Inherent Problems of Tracheo-Bronchial Stenting in Patients With Tracheostomy

FSI Analysis of a Human Trachea Before and After Prosthesis Implantation

In this work we analyzed the response of a stenotic trachea after a stent implantation. An endotracheal stent is the common treatment for tracheal diseases such as stenosis, chronic cough, or dispnoea episodes. Medical treatment and surgical techniques are still challenging due to the difficulties in overcoming potential complications after prosthesis implantation. A finite element model of a diseased and stented trachea was developed starting from a patient specific computerized tomography (CT) scan. The tracheal wall was modeled as a fiber reinforced hyperelastic material in which we modeled the anisotropy due to the orientation of the collagen fibers. Deformations of the tracheal cartilage rings and of the muscular membrane, as well as the maximum principal stresses, are analyzed using a fluid solid interaction (FSI) approach. For this reason, as boundary conditions, impedance-based pressure waveforms were computed modeling the nonreconstructed vessels as a binary fractal network. The results showed that the presence of the stent prevents tracheal muscle deflections and indicated a local recirculatory flow on the stent top surface which may play a role in the process of mucous accumulation. The present work gives new insight into clinical procedures, predicting their mechanical consequences. This tool could be used in the future as preoperative planning software to help the thoracic surgeons in deciding the optimal prosthesis type as well as its size and positioning.

Self-Expanding Bifurcation Stent for Malignant Esophagotracheobronchial Fistula

A 60-year-old man with esophageal carcinoma in the upper 3rd underwent palliative treatment including photodynamic therapy, brachytherapy, external beam irradiation, and esophageal stenting. He developed a symptomatic malignant esophagotracheobronchial fistula that could not be closed by telescope-stenting in the esophagus. Implantation of a self-expanding, covered metal, tracheal bifurcation stent by flexible bronchoscopy resulted in immediate closure of the fistula with an uneventful recovery.