Air Way Stents
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Airway stentsDr. T. BalasubramanianStenting of airway in time has saved a lot of lives. This eBook attempts todescribe the various airway stents available, when to use them and howto use them. Complications of airway Stenting has also been dealt within detail.
Air way stentsBy
Dr. T. Balasubramanian M.S. D.L.O
Introduction: Airway stenting involves stenting of both larynx and trachea. Stents could besolid or hollow, absorbable or non absorbable. Stenting is usually resorted to in order toprevent airway collapse or to stabilize the reconstructed airway.
History: The word stent is derived from in memory of Charles Stent a British Dentist whodeveloped a material to create dental impressions. This moulding material which wasinitially used for dental impressions was later used to prevent grafted material fromcollapsing. In lay terms now the word stent could mean any structure that keeps the lumenof hollow organ patent and functioning.
Montgomery in 1965 first introduced the still popular tracheal stenting tube, which waschristened after him. It was this stent which revolutionized trachea bronchial surgery.
Indications of airway stents:
1. Can be used to stabilize reconstructed airway2. It also helps in keeping the airway expanded after airway surgical procedure3. Useful in managing a traumatized airway facilitating mucosal regeneration and
prevention of airway stenosis4. Can be used to stabilize cricoid plate after anterior / posterior cricoid split & grafting
procedures. It also helps to keep the cartilage graft inserted. It also helps tocounteract scar contracture.
5. Laryngeal web surgeries : Laryngeal keel stenting is resorted to after successfullaryngeal web resection
6. Stenting of trachea may be resorted to in tracheal malignancies as a palliativemeasure
7. Useful in maintaining airway in primary tracheomalacia
Classification of airway stents:
1. Primary laryngeal stents2. Primary tracheal stents3. Bronchial stents4. A combination of laryngeal and tracheal stents
Laryngeal stenting: Is resorted to when stenosis is confined to larynx / subglottic area. Inshort term stenting the stent is left in place for a period of less than 6 weeks and in long termstenting the stent should be left in place for more than 6 weeks.
Laryngeal Stenting is indicated in patients who have undergone resection of laryngeallesions to prevent laryngeal web / stenosis formation.
Short term stenting of larynx can be resorted to in order to stabilize grafts in place afterlaryngeal reconstruction, to keep the laryngeal mucosa apart in patients with laryngealinjury as a prophylaxis against stenosis.
Long term stenting becomes necessary if long term stabilization becomes necessarywhen extensive tracheal segment resection and anastomosis have been performed.Laryngeal keel is the commonly used laryngeal stent.
Stenting should not be resorted to in individuals who are medically unfit / allergic to stentmaterial.
Tracheal Stenting: Is resorted to in patients who have undergone primary resectionanastomosis for stenosis, stabilization of trachea in cases of primary tracheomalacia. It hasbeen demonstrated that Stenting preserved and improved mucociliary function oflaryngotracheal mucosa. Metallic wall stent is preferred for tracheal Stenting as this couldpromote normal mucosal regeneration. Metal wall stents are used for long term Stenting oftrachea and Montgomery T tube is used for short term Stenting.
Fixation of stents:
Stents can usually be fixed in situ by placement of stay sutures. T tubes can be stabilized inposition without sutures because of their shape.
Aboulker stent: This is the most common stent used to stabilize airway after laryngotrachealreconstruction in children. This stent was introduced by Aboulker in 1960. These stents arecigar shaped and is about 120 mms long available in different diameters. This stent is made
of Teflon which is highly polished. This polished Teflon stent minimizes mucosal irritationand granulation formation. If coated with Mitomycin c before insertion this could minimizefibrosis also. This stent has been known to promote healing while keeping thereconstructed area stable. This laryngeal stent should be placed between true and falsecords and sutured in place using large Prolene stitch tied externally to strap muscles.Multiple knots should be administered for later identification during removal. Aboulkerstent can be used as short and long forms. Short forms can be anchored using Prolinestitches where as the long form will have to be anchored additionally to the tracheotomytube also as shown in the figure below
Long Aboulker stent seen anchored to Jacksons tube.
