Patient-specific models of human trachea to predict mechanical consequences of endoprosthesis implantation

Abstract

Nowadays, interventions associated with the implantation of tracheal prostheses in patients with airway pathologies are very common. This surgery may promote problems such as migration of the prosthesis, development of granulation tissue at the edges of the stent with overgrowth of the tracheal lumen or accumulation of secretions inside the prosthesis. Among the movements that the trachea carries out, swallowing seems to have harmful consequences for the tracheal tissues surrounding the prosthesis. In this work, a finite-element-based tool is presented to construct patient-specific tracheal models, introducing the endotracheal prosthesis and analysing the mechanical consequences of this surgery during swallowing. A complete description of a patient-specific tracheal model is given, and a fully experimental characterization of the tracheal tissues is presented. To construct patient-specific grids, a mesh adaptation algorithm has been developed and the implantation of a tracheal prosthesis is simulated. The ascending deglutition movement of the trachea is recorded using real data from each specific patient from fluoroscopic images before and after implantation. The overall behaviour of the trachea is modified when a prosthesis is introduced. The presented tool has been particularized for two different patients (patient A and patient B), allowing prediction of the consequences of this kind of surgery. In particular, patient A had a decrease of almost 30 per cent in his ability to swallow, and an increase in stresses that were three times higher after prosthesis implantation. In contrast, patient B, who had a shorter trachea and who seemed to undergo more damaging effects, did not have a significant reduction in his ability to swallow and did not present an increase in stress in the tissues. In both cases, there are clinical studies that validate our results: namely, patient A underwent a further intervention whereas the outcome of patient B's * Author for correspondence (amaya@unizar.es). surgery was completely successful. Notwithstanding the fact that there are a lot of uncertainties relating to the implantation of endotracheal prostheses, the present work gives a new insight into these procedures, predicting their mechanical consequences. This tool could be used in the future as pre-operative planning software to help thoracic surgeons in deciding the optimal prosthesis as well as its size and positioning.

Simulation of swallowing dysfunction and mechanical ventilation after a Montgomery T-tube insertion

“…Previous simulations made on physiological swallowing and with real-patient-tracheal geometries and swallowing trajectories showed that almost the same axial force, with an average of 13.5 N, is necessary to close the glottis during the swallowing movement (Perez del Palomar et al 2010;Trabelsi et al 2011).…”

“…These are normally focused on quantifying particles deposition for aerosol techniques Balashazy et al 1996;Nowak et al 2003), on the development of analytical models simulating an isolated tracheal ring (Holzhäuser and Lambert 2001), on analyzing the mechanism of mucosal folding that explains the difference in airway narrowing between asthmatic and control airways (Wiggs et al 1997), or on tracheal finite element models used to predict the behavior of animal (Costantino et al 2004) or human trachea (Gustin et al 1996;Perez del Palomar et al 2010;Trabelsi et al 2011Trabelsi et al , 2014Perez del Palomar et al 2010) with and without an inserted prosthesis. While some studies use structural simulations on real human geometries (Perez del Palomar et al 2010;Trabelsi et al 2011Trabelsi et al , 2012Trabelsi et al , 2014 other studies solve the computational fluid dynamics (CFD) problem applied to approximate (Calay et al 2002;Nowak et al 2003;Ma and Lutchen 2006) or real (Tawahai et al 2004;Gemci et al 2008;Luo and Liu 2008;Wall et al 2010) tracheal geometries. Only few studies have been recently oriented to the coupling between fluid and solid.…”

A pre-operative planning for endoprosthetic human tracheal implantation: a decision support system based on robust design of experiments

“…17, No. 7, 750-767, http://dx.doi.org/10.1080/10255842.2012.715639 (Malvè et al 2010(Malvè et al , 2011Perez del Palomar et al 2010;Trabelsi et al 2011).…”

Computational fluid-dynamics optimization of a human tracheal endoprosthesis

“…In particular, in previous studies [23][24][25], we presented numerical analyses of the tracheal stenting technique proposing possible preoperative planning software designed to support thoracic surgical decisions. Recently we also analyze the tracheal behavior under implantations of different stent type (Dumon© and Ultraflex© stent) [21] with the aim of studying the impact of different prostheses on the smooth muscle and evaluate the risk of stent migration.…”