The device provides CPAP (continuous positive airway pressure), a form of oxygen therapy called that has proved effective in helping patients struggling to breathe because of moderate to severe covid.
In a paper published in the Frontiers in Medical Technology, the team said a pilot evaluation involving 10 healthy volunteers has shown that it “...can be used safely without inducing hypoxia [low levels of oxygen in tissues] or hypercapnia [build-up of carbon dioxide in the bloodstream] and that its use was well tolerated by users, with no adverse events reported”.
The researchers are said to have used the principals of ‘frugal innovation’ to design and develop the breathing aid, to ensure the device remains simple while being robust and able to meet clinical demands in poorer-resourced health settings.
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A key innovation was to generate the required air flow using a simple electric fan to overcome the lack of access to high-pressure air and oxygen supplies.
The device was developed by a team of engineers, scientists and doctors from Leeds University, Leeds Teaching Hospitals NHS Trust, Bradford Teaching Hospitals NHS Foundation Trust, Medical Aid International and the Mengo Hospital in Uganda.
In a statement, Nikil Kapur, Professor of Applied Fluid Dynamics at Leeds University and the supervising academic on the project, said: “We have stripped away unnecessary complexity and ensured the device will work in settings where oxygen supplies are scarce and need to be conserved. The prototype is an important step in developing a device that will create greater access to critical-care technology and help save lives.”
Components for the protype device cost around £150 compared to conventional CPAP machines that can cost from around £600 and ICU ventilators that can cost over £30,000.
According to Leeds, a recent UK study has highlighted how CPAP can provide a valuable intervention for covid-19 and the World Health Organisation is encouraging the rapid development of low-cost breathing aids that could be deployed in poorer-resourced healthcare systems.
For that to be possible, the devices must operate with low pressure oxygen systems. Unlike in wealthier countries, clinics and hospitals in poorer settings may not have access to centralised oxygen supplies. Instead, they rely on oxygen concentrators, which are suitcase-sized machines that take in ambient air, strip out the nitrogen and provide a supply of oxygen at low pressure.
Dr Pete Culmer, Associate Professor in the School of Mechanical Engineering at Leeds and the study’s lead author, said: “The Leeds prototype has been specifically made to work with oxygen concentrators. The fan or CPAP blower is connected to…a breathing circuit. That circuit is made up of a filter to catch viruses and bacteria in the air flow, tubing, face mask, a valve which controls the flow of oxygen from the oxygen concentrator, and an expiration outlet.”
The fan system provides a safe air flow supply without needing more complex - and costly - control systems or a high-pressure air source. This provides a simple and robust means to generate an airflow sufficient to open the patient’s airways without risk of adverse effects. The oxygen concentrator is used to enrich this airflow with oxygen. The device can generate four different levels of air pressure dependent on clinical need.
The paper says desirable oxygen saturation levels in the blood – between 96 and 100 per cent – were maintained in healthy volunteers taking part in the trial. The CO2 range at the end of exhalation was between 3.6 and 4.9pKA, which is within accepted healthy limits.
A trial involving sick patients is planned to begin at the Mengo Hospital in Kampala, Uganda, in September.
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