Ann Thorac Surg 2000;69:398-401
© 2000 The Society of Thoracic Surgeons
Original Articles
Flexible bronchoscopy: a safe method for metal stent implantation in bronchial disease
Hubert Hautmann, MDa,
Martin Bauera,
Klaus J. Pfeifer, MDa,
Rudolf M. Huber, MDa
a Medizinische Klinik, Klinikum Innenstadt, Ludwig-Maximilians-University, Munich, Germany
Address reprint requests to Dr Hautmann, Klinikum Innenstadt, Medizinische Klinik, Ziemssenstr 1, D-80336 Munich, Germany
e-mail: hautmann{at}medinn.med.uni-muenchen.de
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Abstract
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Background. Endoscopic bronchoplastic procedures, such as metal stent implantation, are for safety reasons and mainly performed using rigid bronchoscopy. Major complications, such as bleeding and accidental airway occlusion, are thought to be better managed with the rigid device. An increasing number of pneumologists, however, use the flexible fiberscope for endobronchial stenting.
Methods. Sixty-five stent implantations were performed in 51 patients with flexible fiberoptic bronchoscopy. We implanted 27 Tantalum Strecker stents (Boston Scientific Co, Watertown, MA), 20 Nitinol Accuflex stents (Boston Scientific Co) and 18 Wallstents (Schneider, Zurich, Switzerland). Underlying conditions were malignant disease in 84% and benign bronchial collapse in 16%. Sites of implantation were the trachea (45%), the main bronchi (35%), and other locations (20%). In 47 cases the patients received intravenous sedation combined with high frequency jet ventilation, and in 18 cases the patients were treated with topical anesthesia alone.
Results. Mean examination time was 58.3 (standard deviation 29.1) minutes. Eighty percent of patients experienced immediate clinical improvement in respiratory symptoms. Spirometric parameters (forced expiratory volume in one second, peak expiratory flow rate, forced vital capacity) increased. Complications included hypertension (17%), hypotension (12%), hypoxia (5%), bronchospasm (4%), initial displacement of the prosthesis (11%), and diameter mismatch between stent and bronchus (5%). All complications were managed safely. Relevant bleeding or asphyxia during the procedure has not been observed. Late stent migration was observed in 12% of cases. There were 3 fatalities within 30 days of stent placement which, however, were not attributed to the implantation technique.
Conclusions. Flexible fiberoptic bronchoscopy is a safe and suitable method to perform endobronchial metal stent implantation. Complications were rare and not serious. Initial misplacement of the prosthesis occurred in some cases and necessitated removal and replacement within the same procedure.
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Introduction
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Bronchoplastic procedures, such as endobronchial stent insertion, have been developed over the past decade, and their application has greatly increased among bronchologists. The controversy remains whether rigid bronchoscopy (RB) should be used to minimize risk and complications of such therapeutic interventions, or whether flexible fiberoptic bronchoscopy (FFB) proves to be an equally safe method. Silicone prostheses and Dynamic stents (Ruesch AG, Kernen, Germany) require rigid devices due to their application method. Expandable metal stents (Tantalum Strecker stent [Boston Scientific Co, Watertown, MA], Nitinol Accuflex stent [Boston Scientific Co], Wallstent [Schneider, Zurich, Switzerland], Palmaz stent [Cordis Co, Miami, FL], Gianturco stent [Cook Inc, Bloomington, IN]), however, can be placed as well by means of FFB as previously reported [1–9], often in case studies. Supporters of RB state that the risk of severe hypoxia is much greater in FFB, especially if dislocation of the prosthesis occurs [10, 11]. The options of the flexible system to remove or reposition a stent are frequently thought to be greatly limited, due to the indirect access to the site of intervention. To evaluate complications and limitations of flexible stent placement, we performed a prospective analysis of 65 consecutive stent implantations done with FFB in our hospital between 1994 and 1998.
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Material and methods
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We implanted 20 self-expandable Nitinol Accuflex stents, 18 self-expandable Wallstents, and 27 balloon-expandable Tantalum Strecker stents in 51 patients with tracheal or bronchial stenoses. The underlying conditions are listed in Table 1. The majority of patients presented with bronchial carcinoma. The age ranged from 24 to 99 years (mean 58.8 ± 12.3 years). Indications for stent implantation were dyspnea (53%), retention pneumonia (17%), retention of secretions without evidence of pneumonia (15%), dyspnea with stridor (12%), and lung abscess (3%). No condition other than the airway stenosis could sufficiently explain onset, duration, or worsening of the specific symptomatology. Stent placement was considered a reasonable choice of therapy at this particular stage of the disease, especially when alternative therapeutic options were inadequate or not possible. The procedures were carried out under intravenous sedation combined with high frequency jet ventilation or with topical anesthesia alone, respectively.
