| Japanese Journal of Clinical Oncology | Pages |
Introduction
Materials And Methods
Expandable Metallic Stent
Technique
Pre-stenting Studies
Patients
Results
Discussion
References
Experience of Expandable Metallic Stents for Central Airway Obstruction
The aim of this study was to investigate retrospectively the efficacy of expandable metallic stents (EMSs) for severe respiratory distress in patients with central airway obstruction. Twenty patients with central airway obstructions were treated with an EMS. An intraluminal stricture was present in 15 and an extraluminal stricture in 5 patients. Of the 15 patients with intraluminal stenosis, 11 exhibited symptomatic improvement. All 11 patients had tumor infiltration occupying less than 50% of the endoluminal diameter. The other four patients with intraluminal stenosis had tumor infiltration occupying >50% of the endoluminal diameter and demonstrated no improvement. All five patients with extraluminal stenosis were improved. EMS is useful for an extraluminal stricture in the central airway and the effect of EMS for intraluminal stenosis is related to the degree of infiltration and of tumor progression itself.
Introduction
The most common etiology for a central airway obstruction is a primary or metastatic carcinoma of the lung, direct infiltration of esophageal carcinoma or mediastinal lymph node metastasis from other primary tumors. Stenosis of the central airway can lead to severe morbidity with life-threatening symptoms for which the available therapeutic options are limited. Various treatment modalities have been developed for the management of an inoperable malignant stricture in the central airways. The neodynium: yttrium-aluminum garnet (Nd:YAG) laser has become the most widely used method to relieve an obstruction caused by intraluminal tumor growth (1,2). More recently, stents initially developed for the treatment of vascular stenoses have been adapted for use in the tracheobronchial tree (3-9). Here, we report our experience using expandable metallic stents (EMSs) in patients with tracheobronchial strictures caused by various diseases.
MATERIALS AND METHODS
Expandable Metallic Stent
The EMSs used were cylindrical structures made of stainless-steel wire. The stents were available in lengths of 20 mm (single stent) or 40 mm (double stent made from two lengths attached together using monofilament nylon) for use in the trachea and 15 mm (single stent) or 30 mm (double stent) for use in the bronchi. The stents were constructed of 0.45 or 0.40 mm stainless-steel wire for use in the trachea or the main-stem bronchi, respectively. The wires are shaped into zigzag cylinders with six or eight bends (Fig. The stent was inserted in its compressed form into the introducer sheath using the stent pusher. Bronchoscopy was performed under local or intravenous anesthesia to inspect the stricture and clear the airway of any secretions. The tip of the bronchoscope was then positioned immediately above the stricture. The flexible guidewire was passed through the stricture under fluoroscopic control. Two radio-opaque markers were placed on the skin of the chest to outline the extent of the stricture. Once the guidewire was in place across the stricture, the bronchoscope was partially withdrawn to allow better visualization, then the sheath was inserted over the guidewire. The stent was pushed down and held in position with the stent pusher while the sheath was withdrawn, allowing the stent to be released across the stricture. Additional stents were applied for longer strictures. The stent position was assessed using fluoroscopy and bronchoscopy. Repositioning or removal of a stent is virtually impossible. Finally, chest radiographs were obtained to confirm the position of the stent.
Figure
Initially, the stricture, the level and the length of obstruction were assessed using chest radiographs, tomograms and computer tomography. Careful endoscopic examination of the airway was carried out to verify the site and extent of the lesion. There were 20 patients, 12 men and 8 women, ranging in age from 37 to 77 years (mean 59 years) who underwent stenting between January 1991 and March 1995. The etiology of the obstruction included an esophageal carcinoma (n = 11), a primary lung carcinoma (n = 3), malignant lymphoma (n = 1), metastatic lung carcinoma (n = 1), thyroid carcinoma (n = 1), adenoid-cystic carcinoma (n = 1), recurrent lung carcinoma (n = 1) and a recurrent thyroid carcinoma (n = 1). The stented stenotic segment involved the right main-stem bronchus (n = 1), the left main-stem bronchus (n = 3), the trachea alone (n = 9), the trachea and one main-stem bronchus (n = 3) or the trachea and both main-stem bronchi (n = 2). The cause of the airway stenosis was either extraluminal compression (n = 5) or intraluminal obstruction (n = 15). Of the patients with intraluminal obstruction, 10 had esophageal carcinoma, three had lung carcinoma, one had metastatic lung carcinoma, one had recurrent lung carcinoma and one had recurrent thyroid carcinoma (Table 1). Of the five patients with extraluminal compression, there was one with esophageal carcinoma, one with thyroid carcinoma, one with adenoid cystic carcinoma, one with a thyroid carcinoma recurrence and one with malignant lymphoma (Table 1). The number of stents used per patient ranged from one to four. Additional stents were inserted at a second procedure in two patients. In one patient with esophageal carcinoma, a stent was placed in the left main-stem bronchus at 30 days after a double stent had been placed in the trachea. In the other patient with lung carcinoma recurrence, a stent was placed in the right main-stem bronchus at 62 days after a double stent had been inserted along the trachea to the left main-stem bronchus. Of the 15 patients with an intraluminal obstruction disease, eight received Nd:YAG laser vaporization before and after EMS implement and one patient with extraluminal stenosis due to an adenoid cystic carcinoma received Nd:YAG laser therapy after the EMS insertion. The patients were evaluated by clinical response and by improvement in oxygen saturation. Patients whose dyspnea was divided completely or almost completely were improved or resolved (`improved') or did not change (`no change') in symptoms and oxygen saturation after insertion of the EMS. Follow-up examinations were performed in the outpatient department or in our institution.
