Breathing Easier: Developing the Hansen Ventilator
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. Whatthey’ve designed could save millions of preterm infants in thedeveloping world.
The team that designed and developed the Hansen Ventilator includes engineer Jay Zignego, volunteer John Walton, Seattle Children's CEO Dr. TomHansen, Dr. Peter Richardson and respiratory therapist Rob DiBlasi.
Long rows of urgent blue scribbles fill a large ninth-storywindow at Seattle Children’s Research Institute. Thenumbers and diagrams give Peter Richardson ’s lab a certainmad scientist vibe. But there’s nothing farfetched about thelab’s latest project.
Three years ago, Dr. Tom Hansen asked lab members tosolve a problem that costs the lives of a million newbornsaround the world each year. Today, they’re on the verge ofmeeting that challenge.
Hansen, Children’s CEO, is a neonatologist andpulmonologist who makes room in his busy schedule toimprove respiratory care for newborns. “The intellectualstimulation of research keeps me fresh,” he says.
What Hansen sought three years ago – and the labdelivered – is a simple and inexpensive mechanicalventilator for newborns in respiratory distress. The device,dubbed the Hansen Ventilator, promises to dramaticallyimprove the survival rate for newborns in countriesthroughout the developing world.
Less expensive, less complex
An experienced respiratory
therapist, Rob DiBlasi had
a leading role indeveloping
the Hansen Ventilator.
Mechanical ventilators are common in developed nationslike the United States, where the high-tech machines helpmost newborns in respiratory distress – primarily prematurebabies – survive until they’re able to breathe on their own.
“Have you ever had the wind knocked out of you? That’show hard many of these babies have to work every timethey take a breath,” says Richardson.
Standard mechanical ventilators are designed withsophisticated controls that regulate oxygen levels andpressure and adjust precisely to the needs of each newborn. “It becomes sort of an art form to set up and maintain theventilators just right for each baby,” Richardson explains.
But all of that sophistication makes mechanical ventilatorsextremely complex. “You need special training to operatethem safely and effectively, and to maintain them,” saysRob DiBlasi, a respiratory therapist who helped developthe Hansen Ventilator.
That’s a problem in developing countries such as India,where shortages of trained specialists severely limit the useof ventilators. “A lot of donated ventilators sit in the cornergathering dust because no one knows how to use them ormaintain them,” DiBlasi says. “Lack of reliable electricalpower can also be a problem.”
The ventilator can be built for a few hundred dollars incontrast to the $30,000-plus price tag for a conventional unit.
The silver lining is that many babies don’t require thesophisticated level of care delivered by conventionalventilators. Even a very basic machine could provide enoughassistance to mean the difference between life and death.
That’s the goal of the Hansen Ventilator. The simplifieddevice replaces an array of dials and gauges with two knobs – one to control the respiratory rate and the other to controlthe inflation time – and uses far less electricity than aconventional ventilator. “It can run on a laptop battery,”Richardson says.
The simple design removes another problem fordeveloping countries: cost. The Hansen Ventilator canbe 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 timeand
frequency. The oscillations
promote the flow of gas –
oxygen in andcarbon dioxide
out – that helps babies breathe.
The key to the machine’s simplicity is that it uses columnsof water rather than microprocessors to move air in andout of a baby’s lungs. Here’s how it works:
Oxygen from a tank flows through a tube past a pair ofnasal prongs placed in the baby’s nose. The tube continuespast a control unit and into a pair of tubes submergedin water at different depths. A pinch valve – the onlycomponent that requires power – alternates the flowof 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 babyinhale. When it directs oxygen into the shallow tube, theair pressure falls, helping the baby exhale.
That's not all. The bubbles emitted by the exhalationtube create oscillations that further promote gas exchange (oxygen in and carbon dioxide out) in the baby’s lungs. Asthe Hansen Ventilator team tinkered with the design, theydiscovered that bending the exhalation tube at a 135-degreeangle increased the frequency of the oscillations andproduced even greater gas exchange.
Children’s is working with PATH, a Seattle-based globalhealth organization, to move the Hansen Ventilator from thelaboratory to the field. The plan is to manufacture a seriesof prototypes in India and conduct clinical trials there whilealso seeking approval from the U.S. Food and DrugAdministration.
The Hansen Ventilator may lack some of the capabilitiesof conventional mechanical ventilators, but it’s a hugeimprovement over the status quo in the developing world.
“In the long run,” Hansen says, “we think we can save ahalf-million lives a year.”