Health

3D printed splint treats babies' airway disease

Three babies with a life-threatening airway disease have successfully received a 3D printed windpipe designed to grow with them.
As a newborn, Kaiba was turning blue because his lungs weren't getting enough oxygen. Today, the active 3 1/2-year-old is in preschool and doctors say the 3D printed device is doing what it was intended to do. (University of Michigan Health System Department of Communication)

Three babies with a life-threatening airway disease have successfully received a 3D printed windpipe designed to grow with them.

The infant boys all had a terminal form of tracheobronchomalacia, a weakening and collapse of the airway found in about 1 in 2,000 children worldwide who aren't able to fully exhale. The babies had been in intensive care in the U.S. for months, heavily sedated with narcotics and paralytic medication as well as breathing tubes placed through their necks, unable to learn to sit or stand.

Despite artificial ventilation, the boys repeatedly needed to be resuscitated, said Dr. Glenn Green, an associate professor of otolaryngology at the University of Michigan.

"Our process uses the patients' natural windpipe with a precisely created splint that lies on the outside of the airway," Glenn said in a news conference. "It stops the collapse of the trachea or bronchi and allows the airway to grow naturally."

In Wednesday's issue of Science Translational Medicine, Glenn and his colleagues describe how they used computer modelling to 3D print the splints layer by layer, tested them on models of the boy's trachea and bronchi in the lungs and then sutured them in place.

Splints dissolve over time

The splints were made of polycaprolactone, which harmlessly dissolves and is excreted in the body of animal models.

"At the time of publication, these infants no longer exhibited life-threatening airway disease," the study's authors concluded.

The clinical improvements in all three boys were immediate and lasting, which suggests the improvement didn't reflect the natural history of the disease alone, they said.

For the first patient to receive the splint, Kaiba Gionfriddo, 3½, from Youngstown, Ohio, long-term data pointed to growth of the airway as CT imaging showed the device changing shape over time, starting from the width of a pencil lead.

"Allowing growth is part of 4D material design, with the fourth dimensional design being how the splint opens during airway growth because of its geometry," said Scott Hollister, a professor of biomedical engineering at the university.

Babies' long-term prognosis good

The researchers had 10 variables they could customize to each patient, including length, diameter and thickness of the splint, said Dr. Robert Morrison, a resident head and neck surgeon at the University of Michigan.

When the babies with tracheobronchomalacia are doing well at age three, Green said they're generally expected to do well for the rest of their lives because their airways have enough structural integrity. That's why the splints were also designed to naturally dissolve.  

The technique could be useful for other maladies where doctors need to accommodate for a child's growth, including orthopedic, cardiovascular and gastrointestinal conditions. Morrison called the possibilities limitless.

The U.S. Food and Drug Administration is working with the 3D-printing industry to develop such devices. The study offers a framework to potentially develop, evaluate and regulate the devices, Morrison said.

It also holds promise to produce devices and surgical instruments on demand in resource-poor countries, Hollister said. 

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