Systematic Bronchoscopy: the Four Landmarks Approach

Summary

Here, we present a protocol to navigate the bronchial maze in a structured manner, splitting the bronchoscopy into a stepwise approach-the four landmarks approach.

Abstract

Flexible bronchoscopy is a technically difficult procedure and has been identified as the most important procedure that should be integrated into a simulation-based training program for pulmonologists. However, more specific guidelines that govern bronchoscopy training are needed to meet this demand. To ensure patients a competent examination, we propose a systematic, stepwise approach, splitting the procedure into four "landmarks" to support novice endoscopists navigating the bronchial maze. The procedure can be evaluated based on three established outcome measures to ensure a thorough and effective inspection of the bronchial tree: diagnostic completeness, structured progress, and procedure time.

The stepwise approach relying on the four landmarks is used at all simulation centers in Denmark and is being implemented in the Netherlands. To provide instant feedback to novice bronchoscopists when training and to relieve time constraints from consultants, we suggest that future studies should implement artificial intelligence as a feedback and certification tool when training new bronchoscopists.

Introduction

Lung cancer is the leading cause of cancer mortality¹. Flexible bronchoscopy is essential to navigate through the bronchial tree and identify the correct segments for the diagnosis and staging of lung cancer and allocation to the correct treatment for the patient². Lower yields of diagnostic biopsy material, higher complication rates, and increased patient discomfort are seen in the early part of a trainee's learning curve^3,4,5. To ensure independent/unsupervised practice on patients, satisfactory educational levels must be met. A training modality to ensure basic competence is simulation-based mastery learning, where the trainee practices until proficiency criteria are met⁶. Several tools have been developed to assess bronchoscopy performance^7,8, and the following performance measures have been established: (1) diagnostic completeness (DC)-proportion of visualized segments⁹; (2) structured progress (SP)-number of segments visited in the correct progression order¹⁰; and (3) procedure time (PT)-time from passing through the vocal cords to the end of the procedure⁹.

Novice bronchoscopists can be confused by the maze, looking like similar bronchi, and several fail to complete a course in simulation-based bronchoscopy¹¹, even though it has been identified as the most important technical procedure to learn in pulmonary medicine¹². Therefore, through this protocol, we propose a stepwise, structured progression through the bronchial tree (Figure 1), relying on four landmarks as a guide. We suggest that novice operators should be taught according to this approach to ensure visualization of all the bronchial segments in a structured way, in the shortest amount of time, with correct handling of the scope.

Protocol

Following Danish law, an educational study without the participation of patients does not require ethical approval.

1. Handling of the scope

1. Hold the bronchoscope in the left hand with the left thumb on the steering lever and the left forefinger on the suction button. Use the right hand to hold the distal part of the bronchoscope.
2. Holding the scope with a straight arm and wrist, so the suction button is pointing directly forward and the steering lever is in the neutral position, is defined as the neutral position or 0°. By twisting the wrist, turn the scope from the neutral position/0°.
3. Move the thumb up and down the lever to flex and extend the distal end of the endoscope. Move the wrist and hands, not the arm and body.

2. Structured progress: angle of the scope and the four landmarks

1. Enter the airways either through the mouth or nostrils. Pass the vocal cords and enter the trachea.
2. Find the four landmarks systematically from landmarks 1 to 4 and note the correct angle of the endoscope in each position (Table 1).
   NOTE: The four landmarks approach is designed in a memorable way to decrease the cognitive load for novel bronchoscopists. It is based on a pairing between the angle of the bronchoscope and how to access the different lobes/landmarks. The approach, therefore, provides novice trainees with a basic training tool to navigate through the bronchial maze. As an example, by knowing if the bronchoscope is held at a 90° angle to the right, the correct position to inspect the right upper lobe can be determined. When visualizing the lobe or landmark, one should defer from the designated angle to inspect the individual segments.
3. Find the segments chronologically from 1-10, the right side first, then the left side according to the four landmarks.