The patient was placed in supine position. Topical anesthesia was achieved by instillation of 10 mL 2% lidocaine nebulized in the spontaneously breathing patient. Midazolam (2 to 5mg) was then administered. When treating critical ill patients, high frequency jet ventilation (HFJV), combined with intravenous sedation, was principally begun to ensure continuous and safe oxygenation. For intravenous sedation we used short acting narcotics (propofol) and opioid analgesics (alfentanyl). This also applied to most cases in which stents were to be implanted into the trachea or in functional singular airways. In all other cases the initiation of HFJV or intravenous sedation was dependent on clinical state and the need to perform the procedure without disturbance by coughing.
When HFJV was performed, a 14F catheter was introduced transnasally into the trachea over a guidewire, which was placed endoscopically as previously described [12]. A jet injector (AMS1000; Acutronic Medical Systems, Jona, Switzerland) connected to an oxygen regulator was then directly attached to the catheter and HFJV was begun.
For stenting, skin markers specifying the limits of the lesion were attached after endoscopic evaluation. A flexible 0.035-inch guidewire (Amplatz Superstiff; Meditech, Boston Scientific Co) was inserted through the bronchoscope and passed through the lesion. The bronchoscope was then withdrawn. Under fluoroscopic guidance, the stent mounted on the delivery catheter was advanced over the guidewire until the edges of the prosthesis aligned with the skin markers. The prosthesis was then released from its delivery catheter (Wallstent, Nitinol Accuflex stent), or was expanded by inflating the balloon (Tantalum Strecker stent). Correct placement of the stent was confirmed by visual examination through the bronchoscope and by roentgenogram analysis. Late stent migration was defined as stent dislocation later than 48 hours after placement.
The quantification of the stenoses was performed semiquantitavely (Table 1). The stenosis was specified as subtotal when it could only be passed with a 0.035-inch guidewire (0.9 mm), whereas a high-grade stenosis was passed with a closed biopsy forceps (2.1 mm). Medium-grade stenoses could be passed by the bronchoscope (5.8 mm). Bronchial collapse was analogous with a functional stenosis, leading to intermittent airway occlusion during forced expiration or cough.
Lung function studies were recorded before and after stent insertion, including forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEF), forced vital capacity (FVC), airway resistance (Raw) (Bodyscreen; Jaeger, Würzburg, Germany) and arterial blood gas tensions (ABL500; Radiometer, Copenhagen, Denmark). Lung function data obtained within 72 hours before and 72 hours after stenting were available of 31 cases. Chest roentgenograms were performed immediately, and within 48 hours after stenting. Follow-up bronchoscopies were completed within the first 7 days and subsequently when clinically indicated.
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Results
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Eighteen stents (28%) were placed under topical anesthesia. Forty-eight patients (72%) received intravenous sedation. Seventy-three percent of the malignant airway obstructions were entirely extraluminal stenoses, whereas the remainder was partly exophytic. In the latter cases, endoluminal irradiation was initiated to prevent tumor growth through the interstices of the stent. Distribution of stent types and stent locations according to the method of anesthesia are specified in Table 2. Dimensions of the stents ranged from 6 to 22 mm in diameter and from 20 to 80 mm in length. Not all stents were commercially available in all sizes at all times. Therefore the decision of which stent to select for implantation was, in addition to other criteria, dependent on availability. In benign stenoses, we used self-expandable prostheses because they contain more favorable reexpandability characteristics. However, the Wallstent was omitted later in the study due to induction of granulation tissue. In malignant stenoses all three stent types were applied.
