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(Chest. 2003;124:735-739.)
© 2003 American College of Chest Physicians

Use of an Ultrathin Bronchoscope in the Assessment of Central Airway Obstruction*

Macé M. Schuurmans, MD; Gaëtane C. Michaud, MD; Andreas H. Diacon, MD and Chris T. Bolliger, MD, FCCP

* From the Lung Unit (Drs. Schuurmans, Diacon, and Bolliger), Department of Internal Medicine, University of Stellenbosch, Tygerberg, Cape Town, South Africa; and Division of Respiratory Medicine (Dr. Michaud), University of British Columbia, Vancouver, BC, Canada.

Correspondence to: Macé M. Schuurmans, MD, Department of Internal Medicine, Lung Unit, University of Stellenbosch, Clinical Building, PO Box 19063, 7505 Tygerberg, Cape Town, South Africa; e-mail: mms2{at}sun.ac.za


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Study objective: To assess the utility of an ultrathin bronchoscope (UB) in the assessment of central airway obstruction (CAO).

Design: Prospective evaluation

Setting: Tygerberg Hospital, a tertiary teaching hospital.

Patients: Consecutive patients referred to the Lung Unit with CAO.

Interventions: Fiberoptic bronchoscopy (FOB) was performed with a prototype UB (Olympus BF XP40; Olympus Europe; Hamburg, Germany; outer diameter, 2.8 mm; working channel, 1.2 mm). The UB was used whenever a standard bronchoscope (SB) could not pass the obstruction or could not be tolerated by the patient.

Measurements and results: Data relating to indication and performance of FOB, patient demographics, utility in establishing a diagnosis, and planning definitive management were documented. Twenty-four patients (17 men; mean age, 46 years) were studied. Twelve patients (50%) had malignant CAO, 8 patients (33%) had benign tracheal stenosis, 3 patients (12.5%) had stent occlusion, and 1 patient (4%) had bilateral vocal cord paralysis. In 42% of patients, an initial attempt at passing the obstruction with an SB had failed. Vocal cords or trachea were involved in 62% of patients. The mean luminal occlusion was 84% of the total airway lumen (range, 50 to 100%). One complication (desaturation) led to early termination of FOB. In all but three patients with complete obstruction, the UB was able to pass the CAO and allowed assessment of the obstruction and the distal airways (87%).

Conclusion: UB-FOB was useful and safe in the assessment of patients with CAO from both benign and malignant disease. It aided in establishing a diagnosis and/or planning of definitive management in all patients examined.

Key Words: central airway obstruction • interventional bronchoscopy • lung cancer • tracheal stenosis • ultrathin bronchoscopy


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
At the time of presentation, approximately 80% of patients with lung cancer are considered inoperable and are therefore candidates for palliative therapies only.1 Thirty percent of lung cancers cause central airway obstruction (CAO) with consequent respiratory distress (dyspnea, stridor), bleeding, and infection.2 Depending on the severity of the CAO caused by malignant or benign (nonneoplastic) disease, the condition can become life threatening because of impending suffocation. In these patients, surgical resection is generally limited to certain benign lesions, whereas interventional bronchoscopic procedures and other palliative measures such as radiation and chemotherapy are more often used to treat malignant obstructions. The palliative approach to these patients includes maximizing their residual lung function. It is therefore important to assess the airways distal to a stenotic lesion and relieve the obstruction, if there is viable lung parenchyma beyond the obstruction. In the case of benign tracheal stenoses, the choice between endobronchial therapy and tracheal resection is strongly dependent on the bronchoscopic assessment of the lesion type (simple web-like or complex stenoses).

For CAO that cannot be passed with a standard bronchoscope (SB), the only nonsurgical method reported to be useful in the assessment of the obstruction and airway distal to it is virtual bronchoscopy.3 This imaging method uses spiral CT and three-dimensional image reconstruction. The latter is neither widely available nor suitable to assess mucosal changes nor obtain specimens from the distal airways. Fiberoptic bronchoscopy (FOB) is invaluable in the assessment of the airways and may add essential information concerning airway patency and further characterize the obstructing lesion.4 5 6 7 With a high-grade obstruction, the airway may be narrowed to the point where an SB (external diameter for adults usually >= 4.9 mm, pediatric >= 3.5 mm) cannot be advanced to pass the obstruction. Obstructions leading to a strongly reduced luminal area barely allowing an SB to be passed will become completely obstructed during inspection, which may compromise the patient’s ventilation critically. Although the SB can sometimes be forcefully passed beyond an obstructing lesion, the visibility of the airway distal to the lesion is often compromised by bleeding that may be difficult to control. The same is true for rigid bronchoscopy, where the lens may forcefully be advanced to pass the obstruction but often gets soiled by secretions and blood thereby limiting visibility. A bronchoscope with the thinnest possible external diameter yet still equipped with a working channel to clean the optic may therefore prove useful. Such a bronchoscope, the ultrathin bronchoscope (UB) prototype Olympus BF XP40 (Olympus Europe; Hamburg, Germany), with an external diameter of 2.8 mm and a 1.2-mm working channel, was recently developed (Fig 1 ). In comparison to previous prototypes, the XP40 has an increased rigidity of the shaft, which in our view makes it suitable to be tested for this indication. We hypothesized that the UB would be useful and safe for the assessment of, and choice of treatment in patients with clinical and radiographic evidence of CAO in whom either the SB was unable to pass the obstruction or the patient was unable to tolerate SB-FOB.



