Bronchial Branch Tracing

By Noriaki Kurimoto and Katsuhiko Morita

This book summarizes the branch tracing method for bronchoscopic diagnosis.

Cytopathological and histopathological diagnoses are essential to making prognoses and selecting appropriate treatment for peripheral pulmonary lesions, notably lung cancer. In order to collect cell and tissue samples from peripheral pulmonary lesions for cytopathological and histopathological diagnoses, exfoliative cytodiagnosis and biopsy under bronchoscopy with endobronchial ultrasonography (EBUS) are currently used worldwide.

Bronchial Branch Tracing highlights how to identify the bronchial branches that lead to peripheral pulmonary lesions and offers a valuable guide for all respiratory physicians, as well as surgeons, who frequently perform bronchoscopies, helping them understand the method and improve their technique.

• Language: English
• Publisher: Springer
• Release date: Feb 27, 2020
• ISBN: 9789811399053

Book preview

Noriaki Kurimoto and Katsuhiko Morita

Bronchial Branch Tracing

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Noriaki Kurimoto

Division of Medical Oncology and Respiratory Medicine, Shimane University Hospital, Izumo, Shimane, Japan

Katsuhiko Morita

Department of Chest Surgery, Shimonoseki Medical Center, Shimonoseki, Yamaguchi, Japan

ISBN 978-981-13-9904-6e-ISBN 978-981-13-9905-3

https://doi.org/10.1007/978-981-13-9905-3

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The Work was first published in 2015 by Igakushoin Ltd. with the following title: Kikanshikyo Edayomijutsu.

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Preface by Dr. Noriaki Kurimoto

In 2015, we published a book on tracing bronchial branch for bronchoscopy in Japan. To diagnose a peripheral pulmonary lesion represented by lung cancer using a bronchoscope, accurately grasping the bronchial route to reach the peripheral pulmonary lesion is necessary. In recent years, the use of virtual bronchoscopic navigation has become widespread. However, it is ideal if, by looking at the axial computed tomography (CT) images, doctors think and accordingly perform the tracing branch technique, which draws the bronchial route.

We started endobronchial ultrasonography (EBUS) in 1994 and established the standard procedure 23 years after starting EBUS-GS using a guide sheath in 1996. The method is described in detail in this book because the tracing branch technique has been improving since. The progress of the tracing branch technique can be attributed to the emergence of helical CT, which has made it possible to obtain CT images in slices of about 1 mm thickness. In this book, Chap. 1 explains the principles of tracing branch technique, and considering the running direction of the bronchus, the bronchi are divided into vertical and horizontal branches. Chapter 2 provides typical cases in each subsegment, helping the doctors to continuously study. Furthermore, the readers can trace the bronchial branch on the aligned CT images and compare it with actual bronchoscopic findings. Finally, in Chap. 4 , Dr. Morita, another author, describes a detailed study on comparing EBUS images and histopathological findings. For the progress in bronchoscopic diagnosis, it is important to accumulate bronchial-epithelial and subepithelial findings, which can be explained from histopathological findings.

The collaboration of staff who worked together at Iwakuni Minami Hospital, Higashihiroshima Medical Center, St. Marianna University, and Shimane University Hospital, where I worked, was essential for the publication of this book.

In addition, several doctors who came from foreign countries to attend the EBUS training have requested an English version of the textbook on tracing bronchial branch. We hope this book will help several overseas doctors gain the skill of tracing bronchial branch and they will apply this skill on overseas patients.

Noriaki Kurimoto

Izumo, Japan

Preface by Dr. Katsuhiko Morita

Do you remember your first ever case of bronchoscopy? When I was at a small hospital in a remote area of Japan, 3 years after I graduated from medical school, I met a patient I could not forget. This patient left me with the very impressive words It was tougher than the time I had a myocardial infarction! The bronchoscope that I used then was old and thick, one which the operator must look directly into. Of course, it was an era when endobronchial ultrasound (EBUS) was not yet commercialized, anesthesia was inadequate, and the procedure was probably immature. Moreover, I did the bronchoscopy after seeing only a couple of times how the procedure was done. Realizing that everything was unprepared, I went to Iwakuni Minami Hospital every week to study bronchoscopy under Dr. Kurimoto and his colleagues, Dr. Murayama and Dr. Enomoto. More than 20 years ago, only the larger bronchi and central airways could be reached, because only a thick bronchoscope was available.