Aboulker stents of various sizes
Montgomery laryngeal stent: This is a molded silicon prosthesis designed to confirm to thenormal endolaryngeal surface. This stent is radio opaque and is firm enough to support thelaryngeal mucosa. It is reasonably soft also to prevent pressure damage to the laryngealmucosa. This stent is excellent in supporting intralaryngeal grafts (mucosal / skin). Thisstent is provided with two buttons which could be used to suture the stent in place. Thesebuttons are placed over the skin and suture is passed through them to anchor the stent.These buttons facilitate easy post op removal of stent at a later date.
This stent is ideal for prevention & treatment of laryngeal stenosis involving (midglottis,posterior glottis, subglottis and supraglottic singularly or in combination).
Montgomery laryngeal stent
Montgomery laryngeal keel: This umbrella shaped keel made of medical grade silicone. Itcomes in three sizes. It is available in clear and radio opaque versions. Its surface is smoothand non adherent.
Repair of anterior glottis stenosis To prevent stenosis following hemilaryngectomy To maintain anterior commissure after laryngeal web resection Used to hold the laryngeal mucosa apart after laryngeal trauma
Montgomery T tube: This silicone stent has a long central lumen and a smaller lumenprojecting from the side of the stent at an angle of 75 / 90 . The upper end of this stentshould extend through the true cords up to the level of false vocal cords. The lower end ofthis stent should extend up to the level of carina. The side lumen should extend through thetracheostoma. This stent is useful after laryngotracheal reconstruction in adults. This stentmay be unsuitable in children because crusting can cause acute airway obstruction needingimmediate removal which may be difficult in a child. If this stent is used the side arm shouldbe kept blocked most of the time to prevent crusting. A functioning nasal airway providesenough moisture to the inspired air and prevents crust formation. The patency of this stentshould be ensured by frequent suctioning through the side portal.
Montgomery T tube
In tracheal stenosis, when the cervical and thoracic trachea cannot be repaired / as asubstitute for the cervical trachea when it cannot be repaired
To support the reconstructed cervical trachea Prior to reconstruction to maintain airway till inflammation subsides As a palliation in patients with unresectable tracheal tumors With segmental resection & anastomosis In patients with tracheal narrowing and who are not ideal candidates for surgery
Silastic sheets / (Swiss roll stents): This stent was popularized by Evans in 1977. This form ofstent is useful during laryngotracheal reconstructions. This stent is commonly used inchildren. This is actually a thin Silastic sheet rolled and inserted into larynx and uppertrachea. This stent is secured in place by sutures. This stent has a tendency to unroll andcause uniform increase in pressure over mucosa facilitating good healing.
Bricks stent: This is an endotracheal tube made of PVC. This stent is used to stabilizeairway following laryngotracheal reconstruction procedures. This can at most be used as a
short term stent as it is prone to cause granulation of airway mucosa if left in place for morethan 4 weeks.
Silicone stents: This stent is commonly used in adults. This should be introduced only afterdilating the larynx enough to place the stent. The dilatation should be at least 18mm forideal placement of this stent. If dilatation could not cause sufficient enlargement of lumenthen laser luminization should be performed using Co2 laser. This stent should be securedby placing stitches and exteriorizing the knot outside the skin. This stent should always beplaced below the level of vocal cords because it can cause extensive vocal fold oedema ifplaced between the cords. This stent can be used for long term Stenting also.
1. Vocal fold oedema2. Stent migration3. Recurrent stenosis after stent removal
Inflatable stents: Stents of this group has a small balloon attached to a port. This balloon canbe inflated at intervals. This stent may be useful in the management of subglottic stenosis.The balloon should be expanded over a period of 3-6 weeks. Studies have shown that thisstent causes very tissue irritation / reaction.
Tracheobronchial stents: These stents are used for Stenting trachea and bronchus hence canonly be tubular in shape. There are two types of tracheobronchial stents i.e. Silicone andmetal stents.
Metal stents: Metal stents are easier to use in distal trachea & bronchi because they aremade of metal mesh and will not obstruct distal bronchi. Metallic stents are coated withsilicone in order to minimize tissue irritation (these a