The Bag Valve Mask (BVM) ventilator is said to serve two patients simultaneously and its so-called ‘flat-pack’ design means it can be quickly manufactured at scale at a cost of under £75 ($100) per unit.
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According to Cranfield, the ventilator can be easily adjusted and updated as required, and can be linked to an oxygen generator, positive end expiratory pressure (PEEP) valves and filters. The units derive power from standard wall adapters or 12V vehicle batteries.
The BVMs are designed to be used by medical staff, first aiders, nurses, doctors and carers, as a temporary or emergency breathing aid for those with COVID-19.
The ventilator device works with ‘positive displacement’, forcing air into the patient’s lungs, a process that has to be controlled to ensure the right amount of air goes in at the right rhythmic pace, or ‘tidal volume’.
The BVM-ventilator can ventilate two patients at the same respirator rate but with independent tidal volume control, or ventilate one patient at twice the respirator rate allowing for alternating tidal volumes. Cranfield added that the tidal volume control is mechanically set using a bumper and slider, and the respirator rate is set by using a potentiometer connected to a DC motor and gear box.
Professor Leon Williams, head of the Centre for Competitive Creative Design (C4D) at Cranfield University, joined forces with Associate Professor Shannon Yee from Georgia Tech (Georgia Institute of Technology in Atlanta, USA) to rapidly design and build the low-cost and robust makeshift ventilator.
In a statement, Professor Williams said: “We focused on creating something that can be mass-produced using water-jet or laser cutting, and modular in design to make it easy to assemble and switch out parts. Within five days of getting the brief, an initial design from the Cranfield team was sent to Georgia Tech to test.”
Shannon Yee said: “Our goal was to provide the bare essentials for a ventilator to help with patients who have COVID-19 or acute respiratory distress syndrome. What’s unique about our design is that we have two BVMs per ventilator, which allows two people to breathe with each device that is built. We designed the ventilator to be simple to make, cut from sheets of steel. Kits can be assembled and packaged flat for shipping, then reassembled where needed. The manufacturing requires skills that are readily available, and hand tools could even be used.”
Professor Williams added that they paid special attention to the requirements of medical specialists to ensure the system is fit for purpose.
“For example, ensuring that the operator can manually adjust the tidal volume to safeguard the patient, maintaining the lowest pressure possible in the airway to avoid trauma,” he said.
A small batch of the devices has already been assembled for testing. The research team intends to make plans for the device to be available to manufacturers as quickly as possible.
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