Returning to the present, let’s look at the structure of the lungs. Unlike the gastrointestinal tract, the peripheral airways branch out and subdivide from the trachea for several bronchial generations. Therefore, there is a myriad of routes to choose from in order to reach peripheral lesions precisely. In gastrointestinal endoscopy, particularly colonoscopy, insertion technique is important, whereas in bronchoscopy for peripheral lesions, selection technique is important. In my opinion, bronchoscopy to obtain cytologic and histologic diagnosis of peripheral lung lesions requires three techniques/technologies, including (1) accurate localization of a lesion, (2) safe and accurate approach to the lesion, and (3) sampling that is safe and would yield qualitatively optimal cells and tissues. Owing to the recent advancements to date, lesion localization had been made clear by computed tomography (CT), the ability of EBUS to detect lesions has been confirmed, and safe and optimal sampling had been enabled by the use of a guide sheath.

Notably, approaching the lesion is the most difficult task. Although advancements in bronchial navigation can address this difficulty, the limitations of high equipment cost, extraction of navigation data from CT, and the time and effort required to create a navigation image remain. Moreover, the navigation itself cannot always accurately represent the peripheral bronchi. On the other hand, the branch reading technique by Dr. Kurimoto requires only paper and pencil. At one bronchoscopy conference, when this branch reading technique was not yet popular, it was strange that only Dr. Kurimoto was able to draw a schematic representation of the bronchial branching on the white board, based on the consecutive CT images that showed the branches that led to the peripheral bronchus involved with the lesion. At that time, the doctors around me, including myself, were only copying the figure. It seemed that we began to recognize the necessity of using this navigation technique only after the extra small-diameter bronchoscope had been used routinely and enabled observation of the peripheral airways, from the fifth generation and after. Being able to correctly read the bronchial branches, insert a bronchoscope to the periphery, and directly observe peripheral lesions, which used to seem unreachable, strengthened my enthusiasm for learning this branch reading technique.

We are now in an era when peripheral lesions can be directly observed endoscopically, the findings of which can even be correlated with the pathology findings. In order to deepen and spread the understanding of endoscopic findings based on pathology, improvements in both diagnostic rate and branch reading are necessary. Sufficient preparation and planning before bronchoscopy are essential for a safe and successful diagnostic procedure for peripheral pulmonary lesions.

Katsuhiko Morita

Shimonoseki, Japan

Appearance of Bronchus

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Contents

1 To Trace the Bronchial Branch Accurately 1

1.​1 Nomenclature of the Bronchial Branch 1

1.​2 CT Imaging Condition 3

1.​3 Method of the Reading Branch Using CT Images 4

References 21

2 Actual Identification of Bronchial Branch 23

3 EBUS-GS for Peripheral Pulmonary Lesions 127

3.​1 Pharyngeal/​Laryngeal Anesthesia 127

3.​2 Preparing the Guide Sheath 128

3.​3 Setting of the Ultrasonic Processor 129

3.​4 Insertion of a Bronchoscope 131

3.​5 Guiding the Ultrasonic Probe/​Guide Sheath to the Peripheral Bronchus 132

3.​6 Scanning by the Probe 133

3.​7 Solutions When the Probe Does Not Enter Within the Lesion 136

3.​7.​1 Re-select the Appropriate Bronchus Under the Bronchoscopic Image 136

3.​7.​2 Re-select the Appropriate Bronchus Under X-Ray Fluoroscopy (Fig.​ 3.​13) 136

3.​7.​3 Re-select the Appropriate Bronchus Under the EBUS (Fig.​ 3.​14) 136

3.​7.​4 Re-select the Appropriate Bronchus Using the Guiding Device Under X-Ray Fluoroscopy (Fig.​ 3.​15) 137

3.​7.​5 Countermeasure Taken When the Bronchus Is Obstructed at the Margin of the Lesion 138

