Research Of Experiment After Placing Different Tracheal Stent In Experimental Dogs

PrefaceSince metal tracheal stent which covered with membrane was applied successfully to treat the airway stenosis, it has been used wildely in that field today. Airway stenosis can be caused by obstructing tumors. Airway syenosis can cause severe symptoms such as dyspnea, cough, emptysis and may result in progressive dyspnea, hypoxemia and suffocation, which may be life threatening. With the development of interventional tadiolog(IVR) ,the use of metal tracheal stent which covered with membrane for treatment of tracheal stenosis has developed and obtained satisfactory curative effect during the past years. There are some questions;Whether the tracheal stent which covered with membrane was safe or not, the condition after placing tracheal stent,and the effect to airway after placing the membrane - covered tracheal stent and the nomembrane - covered tracheal stent. The purpose of our study was to use animal experiment, so as to provide theoretical basis for rational treat with membrane - covered tracheal stent.Material Methods1. objects and groupThere are totally 18 dogs, matured and healthy. The stents we used were 22mm indiameter and 6cm in length. All dogs were defined three groups, each group include six dogs,and respectively are killed on the 20th weeks.2. Materials and Instrumentstracheal stent, SHIMADZU DIGITEX 2400αDSA,PHILIPS MX8000 MUL-TISPLICE CT,PCNA and so on.3. PtocedureWith fasting 12 hours before operation and then abdominal anesthesia, the dog was fixed lying on its back, with its montx filled up. Under the guidance of fluoroscopy, the stent was deploied in each dog at the predetermined level. Take X -ray films,CT scan and 3D reconstruction.After the stent placement, all the dogs were monitored daily for signs of respiratory distress , coughing , wheezing , stridor and tachypnea . All dogs were monitored by clinical assessment dysphagia or dysphonia. Twenty weeks later, the animals were killed with an IV bolus injection of KCL( 10% ). Then we began to take materials from the upper , middle and lower part of the segment of the stent of dorsal and ventral part. Through dehydration, hualination and waxinfil-tration, the specimen was made into 5 slices. After being HE an being fixed PC-NA test,the specimen was under microscope.4. Levels and StatisticsIf its nuclear was stained, the cell was called PCNA positive one, when no stain, we called it negative. The positive expressing of PCNA at different groups were measured and compared. A probality level of <0. 05 was considered significant.ResultsIn our study, stents placement was technically successful in all dogs, the tracheal stents well tolerated . After the stent placement, all dogs had a cough, which alleviated three to five days later. All dogs did not have dyspnea, dysphagia or dysphonia. There were not difference in symptom between the three group. Inflammation reaction, metaplasia from low columnar epithelium to spua-mous epithelium and gently granulation tissue hyperplasia occurred in part of mucosa occurred which the membrane covered tracheal stent area, but the membrane of tracheal stent was not breached by these pathological changes. A inflammation reaction, metaplasia from low columnar epithelium to spuamous epithelium and gently granulation tissue hyperplasia in part of mucosa, fibrosis and trachea straitness had occurred in the no - membrane - covered area. We foundmore PCNA expressing in no — membrane - covered tracheal stent group.ConclusionThere were not difference in symptom for short time whether membrane covered or not. The biologic compatibility of the membrane - covered tracheal stent is good and would not induce trachea straitness. However, the no —membrane — covered tracheal stent induced a severe pathologic reaction and trachea straitness.