Bioresorbable Airway Splint Created with a Three-Dimensional Printer

correspondence

n engl j med 368;21 nejm.org may 23, 2013 2043

couraging, but given that regorafenib also tar-gets angiogenesis, could it be just reexposure to an antiangiogenic drug that is effective? 5

Raffaella Bracci, M.D.Ospedali Riuniti di Ancona Ancona, Italy [email protected]

Elena Maccaroni, M.D. Stefano Cascinu, M.D.Università Politecnica delle Marche Ancona, Italy

Disclosure forms provided by the authors are available with the full text of this letter at NEJM.org.

1. Demetri GD, van Oosterom AT, Garrett CR, et al. Efficacy and safety of sunitinib in patients with advanced gastrointesti-nal stromal tumour after failure of imatinib: a randomised con-trolled trial. Lancet 2006;368:1329-38.2. Blay JY. Pharmacological management of gastrointestinal stromal tumours: an update on the role of sunitinib. Ann Oncol 2010;21:208-15.3. Zama IN, Hutson TE, Elson P, et al. Sunitinib rechallenge in metastatic renal cell carcinoma patients. Cancer 2010;116:5400-6.4. Bergers G, Hanahan D. Modes of resistance to anti-angio-genic therapy. Nat Rev Cancer 2008;8:592-603.5. Demetri GD, Reichardt P, Kang YK, et al. Randomized phase II trial of regorafenib in patients with metastatic and/or unre-sectable gastrointestinal stromal tumor (GIST) progressing de-spite prior treatment with at least imatinib and sunitinib: GRID trial. J Clin Oncol 2012;30:Suppl:LBA 10008. abstract.

DOI: 10.1056/NEJMc1301237

Bioresorbable Airway Splint Created with a Three-Dimensional Printer

To the Editor: Tracheobronchomalacia in new-borns, which manifests with dynamic airway collapse and respiratory insufficiency, is difficult to treat.1,2 In an infant with tracheobronchoma-lacia, we implanted a customized, bioresorbable tracheal splint, created with a computer-aided design based on a computed tomographic image of the patient’s airway and fabricated with the use of laser-based three-dimensional printing, to treat this life-threatening condition.

At birth at 35 weeks’ gestation, the patient did not have respiratory distress and otherwise appeared to be in normal health. At 6 weeks of age, he had chest-wall retractions and difficulty feeding. By 2 months of age, his symptoms pro-gressed and he required endotracheal intubation to sustain ventilation. The workup revealed the following: an anomalous origin and malposition of the pulmonary arteries, with crisscross anat-omy; right pulmonary-artery hypoplasia; com-pression of the left mainstem bronchus between an abnormally leftward-coursing ascending aorta and an anteriorly displaced descending aorta; air trapping; and postobstructive pneumonia. Despite placement of a tracheostomy tube, mechanical ventilation, and sedation, ventilation that was sufficient to prevent recurring cardiopulmonary arrests could not be maintained.

We reasoned that the localized tracheobron-chomalacia was the cause of this physiological abnormality and made a custom-designed and

custom-fabricated resorbable airway splint. Our bellowed topology design, similar to the hose of a vacuum cleaner, provides resistance against collapse while simultaneously allowing flexion, extension, and expansion with growth. The splint was manufactured from polycaprolactone with the use of a three-dimensional printer (Fig. 1A through 1D).

The institutional review board of the Univer-sity of Michigan consulted with the Food and Drug Administration and approved the use of the device under the emergency-use exemption, and written informed consent was provided by the patient’s parents. After transposition of the right pulmonary artery and failed aortopexy, sutures were placed around the circumference of the malacic left bronchus and tied through inter-stices of the splint, and the bronchus was ex-panded (Fig. 1E). Subsequent bronchoscopy re-vealed normal patency of the bronchus without dynamic collapse (Fig. 1F) and normal ventila-tory variation in the size of the left lung. The partial pressure of carbon dioxide in venous blood decreased from 88 to 48 mm Hg. Seven days after placement of the airway splint, wean-ing from mechanical ventilation was initiated, and 21 days after the procedure, ventilator sup-port was discontinued entirely and the child was discharged home with the tracheostomy in place. One year after surgery, imaging and endoscopy showed a patent left mainstem bronchus (Fig.

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T h e n e w e ngl a nd j o u r na l o f m e dic i n e

n engl j med 368;21 nejm.org may 23, 20132044

A

G

B

DC

E FTrachea

Carina

SVC

Aorta

Figure 1. Placement of the Printed Airway Splint in the Patient.

Panel A shows the airway in expiration before placement of the splint; the image was reformatted with minimum- intensity projection. Panel B shows the patient-specific computed tomography–based design of the splint (red). Panel C shows an image-based three-dimensional printed cast of the patient’s airway without the splint in place, and Panel D shows the cast with the splint in place. Panel E shows intraoperative placement of the splint (green arrow) overlying the malacic left mainstem bronchial segment. SVC denotes superior vena cava. Panel F shows the bronchoscopic view, from the carina, of the left mainstem bronchus after placement of the splint. Panel G shows the airway in ex-piration 1 year after placement of the splint; the image was reformatted with minimum-intensity projection.



n engl j med 368;21 nejm.org may 23, 2013 2045

notices

1G). No unforeseen problems related to the splint have arisen. Full resorption of the splint was estimated to occur in 3 years.

This case shows that high-resolution imag-ing, computer-aided design, and biomaterial three-dimensional printing together can facili-tate the creation of implantable devices for con-ditions that are anatomically specific for a given patient.David A. Zopf, M.D. Scott J. Hollister, Ph.D.University of Michigan Ann Arbor, MI

Marc E. Nelson, M.D.Akron Children’s Hospital Akron, OH

Richard G. Ohye, M.D. Glenn E. Green, M.D.University of Michigan Ann Arbor, MI [email protected]

Supported by a grant (FD0003787) from the Food and Drug Administration.

Disclosure forms provided by the authors are available with the full text of this letter at NEJM.org.

1. Masters IB, Chang AB. Interventions for primary (intrinsic) tracheomalacia in children. Cochrane Database Syst Rev 2005;4:CD005304.2. Carden KA, Boiselle PM, Waltz DA, Ernst A. Tracheomalacia and tracheobronchomalacia in children and adults: an in-depth review. Chest 2005;127:984-1005.

DOI: 10.1056/NEJMc1206319Correspondence Copyright © 2013 Massachusetts Medical Society.

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Bioresorbable Airway Splint Created with a Three-Dimensional Printer