Since its inception in 1897, bronchoscopy has evolved from a rigid esophagoscope and headlight to flexible video bronchoscopy with vastly improved visualization of the airways.1
Older generations of flexible bronchoscopes rely on optical fibers to transmit bronchoscopic images through the insertion tube and handle to an eyepiece or video display. They suffer from degradation in image quality in the setting of broken fiberoptic cables. Continued advances in technology and development of the charged coupled device (CCD) chip have improved image resolution. CCD chips convert energy from light photons into digital information, thereby allowing image capture. This technology is now frequently used in a variety of applications ranging from digital cameras to astronomy telescopes. Current-generation flexible bronchoscopes use CCD chips inserted onto the distal end of the insertion tube. Image resolution of CCD chips that are small enough to fit on a bronchoscope, however, has been largely outpaced by the resolution capabilities of modern video displays.
Furthermore, the outer diameter of the bronchoscope is also limited from a practical sense by the size of the airways. Conventional scopes have typical outer diameters of approximately 4 to 6 mm allowing navigation to the fourth to fifth generation segments. The insertion tube must accommodate the light fibers, working channel, and CCD chip. Therefore, the diameter of the insertion tube must be sufficient to accommodate each of these features; augmentation of one will require a sacrifice in another. For example, therapeutic bronchoscopes have larger working channels that provide improved therapeutic suction capability and permits use of larger bronchoscopy accessories, but usually require a larger insertion tube diameter and smaller, lower resolution CCD chip to accommodate the improved working channel size. Similarly, scopes with a smaller outer diameter and the ability to navigate even further into the bronchial tree may sacrifice image resolution as they have less space available for the CCD chip. Ideal imaging technology would possess high image resolution matching what is available for display screens, but remain small enough so that it does not limit the size of the bronchoscope.
Another limitation of current flexible bronchoscopes is that the working channels are fixed. Although they can be directionally angulated on a 180-degree single axis, the fixed working channel can be limiting when using bronchoscopy instruments. For example, using forceps to obtain tissue samples from an inconveniently positioned endobronchial lesion may be difficult. Similarly, maneuvering a bronchoscope or directing instruments into acutely angled lung segments, such as the apices of the upper lobes or superior basal segments of the lower lobes, can be technically difficult and physically taxing on the bronchoscopist because of the hand and wrist positioning required.
In an effort to improve on the limitations of image quality, fixed working channel, and overall maneuverability of conventional bronchoscopes, a new-generation bronchoscope has been developed. We describe our experience with a novel bronchoscope designed with a rotating working channel, increased distal tip angulation, and a CCD chip capable of capturing higher resolution images.
PATIENTS AND METHODS
A total of 105 nonconsecutive patients presenting to the National Jewish Health, Denver, CO, and the Medical University of South Carolina, Charleston, SC, between November 2010 and August 2011 for planned diagnostic or therapeutic bronchoscopy had their procedures performed using EVIS EXERA III generation bronchoscopes (BF-Q190, BF-H190, and/or BF-1TH190) (Olympus, Tokyo, Japan). Informed consent for bronchoscopy was obtained from all patients before their procedure. The planned procedures were performed as per each institution’s standard protocol and the model(s) selected for use was left to the discretion of the bronchoscopist. Both general and interventional pulmonary procedures were included in this evaluation. Ten bronchoscopists at 2 institutions were responsible for performing all of the procedures.
The type of procedure, sedation used, and intubation approaches were stored in a deidentified database for analysis. Following the trial period, all bronchoscopists participated in a survey to evaluate the features of these bronchoscopes.
EVIS EXERA III Bronchoscopes
The new EVIS EXERA III generation of flexible video bronchoscopes includes the BF-Q190, BF-H190, and BF-1TH190 (Table 1 ). They include a number of modifications and additions to the currently available EVIS EXERA II generation bronchoscopes (BF-P180, BF-Q180, BF-1T180, and BF-1TQ180) including a new light source (CLV-190) and image processor (CV-190).