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  		Figure 1.. Comparison of the diameter of the tip of the ultrathin bronchoscope (BF XP40, 2.8 mm; Olympus Europe) with that of a standard-size bronchoscope (BF 1T20D, 6 mm; Olympus Europe).

 

   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Consecutive patients with CAO in which an attempt to pass a 5.0- to 6.3-mm SB failed or was poorly tolerated by the patient, or, alternatively, the patient was suspected or known to have a high-grade stenosis such that intubation with a standard scope would be hazardous, were prospectively evaluated using the UB. Standard FOB was considered imprudent if the patient had the following: (1) radiographic evidence of a high-grade obstruction on chest radiograph or CT of the thorax, or (2) clinical and spirometric evidence (stridor at rest and maximal air flows of <= 1.5 L/s, respectively) of a high-grade obstruction. The aim of the bronchoscopic evaluation was to evaluate the airways in order to make the most appropriate management decisions in the shortest possible procedure time and with the highest degree of patient safety. The procedures used in this study were in accordance with the recommendations found in the Helsinki Declaration of 1975.8 Written informed consent was obtained prior to each examination.

Bronchoscopy was performed using an UB, the Olympus XP40 prototype with an outer diameter of 2.8 mm and an inner working channel of 1.2 mm (Fig 1) . The prototype used here is identical to the now commercially available model (model XP40), except for the suction channel valve that has since been improved. The tip of the instrument can be flexed upwardly to a maximum of 180° and retroflexed to a maximum of 130°. The angle of the visual field is 90°, with a depth of field of 2 to 50 mm. Patients were monitored during the procedure with an automatic BP monitor, ECG, and pulse oximetry. The UB was inserted either nasally or orally and passed beyond the vocal cords to the level of the obstruction. The upper and lower airways were anesthetized using 1% lidocaine topically. The extent of obstruction was quantified visually by the bronchoscopist and generally reported as percentage of luminal area obstructed, or alternatively, as the diameter of the residual airway in millimeters. The latter method was especially appropriate when the remaining lumen was similar to the instrument’s (SB or UB) outer diameter, thus serving as measuring unit. The percentage of obstruction was arbitrarily chosen by the investigators using the following categories: 50%, 60%, 70%, 80%, 90%, 95% (subtotal obstruction), and 100% (total obstruction). An attempt was then made to pass the UB beyond the obstructing lesion in order to fully inspect the distal airways for further pathology. In case of undiagnosed malignancy, brushings, washings, and biopsies were performed via the UB, and specimens were sent for cytology, microbiology, and histology.

The indication for bronchoscopy, patient characteristics, and the utility of the UB in establishing the diagnosis and planning the definitive management were documented. The extent of the obstruction, prior attempts at standard FOB, location of the obstruction, complications, and ability to pass the UB beyond the obstruction were also logged. Any complication leading to early termination of the bronchoscopy, emergent rigid bronchoscopy, ICU admission, intubation, or death within 48 h of the procedure was considered a negative outcome. The postbronchoscopic mortality at 30 days was documented. The utility of the UB was assessed by the bronchoscopist by stating whether the procedure provided sufficient information for choosing the therapeutic option (positive outcome) or whether further diagnostic investigations were needed (negative outcome).

Sample Size and Statistical Analysis
As there was no previous experience with UB in CAO, a pilot study of 30 patients was planned. It was decided a priori that the study would be terminated early should the results be clearly negative (negative outcome in >= 20% of patients) or positive prior to completion of recruitment. Descriptive analyses were performed on data relating to indication, patient demographics, procedure characteristics, and utility of UB in establishing diagnosis and definitive planning.