3.​7.​6 Pinpoint Biopsy (Fig.​ 3.​16) 138

3.​8 Leave the Guide Sheath In Situ 139

3.​9 Cells and Tissue Collection Through the Guide Sheath 140

3.​10 Removing the Guide Sheath 141

3.​11 Complications and Countermeasures 141

3.​11.​1 Bleeding 141

3.​11.​2 Pneumothorax 141

3.​11.​3 The Bending of the Guide Sheath 141

References 141

4 Comparison of Endobronchial Ultrasonography Images and Resected Specimens 143

4.​1 Inflation-Fixation of Excised Specimens 143

4.​1.​1 Things to Do Before Inflation-Fixation to Enable a Proper Comparison 143

4.​1.​2 Make Every Effort to Restore the Lung to Its In Vivo State 144

4.​2 Cutting Out 144

4.​2.​1 Overall Observation and Photography 144

4.​2.​2 Make an Incision 146

4.​2.​3 Spread Out the Cut Slices of the Specimen and Photograph the Cut Surfaces (Fig.​ 4.​5) 146

4.​2.​4 Reconstruction of the Specimen 147

4.​3 Comparison 147

4.​3.​1 Analysis of Histological Presentation and Correlation with Techniques 149

References 161

© Springer Nature Singapore Pte Ltd. 2020

N. Kurimoto, K. MoritaBronchial Branch Tracinghttps://doi.org/10.1007/978-981-13-9905-3_1

1. To Trace the Bronchial Branch Accurately

Noriaki Kurimoto¹  and Katsuhiko Morita²

(1)

Division of Medical Oncology and Respiratory Medicine, Shimane University Hospital, Izumo, Shimane, Japan

(2)

Department of Chest Surgery, Shimonoseki Medical Center, Shimonoseki, Yamaguchi, Japan

Abbreviations

EBUS

Endobronchial ultrasonography

EBUS-GS

Endobronchial ultrasonography using a guide sheath

GGN

Ground-glass nodule

GS

Guide sheath

STC

Sensitivity time control

1.1 Nomenclature of the Bronchial Branch

The nomenclature of bronchi is based on the direction in which the lungs with the bronchi are located [1–8].

The three principles of the bronchi nomenclature are as follows:

1.

Cranial side → caudal side

2.

Dorsal (posterior) → ventral (anterior)

3.

Lateral side → medial side

Considering these principles, the segmental bronchi (II: second-generation bronchus) are named as 1, 2, 3, …; the subsegmental bronchi (III: third-generation bronchus) are named as a, b, c, … …; the sub-subsegmental bronchi (IV: fourth-generation bronchus) are named as i to i, ii, iii, ……; the sub-sub-subsegmental bronchi (V: fifth-generation bronchus) are named as α, β, γ, … …; and the sub-sub-sub-subsegmental bronchi (VI: sixth-generation bronchus) are named as x, y.

These three principles consider the cranial side as the top priority. When nominating the bronchi, caudal and dorsal side or the cranial and ventral side in these conflicting principles, the bronchi to the cranial side are considered as the top priority (Figs. 1.1 and 1.2).

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Fig. 1.1

Bronchial nomenclature. [Quoted from the Japan Lung Cancer Society (ed.): General Rule for Clinical and Pathological Record of Lung Cancer, 7th edition, p151, Kanehara Publishing, 2010]

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Fig. 1.2

Standard branching of the subsegmental bronchi

When branching further from the subsegmental bronchus, the recognition of the positional relation of the cranial side/caudal side, dorsal/ventral side, and lateral side/medial side becomes challenging.

The bronchus is named referring to the direction of the proximal bronchial branch. However, considering the complicated branch naming at the time of bronchoscopic examination, a more correct nomenclature is possible using the thin-slice CT images after bronchoscopy.

In the actual bronchoscopic examination, expressing the direction of the next-generation bronchial opening, such as up, down, left, right, upper right, lower right, upper left, lower left, etc., is useful without mentioning the name of the bronchus.

This book describes the naming method as follows: the direction from which the next bronchial lumen on the CT images can be indicated, is followed by the name based on the nomenclature in parentheses, for example, from B¹ai to superior (B¹aiα), inferior (B¹aiβ) ….

The nomenclature of the segmental bronchus/subsegmental bronchus was made considering the route and distribution of the bronchus. For example, when the bronchus heading toward the region of S¹b branches off from the cranial side in B³, it is considered to be B¹b branched from B³a and, thus, named B¹b.

Opportunities to identify the lateral branch (daughter branch) heading to the lungs of the inner layer closer to the hilar and