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

The Montgomery T-tube is used as a combined tracheal stent and airway after laryngotracheoplasty, to keep the lumen open and prevent mucosal laceration from scarring. It is valuable in the management of upper and mid-tracheal lesions, while invaluable in long and multisegmental stenting lesions. Numerical simulations based on real-patient-tracheal geometry, experimental tissue characterization, and previous numerical estimation of the physiological swallowing force are performed to estimate the consequences of Montgomery T-tube implantation on swallowing and assisted ventilation: structural analysis of swallowing is performed to evaluate patient swallowing capacity, and computational fluid dynamics simulation is carried out to analyze related mechanical ventilation. With an inserted Montgomery T-tube, vertical displacement (Z-axis) reaches 8.01mm, whereas in the Y-axis, it reaches 6.63mm. The maximal principal stress obtained during swallowing was 1.6MPa surrounding the hole and in the upper contact with the tracheal wall. Fluid flow simulation of the mechanical ventilation revealed positive pressure for both inhalation and exhalation, being higher for inspiration. The muscular deflections, considerable during normal breathing, are nonphysiological, and this aspect results in a constant overload of the tracheal muscle. During swallowing, the trachea ascends producing a nonhomogeneous elongation. This movement can be compromised when prosthesis is inserted, which explains the high incidence of glottis close inefficiency. Fluid simulations showed that nonphysiological pressure is established inside the trachea due to mechanical ventilation. This may lead to an overload of the tracheal muscle, explaining several related problems as muscle thinning or decrease in contractile function.