TABLE 1: Comparison of EVIS EXERA III Generation to Current Bronchoscopes
The scope design includes 4 novel additions: (1) rotation of the insertion tube and working channel 120 degrees clockwise and counterclockwise through a rotating ring at the bottom of the bronchoscope control section (Fig. 1 ). (2) An increased 210-degree range for distal bronchoscope tip flexion (BF-Q190 and BF-H190) (Fig. 1 ). (3) High-definition image resolution (BF-H190 and BF-1TH190). (4) Electronic zoom to Ă—1.2 and Ă—1.5 image magnification (Fig. 2 ).
FIGURE 1: Demonstration of insertion tube rotation and increased flexion. Insertion tube rotation along an anterior 180-degree arc is controlled by the positioning of the control knob at the distal end of the bronchoscope handle (inset: A and B). Note the change in position of the bronchoscope tip and rotation knob (insets) relative to the handle in the neutral position (A) and after rotation to the right (B) and left (C). The bronchoscope is shown in the full 210-degree flexed position.
FIGURE 2: Demonstration of electronic magnification. Airways visualized with white light imaging (A) and narrow band imaging (B) under normal Ă—1.0 (image 1), Ă—1.2 (image 2), and Ă—1.5 (image 3) magnification.
EVIS EXERA III Bronchoscope Evaluation
Each bronchoscopist completed a survey evaluating the following features of the bronchoscopes.
White light imaging quality and resolution.
Narrow band imaging (NBI) quality and resolution.Electronic magnification.
Insertion tube rotation.
Greater flexion.
Overall function as a flexible bronchoscope.
A 7-point Likert scale rating system of −3 to +3 was used with −3 equating to significantly worse/detracts from functionality and +3 equating to significant improvement/addition to functionality compared with the prior generation of bronchoscopes. A value of 0 indicated no difference or clinical utility compared with EVIS EXERA II generation flexible bronchoscopes currently in routine use at each participating institution. Mean scores and SD were calculated for each question. Comments and observations of each bronchoscopist were also collected and used in aggregate for the interpretation of the findings.
RESULTS
A total of 105 patients underwent flexible bronchoscopy (Table 2 ); the diagnostic bronchoscopes (BF-Q190 and BF-H190) were used in 81 patients and the therapeutic bronchoscope (BF-1TH190) was used in 27 patients. A variety of insertion routes were used, including 13 nasal, 86 oral, 8 laryngeal mask airway or endotracheal tube, and 1 tracheostomy. The total number of bronchoscopes used exceeds the number of patients because some procedures utilized both diagnostic and therapeutic bronchoscopes with varying routes of insertion.
TABLE 2: Summary of the Procedures Performed With the EVIS EXERA III Bronchoscopes
The procedures performed included airway inspection, bronchoalveolar lavage, endobronchial brushing and/or biopsy, transbronchial biopsy, transbronchial needle aspiration, and transbronchial needle injection. Peripheral navigation with tissue sampling was performed in 16 cases; radial endobronchial ultrasound (EBUS) was used for 14 cases and combination radial EBUS and electromagnetic navigation in 2 cases. Large airway therapeutic interventions were performed in 10 patients, including 6 balloon dilation, 2 laser ablation, 4 electrocautery ablation/resection, and 1 endobronchial stent placement.
The 10 bronchoscopists trialing the new scopes evaluated the utility and function by survey (Table 3 ). Overall, the users felt the new-generation scopes had features that improved the performance of fiberoptic bronchoscopy when compared with current-generation bronchoscopes. The 2 features rated as adding the most to functionality were the rotation capability of the insertion tube (average 2.4/3; range, 1 to 3) and the 210-degree angulation (average 2.4/3; range, 0 to 3). White light image quality and resolution was also ranked as being a significant improvement (average 2.2/3). The addition of electronic image magnification was rated as contributing the least to overall scope functionality (average 1.4/3).