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Data were collected for 24 consecutive patients with CAO over an 18-month period between November 2000 and April 2002. Interim data analysis after 24 patients showed overwhelmingly positive outcomes without major complications so that the final analysis was performed. The mean age of the study patients was 46 years (range, 18 to 70 years; 17 men [71%] and 7 women [29%]). The indications for the procedure are given in Table 1 .


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  		Table 1.. Indication and Location of Obstruction Assessed by UB*

 
In 42% of cases (n = 10), there was a prior attempt to perform standard FOB. The remaining 14 patients had documented evidence for high-grade stenoses (on radiologic, spirometric, and clinical [stridor, dyspnea] assessments), which rendered the risk of further airway compromise too great to undertake standard FOB. The mean luminal occlusion was 84% (range, 50 to 100%) of the total airway lumen at the level of the obstruction. The obstructing lesion was localized to the vocal cords or trachea in 62% (n = 15), left main bronchus in 25% (n = 6), and the right main bronchus or bronchus intermedius in 12.5% (n = 3). In the three stent evaluations, the obstruction was due to granulation tissue in the left main bronchus (n = 2) and at the main carina (n = 1) due to stent dislocation following radiotherapy.

A single case was terminated early secondary to desaturation to 84% during the standard FOB. The patient refused a second bronchoscopy the same day for fear of suffocation, so that UB-FOB could only be performed 1 week later after her dyspnea had improved with treatment with high-dose steroids. The UB examination was well tolerated. The remaining cases (96%, n = 23) were examined without negative outcomes as defined above. In three patients, the UB could not be passed beyond the CAO due to a complete obstruction. In one of these patients, the UB tip inverted on pressure when attempting to pass the obstruction through a slit from which pus was oozing intermittently. The tip inversion was visualized by fluoroscopy. In the remaining 21 patients (87%), the airways distal to the obstruction were fully inspected.

The nature of the obstruction was readily established in all 12 cases of benign disease. Histology and cytology was not necessary in 11 of the 12 patients with malignancy. In those cases, the diagnosis was either pre-established (n = 8) or the UB was performed concurrently with rigid bronchoscopy (n = 3), and therefore the specimens were derived from biopsies via the rigid scope. The histologic and cytological diagnoses of the patients diagnosed with malignancy were as follows: five squamous cell carcinomas (three at the tracheal level), four small cell carcinomas, and three poorly differentiated carcinomas. The mean duration of the bronchoscopy with the UB was 6 min (range, 1.5 to 15 min). All of the bronchoscopies were performed by either qualified pulmonologists (n = 2) or senior pulmonary fellows (n = 2).

The results of the bronchoscopy with the UB aided in the planning of definitive management of all study patients by providing information on location and dimensions of obstruction, condition of airway beyond the CAO, and complications of the CAO such as postobstructive infection (pus), and hemorrhagic or necrotic tissue. Spiral CT scans were performed in six patients only because of limited availability (long waiting list) or because the patient was considered to be unfit for the scan (dyspnea grade IV or orthopnea). Of the six patients with spiral CT scans (including sagittal reconstruction of the trachea in four patients), the location and dimensions of the obstruction were assessable in four patients. In the remaining two patients, the airway patency at the level of obstruction was not correctly assessed because the degree of obstruction was overestimated based on the CT scans (apparently complete obstructions were readily passed by the UB). Vitality of the tissue, local complications (necrosis, hemorrhage, pus), and dynamic information (malacic component, n = 2) were only available from the UB. Regarding the utility of the UB in determining the appropriate treatment, no negative outcomes were noted. Treatment modalities employed are listed in Table 2 . None of the patients died within 30 days of bronchoscopy.


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  		Table 2.. Definitive Management Based on UB Results

 
One of the patients, a 61-year-old woman presenting with a grade IV dyspnea and inspiratory stridor due to a locally advanced inoperable squamous cell carcinoma of the right neck, was referred to us for possible stent insertion to relieve a high-grade midtracheal extrinsic obstruction visible on the chest radiograph (Fig 2 ). The UB showed a 80% obstruction (Fig 3 ) with patent distal trachea and main bronchi. Rigid bronchoscopy was performed with dilation and stent placement resulting in immediate resolution of stridor and dyspnea. The patient was followed up as an outpatient and died 2.5 months later of massive hemoptysis.



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  		Figure 2.. Chest radiograph of a 61-year-old woman presenting with inspiratory stridor and a right cervical mass showing a leftward displaced trachea, a high-grade stenosis of the middle trachea (between arrows), and a peripheral lesion in the right lower lobe.

 


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  		Figure 3.. Endobronchial photograph of the same patient as in Figure 2 at rigid bronchoscopy prior to dilation of an 80% stenosis of the tracheal lumen with an UB passing the obstruction.