In 52 patients (80%), the implanted prosthesis led to immediate clinical improvement in respiratory symptoms. This was also confirmed by improvement in lung function (Table 3). Except for blood gas measurements, there was a significant increase in FEV1, PEF, and FEV1/FVC. By the time of data analysis, 46 patients (90%) were deceased, however there was no fatal event within 24 hours of stent placement. One patient with advanced bronchial carcinoma died of asphyxia 24 hours after stent implantation, due to a dislocated prosthesis, which was confirmed by necroscopy. The patient refused to have another intervention, which may have potentially reestablished airway patency. Septic shock was the cause of death in another patient, 5 days after stent placement. In this case repeated stent obstruction by viscous mucus prevented drainage and resolution of retention pneumonia. Fatal hemoptysis occurred in one patient 10 days after the procedure. In all 3 cases, the stents were initially well positioned. In all other cases minimum survival time after stent implantation was 31 days (mean 98 days, median 64 days, range 31 to 1067 days). The average time the stents were in place was 152 days (median 39 days, range 0 to 1561 days). Complications and their frequency are displayed in Table 4. Systemic complications were rare and not life threatening. In 2 patients, arterial hypotension had to be treated with dopamine. Poor placement of the prosthesis occurred in 7 cases, and necessitated the immediate removal and replacement in 4 cases (2 Tantalum Strecker stents, 2 Nitinol Accuflex stents). In 3 cases the stents could be repositioned by using biopsy forceps and inflatable balloon catheters. In 3 cases the diameter of the selected stent was too small (2 Tantalum Strecker stents, 1 Nitinol Accuflex stent). A satisfying result could still be achieved in 1 case (Tantalum Strecker stent) by dilating the stent with a balloon until it fitted tightly within the lesion. In the remaining 2 cases the stents migrated immediately. They could not be repositioned and had to be replaced. Late stent migration occurred in 8 cases. In 3 of these cases the stents migrated due to tumor regression, and were eventually removed without the need for further local treatment. Two stents migrated in proximal direction (8 mm and 10 mm, respectively, measured on chest roentgenogram) but maintained adequate function. No intervention was necessary. In 3 cases, the stents could neither retain position or function, and 2 of these stents had to be removed. Mean duration of all bronchoplastic procedures was 58.3 min (median 53.8, range 38 to 156).
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Comment
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The competition between rigid and flexible fiberoptic bronchoscopy is still a matter of controversy among pneumologists when it comes to endobronchial stent implantation. Technically, expandable metallic stents can easily be placed by means of fiberoptic bronchoscopy potentially [3]. This study demonstrates that flexible bronchoscopy is safe and effective for endobronchial stent implantation, to restore the patency of stenotic or malacic airways. We implanted three different models of metallic stents that are generally in use for endobronchial and tracheal splinting [13–15], but were reluctant to use all available stents. Palmaz stents were not considered due to the inability to reexpand when compressed [9]. The Gianturco stent was reported to cause a high rate of complication [16]. The Polyflex stent (Ruesch AG, Kernen, Germany) only became available at the end of the study, and is made of silicone [17]. The use of HFJV, in combination with intravenous sedation, proved to be beneficial not only in establishing safe ventilation, particularly in the treatment of singular airways, but it also guaranteed a minimum of cough and respiratory excursions to facilitate accurate stent placement. Still, poor stent placement accounted for 11% of all implantations. As expected, this was less often observed in patients treated with intravenous sedation. Specific data on displacement rates of metallic stents during implantation are rare. Monnier and colleagues report a primary insertion failure in 12% [7], when using rigid bronchoscopes. Causes were poor placement, immediate migration, and anesthesiologic complications. There is no clear evidence that the method of bronchoscopy is a major determinant of accurate stent placement. Initial displacement of the stent occurred more often when topical anesthesia was used alone, implicating that respiratory excursions might complicate the exact embedding of the prosthesis within the bronchus. Other factors, which, in our view contribute substantially to the accuracy of stent placement, are the experience of the investigator, the anatomy of the lesion, and the system of stent release. For example, the Strecker stent appears easier to position than the Accuflex stent since it does not shorten during deployment. The majority of poor stent placements and diameter mismatches occurred in the early phase of the investigation. This demonstrates the importance of the investigator’s experience with the material and the method of stent implantation, in order to achieve the desired result.
More detailed data are available on late stent migration, which ranges from 0 to 17.5% [8, 13, 18, 19], irrespective of stent type and method of implantation. We experienced late stent migration in 12% of cases. Bronchial bleeding has not been observed. Only in 2 patients with arterial hypotension was pharmacologic treatment with dopamine necessary. The most likely cause was the application of propofol. None of these events was harmful.
Immediate removal of prostheses, when necessary, was straightforward. The Tantalum Strecker stent and the Nitinol Accuflex stent could easily be extracted using a simple biopsy forceps.
Median survival data of the patients with stents in place compare well with studies of similar design [8, 20, 21], but it makes no difference whether the prostheses are implanted with the flexible or the rigid bronchoscope.
In conclusion, the study demonstrates the feasibility of flexible fiberoptic bronchoscopy for the implantation of expandable metal stents. With topical anesthesia, or HFJV combined with intravenous sedation, it can be considered highly safe and effective, even in the critically ill patient. Poor stent placement is a well-known complication of metal stent implantation, and is not to be attributed to the method of bronchoscopy, as it is also described when rigid bronchoscopy is used for implantation. When immediate stent extraction is necessary it can also easily be achieved with the flexible bronchoscope. This applies to the Tantalum Strecker stent and the Nitinol Accuflex stent. Rigid bronchoscopy should not be considered essential for the endoscopic placement of expandable metal stents. However, it will still keep its importance for a variety of indications (eg, selected cases, and silicone stents).
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Accepted for publication July 30, 1999.
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Abstract
Introduction
