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| Bare Bones Bag-Mask Ventilator |
While government orders for social distancing and travel restrictions are in place to mitigate the spread of coronavirus, the development and implementation of technology to produce critical medical supplies is becoming crucial as overcrowded hospitals face shortages of ventilators and masks. In addition, technology is driving efforts to detect the presence of COVID-19 in patients and in biomarkers that could signal the presence of the disease in specific geographic regions.
But more than technology is needed. Making sure the ventilators work properly is important, and so is the presence of a strong supply chain to ensure supplies get to critical locations in a timely manner.
Because ventilators serve a critical patient need, ensuring they work properly is of utmost importance. One company playing a role is National Instruments, which makes automated testing and measurement systems to measure an array of devices. As no two ventilator models are alike, National faces the daunting challenge of testing ventilators with different shapes, features, etc. National is partnering with a number of companies in their testing efforts.
The urgency of producing ventilators has received a strong response from crowdsourced efforts and universities. Some of the current university efforts involve researchers from MIT, the University of Minnesota, and Vanderbilt University. All are based on advancing the manually bag-operated valve mask, known as a BVM or Ambu-bag.
Advanced technology, such as robots, is also being used to expedite COVID-19 testing. At the University of California at Berkeley, a pop-up diagnostic lab has been set up that uses a liquid handling robot able to process more than 1,000 patient samples daily. The lab is initially handling the UC Berkeley community but could expand its efforts to the greater East Bay area.
Artificial intelligence, not surprisingly, is also getting into the act. Two Dutch companies are providing artificial intelligence (AI) software free of charge to hospitals to help triage COVID-19 cases by highlighting affected lung tissue in chest X-ray images. The software tool, called CAD4COVID, builds on an existing tool certified by the Dutch Ministry of Health called CAD4TB that has been used in more than 40 countries with 6 million people to screen for tuberculosis, according to the joint companies involved, Thirona and Delft Imaging.
Detecting signs of coronavirus before it can spread will be the key to controlling future outbreaks. Researchers from Cranfield University in the UK are using paper-based kits to test wastewater for the presence of biomarkers in urine and feces samples, that could determine if there are carriers for COVID-19 present.
A team at the University of Minnesota is pursuing a design, called the Coventor, based on a bag-valve-mask that uses an electric motor that turns a crank that pushes a piston up and down. Two weeks ago, a prototype proved successful in a trial run.
Vanderbilt University’s design similarly involves an Ambu-bag, retrofitted with a mechanism to apply the necessary squeezing action. The first prototype consisted of nylon webbing wrapped around an Ambu-bag attached to the crank arm of a windshield wiper motor to apply the repetitive squeezing force
In all three cases, the basic engineering challenge is to take a low-cost design and figure out an economical way to eliminate the need for an operator.
But that’s not the end of the story: A low-cost ventilator will ultimately need specific performance characteristics and features—the very blueprint of any product design—to be safely used in a clinical setting. And determining what those are will require the practical, real-world experience and medical know-how of doctors.
To that end, the three teams consist of a mix of engineers and doctors, bringing together the best technical and medical expertise to bear on the issue.
MIT Mechanical Engineering Professor Alexander Slocum, one of the authors of the MIT paper on a low-cost mechanical ventilator, stressed that no engineering team can come up with a low-cost ventilator design without specific performance requirements (other than cost) and be effective. “Which is why we work with doctors on the problem and where we post [to the website MIT E-Vent] as we learn,” he noted in an email response.
From that learning is emerging a more detailed set of specifications, which the team is sharing with others who may be seeking to manufacture a low-cost emergency ventilator.
For example, the website states that, “Any low-cost ventilator system must take great care regarding providing clinicians with the ability to closely control and monitor tidal volume, inspiratory pressure, bpm (breaths per minute), and I/E ratio, and be able to provide additional support in the form of PEEP, PIP monitoring, filtration, and adaptation to individual patient parameters. We recognize and would like to highlight for anyone seeking to manufacture a low-cost emergency ventilator, that failing to properly consider these factors can result in serious long-term injury or death.”
