the stent is usually deployed under general anesthesia through an orotracheal tube or by transtracheal ( in tracheostomized patients ) access . however , laryngeal mask , laryngoscopy , and conscious sedation have been used to minimize patient discomfort time and procedure time . we describe three patients with severe malignant central airway narrowing managed by self - expandable nitinol stent placement through endonasal route with the help of a flexible bronchoscope and fluoroscopic guidance under local anesthesia . three men with inoperable malignant severe tracheal or bronchial stenosis were treated between october 2012 and march 2015 [ table 1 ] . 1 and 2 [ figures 1a and b , 2a ] and left bronchial narrowing of 60% in patient no . the first two patients presented with significant dyspnea and stridor , while the third patient had the complaint of tracheoesophageal fistula but was not symptomatic for left bronchial narrowing [ figure 3b ] . however , this patient risked imminent left bronchial obstruction either due to disease progression or during esophageal stenting , as its radial force might further displace the infiltrating mass into the left bronchus . these procedures were approved by our institute review board and were performed in accordance with the ethical standards of our institute . summary of the patients who underwent transnasal tracheobronchial stenting with bronchoscopic and fluoroscopic guidance under local anesthesia ct findings and steps of transnasal stent deployment in patient no . 1 . ( a ) contrast - enhanced ct axial image and ( b ) coronal ct reconstruction image with volume - rendered tracheal lumen shows severe tracheal narrowing due to a nodal mass from the right side just above the carina . ( c ) transnasal introduction of bronchoscope in sitting position . ( g ) radiographs showing fully deployed tracheal stent in antero - posterior and lateral views ( a and b ) tracheal stenting in high tracheal obstruction ( patient no . ( a ) coronal ct reconstruction image showing upper tracheal narrowing due to an infiltrating paratracheal mass causing significant obstruction ( white arrows ) . ( b ) radiograph shows tracheal stent deployed across the obstruction . note vocal cords indentations safely above the stent margin ( white arrows ) ( a - g ) stenting for left bronchial narrowing ( patient no . 3 ) . ct images taken before and after the procedure with radiographs and photographs of the procedure . ( a ) ct images show left bronchial infiltration of the esophageal mass and ( b ) associated tracheoesophageal fistula ( open white arrow ) . ( c ) photograph shows transnasal access of left bronchus with the guidewire through the right nostril and bronchoscope re - introduced through the left nostril . ( d ) radiograph shows transnasal bronchoscope proximal to the undeployed stent in the left bronchus . ( f ) pre - treatment and ( g ) post - treatment oblique ct reconstructions along the left bronchus for comparison , showing the severity and extent of left bronchial narrowing which is resolved after stenting the procedure was performed on a c - arm compatible ot table with monitoring of vitals . in patient 1 , the procedure was done with the patient in sitting position due to severe dyspnea . flexible adult bronchoscope ( model 11001bn1 ; storz , tuttlingen , germany ) with a diameter of 5.2 mm and a working channel of 2.3 mm was introduced through a nostril to the site of narrowing and negotiated beyond the lesion [ figure 1c and d ] . a guidewire ( j - tip 0.035 , 260 cm superstiff amplatz guidewire ( cook , bloomington , usa ) was passed through the working channel of the bronchoscope across the stenosis up to a segmental bronchus under fluoroscopy ( bv endura mobile 9 c - arm ; philips , da best , the netherlands ) [ figure 1d ] . the bronchoscope was withdrawn carefully keeping the guidewire in place and re - introduced through the other nostril to monitor the stent deployment [ figure 3c ] . for tracheal stenosis , a niti - s comvi tracheobronchial self - expandable nitinol stent 20 mm 60 mm with 18f delivery system ( taewoong medical , gyeonggi - do , korea ) was used [ figures 1f and g , 2b ] . this delivery device has a yellow marker at the proximal end of the stent to aid easy positioning without fluoroscopy . the yellow marker must be beyond the vocal cord to avoid accidental deployment at supraglottic or glottis level [ figure 1e ] . for left bronchial stenting , a 12 mm  40 mm maris plus self - expandable nitinol stent ( medtronic , minneapolis , usa ) with 6f delivery system was used [ figure 3d , e and g ] . all stents could be easily negotiated over the guidewire across the stricture under bronchoscopic and fluoroscopic guidance and deployed . 