THENEWYORKER,M AY18, 2020 17
ment titled “APRV for $10 (okay, maybe
$50 ... ). ”
In an included schematic, Bates had
sketched a simple device: a box with
three holes in it. Gas under pressure—
which many hospitals have available
from wall outlets—would flow into one
hole and out another, to the patient. In
normal breathing, exhalation typically
takes about two to three times as long
as inhalation; in A.P.R.V., the length
of exhalation is reduced from several
seconds to about half a second, while
inhalation can take five seconds or more.
To create this modified rhythm, the
box’s third hole would be blocked by a
rotating disk that also had a hole in it,
and that was spun by a motor. When
the holes briefly aligned, the machine
would exhale through the opening.
By the next day, Silver had built a
prototype and sent Bates a video. A
rubber glove was attached to the side
of a box with some zip ties. The glove
inflated, then deflated, then inflated
again. “I saw that and everything
changed,” Bates said. Soon, the univer-
sity agreed to fund the device. Kittell
and Silver were given free rein in the
shop; a lung analogue was brought in
from the hospital for testing; a regula-
tory expert began preparing an emer-
gency report for the Food and Drug
Administration, which had created a
special approval process for stopgap
ventilators; and several local contract
manufacturers were lined up so that the
device, now known as the Vermontila-
tor, could be mass-produced.
Engineering is quiet, methodical
work, not often the stuff of high drama.
But for many engineers the coronavirus
has been a call to arms. Not since the
space race has the whole world been so
invested in problems that are funda-
mentally technical. During the Apollo
mission, a buildup of carbon dioxide
was slowly poisoning the crew; the na-
tion watched as the astronauts, work-
ing with engineers in Mission Control,
jury-rigged a filter using duct tape and
spare parts. In the film “Apollo 13,” from
1995, an engineer with a pocket protec-
tor explains the situation to his col-
leagues: “The people upstairs handed
us this one, and we gotta come through.”
Since February, engineers in indus-
try and academia have been working
on designs for cheap, easy-to-build ven-
tilators. Ford has christened its effort
Project Apollo. And yet comparisons to
the moon landings may understate the
complexity of the problem. COVID-
is a mysterious illness, and ventilators
admit to many styles of operation. In
the best case, the machines keep pa-
tients with failing lungs alive, buying
time for the body to heal. In the worst
case, they can aggravate lung damage.
In the course of the pandemic, critical-
care specialists have disagreed about
how the devices should be operated and
at what point in a patient’s decline they
should be used; mortality rates for
COVID-19 patients on ventilators have
ranged widely. Manufacturing a venti-
lator is difficult, especially during a pan-
demic, when supply lines are unreliable.
Different designs negotiate different
bargains between cost and functional-
ity. Reaching the moon is challenging
enough. It’s harder when no one is sure
where the moon is.T
he lung is a passive participant in
breathing. It’s the diaphragm, a
large muscle that cuts the human body
horizontally in half, that does the work.
When you inhale, your diaphragm pulls
down like a piston, creating negative
pressure around the lungs, while the
muscles of the chest wall pull up and
out. Air, drawn in through the nose and
the mouth, flows through the trachea
and into the bronchial tree, which fans
out into the lungs. There, the breath
nestles into hundreds of millions of
gossamer sacs called alveoli. Blood,
meanwhile, has arrived at the rendez-
vous through a network of capillaries,
the smallest vessels in the circulatory
system. Under a microscope, the alve-
oli look like bunches of grapes, and the
capillaries like the mesh sacks that hold
them. The tissues are so exquisitely thin
that oxygen and carbon dioxide can
diffuse across them, between air and
blood. The contact surface between the
two networks, if it were unfolded flat,
would be more than half the size of a
tennis court.
The alveolar flesh is elastic, and del-
icate like fruit pulp. It fares poorly when
infected. The coronavirus multiplies in
the alveolar cells, tearing them apart as
it escapes; in the resulting chaos, fluid
can leak into the air sacs, capillaries can
constrict or clot, and tissues can be-come inflamed and stiffen. As the in-
fection spreads, the number of healthy
air sacs declines, and the exchange of
gases becomes less efficient. A patient
whose lung function degrades in this
way can develop acute respiratory dis-
tress syndrome, or ARDS.
When a COVID-19 patient arrives at
the hospital with shortness of breath,
physicians use a pulse oximeter, clipped
to a finger, to monitor her blood-oxy-
gen level, while supplemental oxygen is
delivered. If the oxygen level continues
to decline, doctors bring in a ventilator.
A device that looks like an oversized
shoehorn is wedged over the patient’s
tongue and used to peel back the epi-
glottis. Then a tube is fed down the tra-
chea, where a small balloon is inflated
to hold it in place. Patients are usually
sedated and paralyzed before being in-
tubated; people suffering from COVID-
19 may have to stay on ventilators for
weeks, remaining sedated for the dura-
tion, and they are sometimes paralyzed
again if their movement makes them
hard to manage. It is an extreme inter-
vention that, even when it saves a pa-
tient’s life, takes a toll on the body.
At the most basic level, a ventilator
is a pump, no different from the plas-
tic resuscitator bags that paramedics
squeeze to push air into a patient’s lungs,
in lieu of mouth-to-mouth. But, to
avoid VILI, the lungs must be venti-
lated with care. Too little air pressure
and the alveoli won’t inflate; too much
and they’ll distend and get damaged.
The balance grows harder to maintain
as ARDS progresses. The lung is like a
lattice, with each air sac supporting its
neighbors. Damaged alveoli can press
up against one another, spreading weak-
ness with each breath; strained alveoli
can burst. During exhalation, the in-
sides of the alveoli, which get stickier
as they fill with fluid, touch and cling
together; inflating them again requires
peeling them apart. In lung-physiol-
ogy circles, this is sometimes called the
“Velcro effect.” “If you have that Vel-
cro effect going on with every single
breath, breath after breath, that’s in-
credibly damaging in a fairly short
time,” Bates said. “You get in this
vicious spiral that’s really hard to get
back from.”
With a typical I.C.U. ventilator, a
clinician has a few ways to modulate