## ***OperationAIR - Assist In Respiration -*** ## OperationAIR is a student team of Delft University of Technology that developed a simplified ventilator: the AIRone. It was developed as a non-certified, advanced emergency ventilator at times of a national shortage due to the covid-19 pandemic, in close contact with experts from Leiden University Medical Center and Erasmus Medical Center. ---------- *AIRone: Type of ventilator* The AIRone operates and functions as a regular, pressure-regulated ventilator, but with essential functionalities only. In short, it uses a pressurised gas source, reduces the pressure accordingly and delivers gas to the patient by a set of proportional valves (see below for more details). Oxygen concentration is regulated using two Mass Flow Controllers on the gas inlets. ![Product specifications of the AIRone][1] ---------- *Intended use* The AIRone provides positive-pressure ventilation (PPV) for emergency automatic ventilation, created for the use on adult (suspected) COVID-19 patients who need non-weaned respiratory support to bridge a longer period of time until conventional ventilation becomes available. ---------- *Adjustable settings* * Inspiratory pressure (Pinsp) * Positive end-expiratory pressure (PEEP) * Respiratory rate (RR) * I:E ratio * Oxygen concentration(%) (FiO2) ---------- *Project Status* The design of the AIRone is final. As national ICU admissions are dropping large scale production is not necessary. The AIRone is currently being produced in a small batch to complete the design cycle and to share this expertise with the international community. Software engineers will continue to work on an additional module to enable patient respiration triggers for weaning. The AIRone was recommended by clinicians to be used at times of national shortage of certified ventilators. Official approval has not been obtained, due to the disappeared urgency of emergency ventilators. Therefore, the safety or efficacy of the AIRone for use in humans has not been proven. However, thorough design verification was performed using an advanced artificial test lung. Additionally, design documentation is under review by a notified body. Also, multiple usability tests by doctors and nurses lead to the current user-friendly design. ![Interior of the AIRone][2] ---------- *General Working Principle* The AIRone uses pressurized medical air and oxygen that is available in most Dutch hospitals, reduces it to the required pressure, and delivers this to the patient using a set of proportional valves that are controlled using a central microcontroller. The physician can start up the device and use the touchscreen (GUI) to set ventilation parameters to the desired settings. The GUI will communicate these setting to the MicroController Unit (MCU). The MCU then controls all valves to ventilate the patient accordingly. The AIRone has two male NIST (Non-interchangeable screw thread) connectors, one for compressed medical air and one for oxygen. The female counterparts of these connectors should be available in the Dutch hospital and can be connected to the AIRone. The input pressure of both oxygen and compressed air may vary between 4 and 8 bar. In the device, the oxygen and air pressure is reduced to 4 bar. Two Mass Flow Controllers (MFCs) are used to control the flow of both gasses into a mixing chamber. This ensures a highly controlled mixing ratio, having a gas with the desired oxygen concentration as result. A pressure sensor in the mixing chamber gives feedback to the MFCs, adjusting their flow to keep the pressure in the chamber at 650 mbar. As a back-up, a back pressure regulator ensures the pressure in the chamber will never exceed 1 bar by blowing off air when the pressure is too high. Downstream of the mixing chamber, a proportional valve regulates the pressure going into the patient. Generally, the valve will open at the start of inspiration and close when the pressure at the lungs is at the desired plateau pressure. Before the gas mixture flows to the patient it passes a check valve which blocks flow coming back from the patient. During expiration, the gas is filtered by a HEPA filter. The gas then passes another check valve, and also a pressure relief valve, which opens when the pressure in the system rises above 70 cmH20. The gas is then released to outside the system by another proportional valve that opens at the beginning of the expiration and closes at the end of the expiration. ---------- **Be aware this design explicitly focuses on use in the Dutch healthcare infrastructure. Alterations of this design will be needed for local implementation. Please leave your contact information and additional information in this form so we can discuss matters or offer advice and support:** https://forms.gle/rWXyzbqTNrqdJqee8 [1]: https://files.osf.io/v1/resources/mn7xq/providers/osfstorage/5eb12de362d4ab01306c5f56?mode=render [2]: https://files.osf.io/v1/resources/mn7xq/providers/osfstorage/5eb12e4d62d4ab01316c68ed?mode=render