Mechanical Properties of Airway Stents

Freitag, Lutz; Eicker, K.; Donovan, Terrence J.; Dimov, D

doi:10.1097/00128594-199510000-00003

Cited by 63 publications

(36 citation statements)

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“…This suggests that the presence of a stent in itself, and not the bronchoscopic procedure used to insert it, is the probable cause of airway colonization/infection, since in both comparable patient groups therapeutic bronchoscopy resolved any airway obstruction, when present. Inherent "stent-related" mechanisms, such as irregularities on the internal stent surface (as with colonization of endotracheal tubes) [13], bacterial cell wall material promoting bacterial binding to the stent (as has been shown for P. aeruginosa) [2,14], or stent-induced mucus-retention due to interruption of mucociliary clearance [15] or increased "reflex" mucussecretion [16] may play a role.…”

Section: Discussionmentioning

confidence: 99%

Absence of bacterial colonization of the airways after therapeutic rigid bronchoscopy without stenting

Noppen¹,

Piérard

Meysman

et al. 2000

Eur Respir J

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Absence of bacterial colonization of the airways after therapeutic rigid bronchoscopy without stenting. M. Noppen, D. Pie Ârard, M. Meysman, R.V. Herreweghe, W. Vincken. #ERS Journals Ltd 2000. ABSTRACT: Following airway stenting, bacterial colonization of the airways with potentially pathogenic micro-organisms occurs within 4 weeks after treatment in the majority of patients. The objective of this study was to prospectively investigate whether nonstenting therapeutic rigid bronchoscopy (using laser, cryotherapy, mechanical dilatation or debridement) is followed by airway colonization or infection.Protected specimen brush sampling of the central airways and quantitative culture were performed immediately prior to, and 4 weeks after nonstenting therapeutic rigid bronchoscopy in 20 consecutive patients with central airway lesions.Prior to therapeutic bronchoscopy, airway colonization/infection was present in nine of 20 (45%) patients. In these nine patients, 10 different potential pathogens were identified: Streptococcus pneumoniae (four cases), Pseudomonas aeruginosa (three), Haemophilus influenzae (two), and Serratia marcescens (one). Eight of these nine patients had a history of postobstructive infections, of which three were currently being treated with antibiotics. Four weeks following therapeutic bronchoscopy, airway colonization/infection was present in five of 20 (25%) patients, each of whom had airway colonization/infection prior to bronchoscopy. In three of these five patients, the same organisms were found 4 weeks after bronchoscopy as at baseline bronchoscopy. In two of five patients new organisms were identified: one case of Streptococcus viridans and one case of Haemophilus parainfluenzae, both considered to be nonpathogens. In four of nine patients with airway colonization/infection prior to bronchoscopy, the airways were clear of micro-organisms after the procedure.The authors conclude that: 1) nonstenting therapeutic rigid bronchoscopy is not complicated by airway colonization or infection by new potential pathogens; and 2) therapeutic rigid bronchoscopy led to clearing of airway colonization/infection in almost half of the patients studied. Although rigid bronchoscopy is performed less often than flexible bronchoscopy in adult pulmonary medicine, it is preferred for therapeutic intervention in the central airways, including laser treatment, cryotherapy, dilatation procedures, mechanical debridement and stenting [1].The authors recently showed that following airway stenting, bacterial colonization of the airways with potentially pathogenic micro-organisms (PPM's) occurs within 3±4 weeks of the procedure in the majority of treated patients.The mechanism of this airway colonization after stenting remains unclear. One possible explanation is contamination of the airways via the rigid bronchoscope itself, by translocation of bacteria that may already colonize the oropharynx and/or proximal airway [2].In order to confirm or refute this hypothesis, the authors performed quantitative protected specimen b...

