Written by Markus MacGill
3D printing has come to the rescue of severe cases of a childhood disease in which the windpipe is softened, leading to collapse of the airway and breathing failure. Previously lacking any adequate intervention, tracheobronchomalacia has found an innovative fix in three babies whose condition presented them with little chance of reaching young childhood.
Researchers at the University of Michigan's C.S. Mott Children's Hospital in Ann Arbor say the three boys have become the "first in the world to benefit from groundbreaking 3D-printed devices" to stent their airways in such a way as to allow the supports to keep up with their growth.
A follow-up of all three patients published in the journal Science Translational Medicine shows the personalized bioresorbable splint implants have worked with "promising results."
Pediatric tracheobronchomalacia (TBM) sees excessive collapse of the airways during breathing that can lead to life-threatening cardiopulmonary arrests (halted heart and breathing).
The cartilage supporting the airway can strengthen as children with the condition grow, the study paper goes on to explain, but severe cases of the disease require aggressive treatment - and those children are at "imminent risk of death."
Before this new approach to provide an early treatment option for TBM, the only conventional therapies available also carried life-threatening complications of their own.
Babies needed tracheostomy tube placement with mechanical ventilation, requiring prolonged hospitalization, and complications often led to cardiac and respiratory arrest. For example, the rate of respiratory arrest owing to tube occlusion runs as high as 43% of pediatric tracheostomy procedures a year.
Survivors: Kaiba, Ian and Garrett
But none of the newly developed 3D-printed devices have caused any complications for the three children treated, including Kaiba, who at 3 months old was the first to receive the new technology, 3 years ago. The stents were also inserted into 5-month-old Ian and 16-month-old Garrett.
Designed to accommodate airway growth while preventing external compression over a period of time before bioresorption, the technology allows for the particular problem of radial expansion of the airway over the critical period of growth. "If a child can be supported through the first 24 to 36 months of tracheobronchomalacia, airway growth generally results in a natural resolution of this disease," write the authors.
Senior author Dr. Glenn Green, associate professor of pediatric otolaryngology at C.S. Mott, says: "Before this procedure, babies with severe tracheobronchomalacia had little chance of surviving. Today, our first patient Kaiba is an active, healthy 3-year-old in preschool with a bright future." Dr. Green adds:
"The device worked better than we could have ever imagined. We have been able to successfully replicate this procedure and have been watching patients closely to see whether the device is doing what it was intended to do.
We found that this treatment continues to prove to be a promising option for children facing this life-threatening condition that has no cure."
Dr. Green describes in the video below how he and his colleagues at the University of Michigan worked on finding the solution.
Dr. Green strives enthusiastically for the lives of babies born with the condition, which he says in a post on the hospital's Hail to the little victors blog is often misdiagnosed as treatment-resistant asthma. He adds that it is a rare congenital condition affecting about 1 in 2,200 births, and the severe cases are even rarer, with most children growing out of the milder cases by 2 or 3 years of age.
"Kaiba's parents, April and Bryan, were left watching helplessly each time he stopped breathing, praying that something would change and doctors' predictions that he would never leave the hospital again weren't true," writes Dr. Green in 2013.
The 3D-printed splints were computational image-based designed to be customizable so that the following parameters could be made bespoke to the individual patient's anatomy on "the submillimeter scale:"
- Inner diameter, length and wall thickness of the device
- Number and spacing of suture holes.
Not being a closed cylinder, the design of the tubes gave an opening to allow placement but also expansion of the radius as the airways grew. All the inserts placed around the airways were made of polycaprolactone, a polymer that harmlessly dissolves in the body at a rate to allow the technology time to support the growing cartilage.
For Garrett's bespoke device on his left bronchus, the opening had a spiral shape to it, to allow a device to be fitted concurrently around, and grow with, his right bronchus, too.
Freedom from intensive care treatments
The Michigan team also share findings showing that the success of the devices meant the young children were able to come off of ventilators and no longer needed paralytic, narcotic and sedating drugs.
There were improvements in multiple organ systems and problems that had prevented the babies from absorbing food, so now they could be free of intravenous therapy.
The research doctors had received urgent approval from the US Food and Drug Administration to do the procedures, but it is early days for the strategy to become routine for babies with TBM. The case report published today was not designed to test the safety of the devices - so it may yet be possible that rare complications are found to result from treatment in some cases. Dr. Green says:
"The potential of 3D-printed medical devices to improve outcomes for patients is clear, but we need more data to implement this procedure in medical practice."
The specialist surgeon performing the operations, Dr. Richard Ohye, head of pediatric cardiovascular surgery at C.S. Mott, believes the cases provide the groundwork for a potential clinical trial in children with less-severe forms of TBM.
