A team from research and technology from the Philipps University of Marburg and the University Hospital Gießen and Marburg (UKGM), in the face of fears that the ventilation capacity in the corona pandemic might not be sufficient, developed two different concepts for simple ventilation devices in a very short time. The devices can be manufactured quickly and comparatively inexpensively and can be used in situations in which clinics no longer have sufficient regular ventilation spaces.
The first concept is based on the use of so-called CPAP (Continuous Positive Airway Pressure) devices. These devices are used, for example, to treat sleep apnea and are available in many private households. According to an idea from the sleep medicine center in Marburg, the CPAP devices are being expanded so that they can be used for artificial ventilation. The first prototypes are already running and have been rated very positively by the relevant medical professionals at the University Hospital in Marburg. Production options for the devices are currently being sought.
The Chancellor of the Philipps University, Dr. Friedhelm Nonne says: “I am deeply impressed and grateful that within a few days this team, with exceptional dedication and in an unprecedented collaboration, has developed devices from many areas of the university and the university hospital that can help to improve the current coronavirus pandemic to manage something. The example shows how the expertise bundled in universities can be used to quickly contribute to overcoming societal problems. ”
The modified CPAP devices are not as powerful as professional ventilators. They are not suitable for the primary care of acute, severe COVID 19 cases with severe shortness of breath. In such cases, clinical ventilators must be used. However, if the patients have recovered after a few days to such an extent that they need less ventilation, the modified CPAP devices could be used for ventilation. Then clinical ventilators would be free again and available for the next person with acute problems.
For countries in which CPAP devices are not widespread, the team is currently developing simple devices based on so-called “ambu bags” as a second approach. These "Ambu Bags" or respiratory bags are used in first aid for primary care and are available in large numbers at low cost. They consist of a mask that is pressed onto the face and a compressible pouch that is pressed together by hand at regular intervals for ventilation. The team is now developing mechanical devices that periodically compress the bags.
The goal of the team is to make all technical information and building instructions publicly available. This is intended to create the opportunity to replicate the devices worldwide and to manufacture them in large numbers.
The medical director of the University Hospital in Marburg, Prof. Dr. Harald Renz says: "Our senior physicians confirm that the developed devices would be used as a 'last line of defense' for ventilation if you had no other option. We are currently well positioned in Germany. But there are other regions of the world in which one would certainly be grateful to use these devices in the ‘first line of defense’ as well. "
The team is currently looking for premises and financial resources for production.
Contact:
Prof. Dr. Martin Koch
Mail: breathing.project@physik.uni-marburg.de
Fachbereich Physik
Philipps-Universität Marburg
35032 Marburg
The CPAP-Approach
CPAP (Continous positive airway pressure)-ventilation is a common form of medical therapy when people suffer from sleep related respiratory problems like sleep apnoa. Worn at night, these masks keep the patients' respiratory tracts open by inducing a continous overpressure. CPAP units are available in large numbers in common households as well as in hospitals.
We have developed a method to extend a CPAP unit to a convenient non-invasive ventilation system to support a patient's breathing. This will help preventing problems due to a shortage of high-end ventilation systems.
To allow for a successful ventilation of a patient, different levels of pressure have to be applied during inhalation and exhalation. Our unit will be inserted between the CPAP unit and the air tube and allows tuning the provided continuous CPAP-pressure such that alternating levels of pressure are achieved.
Our solution consists of two components:
- a) a small hatch
- b) a microcontroller unit
The hatch is used to tune the pressure at the pressure mask by applying opening and closing sequences. A servodrive is controlled by a microcontroller to control this process. Our team has written the respective code to allow for a periodic opening-closing sequence and thereby supporting the breathing process as good as possible. Additional parts within our design will ensure that the pressure stays within a certain regime. Moreover, connections are planned which allow for a potential attachement to a direct oxygen supply.
Most of the components for our solution can be printed with a 3D-printer. Additional components, like the microcontroller and the servomotor, can be bought in electronics stores.
We have recently built our first working prototype to verify our concept and to test basic operations.. The prototype is shown in operation in the following video: youtube.com/video/RCZkSUAaGAo
A further test of our prototype can be seen here (as of March 21st): youtu.be/A6qe4ckgw8U
This video shows a test of our second, further improved prototype (evening of March 21st):youtu.be/xVVP6O_0aLg
Our newest prototype can be seen here (as of March 24th): youtu.be/OQiMXHRqIqg
We have already presented our prototype to physicians who gave us a positive evaluation of our design.