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Section: Discussionmentioning

confidence: 99%

Absence of bacterial colonization of the airways after therapeutic rigid bronchoscopy without stenting

Noppen¹,

Piérard

Meysman

et al. 2000

Eur Respir J

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“…The silicone stents radial force is higher than the metallic stents. Among metallic stents, the Nanjing stent has the highest radial force and the Ultraflex has the lowest (the Aero stent being in between) [21,24]. Another consideration is the behavior of a stent during coughing.…”

Section: Physical Properties Of Metallic Stentsmentioning

confidence: 99%

“…The airways are under constant repetitive pressure swings from [24,92,93]. Despite the claims made by most manufacturers, typical fatigue fractures are often found in metallic stents, regardless of their design or material.…”

Section: Fractures and Stent Failuresmentioning

confidence: 99%

“…The knitted design permits axial and radial movements of the wire filaments. Thus, an Ultraflex stent can adapt well to the irregular contours of the airways [24]. Uncovered and partially covered (polyurethane) versions are available.…”

mentioning

confidence: 99%

“…Rarely is the extrinsic compression so strong that a stent does not expand provided that it has been selected and released properly. Commercially available airway stents behave differently in a stress-strain test [21,24]. Looking at the chart displaying stress-strain curves of currently popular stents, it is obvious that we still do not know how much expansion force is really required for particular airway problems [21,24].…”

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The use of self-expandable metallic stents in the airways in the adult population

Dutau¹,

Musani

Plojoux³

et al. 2014

Expert Review of Respiratory Medicine

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The airway stents restore patency in the face of luminal compromise from intrinsic and/or extrinsic pathologies. Luminal compromise beyond 50% often leads to debilitating symptoms such as dyspnea. Silicone stents remain the most commonly placed stents worldwide and have been the "gold standard" for the treatment of benign and malignant airway stenoses over the past 20 years. Nevertheless, silicone stents are not the ideal stents in all situations. Metallic stents can serve better in some selected conditions. Unlike silicone stents, there are large and increasing varieties of metallic stents available on the market. The lack of prospective or comparative studies between various types of metallic stents makes the choice difficult and expert-opinion based. International guidelines are sorely lacking in this area.KEYWORDS: airway stenting . benign airway stenosis . bronchoscopy . central airway obstruction . self-expandable metallic stentDumon was the first physician to place a dedicated and specially designed airway stent in 1987 in Marseille. This dedicated stent consisted of a silicone tube with small studs on the external surface to reduce migration [1]. Consequently, several companies started to develop other airway stents with silicone and metal. In the last 20 years, numerous reports have been published about the use of selfexpanding and balloon expandable metal stents for the treatment of tracheobronchial malignant and benign stenoses, tracheobronchomalacia (TBM), fistulas and dehiscences [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].Self-expandable stents are made of a shapememory alloy, generally nitinol (nickel-titanium). When the stent is released, it expands spontaneously to reach its original shape and diameter. On the other hand, balloon expandable metallic stents (the first generation of airway metallic stents) were made of metal (steel) meshes that did not possess a memory shape. A balloon was then necessary to deploy them. Most of these stents had originally been developed for use in the vascular system but were found to be adequate for placement in the central airways after only minor modifications, if any at all. The latest developments include stents made of shape memory alloys and composite stents made from metals and polymers [17][18][19]. But, so far, the Dumon stent (Tracheobronxane Ò , Novatech, La Ciotat, France) remains the most commonly placed stent worldwide. Dumon stents have been the 'gold standard' for the treatment of benign and malignant airway stenoses over the past 20 years [20,21], with two specific designs: straight and Y-shaped (for disease involving the carina) [22]. By the way, it is interesting to notice that, in the Thoracic Endoscopy Unit of Marseille, where the Dumon stent was conceptualized and used, the percentage of silicone stent placement has dropped from 100% in 2000 to 65% in 2013. The remaining 35% of the stents used are now fully covered, selfexpandable, metallic stents (SEMS). This goes to prove that the Dumon stents are not the ideal stents in all situa...

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