Our ‘LeVe’ (Light) Breathing Systems have been developed to provide respiratory support for use in low-resource, or resource-stressed environments. The LeVe systems are designed to be resource-light, both in terms of manufacture and usage. They are targeted to provide essential early-stage respiratory support to patients with conditions such as COVID-19 or pneumonia.
The provision of CPAP (Continuous Positive Airway Pressure – where an always present pressure in the patients mask holds airways open) delivered through a mask has proved important in the treatment of patients with COVID-191. The patient breaths against a modest pressure within the mask which supports opening of the airways, with oxygen enriched air providing further support in achieving oxygenation. With the significant numbers of patients requiring such therapy, the efficiency of oxygen utilisation has been brought to the fore; in clinical settings where oxygen is generally readily available then patient numbers have stretched supply resources, and in LMICs where oxygen is less available then matching oxygen provision to CPAP ventilator equipment becomes crucial2. In these low-resource settings, oxygen concentrators are the only cost-effective and reliable means of providing medical grade oxygen, but their output flow rate is limited3–5. Concentrators only provide a limited oxygen flow (5-10 L/min) under low pressures, too low to support many existing CPAP systems which have not been designed for O2 efficiency.
The LeVe approach
To provide CPAP breathing systems suitable for LMICs or resource-stressed environments requires a solution which is oxygen efficient, resource-efficient, and robust. Our requirements are therefore to:
- Deliver CPAP at 10cmH20 over flow-rates up to 60l/min
- Provide air enriched with oxygen using portable oxygen concentrators
- Develop systems which can be readily manufactured in resource-limited environments
Using a frugal engineering approach, we have developed two systems which are focused on providing the core functionality required to deliver CPAP with enriched oxygen, enabling resource-light solutions while maintaining performance comparable to commercial systems. The two systems comprise
- The LeVe Blower System: a fan driven equivalent to a sleep apnoea machine
- The LeVe Venturi System: a system generating CPAP through a novel Venturi valve
The ‘LeVe Blower System’ uses an electric fan-blower to generate a flow of pressurised air. The fan system is carefully selected and coupled with a custom breathing-circuit interface to provide CPAP comparable to a apnoea system without the need for more complex control features. It contains inherent safety features necessary for clinical use (limiting maximum pressure and flow) while maintaining a simple, low-cost solution.
The ‘LeVe Venturi System’ is based around an air-driven Venturi valve, and used to generate a flow of pressurised air which drives a breathing circuit capable of delivering CPAP with enriched oxygen. Despite the simplicity of the system, it achieves pressure and flow characteristics equivalent to those achieved using dedicated CPAP machines. The key innovation lies in the system design – because the LeVe valve is powered by compressed air, it separates the function of creating a positive airway pressure and oxygenation. Unlike other oxygen-driven Venturi systems, this provides an oxygen-efficient system compatible for use with oxygen concentrators.
The LeVe Venturi System: a system generating CPAP through a novel Venturi valve
Publications and media
The LeVe System has been developed by a team of researchers from the University of Leeds, Leeds Teaching Hospitals NHS Trust (LTHT) and Bradford Teaching Hospitals NHS Foundation Trust, collaborating closely with MedAid International to deliver the system into LMIC settings.
The LeVe system is freely available under license from the University of Leeds. A downloadable package is provided which contains full details on how to manufacture and use the LeVe system.
For details on how to get the LeVe system, please contact Dr Pete Culmer.