Breathing Easier: Developing the Hansen Ventilator
CEO Dr. Tom Hansen challenged a team to develop a low-tech,
low-cost ventilator for use in resource-limited areas. What
they’ve designed could save millions of preterm infants in the
developing world.
The team that designed and developed the Hansen Ventilator includes engineer Jay Zignego, volunteer John Walton, Seattle Children's CEO Dr. Tom
Hansen, Dr. Peter Richardson and respiratory therapist Rob DiBlasi.
Long rows of urgent blue scribbles fill a large ninth-story
window at Seattle Children’s Research Institute. The
numbers and diagrams give Peter Richardson’s lab a certain
mad scientist vibe. But there’s nothing farfetched about the
lab’s latest project.
Three years ago, Dr. Tom Hansen asked lab members to
solve a problem that costs the lives of a million newborns
around the world each year. Today, they’re on the verge of
meeting that challenge.
Hansen, Children’s CEO, is a neonatologist and
pulmonologist who makes room in his busy schedule to
improve respiratory care for newborns. “The intellectual
stimulation of research keeps me fresh,” he says.
What Hansen sought three years ago – and the lab
delivered – is a simple and inexpensive mechanical
ventilator for newborns in respiratory distress. The device,
dubbed the Hansen Ventilator, promises to dramatically
improve the survival rate for newborns in countries
throughout the developing world.
Less expensive, less complex
An experienced respiratory therapist, Rob DiBlasi had a leading role in
developing the Hansen Ventilator.
Mechanical ventilators are common in developed nations
like the United States, where the high-tech machines help
most newborns in respiratory distress – primarily premature
babies – survive until they’re able to breathe on their own.
“Have you ever had the wind knocked out of you? That’s
how hard many of these babies have to work every time
they take a breath,” says Richardson.
Standard mechanical ventilators are designed with
sophisticated controls that regulate oxygen levels and
pressure and adjust precisely to the needs of each newborn.
“It becomes sort of an art form to set up and maintain the
ventilators just right for each baby,” Richardson explains.
But all of that sophistication makes mechanical ventilators
extremely complex. “You need special training to operate
them safely and effectively, and to maintain them,” says
Rob DiBlasi, a respiratory therapist who helped develop
the Hansen Ventilator.
That’s a problem in developing countries such as India,
where shortages of trained specialists severely limit the use
of ventilators. “A lot of donated ventilators sit in the corner
gathering dust because no one knows how to use them or
maintain them,” DiBlasi says. “Lack of reliable electrical
power can also be a problem.”
The ventilator can be built for a few hundred dollars in
contrast to the $30,000-plus price tag for a conventional unit.
The silver lining is that many babies don’t require the
sophisticated level of care delivered by conventional
ventilators. Even a very basic machine could provide enough
assistance to mean the difference between life and death.
That’s the goal of the Hansen Ventilator. The simplified
device replaces an array of dials and gauges with two knobs – one to control the respiratory rate and the other to control
the inflation time – and uses far less electricity than a
conventional ventilator. “It can run on a laptop battery,”
Richardson says.
The simple design removes another problem for
developing countries: cost. The Hansen Ventilator can
be built for a few hundred dollars in contrast to the
$30,000-plus price tag for a conventional ventilator.
Tiny bubbles, big benefits
These charts show the oscillations created by the ventilator in both time
and frequency. The oscillations promote the flow of gas – oxygen in and
carbon dioxide out – that helps babies breathe.
The key to the machine’s simplicity is that it uses columns
of water rather than microprocessors to move air in and
out of a baby’s lungs. Here’s how it works:
Oxygen from a tank flows through a tube past a pair of
nasal prongs placed in the baby’s nose. The tube continues
past a control unit and into a pair of tubes submerged
in water at different depths. A pinch valve – the only
component that requires power – alternates the flow
of oxygen between the pair of submerged tubes.
When the valve directs oxygen into the deep tube,
the air pressure within the system rises, helping the baby
inhale. When it directs oxygen into the shallow tube, the
air pressure falls, helping the baby exhale.
That's not all. The bubbles emitted by the exhalation
tube create oscillations that further promote gas exchange
(oxygen in and carbon dioxide out) in the baby’s lungs. As
the Hansen Ventilator team tinkered with the design, they
discovered that bending the exhalation tube at a 135-degree
angle increased the frequency of the oscillations and
produced even greater gas exchange.
Children’s is working with PATH, a Seattle-based global
health organization, to move the Hansen Ventilator from the
laboratory to the field. The plan is to manufacture a series
of prototypes in India and conduct clinical trials there while
also seeking approval from the U.S. Food and Drug
Administration.
The Hansen Ventilator may lack some of the capabilities
of conventional mechanical ventilators, but it’s a huge
improvement over the status quo in the developing world.
“In the long run,” Hansen says, “we think we can save a
half-million lives a year.”