Table
Technique
Pre-stenting Studies
Patients
Primary diagnosis
No.
Intraluminal stenosis:
Esophageal carcinoma
10*
Lung carcinoma
3
Metastatic lung carcinoma
1
Lung carcinoma recurrence
1*
Extraluminal stenosis:
Esophageal carcinoma
1
Thyroid carcinoma
1
Adenoid cystic carcinoma
1
Thyroid carcinoma recurrence
1
Malignant lymphoma
1
Results
Placement of the stents was relatively simple. Stenting was performed successfully in all 20 patients. No migration of the EMS occurred and none of the patients complained of post-operative respiratory symptoms, such as coughing, discomfort or other evidence of tracheobronchial irritation. Of the 10 patients with intraluminal stenoses from esophageal carcinoma, nine received EMS at one operation while the other one received EMS at two operations. Of the 10 patients, six (60%) showed relief from distress. The other four patients (40%) exhibited no improvement and died within 2 months of EMS implantation (Table 2). Relief from stridor was dramatic and occurred within hours to days soon after the procedure. Patient 8 underwent additional double stenting of the left main-stem bronchus due to intraluminal re-stenosis. A dramatic improvement in stridor was observed after placement. However, this patient with progressive esophageal carcinoma developed necrosis with intraluminal invasion. The region of this EMS showed a bronchoesophageal fistula on the eighth day and the patient died. Patient 9 developed hemoptysis from the tumor after stent emplacement and died on the second day. This patient had progressive esophageal carcinoma invading the pulmonary artery and left main bronchus. With hindsight, an EMS may induce a bronchial fistula and/or hemoptysis in this situation. Nine (90%) of the 10 patients with intraluminal stenoses due to an esophageal carcinoma died within 3 months (Table 2). The other five patients with intraluminal stenoses showed improvement immediately after stent emplacement and were followed for 28-395 days (Table 3). Death in the late post-operative period occurred as a result of progression of the primary disease without evidence of central airway obstruction. The tumor occupied less than 50% of the endoluminal circumference in all the patients with intraluminal stenoses that had improvement in their symptoms after stenting and greater than 50% in all of those who had no change in their respiratory symptoms. Pre-procedure, 10 patients with intraluminal stenoses had an oxygen saturation <95% on 5 l min-1 of oxygen delivered via a nasal cannula. Of these patients, seven exhibited improved oxygenation immediately after the EMS emplacement. The other three patients had local progressive disease and tumor growth was seen to occur between the wires of the stent.
All five patients with extraluminal stenoses showed improvement in their oxygen saturation immediately after the procedure (Table 4). The mean follow-up was 2.5 years (with follow-up ranging from 140 to 1610 days). Patient 1 developed tracheomalacia as a consequence of long-term intubation following resection of an esophageal carcinoma. The post-EMS implantation course was satisfactory. The patient underwent bronchoscopy at 7 and 30 days, after the EMS emplacement. The EMS was clearly observed at 7 days (Fig.
Figure
Figure
The EMS is a conservative treatment for a number of tracheobronchial and mediastinal conditions which result in an obstruction in the central airway (3-5). This procedure is suitable for tracheomalacia due to long-term endobronchial intubation or for chronic external compression on the trachea. Dramatic relief in stridor has been observed after stenting with gradual alleviation of dyspnea (10-12). On the other hand, since the first description of a tracheobronchial stent by Dumon, the use of a silicon endoprosthesis has gained increasing popularity (1,13).
