Complications of airway self-expandable metallic stent in benign airway diseases

doi:10.4236/abb.2013.41A016

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Advances in Bioscience and Biotechnology, 2013, 4, 113-117 ABB

http://dx.doi.org/10.4236/abb.2013.41A016 Published Online January 2013 (http://www.scirp.org/journal/abb/)

Complications of airway self-expandable metallic stent

in benign airway diseases

Fu-Tsai Chung1,2,3*#, Shu-Min Lin1#, Chun-Liang Chou1,3, Hao-Cheng Chen3,4, Chih-Hsi Kuo1,

Horng-Chyuan Lin1, Chien-Ying Liu1, Chun-Hua Wang1, Han-Pin Kuo1, Chih-Teng Yu1*

1Department of Thoracic Medicine, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taipei, Taiwan

2Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan

3Department of Thoracic Medicine, Saint Paul’s Hospital, Taoyuan, Taiwan

4Department of Thoracic Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan

Email: *[email protected]

Received 5 November 2012; revised 17 December 2012; accepted 14 January 2013

ABSTRACT

Objectives: To present the complications of Ultraflex

Self-Expandable Metallic Stents (SEMSs) applied in

patients with benign tracheobronchial diseases. Meth-

ods: Eighty patients received 124 SEMSs were retro-

spectively reviewed in a tertiary hospital. Results:

The baseline characteristics of patients rec eived S EM S

implantation including age (mean + standard devia-

tion: 62.5 + 14.8 years), gender (male, 60.5%), smok-

ing (46.8%), forced expiratory volume in first one

second (FEV1) (mean + standard deviation, 0.92 +

0.41 L/s), follow-up days after SEMS implantation

(median (interquartile range); 457 (131 - 897)) and

covered SEMS (33.9%) were listed. Symptoms im-

proved after SEMS implantation among 95 patients

(76.6%). Time to complications developed was 236

(median; interquartile range, 59 - 672) days. The

overall complication rate was 41.9% after SEMS im-

plantation. The complications included SEMS migra-

tion (6.5%), granuloma (19.3%) and SEMS fracture

(16.1%). Successful management rates of SEMS mi-

gration, granuloma and SEMS fracture were up to

100%, 83.3%, and 85% respectively. Conclusions:

Patients received SEMS implantation due to benign

conditions had poor lung function and were old. The

complication rate in patients with benign conditions

was high after longer follow-up period, however, suc-

cessful management achieved in most patients with

complications.

Keywords: Ultraflex Self-Expandable Metallic Stent;

Benign Airway Disease; Complication; Management

1. INTRODUCTION

Patients with symptomatic central airway obstruction

could be managed in the past ten years [1-3]. Interven-

tional bronchoscopic techniques have been widely ap-

plied in patients with central airway lesions because of

the advances in endobronchial stents and insertion skills

[4-7]. Bronchoscopy with rigid or flexible bronchoscope

is the common procedure of stent placement in those

patients. However, some patients are not suitable to re-

ceive surgical intervention with rigid bronchoscope with

a general anesthetic, due to illness severity and comor-

bidities. Self-Expandable Metallic Stents (SEMSs) can

be successfully inserted using a flexible bronchoscope

while the patient receives conscious sedation and a local

anesthetic [8-10]. For some patients who are not eligible

for surgical procedures or rigid bronchoscopy, self-ex-

pandable metallic stents (SEMSs) insertion offers a ch an ce

to relieve their symptoms [10,11].

Despite SEMSs could relieve central airway obstruc-

tion in large tracheobronchial diseases, some complica-

tions such as migration, granuloma formation, stent frac-

ture, recurrent lumen obstruction of the stent and in-

creased bacterial colonization and impaired mucocilliary

clearance were reported [10,12-14]. The United States

Food and Drug Administration (FDA) has warned that

SEMS implantation should be considered only if the pa-

tient is not eligible for surgery, rigid bronchoscopy, or

silicone stent implantation due to these potentially haz-

ardous complications. Despite the fact, studies [10,15]

also concluded that the SEMS are useful management

options for central airway obstruction symptoms in pa-

tients with benign and malignant diseases. The complica-

tions of this management modality in patients with be-

nign obstructing lesions after placement of SEMSs re-

main the important issues to be concerned.

*Corresponding authors.

