3D-printed device used to treat life-threatening airway disease in infants

Doctors have for the first time treated infants with a rare, life-threatening airway disease by using a 3D-printed device, a study published Wednesday in Science Translational Medicine revealed. The device, an airway splint tailored to each child’s anatomy, is designed to adapt to tissue growth over time and will eventually be absorbed into the body. Doctors consider one of the patients who had the splint implanted three years ago cured of the disease.

The children suffer from trachealbronchomalacia, or the weakening and collapsing of airways, which affects about one in every 2,000 children worldwide. Patients with the condition are unable to fully exhale and typically must undergo tracheostomies, wherein breathing tubes are inserted into their necks and they are placed on artificial ventilators. For these children, a simple cold could require an extended hospital stay in the intensive care unit.

In their study, doctors sought to create device that would act as a cure for trachealbronchomalacia. The flexibility of the airway splint’s geometric design promotes the growth of the airway over time and then reabsorbs into the body. The splint was constructed of polycaprolactam, which is from a family of polymers, known as polyesters, which can absorb fluid leading to its eventual breakdown. The breakdown process typically takes between three and four years, at which time the child would have outgrown the condition and could go on to live a healthy life.

The new study focused on three infants, Kaiba Gionfriddo, Garrett Peterson and Ian Orbich, who were treated at University of Michigan’s C.S. Mott Children’s Hospital. The children were between 3 and 16 months old at the time of implantation. Each child had been in the intensive care unit for months, requiring heavy sedation, narcotic and even paralytics to stay alive.

“They still had repeated episodes that required resuscitations. [Ian] was unable to have any food in his stomach without having cardiac arrest. [Garrett] had to get repeated infusions of protein benzene. His immune system was weakened, and minor colds were life-threatening,” Dr. Glenn Green, senior author and associate professor of pediatric otolaryngology at C.S. Mott Children’s Hospital, said in a teleconference with reporters Tuesday. “There was no cure and life expectancies for each of these children were grim.”

Green and his colleagues Dr. Scott Hollister and Dr. Robert Morrison spearheaded the trial.

Before the procedure, each child was cleared to receive the splint under the Emergency Use Exemption by the Food and Drug Administration (FDA). The doctors used CAT scan images of the children to create virtual 3D-printed models of their airways, which they used to determine the correct splint size needed. The procedure had never been performed in animals or humans before, and, according to the doctors, required a lot of “guesswork” as they worked toward the end result.

“We had 10 different variables we could customize to this patient including length, diameter and thickness of the airway splint,” Morrison told reporters.

Once the splint was implanted— sutured to the outside of the airway— subsequent CAT scans were taken to monitor airway growth in the months and years after surgery. The images were used to create and measure virtual models again to ensure the airway was growing as the children aged.

“Long-term, our greatest concern was whether the airway splint would open up as we designed it to. If it did not, the child’s airway could be prevented from growing normally and there could be narrowing of the airway, which would be as serious of an issue as their original condition,” Morrison said.

Kaiba, who was fitted with a splint three years ago, appears to be cured of trachealbroncomalacia, and according to scans, the splint has absorbed into his body. Garrett, now 2, no longer needs ventilator support and continues to improve, while Ian, who received his splint one year ago, also shows improvement and continues to be monitored.

“When we performed endoscopy of [Kaiba’s] airway, we see normal physiologic motion of the bronchus, and that means that the splint is longer holding the bronchus open in a stiff-type manner— that it’s functionally degraded at this point,” Green said.

Next steps

The team has been in talks with the FDA to set up a clinical trial involving 30 children. The patients will have severe trachealbroncomalacia, but not as life-threatening as the conditions of the first three patients. Some of the children will be given the splints immediately, while others will receive it in a delayed fashion, creating the control group.

The cost for the material to create the airway splint is around $10, and the doctors said that, on average, the children receiving their device will save more than $1 million dollars in medical expenses because of decreased hospitalization. The researchers' personal funds, as well as was  grants from the FDA and the National Institutes of Health (NIH), helped fund the study.

Researchers are also investigating other 3D-printed technologies.

“We have about a dozen devices that we are making right now,” Green said, adding that the team has published preliminary studies in animals on 3D-printed ears and noses for people that have defects that need to be reconstructed.

Morrison said the medical possibilities with 3D-printing are limitless.

”When we talk about 3D-printing and medicine, we talk about how you really need to switch how you even think about approaching these conditions,” he said. “With patient-specific computer-aided design and modeling, you can really create anything that you could imagine to eventually become a medical device.”

This study was published by the American Association for the Advancement of Science.