3 , a covered self - expandable nitinol esophageal stent ( expanse , indus medical , kolkata , india ) was deployed transorally under fluoroscopic guidance to treat the tracheoesophageal fistula [ figure 3e and g ] . transnasal tracheobronchial interventions including bronchoscopic biopsies , lavage , balloon dilatation of tracheobronchial stenosis , and treatment of bronchobiliary fistula have been described ; however , to our knowledge , successful tracheal stenting through the nasal route has not been described earlier . no prior intubation or general anesthesia is necessary , thereby significantly shortening the procedure time . smaller diameter fiber - optic bronchoscopes and smaller profile flexible stent introducer system have enabled us to perform these procedures in a quick and safe manner . in our institute maximum diameter of covered comvi tracheobronchial stent delivery system is 6 mm ( 18f ) , which is similar to most bronchoscopes , ultrathin endoscopes ( 4.96 mm ) , and wide bore nasogastric tubes ( up to 20f , 6.67 mm ; romsons scientific , agra , india ) for transnasal use . easy transnasal passage of our flexible bronchoscope , which has a diameter of 5.2 mm , ensured easy navigation of the 6 mm ( 18f ) delivery device . a failed attempt to deploy tracheal stent transnasally has been described possibly due to a larger delivery system ( 9 mm , 27f ) of 20 mm  40 mm ultraflex tracheal stent . one possible limitation of our technique includes any significant obstruction in the nasal cavity including deviated nasal septum , nasal polyp , etc . in unilateral obstruction such as deviated nasal septum , initial access can be made through the other nostril for bronchoscopy followed by stent deployment , while bronchoscopic monitoring can be done via transoral access without any other modification . a variety of self - expandable stents are available to treat airway narrowing , the most common being wallstent and ultraflex stents ( boston scientific , marlborough , ma , usa ) . despite their limitations , silicone stents are also used by bronchoscopists , especially for benign diseases , and they require direct bronchoscopy under general anesthesia for deployment . choice depends largely upon expertise , user preference , availability , and patient - specific requirements . tracheobronchial stenting is performed using various techniques utilizing a flexible or rigid endoscope often under general anesthesia with endotracheal intubation or laryngeal mask . veno - venous extracorporeal membrane oxygenation ( vv ecmo ) has also been used for critical stenoses . others have described the procedure under conscious sedation and local anesthesia with either fluoroscopic or bronchoscopic guidance . we consider fluoroscopic guidance absolutely necessary for accurate self - expandable nitinol airway stent placement . performing the procedure through the nasal route is convenient for the patient and easier for the therapist to manipulate the instruments even in awake patients . in addition , oral route is kept free for any anesthetic intervention during the procedure . to conclude , tracheobronchial stenting using self - expandable nitinol stent through transnasal route is safe . the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s ) has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal . the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed . the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s ) has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal . the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .
purpose : to study the technical feasibility of tracheobronchial stenting via transnasal route under bronchoscopy and fluoroscopic guidance in severe malignant airway strictures using self - expandable nitinol stents.materials and methods : we describe three patients with malignant airway strictures , treated entirely via transnasal route under local anesthesia using bronchoscopic and fluoroscopic guidance . 
 nasal route allowed convenient access to the airway for the bronchoscope across the stricture and a guidewire was introduced through its working channel . 
 the 18f tracheal stent and the 6f bronchial stent assembly could be easily introduced and deployed under bronchoscopic ( reintroduced through the other nostril ) and fluoroscopic guidance.results:we achieved technical success in all the three patients with immediate relief of dyspnea.conclusion:transnasal airway stenting with self - expandable nitinol stent using bronchoscopic and fluoroscopic guidance under local anesthesia is a safe and effective method with minimal patient discomfort .