#Drs. F.-T. Chung and S.-M. Lin equally contribute to this article as f irs t

authors. None of the authors have any conflicts of interest to disclose.The goal of this study was to describe the baseline

OPEN ACCESS

F.-T. Chung et al. / Advances in Bioscience and Biotechnology 4 (2013) 113-117

114

characteristics, clinical features, overall symptomatic re-

sponse and complication rates after placement of SEMS

in patients with benign airway diseases. The manage-

ments of SEMS-related complications were also reported.

2. PATIENTS AND METHODS

2.1. Design

This investigation was a retrospective study. Informed

consents were obtained from all patients or their surro-

gates prior to the procedure of bronchoscopic SEMS

implantation and follow up. Methodology and patient

confidentiality were approved b y our institutional review

board (IRB No. 98-3287B). The IRB was also asked to

review the design of the project in December 2006 and

approved this retrospective study in March 2007.

2.2. Patients

From August 2001 to March 2008, 80 p atients (mean age

62.5 + 14.8 years) with benign airway diseases under-

went 124 endoscopic airway stents placement at Chang

Gung Memorial Hospital, a university-affiliated hospital

in Taiwan. Thoracic surgeons were routinely consulted

for feasibility of surgical intervention or rigid broncho-

scopy in all patient before SEMS implantation. If pa-

tients were unsuitable for surgical intervention due to

poor lung function, co-morbidities or they refused sur-

gery, SEMS implantation under fiberoptic bronchoscopy

was used if no other treatment options were available.

The development of new or progressive symptoms was

closely monitored and follow-up radiographic and bron-

choscopic examinations were arranged.

2.3. Stent Implantation

Ultraflex (Bosto n Scien tif ic, Natick , MA), a tigh tly w ove n,

self-expandable metallic stent composed entirely of a

single strand of nickel-titanium alloy, was the stent of

choice for this study. The principles of SEMS implanta-

tion in our institution under conscious sedation and local

anesthesia, and the assessment of stent condition were

reported in previous studies [16-18]. The choice of stent

length and type (with or without cover) was determined

by previous endoscopic examination and chest CT scan.

2.4. Assessment of Stent Condition

After placement of the stent, a follow-up bronchoscopy

was performed in 48 hours. The presence of incomplete

stent expansion or incomplete stented airway lumen were

recorded. Therefore, those post-procedure factors could

be evaluated by the follow-up bronchoscopic studies. In

addition, each patient underwent bronchoscopic exami-

nation one week after implantation and then every 3 - 6

months thereafter to evaluate stent position and degrada-

tion, granulation tissue formation and airway alignment.

If new or progressive symptoms including dyspnea, se-

vere cough, increased mucous production or other symp-

toms that suggest stent fracture occurred, additional br on-

choscopy was done.

2.5. Definition of Complications Related to

SEMS

All the possible complications related to SEMS were

confirmed by bronchoscopic examination. According to

patients’ records, complications in our study included

stent migration, granuloma formation, stent fracture, and

pneumothorax. Successful management defined as the

relief of complications after management without the

need for additional procedures during the follow-up pe-

riod. Five patients with SEMS migration did not require

further management as they did not have significant

symptoms. The 5 patients were considered as successful

management but included in the analysis of stent migra-

tion.

2.6. Statistical Analysis

Data are expressed as either group percentages (cate-

gorical variables) or mean ± SD (continuous variables).

Time variables were expressed as median and Interquar-

tile Range (IQR). All analysis used GraphPad Prism 3.0

(GraphPad Sof t ware, San Diego, Calif).

3. RESULTS

From August 2001 to March 2008, 80 p atients (mean age

+ standard deviation, 62.5 + 14.8 years) with benign

tracheobronchial disease received 124 Ultraflex SEMSs.

The indications of SEMS implantation are listed in Table

Table 1. Our experience with SEMS.

Conditions Patients numbers SEMS numbers

Malacia 30 65

Post-intubation st enosis10 12

Post-TB stenosis 10 12

Granulation restenosis12 16

Stent fracture 8 8

Goiter 4 4

Corrosive injury 2 3

Mediastinitis 2 2

Tracheitis 2 2

Total 80 124

Abbreviations: SEMS: Self-Expandable Metallic Stent; TB: Tuberculosis.

