3D printing for airway disease

Abstract

It has been 30 years since the first commercial three-dimensional (3D) printer was available on market. The technological advancement of 3D printing has far exceeded its implementation in medicine. The application of 3D printing technology has the potential of playing a major role within interventional pulmonology; specifically, in the management of complex airway disease. Tailoring management to the patient-specific anatomical malformation caused by benign or malignant disease is a major challenge faced by interventional pulmonologists. Such cases often require adjunctive therapeutic procedures with thermal therapies followed by dilation and airway stenting to maintain the patency of the airway. Airway-stent size matching is one key to reducing stent-related complications. A major barrier to matching is the expansion of the stent in two dimensions (fixed sizes in length and diameter) within the deformed airway. Additional challenges are created by the subjective oversizing of the stent to reduce the likelihood of migration. Improper sizing adversely affects the stability of the stent. The stent-airway mismatch can be complicated by airway erosion, perforation, or the formation of granulation tissue. Stents can migrate, fracture, obstruct, or become infected. The use of patient-specific 3D printed airway stents may be able to reduce the stent airway mismatch. These stents allow more precise stent-airway sizing and minimizes high-pressure points on distorted airway anatomy. In theory, this should reduce the incidence of the well-known complications of factory manufactured stents. In this article, the authors present the brief history of 3D printed stents, their consideration in select patients, processing steps for development, and future direction.

Keywords: Airway stent; bronchoscopy; three-dimensional printing (3D printing).

Figure 1

Formation of mucus plug within a stent. The inability to clear secretions due to the obstruction leads to the development of a pneumonia.

Figure 2

Stent fracture of a self-expanding metallic stent. This complication occurred in a patient who had excessive coughing due respiratory syncytial virus infection.

Figure 3

Proximal migration of straight silicone stent into the distal portion of the trachea. The stent was initially seated in the left main stem bronchus.

Figure 4

Granulation tissue formation with complete occlusion at the distal end of a SEMS. SEMS, self-expandable metal stent.

Figure 5

Bronchoscopic image of tissue ingrowth through a fully covered SEMS. The tissue is seen growing over the nitinol wire frame. SEMS, self-expandable metal stent.

Figure 6

Silicone stents can be customized in a variety of ways to improve matching with the airway. Cutting and end-to-end suturing of multiple stents can help create a specific shape.

Figure 7

Illustration of the prescription software using a virtual image to build a 3D stent platform. The virtual file generated by a computer-aided design from DICOM that converted to a STL. DICOM, digital imaging and communications in medicine; STL, standard tessellation language.