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发帖数: 107 | 1 http://news.mit.edu/2020/ventilator-covid-deployment-open-source-low-cost-0326
MIT-based team works on rapid deployment of open-source, low-cost ventilator
Clinical and design considerations will be published online; goal is to
support rapid scale-up of device production to alleviate hospital shortages.
David L. Chandler | MIT News Office
March 26, 2020
One of the most pressing shortages facing hospitals during the Covid-19
emergency is a lack of ventilators. These machines can keep patients
breathing when they no longer can on their own, and they can cost around $30
,000 each. Now, a rapidly assembled volunteer team of engineers, physicians,
computer scientists, and others, centered at MIT, is working to implement a
safe, inexpensive alternative for emergency use, which could be built
quickly around the world.
The team, called MIT E-Vent (for emergency ventilator), was formed on March
12 in response to the rapid spread of the Covid-19 pandemic. Its members
were brought together by the exhortations of doctors, friends, and a sudden
flood of mail referencing a project done a decade ago in the MIT class 2.75
(Medical Device Design). Students working in consultation with local
physicians designed a simple ventilator device that could be built with
about $100 worth of parts. They published a paper detailing their design and
testing, but the work ended at that point. Now, with a significant global
need looming, a new team, linked to that course, has resumed the project at
a highly accelerated pace.
The key to the simple, inexpensive ventilator alternative is a hand-operated
plastic pouch called a bag-valve resuscitator, or Ambu bag, which hospitals
already have on hand in large quantities. These are designed to be operated
by hand, by a medical professional or emergency technician, to provide
breaths to a patient in situations like cardiac arrest, until an
intervention such as a ventilator becomes available. A tube is inserted into
the patient’s airway, as with a hospital ventilator, but then the pumping
of air into the lungs is done by squeezing and releasing the flexible pouch.
This is a task for skilled personnel, trained in how to evaluate the
patient and adjust the timing and pressure of the pumping accordingly.
The innovation begun by the earlier MIT class, and now being rapidly refined
and tested by the new team, was to devise a mechanical system to do the
squeezing and releasing of the Ambu bag, since this is not something that a
person could be expected to do for any extended period. But it is crucial
for such a system to not damage the bag and to be controllable, so that the
amount of air and pressures being delivered can be tailored to the
particular patient. The device must be very reliable, since an unexpected
failure of the device could be fatal, but as designed by the MIT team, the
bag can be immediately operated manually.
The team is particularly concerned about the potential for well-meaning but
inexperienced do-it-yourselfers to try to reproduce such a system without
the necessary clinical knowledge or expertise with hardware that can operate
for days; around 1 million cycles would be required to support a ventilated
patient over a two-week period. Furthermore, it requires code that is fault
-tolerant, since ventilators are precision devices that perform a life-
critical function. To help curtail the spread of misinformation or poorly-
thought-out advice, the team has added to their website verified information
resources on the clinical use of ventilators and the requirements for
training and monitoring in using such systems. All of this information is
freely available at e-vent.mit.edu.
“We are releasing design guidance (clinical, mechanical, electrical/
controls, testing) on a rolling basis as it is developed and documented,”
one team member says. “We encourage capable clinical-engineering teams to
work with their local resources, while following the main specs and safety
information, and we welcome any input other teams may have.”
The researchers emphasize that this is not a project for typical do-it-
yourselfers to undertake, since it requires specialized understanding of the
clinical-technical interface, and the ability to work in consideration of
strict U.S. Food and Drug Administration specifications and guidelines.
Such devices “have to be manufactured according to FDA requirements, and
should only be utilized under the supervision of a clinician,” a team
member said. “The Department of Health and Human Services released a notice
stating that all medical interventions related to Covid-19 are no longer
subject to liability, but that does not change our burden of care.” he said
. “At present, we are awaiting FDA feedback” about the project. “
Ultimately, our intent is to seek FDA approval. That process takes time,
however.”
The all-volunteer team is working without funding and operating anonymously
for now because many of them have already been swamped by inquiries from
people wanting more information, and are concerned about being overwhelmed
by calls that would interfere with their work on the project. “We would
really, really like to just stay focused,” says one team member. “And that
’s one of the reasons why the website is so essential, so that we can
communicate with anyone who wants to read about what we are doing, and also
so that others across the world can communicate with us.”
“The primary consideration is patient safety. So we had to establish what
we’re calling minimum clinical functional requirements,” that is, the
minimum set of functions that the device would need to perform to be both
safe and useful, says one of the team members, who is both an engineer and
an MD. He says one of his jobs is to translate between the specialized
languages used by the engineers and the medical professionals on the team.
That determination of minimum requirements was made by a team of physicians
with broad clinical backgrounds, including anesthesia and critical care, he
says. In parallel, the group set to work on designing, building, and testing
an updated prototype. Initial tests revealed the high loads that actual use
incurs, and some weaknesses that have already been addressed so that, in
the words of team co-leads, “Even the professor can kick it across the room
.” In other words, early attempts focused on super “makability” were too
optimistic.
New versions have already been fabricated and are being prepared for
additional functional tests. Already, the team says there is enough detailed
information on their website to allow other teams to work in parallel with
them, and they have also included links to other teams that are working on
similar design efforts.
In under a week the team has gone from empty benches to their first
realistic tests of a prototype. One team member says that in the less than a
week full they have been working, motivated by reports of doctors already
having to ration ventilators, and the intense focus the diverse group has
brought to this project, they have already generated “multiple theses worth
” of research.
The cross-disciplinary nature of the group has been crucial, one team member
says. “The most exciting times and when the team is really moving fast are
when we have an a design engineer, sitting next to a controls engineer,
sitting next to the fabrication expert, with an anesthesiologist on WebEx,
all solid modeling, coding, and spreadsheeting in parallel. We are
discussing the details of everything from ways to track patients’ vital
signs data to the best sources for small electric motors.”
The intensity of the work, with people putting in very long hours every day,
has been tiring but hasn’t dulled their enthusiasm. “We all work together
, and ultimately the goal is to help people, because people’s lives
understandably hang in the balance,” he said.
The team can be contacted via their website. |
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