Design,Preparation And Performance Study Of Woven Tracheal Stent For Tracheal Fistula Closure

Congenital injury,trauma,tumor resection and other reasons can cause partial tracheal defects.Tracheal fistula is a major type of tracheal injury,and the artificial tracheal stent is an important method to seal treatment.The preparation process of tracheal stent includes 3D printing,electrostatic spinning,knitting,braiding and machine weaving.Among them,the woven technology has the advantages of multiple alternative materials,strong structural plasticity and good process parameters,which provide many possibilities for developing ideal tracheal stent.First of all,based on the performance requirements of tracheal stent for tracheal fistula closure,four kinds of fabrics,namely 1/3 change honeycomb,R=6 simple openwork,fancy lace and transvers bedford cord,were designed respectively.The 0.25 mm polyester monofilament was selected as the warp and weft-yarns,the ends density was 320 ends per 10 centimeters,and the fillings density was set at 320,420 and 520 fillings per 10 centimeters to weave the corresponding straight tube shaped tracheal stent.0.15 mm polyester monofilament was selected as warps be woven with 0.15 mm,0.25 mm and 0.35 mm polyester wefts respectively.The 0.35 mm polyester monofilament was selected as the weft yarns,and the 0.15 mm,0.25 mm and 0.35 mm polyester warp monofilament were woven,respectively.The non-degradable straight tube tracheal stents with 1/3 change honeycomb structure were obtained.The 0.25 mm polyester monofilament was selected as the warps and wefts,and the non-degradable "dumbbell" shaped tracheal stents with R=6 simple perforated structure were obtained.Then,the three structural properties(wall thickness,pore size and porosity)and the three mechanical properties(radial supporting force,elastic recovery rate and pulling force)of the prepared non-degradable straight tubular tracheal stent were tested.By analyzing the test results,the following conclusions were obtained: fabric structure had great influence on the structural performance,radial support force and pulling force of the tracheal stent,but had few influence on the elastic recovery rate of the tracheal stent.Among the four kinds of tracheal stent structures,the tracheal stent with transverse bedford cord structure had the largest wall thicknes;The tracheal stent with fancy lace structure had the smallest pore size and porosity.The tracheal stent with 1/3 change honeycomb structure had the largest radial supporting force.The tracheal stent with fancy lace structure had the highest pulling force.The correlation analysis of three structural properties and radial supporting force showed that the radial supporting force had a significant positive correlation with wall thickness,a significant negative correlation with pore size,and no correlation with porosity.The correlation analysis of the three structural properties and pulling force showed that the pulling force had a significant positive correlation with wall thickness,a significant negative correlation with pore size,and no correlation with porosity.Then,PDO monofilaments with good biocompatibility and strong elastic deformation ability were selected as the materials for degradable "dumbbell" shaped tracheal stent based on the test analysis conclusion and design preparation process of non-degradable tracheal stent.The0.35 mm PDO monofilaments was selected as the warp and weft-yarns,and the warp density of the middle straight pipe segment was 388 ends per 10 centimeters and the weft density of the middle straight pipe segment was 236 fillings per 10 centimeters according to the surface pore size requirements(0.2-0.3mm)of the tracheal stent used for plugging.A degradable "dumbbell" tracheal stent with R=6 simple perforating structure was woven.The three structural properties of the tracheal stent,namely wall thickness,pore size and porosity,and radial support force,elastic recovery rate and pull force,were determined and analyzed.Finally,the degradable "dumbbell" shaped tracheal stent was implanted into the experimental dog,and the 8-week follow-up observation showed that the experimental dog breathed smoothly,and no stent collapse or migration occurred.Scanning electron microscopy and radial compression test were performed on the implanted tracheal stents at different times.It was found that the degradation rate and mechanical retention rate of the stents met the requirements of the cooperation unit.In this paper,a series of degradable "dumbbell" shaped tracheal stent with fabric structure for tracheal fistula closure was designed and prepared.The influence of different fabric structure,monifilament diameter,warp and weft density,shape and size on the performance of the stent was explored.Animal experiments showed that the preferred stent developed fully met the requirements of the cooperation unit.