| Airway stenosis can be caused by malignant diseases, trauma, infection, tracheobronchial malacia, obstructing tumors, bronchial anastomasis , or by ex-trinsic compression, also have been very common in lung transplant patients. Airway stenosis can cause severe symptoms such as dyspnea, cough, emptysis and may result in progressive dyspnea , hypoxemia and suffocation , which may be life threatening. In 1986, Wallace et al first reported using self - expanding metallic stent (SEMS) treated tracheal stenosis . With the development of inter-ventional radiology ( FVR) , the use of SEMS for treatment of trachea! stenosis has developed and obtained satisfactory curative effect during the past years.Presently, however, SEMS are mostly used for lower tracheal or bronchial stenosis . Stenting in the upper trachea has the possibility of result in larynx and glottis edema which may cause suffocation in the patients . In this study ,we de-ploied SEMS in the upper trachea in dogs. The purpose of our study was to evaluate the security and correlative factor of stents placement in the upper trachea , so as to provide theoretical basis for rational treat in patient with tracheal steno-sis in the upper trachea.Materials and MethodsWe used twenty - four almost fully grown dogs, all were 18 to 24 monthes of age with a mean weight of 16 kgs. The stents we used were 20 mm in diameter and 50 mm in length . The dogs were kept in the animal facility of the hospital for at least three days prior to the start of experiment to observe their status of breath , eating and phonation. All dogs were defined three groups ,each groupinclude eight dogs . The dogs underwent general anesthesia with an intrperitone-al injection of sodium thiopental(30 mg/kg) . Under the guidance of fluorosco-py ,the stent was deploied in each dog at the predetermined level. Group A: proximal margin of the stent at the level of the lower margin of glottis; Group B: proximal margin of the stent at the level of 5mm below the lower margin of glottis ; Group C: proximal margin of the stent at the level of 15 mm below the lower margin of glottis.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. Two dogs in each group were killed at the time of one week , one month , three monthes and six monthes after the stent placement respectively . The animals were killed with an IV bolus injection of KC1 (10% ). Before the dogs were killed ,CT examination were performed to evaluate migration of the stents , compared the distance of migration between each group. After the dogs were killed,the trachea!, bronchi, e-sophagus were examined grossly and histologically . The thickness of hyperplasia tissue at different time , different part were measured and compared . A probality level of < 0. 05 was considered significant .ResultIn our study , Stents placement was technically successful in all dogs , the stents were 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 . One dog in group A died of diarrhea five days after the stent placement and One dog in group C died of accident , examination of a cadaver can not confirm the cause of death . Eight dogs underwent stridor or dyspnea eight to twelve weeks after the operation, CT examination indicated that there were serious stenosis in trachea! lumen , five dogs were killed at the time of three monthes, in other three dogs, the symptom alleviated when observed to six monthes .At the time of CT examination , all stent migrated downwards slightly , therewere not statistical difference in migration distance between each group (P >0. 05 ), the mean migrated distance was 9.86 5.27mm . There were not statistical difference in the thickness of hyperplasia tissue between each gro... |
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