks, in order to overcome a possible catastrophic scenario of a shortage of devices and to spare the nursing staff from having to make choices.
HEPIA then set up, in one day, a team of professors and research assistants in the fields of design, mechanics, automation, electronics, computer science, etc., but also included in this team the start-up ANGARA Technology; specialised in measurement, control and automation.
The first 48 hours were devoted mainly to studying the characteristics of the respirators used in the COVID-19 crisis and to identifying the devices created in the health emergency by many research institutes around the world.
Copying a system whose plans are available on the Internet or designing a system that meets the needs expressed by our hospitals? For reasons of reliability of the device, it was decided to start with materials that are quickly available and above all extremely reliable in terms of operation and life span.
A study of the various technical solutions was carried out (rotary motors, linear motors, etc.) and, given the time constraint, a solution quickly emerged: to automate AmbuBag manual ventilators.
The next two days were used to define the different physical parameters that the respirator should have, to find the materials (price and delivery times) and to identify the workshops where the different parts could be made (by machining, 3D rapid prototyping), etc.
First electronic and mechanical architecture schematics
Proposed electronic architecture 2 days after receipt of initial application. © HEPIA, inSTI institute
Mechanical architecture proposed 3 days after receiving the initial application. © HEPIA, inSTI institute
The system will be managed by an Arduino microcontroller, with 3 user adjustable parameters: the number of breaths per minute BPM, the VT air volume in litres and the IE inhalation/exhalation ratio. In addition, the pressure measurement will be monitored as close as possible to the patient as well as the feedback signals from the LECPA linear motor control driver.
At any time, the pressure is measured, as well as the diagnostic signals for engine operation. If a fault is detected, the alarm is triggered and a command to open the system is sent to release the AmbuBag so that it can be activated manually.
The system will also display the "pressure plateau" between inhalation and exhalation, necessary for diagnosis.
Communication via a USB port will allow the measurements to be sent to a PC, so they can be displayed via a graphical interface.
All mechanical, electronic, wiring and software design plans are free. They may be disseminated and/or modified but must always mention the authors.
The GEVE Open Source Project concerns the design of a prototype respirator for experimental use only and is given here for information. Under no circumstances may such a device be used on a patient without the agreement of the medical profession. Attempting to use a ventilator or similar device without medical supervision may result in death or permanent disability. The GEVE project information is provided without any explicit or implicit guarantee.
Prof. Nicola Giandomenico (HEPIA)
Ont contribués au projet de façon exceptionnelle: Harley Stoeckli (HEPIA), Bassem Sudki (HEPIA), Antoine Benoit (Angara), Ralf Rossel (Angara)
HEPIA
Prof. Stéphane Bourquin
Florian Chays
Prof. Nicola Giandomenico
Prof. Michel Lauria
Harley Stoeckli
Bassem Sudki
Prof. Gilles Triscone
Hôpitaux Universitaires de Genève (HUG)
Dr Georg Ehret
ANGARA Technology
Antoine Benoit
Gary Boorman
Adriaan Rijllart
Ralf Rossel
Société SMC (pour le prêt du matériel, moteur linéaire et driver)
Pierre-André Borne
Joël Faivre
Impression pièces 3D
Michael Jaussi
