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Breathing Easier: Developing the Hansen Ventilator

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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.

Daniel Kelley and brother Jack

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

Dr. Rusty Novotny

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

Dr. Rusty Novotny

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.”

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