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
In this prospective case series of 24 patients with high-grade CAO, the UB was well tolerated, and proven both safe and useful in determining the luminal characteristics of the CAO. The examination with the UB provided information on the dimensions of the obstruction and visualized the condition of the airway at and beyond the CAO, allowing planning of interventional endoscopic procedures or deciding on other appropriate treatment modalities such a surgery or radiotherapy (Table 2) . In most patients, it helped determine the treatment without the need for a spiral CT scan. Limited availability of our spiral CT scanner and inability of some patients to lie for the scan due to orthopnea made the assessment by UB particularly useful because it was immediately available and could be performed in a sitting position, thus allowing treatment to be initiated without delay. Overall, the UB proved to be a useful adjunct to both rigid and standard FOB, in patients with CAO due to either benign or malignant disease.

According to our literature search (EMBASE, MEDLINE), no systematic evaluation of the use of UB for CAO in adults has been published to date. The UB has been used in the pediatric population in situations where the airway lumen is limited based on prematurity, anatomic anomalies, and tracheomalacia.9 10 11 12 13 It has also been used to assess endotracheal tube (ETT) position as a standard pediatric bronchoscope can only be safely passed through a 5.5-mm ETT in a patient requiring ventilatory support.13

In a review article, Raoof et al14 suggested some potential uses for the UB in adult patients in the ICU, including the evaluation of nature and extent of upper airway obstructions and endobronchial tumors, visualization of the airways distal to the obstruction, assessment of ETT or tracheostomy tube position, and planning of interventional endoscopic procedures. Previous studies using the UB as a diagnostic tool in adults are few; however, it has been shown in small studies to be beneficial in the assessment of the peripheral airways in both COPD and panbronchiolitis.14 15 16 In two other small studies,17 18 the UB was used to perform transbronchial biopsies and to obtain specimens for cytology in peripheral lung lesions suspected to be malignant.

A limitation of the current study was the fact that in only one patient specimens for cytology had to be obtained using the UB, with positive findings. As such, we cannot comment on the utility of the instrument in obtaining histologic or cytologic specimens to establish the diagnosis. The small size of the working channel and biopsy instruments may limit their diagnostic yield. This, however, was not the objective of this study.

The limited ability to clear secretions via the UB, particularly if they are tenacious (ie, thick pus), is due to the small size of the suction channel. Although the UB is easily inserted via the mouth or nose, there is an initial tendency for disorientation in the oropharynx and nasopharynx because the ultrathin shaft of the instrument is not that well guided. This also brings about an important point of discussion with respect to the definition of an ultrathin bronchoscope. Other authors have used the term ultrathin bronchoscope liberally in reference to bronchoscopes with outer diameters as large as 3.6 mm.17 We would propose that this term be reserved for bronchoscopes with a maximal external diameter of 3.0 mm.

In conclusion, the UB proved to be a useful and safe tool for the evaluation of our 24 patients with CAO. It was safe even in high-grade obstructions, and it enhanced the evaluation and management of patients with CAO.


   Footnotes
 
Abbreviations: CAO = central airway obstruction; ETT = endotracheal tube; FOB = fiberoptic bronchoscopy; SB = standard bronchoscope; UB = ultrathin bronchoscope

This work was supported by the Novartis Foundation and the Foundation Krebsliga beider Basel (Dr. Schuurmans). The ultrathin bronchoscope was provided to us on loan by Olympus Europe without any conditions regarding research.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (e-mail: permissions{at}chestnet.org).

Received for publication August 15, 2002. Accepted for publication February 6, 2003.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Belani, CP (1993) Multimodality management of regionally advanced non-small-cell lung cancer. Semin Oncol 20,302-314[ISI][Medline]
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  3. Liewald, F, Lang, G, Fleiter, T, et al Comparison of virtual and fiberoptic bronchoscopy. Thorac Cardiovasc Surg 1998;46,361-364[ISI][Medline]
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  6. Hoheisel, G, Chan, BK, Chan, CH, et al Endobronchial tuberculosis: diagnostic features and therapeutic outcome. Respir Med 1994;88,593-597[CrossRef][ISI][Medline]
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  8. World Medical Association Declaration of Helsinki. Recommendations guiding physicians in biomedical research involving human subjects. JAMA 1997;277,925-926[CrossRef][ISI][Medline]
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  13. Wood, RE, Azizkhan, RG, Lacey, SR, et al Surgical applications of ultrathin flexible bronchoscopes in infants. Ann Otol Rhinol Laryngol 1991;100,116-119[ISI][Medline]
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