FROM SCIENCE TRANSLATIONAL MEDICINE
Immediate and continued life-sustaining improvement was seen in three pediatric patients implanted with 3-D–printed tracheobronchial splints as a treatment for terminal tracheobronchomalacia (TBM), a condition of excessive collapse of the airways during respiration leading to cardiopulmonary arrest.
The particular value of such 3-D–printable biomaterials to pediatric surgery is their ability to adopt a 4-D modality – to exhibit specifically engineered shape changes in response to surrounding tissue growth over a defined time period. In addition to their malleability, these devices also are designed to biodegrade. These features have proven especially useful as seen in this medical device emergency use exemption study performed at the University of Michigan, according to a report published in Science Translational Medicine ( 2015 Apr 29. [doi: 10.1126/scitranslmed.3010825]).
“Our multidisciplinary team designed an archetype device to allow radial expansion of the affected airway over the critical growth period while resisting external compression and intrinsic collapse,” wrote Dr. Robert J. Morrison of the University of Michigan, Ann Arbor, and his colleagues.
The study population involved three infant boys, aged 3 months, 5 months, and 16 months at time of treatment. In each patient, a sternotomy exposed their affected airways. The 3-D–printed splint, consisting of conjoined rib-like C-shaped arches was placed around the affected airway and secured with polypropylene sutures. The splint counters external pressure on the airway and holds it open. Because the splint is malleable, with an expandable opening placed opposite to the main collapsing pressure, it is capable of expanding as the airway grows.
Examination of the airway immediately after placement demonstrated patency, which was confirmed 1 month later. Results showed the benefit of the splints for all three patients, although total results were complicated by additional comorbidities:
• Patient 1: Blood gases returned to normal immediately after implantation and remained normal at 3 months’ follow-up. A week after implantation, weaning from mechanical ventilation was initiated and, 3 weeks after the procedure, the child was discharged to home. Repeat imaging at 1, 3, 6, 12, and 39 months postoperatively demonstrated continued resolution of the TBM, with evidence of fragmentation and degradation of the splint at 39 months.
• Patient 2: Immediately after implantation of the device, blood gases improved greatly and the left lung perfused. The patient had opioid and benzodiazepine dependence from long-term ventilator support, requiring a longer controlled wean from the ventilator. Four weeks after surgery, the patient was transitioned to a portable ventilator system, completely weaned at 15 weeks, and discharged from the hospital to home for the first time in his life.
• Patient 3: After implantation, the patient ceased experiencing life-threatening desaturation episodes and showed sustained improvement in blood gases. Imaging showed continued patency of the left main bronchus with resolution of left-lung air trapping. However, at 14 months post implantation, he remained on permanent ventilator support, “presumably because of distal left segmental bronchomalacia beyond what the splint was designed to address,” according to Dr. Morrison and his colleagues.
“We report successful implantation of patient-specific bioresorbable airway splints for the treatment of severe TBM. The personalized splints conformed to the patients’ individual geometries and expanded with airway growth (in the ‘fourth dimension’),” the researchers summarized.
“The three pediatric patients implanted with these 3-D–printed airway splints had a terminal form of TBM. The clinical improvement in each case was immediate and sustained, suggesting that improvement is not attributable to the natural history of the disease alone,” they concluded.
The study was funded by the National Institutes of Health. Two of the study authors were coinventors of the device for which they have filed a patent. There were no other disclosures.