3. Systematic bronchoscopy: the four landmarks approach

1. Landmark 1: The carina with the right and the left main bronchus as seen from the trachea (Figure 2)
   1. Locate the bronchoscope in the distal part of the trachea at a 0° angle-the neutral position. If the orientation is lost, go back to landmark 1 to reorientate.
2. Landmark 2: Right segments 1, 2, and 3 (upper lobe) (Figure 3)
   1. Turn the endoscope 90° to the right while at the same time flexing the distal end of the bronchoscope upward by pushing the left thumb down to investigate the upper lobe. This landmark resembles the Mercedes star.
   2. When visualizing the Mercedes star, defer from the 90° angle to inspect segments 1, 2, and 3.
3. Landmark 3: Right segments 4 and 5 (middle lobe) plus 6, 7, 8, 9, and 10 (lower lobe) (Figure 4)
   1. Move on to the bronchus intermedius by placing the distal end of the endoscope at a 45° angle to the right to see segments 4 and 5 (numbers from the lateral side at an oblique angle).
   2. Again, defer from the 45° angle to inspect segments 4 and 5. Go back to the 45° angle and extend the tip of the endoscope by pushing the stewing lewer upward with the left thumb to inspect segment 6 (just opposite the middle lobe).
   3. Turn the scope to a 0° angle and progress to the lower lobe. Segment 7 is located medially, and segments 8, 9, and 10 (numbers from the lateral side at an oblique angle) at the bottom. Defer from the 0° angle to inspect segments 7-10.
4. Landmark 4: Left segments 1+2, 3, 4, and 5 (upper lobe), plus segments 6, 8, 9, and 10 (lower lobe) (Figure 5)
   1. Move the bronchoscope to the left main bronchus (90° angle to the left), upward to see the upper lobe, and downward to see the lower lobe.
   2. Keep the scope at a 90° angle to inspect the left upper lobe with the lingula. Defer from the 90° angle to inspect segments 1+2 and 3 (left upper lobe) and segments 4 and 5 (lingula).
   3. Go back to the left main bronchus, turn the scope to a 45° angle, and extend the end of the bronchoscope to inspect segment 6, which is opposite segments 4 and 5 (lingula).
   4. Turn the scope to a 0° angle to visualize the lower lobe with segments 8, 9, and 10. Defer from the 0° angle to inspect the segments.
      NOTE: There is no segment 7 on the left side, as this area is filled out by the heart. Segments 4 and 5 plus 8, 9, and 10 follow the same numbering as for the right side, and are numbered from the lateral side at an oblique angle (Figure 6).

Representative Results

The four landmarks approach has been taught at CAMES since 2011, where the simulation-based bronchoscopy course is concluded by passing a finalizing test¹³. From 2015-2017, 77 participants entered the course, of which only 33 (43%) completed it¹¹. The low completion rate was due to several factors: time constraints, the course not being mandatory, maternity leave, and no protected time to train. Of those who completed the course, 14 (42%) found the most important factor for completing the course to be: "A systematic simulation-based course is valuable" (Table 2).

Figure 1: The bronchial tree with the four landmarks. To help the operator navigate the bronchial tree, the path can be split into four landmarks: Landmark 1, the trachea; landmark 2, the right upper lobe; landmark 3, the right middle and lower lobe; and landmark 4, the left upper lobe, lingula, and left lower lobe. Please click here to view a larger version of this figure.

Figure 2: Landmark 1. Trachea with the carina. The scope should be held at a 0° angle. Please click here to view a larger version of this figure.

Figure 3: Landmark 2. Right upper lobe-the Mercedes star. The scope should be held at a 90° angle clockwise for vizualising the upper lobe. Please click here to view a larger version of this figure.

Figure 4: Landmark 3. Right middle and lower lobe. The scope should be held at a 0° angle clockwise for visualizing the middle lobe, and at a 0° angle for vizualising the lower lobe. Please click here to view a larger version of this figure.

Figure 5: Landmark 4. Left lung with left upper lobe including the lingula, and the left lower lobe. The scope should be held at a 90°, 45°, and 0° angle counter-clockwise for vizualising the upper lobe, lingula, and lower lobe respectively. Please click here to view a larger version of this figure.

Figure 6: The lungs with their segments seen laterally. Top: The left lung seen laterally with landmark 4, consisting of the upper lobe, lingula (left), and the lower lobe (right). Botton: The right lung seen laterally with landmark 1, consisting of the upper lobe (right upper corner), and landmark 2, consisting of the middle lobe (right lower corner) and the lower lobe (left). Please click here to view a larger version of this figure.

