Disclaimer: This project is not meant to be used as a medical device as it is. It has not been reviewed nor validated by any trained professional and should not be used with any patients. In its current state it is only meant to demonstrate what is achievable with a very low resource design and provide inspiration for other projects.
This projects ultimate aim is to offer an open-source, affordable, and easy to make respiratory sensor design. The primary focus of this sensor is to be used with a feedback device to assist in the safe operation of a manual ventilation device (bag valve mask). It is however not limited to that use and could also be used as part of a mechanical ventilator.
The project is composed of the sensor device itself as well as of a ventilation feedback device (VFD) that uses the sensor readings to provide visual and auditory feedback to the bag valve mask operator.
Many developing countries have a critical lack of mechanical ventilator, with at least 10 countries in Africa having none at all and 9 other having less than 1 per million people [1]. In that context, practicians are often forced to use manual ventilation with bag valve masks (BVM) in lieu of mechanical ventilation. However, such manual ventilation requires around-the-clock operation and the lack of trained practician in those settings often mean that the family members of the patients are asked to operate the manual ventilators themselves for extended periods of time [2]. This present serious risks as improper use of BVMs can cause very serious lung injuries that can cause long term disability and even death [3],[4]. Several studies have found that even amongst trained professionals improper use of BVM was endemic [5] with one study finding that over 88% of practicians evaluated delivered excessive pressure and 73% delivered excessive volume [6]. To remedy this issue, devices providing feedback on manual ventilation have already been shown to decrease the risk of misuse by >70% [6]. However, the current designs are not open source, too complex to replicate and too expensive for use in low resource settings. Our proposed open source design is optimized for affordability and ease of replication to fill that current gap.
The sensor device provides measurement of airway pressure and gas flow (bi-directional). It is designed to be placed close to the patient and measure those metrics with a meaningful range and accuracy for respiratory monitoring.
Documentation:
- Requirements
- Design specifications
- Tests (TODO)
Design Files:
- The CAD folder for the Fusion 360 archive including the full assembly.
- The source folder includes an Arduino project with the source code to read the sensor
Manufacturing Files:
- The CAM folder includes an STL file for 3D printing
- The assembly_manual file includes instruction on how to 3D print the part and assemble them.
The main aim of the ventilation feedback device is to provide feedback to someone manually operating a bag valve mask in order to ensure safe usage and reduce the risk of lung damage from improper use.
Documentation: (TODO)
A first version of the sensor device has been designed and manufactured. First tests have started and early results are promising but more work is needed to properly assess the performance of the sensor.
The most critical next task is to properly test and qualify the sensor. This involve validating the design as well as defining protocols to easily test manufactured units in a low resource environment. Creative solutions will be needed and any help is highly appreciated.
Moreover, during manufacturing and early tests of the sensor, a few areas for improvements have been identified, in particular:
- Firmware: Add temperature compensation of the fluid density
- Firmware: Add noise filtering
- Mechanical: Add additional pressure leakage protection close to the sensors
Once this is done, the proper design of the Ventilation Feedback Device can be started.