In a press release on Vanderbilt University’s website, Robert Webster, Professor of Mechanical Engineering, described why his colleagues added sensors and controls to the design. “This was the result of a lot of conversations with doctors where it became clear that a pressure sensor with an alarm on it for too-high or too-low pressure was essential to the design,” noted Webster. “This is something we would not have known without having many Vanderbilt physicians involved in the project.”
The teams anticipate it will be an iterative process and the concepts will evolve, as doctor’s feedback from early tests is incorporated into the designs.
Many engineers with specific areas of expertise may be interested and wondering how they can contribute to these efforts. Slocumb offered some very good advice: “Stay isolated and do not spread it. And when you see a design on-line, offer constructive peer review.“
What trade-offs to make in a low-cost ventilator design?
In the wake of a growing number of COVID-19 hospitalizations, health care facilities will be facing a critical shortage of ventilators. In response, some of the world’s most gifted, competent engineers at MIT, the University of Minnesota, and Vanderbilt University are pursuing the development of open-source, low-cost ventilators that can be brought to market quickly. The idea is to make the designs available to the public so that anyone can build them.
In essence, the concept for the designs came from a common starting point: Take a simple design—a manually-operated bag-valve-mask (known as a BVM or Ambu-bag) and figure out a way to automate it.
MIT’s team, called MIT E-Vent, is using as its reference a design detailed in a 2010 paper, presented at the Design of Medical Devices Conference, titled “Design and Prototyping of a Low-cost Portable Mechanical Ventilator.” The low-cost design is based on a conventional bag-valve-mask, employing a mechanical cam arm to eliminate the need for a manual operator.
FORD and General Motors are also converting production to building ventilators to assist patients with acute respiratory distress resulting from COVID19 infection.
Workers are beginning to produce life-saving ventilators at Michigan plants that normally make cars and trucks. This will take several weeks to design and manufacture them in volume.
While full production won’t begin until May, the many thousands of ventilators they make will be useful then and in later months should a COVID-19 resurgence occur in the fall or later in 2021 before a vaccine is ready and widely used.
“We’re used to building big automotive products but scaling to produce a small ventilator requires different sourcing of components and capabilities,” Adrian Price, Ford’s director of global core engineering, said in an interview with CBS This Morning.
“There’s quite a bit that goes into making a design that is currently produced at the rate of two a day and scaling that to over 7,000 a week,” he added.
GM is bringing back hundreds of workers to produce ventilators next week and will be imposing safety guidelines that include distancing between workers, the periodic taking of temperature and scrubbing down work areas between shifts, according to the CBS report.
The two companies together are enlisting up to 1,500 workers to make ventilators, while Ford wants to produce 50,000 by July 4 and GM wants to build 200,000 overall, according to The Washington Post.
Getting fully functioning machines ready for use that are tested and reliable will be part of the process. Some ventilators are built to operate only for short periods of time, pumping air or oxygen into a patient’s lungs, while others must pump for days. There can be an array of electronics for controlling alarms and fail-safes, as well as redundancy. Testing of the machines will typically take a few minutes, looking at plastic and metal parts but also assessing how well a machine responds when in use, even when a patient coughs into a tube that is connected to the device, according to engineers. The engineering feat of converting from making vehicles to ventilators is complex, not only because of the technology involved. Both cars and ventilators share electronics and metal and plastic parts that need to be assembled, but there are the added challenges of building thousands of medical devices rapidly with high accuracy and of keeping workers safe while they maintain personal distancing on an assembly line. Some ventilators are elegantly designed and will take more time to produce in large numbers, and they may not meet the peak demand. Others are simple, not complex and designed to work in a third world country where there is no electricity.
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| Bag-Mask Ventilator with Enclosure and Intubation |
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| Simple Bag-Mask Ventilator |
The researchers noted that live SARS-CoV-2 can be isolated from the feces and urine of infected people, and the virus can typically survive for up to several days in an appropriate environment after exiting the human body.
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