TABLE 3: Bronchoscopist Survey
DISCUSSION
The tools used to visualize the airway have evolved tremendously since the initial development of bronchoscopy. Current flexible bronchoscopes are now highly specialized to encompass a wide range of niche uses, including specialty bronchoscopes to maximize mobility,2 3 4,5
Our collective experience with this new generation of flexible bronchoscopes involved a wide range of procedures, ranging from routine airway examination to advanced diagnostic and therapeutic interventions. In addition, the participating bronchoscopists included both general and interventional pulmonologists with the intent that these scopes were to be evaluated by the full spectrum of potential users. The EVIS EXERA III flexible bronchoscopes were collectively felt to be significantly better in all evaluated aspects compared with their predecessors, although some design features contributed more to scope functionality.
Increased maneuverability was perceived to be the most notable improvement in functionality compared with current bronchoscopes. Currently available bronchoscopes require a combination of rotation by the bronchscopist’s wrist and distal tip flexion or extension to achieve movement in the horizontal plane. The combination of a greater flexion range of 210 degrees in the diagnostic bronchoscopes and the ability to rotate the insertion tube while the hand is in neutral position allows for the most improvement in scope functionality. Of note, gastrointestinal colonoscopes have long featured wide-ranging 4-way angulation (180 degrees up/down and 160 degrees right/left). Translating this feature to bronchoscopes can facilitate easier access to traditionally difficult-to-reach locations, such as the apical segments of the upper lobes (RB1 and LB1+2) and superior basal segments of the lower lobes (RB6 and LB6). In some circumstances, this may permit navigation into areas impossible to reach with current-generation bronchoscopes. Standard bronchoscopy accessories were equally as easy to use with the new bronchoscopes. Although the duration of many of the procedures in the study were short, we would suggest that the rotation function may also reduce the bronchoscopist’s fatigue when having to maintain a stable position in acute-angled lung segments for prolonged periods of time, such as during navigational bronchoscopy with electromagnetic navigation and radial EBUS. However, a larger sample size of both cases and bronchoscopists is required to objectively evaluate the extent of this potential benefit or the effect of increased maneuverability on diagnostic yield with a specific bronchoscopic technique.
The high-definition CCD chip on the BF-H190 and BF-1TH190 bronchoscopes resulted in a noticeable improvement in both white light and NBI image resolution. They also produce a 50% increase in NBI image brightness compared with current-generation bronchoscopes. It is difficult to independently evaluate the isolated impact of NBI image brightness on image quality given the concurrent addition of high-definition resolution. Similarly, the EVIS EXERA III bronchoscopes allow the bronchoscopist to examine subtle findings in greater detail with electronic image magnification. However, many of the bronchoscopists evaluating these added features did not feel that they improved upon the utility of currently available equipment and it is uncertain if these improvements in image quality and magnification will result in a clinically relevant difference in visual detection of mucosal abnormalities.
Our comparisons were made relative to the EVIS EXERA II generation of equipment used at our respective institutions. Differences in scope performance, however, may be more pronounced for bronchoscopists using older generations of equipment. It is important to note that the EVIS EXERA III bronchoscopes require a new-generation xenon light source (CLV-190) and video processor (CV-190), which are backwards compatible with current EVIS EXERA II bronchoscopes.
Although we feel that our experience with these new bronchoscopes represents a wide range of procedures, our evaluation was admittedly limited by the small number of new bronchoscopes available for trial and the small number of users. In addition, the Likert scale measures perceived benefits, which will be influenced by the experience level of each individual user as well as the types of bronchoscopic techniques they performed. As noted, our experience does not permit evaluation of how these new features of the bronchoscope may affect procedural outcomes or physical impact on the bronchoscopist. However, these limitations are typical for trials of new equipment and we believe that our experiences are representative of the types of procedures performed by most bronchoscopists.
In conclusion, the latest generation EVIS EXERA III bronchoscopes offer improvements on traditional bronchoscope features including greater distal tip flexion, a rotating insertion tube, high-definition imaging, and magnification. The increased tip angulation and novel rotating insertion tube are the most significant improvements in design affording the bronchoscopist an improved ability to navigate the airways. Ultimately, the potential benefits of these new bronchoscope features will have to be evaluated by each individual bronchoscopist or institution to assess whether the functional benefit of the new design justifies the cost associated with upgrading their current equipment.
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