Table 2
Table 3
Table 4
The EMS is well tolerated and allows for the normal clearance of secretions since ciliary movement is not interrupted. It is easy to place, requiring only a flexible bronchoscope. However, the EMS has some disadvantages: (1) bronchoscopic removal is a difficult procedure; (2) emplacement in the trachea is not precise; (3) it is not effective for tracheobronchial stenosis; (4) the weakest part of the tandem double stent is the junction of its two components and so the double stent is usually emplaced with one of the halves at the center of the narrowest segment of stenosis; and (5) intraluminal tumors can exhibit ingrowth through the gaps in the stent and after emplacement, making it more difficult to remove an EMS (10,11,14,15). We therefore changed from six to eight bends and fixed two additional wires on the distal and proximal side as a tip to the double stent with both components of the tandem connected with monofilament nylon sutures after March 1992. The patients in this series were divided into groups based on the nature of the stenosis. The patients with an extraluminal compression all exhibited marked improvement in their respiratory symptoms after stenting. The patients with an intraluminal obstruction in whom the tumor reduced the lumen by <50% of the endoluminal diameter also benefited from stenting. In the patients with an intraluminal obstruction or in whom the tumor reduced the lumen by >50% of the endoluminal diameter, only a slight improvement was observed after stenting. Of the 15 patients with an intraluminal obstruction, eight received Nd:YAG laser vaporization before and after EMS emplacement. Laser vaporization was necessary to open the lumen in patients with mucosal proliferation by the tumor or granulation (16). In these patients, a covered EMS or a Dumon stent may be better indicated (15,16). Nomori et al. (15) have proposed that an EMS may be better than a Dumon tube for extrinsic compressive stenosis due to tumor. However, for patients with tracheobronchial stenosis due to intraluminal tumor invasion or granulation tissue, a Dumon tube is indicated rather than an EMS. The studded silicone stent is easy to insert and remove and does not lead to the dreaded complication of trachea erosion or tumor/granulation growth between the wires, which is intrinsically associated with a Giantuco stent (15). Sawada et al. (17) have reported the emplacement of Gianturco stents in the trachea of dogs. Their histological examination confirmed that endothelialization over the stent takes place by 3 weeks with the formation of ciliated columnar epithelium on the luminal surface and the stent does not appear to penetrate beyond the cartilage. In our study, two patients with extraluminal stenosis underwent endobroncoscopy at 1 month after insertion. The inserted EMS had become gradually covered by respiratory mucosa. We therefore concluded that an EMS was effective for an extraluminal stricture in the central airway, that the effect of an EMS in intraluminal stenosis was related to the degree of infiltration and tumor progression itself and also that the Dumon tube or wall stent was indicated rather than an EMS for intraluminal stenosis. Our group has not yet used a covered EMS in any patient with a central airway obstruction because of the possibility of bacterial infection from the mesh-covered EMS. EMS placement is strictly palliative, but combined treatment with laser vaporization, followed by stent insertion and subsequent radiotherapy may improve the quality of life in patients with an otherwise poor prognosis.
Discussion
Patient No.
Site
EMS
Laser
Follow-up (days)
Infiltration (%)
Outcome
Single
Double
1
Tr.
1
+
60
30
Improved
died
2
Tr.
1
-
58
50
No change
died
3
L.m.br.
1
-
89
50
Improved
died
4
R.m.br
1
-
10
60
No change
died
5
L.m.br.
1
=
40
60
No change
died
6
Tr.
1
=
72
30
Improved
died
7
Tr.
1
-
250
40
Improved
alive
8
(a) Tr.
1
-
38
30
Improved
died
(b) L.m.br.
1
-
8
30
Improved
died
9
L.m.br.
1
-
2
60
No change
died
10
Tr.
1
-
34
50
Improved
died
PatientNo.
Diagnosis
Site
EMS
Follow-up (days)
Outcome
Single
Double
11
Lung carcinoma
R.m.br. L.m.br.
1
103
Improved
died
12
Lung carcinoma
Carina-L.m.br.
1*
110
Improved
recurrence
R.m.br.
1
48
Improved
died
13
Lung carcinoma
R.m.br.
1*
62
Improved
died
14
Lung carcinoma
Tr.
2*
28
Improved
died
15
Metastatic lung carcinoma
R.m.br.
1
395
Improved
died
Patient No.
Diagnosis
Site
EMS
Follow-up(days)
Outcome
Single
Double
16
Esophageal carcinoma
Tr.
4
1150
Improved
alive
17
Thyroid carcinoma
Tr
1
2
910
Improved
alive
18
Adenoid cystic carcinoma
Tr.
1*
1610
Improved
alive
R.m.br.
1
19
Thyroid carcinoma
Tr.
1
780
Improved
alive
recurrence
Bi.m.br
1
1
15
Malignant lymphoma
Tr.
2
140
Improved
alive
References
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Last modification: 19 May 1998
Copyright© Japanese Journal of Clinical Oncology, 1997.
This page is run by Oxford University Press, Great Clarendon Street, Oxford OX2 6DP, as part of the OUP Journals
Comments and feedback: www-admin{at}oup.co.uk
Last modification: 19 May 1998
Copyright© Japanese Journal of Clinical Oncology, 1998.
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M. D. Eisner, R. L. Gordon, W. R. Webb, W. M. Gold, S. E. Hilal, K. Edinburgh, and J. A. Golden
Pulmonary Function Improves After Expandable Metal Stent Placement for Benign Airway Obstruction
Chest,
April 1, 1999;
115(4):
1006 - 1011.
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