F.-T. Chung et al. / Advances in Bioscience and Biotechnology 4 (2013) 113-117 11 5

The demographics of the patients who had placement

of SEMSs are listed in Table 2. The baseline characteris-

tics of patients received SEMS implantation including

age (mean + standard deviation: 62.5 + 14.8 years), gen-

der (male, 60.5%), smoking (46.8%), forced expiratory

volume in first one second (FEV1) (mean + standard

deviation, 0.92 + 0.41 L/s), follow-up days after SEMS

implantation (median (interquartile range); 457 (131 -

897)) and covered SEMS (33.9%) were listed. Symptoms

improved after SEMS implantation among 95 patients

(76.6%). The clinical presentation in patients with benign

airway obstruction included dyspnea (96%), cough (1.6 %)

and respiratory failure (2.4%).

The clinical response and complications after place-

ment of SEMS in patients are listed in Table 3. Symp-

toms improved after SEMS implantation among 95 pa-

tients (76.6%). Time to complications developed was

236 (median; interquartile range, 59 - 672) days. The

overall complication rate after SEMS implantation in

patients with benign conditions was 41.9%. The 30 days

complications rate and the 60 days complications rate

were 4.0% and 8.1%, respectively. The complication

episode/patient/month was 0. 008.

Table 4 summarizes the complications rates and the

time to detect complications after SEMS implantation.

The complication rates included stent migration (6.5%),

granuloma formation (19.3%) and stent fracture (16.1%)

after SEMS implantation. The time to detect granuloma

formation after SEMS implantation in patients with be-

nign airway obstruction was 212 (59 - 489) (median,

(IQR) days. The time to detect SEMS migration and

fracture were 45 (IQ R, 9 - 109) and 686 (IQR, 2 77 - 856 )

days, respectively.

Table 2. Demographics of patients with SEMS placement.

SEMS (n = 124)

Demography

Age 62.5 ± 14.8

Gender, Male, n (%) 75 (60.5)

Smoking, n (%) 58 (46.8)

FEV1 (L/s) 0.92 ± 0.41

SEMS follow up days, median (IQR) 457 (131 - 897)

Cover SEMS, n (%) 42 (33.9)

Clinical manifestation before SEMS implantation

Dyspnea, n (%) 119 (96.0)

Cough, n (%) 2 (1.6)

Respiratory failure, n (%) 3 (2.4)

Abbreviations: SEMS: Self-Expandable Metallic Stent, FEV1: Forced Expi-

ratory Flow in One Second, FVC: Forced Vital Capacity, IQR: Interquartile

Range.

Table 3. Summary of response after SEMS implantation.

Response SMES (n = 124)

Resolution of symptom, n (%) 95 (76.6)

Complication related to SEMS in 30 days, n (%) 5 (4.0)

Complication related to SEMS in 60 days, n (%) 10 (8.1)

Overall complications related to SEMS, n (%) 52 (41.9)

Time to complicat ions developed. Median (IQR) 236 (59 - 672)

Complication ep isode/patient/month 0.008

Abbreviations: SEMS: Self-Expandable Metallic Stent; IQR: Interquartile

Range.

Table 4. Complications rate and time to detect complications

after SEMS placement.

SEMS (n = 124)

Complication rate

Stent migration, n (%) 8 (6.5)

Granulation tissue formation, n (%) 24 (19.3)

Stent fracture, n (%) 20 (16.1)

Time to detect complication after SEMS

implantation (days)

Stent migration 45 (9 - 109)

Granulation tissue formation 212 (59 - 489)

Stent fracture 686 (277 - 856)

Abbreviations: SEMS: Self-Expandable Metallic Stent.

The management and outcomes of complications after

SEMS placement are listed in Table 5. In patients with

stent migration, reposition (n = 4, 50%), another stent

placement (n = 3, 37.5%), and stent removal (n = 1,

12.5%) were the measures used to manage this compli-

cation. Granuloma formation related to SEMS placement

(n = 24) was managed by electrocautery (n = 10, 41.7%),

balloon dilatation (n = 1, 4.2%), stent removal (n = 8,

33.3%), or another stent implantation (n = 5, 20.8%).

Stent fracture (n = 20) was managed by removal of the

fractured stent (n = 10, 50%) or implantation of another

stent (n = 5, 25%). There were 5 fractured stents without

any intervention (rate, 25%) due to minimal protrusion of

the stent with patent lumen and preserved architecture.

Successful management of SEMS migration, granuloma

formation, and SEMS fracture were 100%, 83.3%, and

85%, respectively.

