MIT | 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 and faculty working in consultation with local
physicians designed a simple ventilator device that could be built with
about $100 worth of parts, although in the years since prices have gone
up and the device would now cost $400 to $500 in materials. 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.
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