Landmarks	Angle of the bronchoscope
Landmark 1, Trachea with Carina.	0° angle.
Landmark 2, Right Upper Lobe – The Mercedes Benz Sign.	90° angle to the right.
Landmark 3, Right middle and lower lobe.	45° angle to the right for middle lobe and with a fully extended tip for segment 6.
	0° angle for segments 7, 8, 9 and 10.
Landmark 4, Left lung with left upper lobe including lingula, and left lower lobe.	90° angle to the left for left upper lobe and lingula.
	45°angle to the left with a fully extended tip for segment 6.
	0° angle for segments 8, 9 and 10.

Table 1: Correspondence between the four landmarks and the angle of the bronchoscope. After accessing each lobe, defer from the designated angle to inspect the lung segments.

Most important factors	Responses (percent)
Clinically relevant course	17 (57%)
High Value of a systematic simulation-based course	14 (47%)
Certification was needed	3 (10%)

Table 2: Most important factors for completion of a simulation-based course in flexible bronchoscopy. Values are presented as number (percentage). The total is greater than 100%, as some participants mentioned more than one factor. Respondents = 30.

Discussion

We propose a systematic and complete inspection of the bronchial segments, splitting the bronchoscopy into four landmarks to help guide novice bronchoscopists through the bronchial maze. As more specific guidelines that govern bronchoscopy training are needed¹⁴, we propose that our systematic and stepwise approach should be evaluated using three basic outcome measures: DC, SP, and PT.

DC and PT are established outcome measures and the first used when evaluating bronchoscopy performance⁹. The naming of bronchial segments follows a structured sequence to match the intended progression during bronchoscopy¹⁵. However, other assessment studies have yet to evaluate the level of systematic progression, even though a systematic approach is important when performing endoscopic pulmonary procedures¹⁶. The SP score can differentiate bronchoscopy performance between novices and experts and even the performance level within the expert group¹⁰. When comparing a systematic approach to a targeted endobronchial ultrasound-guided biopsy (EBUS-TBNA), the former resulted in a higher diagnostic yield for the staging of lung cancer¹⁷. Therefore, we suggest adding SP as an outcome measure for future assessment studies and making it a focus when training novice bronchoscopists to ensure no segments are missed.

There are several other important aspects to consider when performing a bronchoscopy, such as biopsy technique, wall collisions, patient communication, sedation, etc., but these aspects do not fall within the scope of this manuscript. Our study demonstrates a basic concept that we believe should be taught as a first step in bronchoscopy education. Additionally, novice operators desire more feedback, and the lack of feedback has been identified as a key reason for not completing a bronchoscopy course¹¹. The four landmarks are meant as a support to novice trainees, but autogenerated feedback could be desirable as a replacement for senior supervised feedback. Autogenerated assessment of scope handling has already been developed for bronchoscopy^18,19, and should as well be developed for segment inspection. Feedback through electromagnetic navigation bronchoscopy enhances the amount of visualized lobes but is not able to guide and ensure that the operator visualizes all segments²⁰. We hope that, with its rapid development and usefulness , future studies can try to develop AI that can help guide novice bronchoscopists through all the bronchial segments and provide them with instant feedback to optimize and certify their performance through bronchial identification systems.

Our approach to learning bronchoscopy has several strengths. It follows current evidence using a mastery learning approach in a simulation-based setting²¹, based on a four-step model²². It has been taught this way at CAMES since 2011²³, and it has been implemented at the other three simulation centers in Denmark. Furthermore, it is currently being implemented in the Netherlands. With this article and video, we hope to expand and generalize the initial part of learning flexible bronchoscopy based on the most current evidence.

Flexible bronchoscopy should be taught in a simulation-based setting, where the trainee is taught the basic concepts of a systematic and thorough bronchoscopy with correct handling of the bronchoscope. By splitting the procedure up into a stepwise approach consisting of four landmarks, we propose a guideline for learning bronchoscopy in a simulation-based setting.

Materials

Name	Company	Catalog Number	Comments
Evis Exera II	Olympus	Not provided	Endoscopy Tower
BF-Q180 Bronchoscope	Olympus	Not provided	Flexible Bronchoscope
CLA Broncho Boy	CLA	Not provided	Bronchial Tree Phantom