Biodegradable airway stents in infants – Potential life-threatening pitfalls

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Abstract

Objective

The solution of severe tracheobronchial obstructions in early childhood means a great challenge. Biodegradable stents were intended to be a minimally invasive temporary solution which may decrease the number of interventions and limit the possible complications of stenting procedures. However, our first experiences have brought out a new, - especially in childhood - potentially life-threatening complication of this concept.

Methods

Five SX-ELLA biodegradable polydioxanone stents was applied in three patients because of severe tracheobronchial obstruction: congenital tracheomalacia (7 day-old), acquired tracheomalacia (10 month-old), and congenital trachea-bronchomalacia (10 month-old).

Results

The breathing of all children improved right after the procedure. We observed degradation of the stent from the 5th postoperative week which resulted in large intraluminar fragments causing significant airway obstruction: one patient died of severe pneumonia, the other baby required urgent bronchoscopy to remove the obstructing ‘foreign body’ from the trachea. In the third case repeated stent placements successfully maintained the tracheal lumen.

Conclusions

Polydioxanone stents may offer an alternative to metallic or silastic stents for collapse or external compression of the trachea in children; however, large decaying fragments mean a potential risk especially in the small size pediatric airway. The fragmentation of the stent, which generally starts in the 4–6 postoperative weeks, may create large sharp pieces. These may be anchored to the mucosa and covered by crust leading to obstruction. As repeated interventions are required, we do not consider the application of biodegradable stents unambiguously advantageous.

Introduction

Severe tracheobronchial obstruction is rare in early childhood and is generally caused by non-malignant lesions. The most frequent anomalies are malacia and stenosis, either congenital or acquired [1]. Surgical intervention is challenging due to the specific anatomical situation, the small size, thin, soft and vulnerable tissues of the pediatric airways. Stenting is an important therapeutic modality for the maintenance of the lumen patency through primary application, or through an external approach with reconstructive surgery [2]. Silicone and metallic stents have been widely used [3], [4]. Unfortunately, several complications are associated with them. Silicone stents might tend to migrate and disturb airway mucociliary clearance. Metal stents are hard to remove once embedded in the tracheal because of hyperplastic granulation [3], [4], [5]. To avoid these complications new biodegradable stents have been developed [6]. They are completely dissolvable after a predetermined period of time or by an enzymatic triggering mechanism, so theoretically their removal is not required. Biodegradable stents have been used experimentally for airway stenting since 1998. These stents were originally designed for alimentary tract, but after encouraging animal studies [7] they were recently utilized for treatment of benign airway stenosis [8], [9]. Considering these advantages we started our study; however, our controversial first experiences revealed an unexpected life-threatening complication.

Section snippets

Method

In 2012–2013 five Self-expanding SX-Ella Biodegradable polydioxanone stent (Ella-CS, Hradec Kralove, Czech Republic, www.ellacs.eu) in three young children were applied in two tertiary care centres in Hungary, Department of Otorhinolaryngology Head and Neck Surgery, University of Szeged and Heim Pál Children's Hospital. The sizes of the stents applied were decided on the basis of measurements made on computer tomography and trachea-bronchography.

The compressed stents loaded in their delivery

Discussion

The main causes of serious tracheobronchial obstructions are the following: congenital malacia, postsurgery stricture and airway compression caused by enlarged great vessels [1], [4]. Montgomery first described the use of silicone T-tubes in the adult trachea in 1965 [11]. Airway stent insertion has been extremely useful in treating neonates and infants with severe localized airway narrowing since the 1990s [1], [2], [3], [4], [5]. An ideal airway stent should have the following properties: (I)

Conclusions

Polydioxanone stents may offer an alternative to metallic or silastic stents for collapse or external compression of the trachea. They may avoid the need for permanent stenting and allow subsequent growth of the airway. However, large decaying fragments mean a potential risk especially in the small size pediatric airway. The fragmentation of the stent, which generally starts in the 4–6 postoperative weeks, may create large sharp pieces. These may be anchored to the mucosa and covered by crust

References (20)

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