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3D-Printed, Personalized Device Treats Airway Disease in Infants

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Kaiba Gionfriddo was the first child treated with the 3D printed tracheal splint at University of Michigan's C.S. Mott Children's Hospital. | University of Michigan Health System

An implantable 3D-printed device has improved breathing in three infants with collapsed airways for up to nearly three years, according to a new study. The findings demonstrate the potential of 3D printing to create ever more precise devices that are tailored to a patient's anatomy and can adapt to tissue growth.

"This is the first 3D-printed implant specifically designed to change shape over time — the fourth dimension — to allow for a child's growth before finally resorbing as the disease is cured," said Glenn Green from the University of Michigan, senior author of the study, at a 28 April press teleconference.

The researchers are currently pursuing a clinical trial to treat about 30 patients with severe airway collapse, or tracheobronchomalacia, with the 3D-printed device. Their study appears in the 29 April issue of Science Translational Medicine.

Three-dimensional printing has enabled rapid and low-cost production of customized medical devices, from hearing aids and dental implants to stents and prosthetics. The next generation of "smart" 3D-printed material is expected to respond to environmental changes like temperature, moisture, or sound. Young patients, in particular, need medical devices that accommodate tissue growth, as rigid material can move around or require frequent resizing as children grow.

Green and colleagues designed airway splints that expanded with airway growth in three infants, between three and sixteen-months old, with life-threatening tracheobronchomalacia. With this condition, weakening of the trachea and bronchi that lead into the lungs causes airway collapse during breathing, which can lead to respiratory failure and cardiac arrest. The disease affects about one in 2,000 children worldwide and usually improves with time as the patient's airway grows stronger, but often requires ventilator support or a breathing tube and heavy sedation.

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The resulting 3D splint design was digitally fit to the affected airway for all patients. | Morrison et al./ Science Translational Medicine

Combining computer modeling, imaging, and 3D printing, the researchers designed splints to support and keep open the collapsed airway. Design variables, including the splint's length, diameter, and thickness, were tailored to each patient's unique anatomy. The material's geometry and flexibility took into account expected airway growth. Infants' bronchi start at about the size of a pencil lead, but nearly double in size in a short period of time, according to Green.

"This ability to customize a device for a patient before it is made demonstrates the power of 3D printing," said Robert Morrison, also from the University of Michigan.

The final 3D-printed product was a hollow and porous tube that could be sutured over the affected airway. "The airway becomes suspended at the splint kind of like [in] a tent pole system," said Morrison, allowing both to expand together. The device, made of a type of polyester, harmlessly dissolves in the body in a few years and leaves a normally functioning airway.

One month after the devices were implanted, the three patients experienced continued opening and growth of the airways. As of the study's publication date, all three children have experienced improved breathing and no complications related to the device. They are now home from the hospital and are no longer sedated.

"It's very rewarding to see that things have worked exactly as intended [in the patients]," said Green.

Altogether, each airway splint cost about $10 in material and took five or fewer days to design and print. According to Green, the three children saved an estimated $1 million in health care costs by shortening their stay in the intensive care unit.

"[A] beauty of 3D printing is we can print tens or a hundred of the exact same splint design no matter how complicated the geometry," said Scott Hollister, also from the University of Michigan. "3D-printed patient implants as we saw in this case are going to represent a paradigm change in medicine."