4. DISCUSSION

In patients with benign airway obstruction not willing to

surgery, or medically inoperable, airway stenting may be

the only possible treatment [19]. Silicone stents remain

the first choice in benign airway obstruction except in

patients are unsuitable. In such patients, SEMS are gen-

erally indicated [20,21]. Our study demonstrated that

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OPEN ACCESS

Table 5. Management and outcomes of SEMS-related complications.

Complication Management Total n (%) Successful management, n (%)

Migration

Reposition 4 (50%) 4 (50%)

Another SEMS stenting 3 (37.5%) 3 (37.5%)

SEMS removal 1 (12.5%) 1 (12.5%)

Subtotal 8 (100%) 8 (1 0 0%)

Granulation tissue formation

Electrocautery only 10 (41.7%) 8 (33.3%)

Ballon dilatation 1 (4.2%) 1 (4.2%)

SEMS removal 8 (33.3%) 7 (29.1%)

Another SEMS stenting 5 (20.8%) 4 (16.7%)

Subtotal 24 (100%) 20 (83.3%)

Stent fracture

None 5 (25%) 5 (25%)

SEMS removal 10 (50%) 9 (45%)

Another SEMS stenting 5 (25%) 3 (15%)

Subtotal 20 (100%) 18 (85%)

Abbreviations: SEMS: Self-Expandable Metallic Stent.

patients with benign airway obstruction who had place-

ment of SEMS to relieve symptoms had poor lung func-

tion and were old. Most of our patients with benign air-

way obstruction presented with dyspnea other than cough

and/or respiratory failure. We observed the complication

rate in patients with benign airway obstruction. Specifi-

cally, granuloma formation and SEMS fracture were not

uncommon in patients with benign airway obstruction.

This was probably related to the longer period of time

the stent was present in the airways of patients with be-

nign airway obstruction and exposure of the stent to the

natural and probably excessive compression-decompres-

sion cycles of the airway wall during breathing and

cough (stress fracture). Most of the complications were

managed well and safely by experienced bronchoscopists.

In our institute, surgical treatment in patients with

such benign airway diseases is the first choice. If patients

were unsuitable for surgical intervention because of poor

lung function, comorbidities, or because they refuse sur-

gery, then conservative management and close monitor-

ing will be advised. SEMS placement is considered when

patients present with severe symptoms that affect their

life quality. The high incidence of dyspnea at the time of

presentation in patients with benign airway obstruction

may be explained by the worse lung function and older

age. The presenting symptoms resolved in 3/4 patients

with benign airway obstruction after placement of the

SEMS. This is probably related to the isolated involve-

ment of the central airways in patients with benign air-

way obstruction.

Granulation tissue formation and fractures of SEMS

are not rare in patients with benign airway obstruction.

However, complications rates were similar in patients

with malignant airway obstruction than patients with

benign airway obstruction after 30 and 60 days of fol-

low-up evaluation in previous report [10]. On the other

hand, patients with malignancy-induced central airway

obstruction may develop certain complications like tu-

mor progression after placement of SEMS. Relationship

of this observation to underlying malignancy is possible.

The overall complications rates in our study are simi-

lar to previous studies [10,16]. SEMS related granuloma

formation and stenosis can be managed with a variety of

flexible bronchoscopic interventions including electro-

cautery, cryotherapy, laser photocoagulation, radiofre-

quency ablation and stent removal (when necessary). In

our report, management of SEMS-related complications

was feasible and the success rate was more than 80%.

However, such interventions for SEMS-related compli-

cations require experienced bronchoscopists who are

familiar with techniques like electrocautery, balloon di-

lation, cryotherapy and other interventional pulmonary

procedures. Patients who require placement of SEMS

must be monitored closely for related complications.

In conclusions, SEMS could be placed under flexible

bronchoscopy and conscious sedation with minimal im-

mediate procedure-related complications. Our experience

confirms that patients received SEMS implantation due

to benign conditions had poor lung function and were old.

The complication rate in those patients with benign con-

ditions was high after longer follow-up period. However,

interventional p ulmonary techniques can be utilized with

reasonable success to palliate some SEMS related com-

placations.

F.-T. Chung et al. / Advances in Bioscience and Biotechnology 4 (2013) 113-117 11 7

5. ACKNOWLEDGEMENTS

This study was partial supported by grants from Change Gung Memo-

rial Hospital (CMRPG391211 by Drs. F.T.C., C.T.Y., and C.S.K.;

CMRPG3B0981-3 by Dr. F.T.C. and CMRPG3B0831-3 by Dr. F.T.C.).

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