Xv: Describe the anatomy of the bronchial tree relevant to bronchoscopy

Bronchoscopy

  • Examination of airway via flexible telescope (bronchoscope)

Purpose

Some of the reasons to perform a bronchoscopy, but not limited to:

  • Diagnosis of tracheobronchial tree disease
  • Lung sampling (ie. Bronchoalveolar lavage, biopsies)
  • Visualisation of percutaneous tracheostomy
  • Treatment of lung disorders (ie. Controlling bleeding within lungs)

Bronchial anatomy

Initial insertion via nose or mouth (in ICU typically through ETT

Travels down trachea

  • Conducting airway
  • Dimensions: 11cm L, 2.5cm W, 1.8cm D
  • Begins: cricoid (C6)
  • Ends: carina (T4/5)
  • D shaped
    • Trachaelis muscle posteriorly – runs length of trachea
    • Curved cartilage (approximately 20 rings) anteriorly
    • During bronchoscopy should be able to visually see the difference in muscle + cartilage as travelling down trachea

First structure – bifurcation / carina

  • T4/T5
  • Cartilaginous ring

Right main bronchus

  • Part of conducting airway
  • Contains turbulent flow
  • Shorter (3cm), wider, vertical
    • Note: this is the reason why foreign bodies are more likely to enter right main bronchus
  • Branches:
    • Right upper lobe bronchus
      • Apical, anterior, posterior
      • From the right main bronchus: described as 0300
    • Right bronchus intermedius
      • Right middle lobe bronchus
        • Medial, lateral
        • From the right bronchus intermedius: described as 1200
      • Right lower lobe bronchus
        • Superior, medial, lateral, anterior, posterior
        • From the right bronchus intermedius: described as 0600

Left main bronchus

  • Part of conducting airway
  • Contains turbulent flow
  • Longer (5cm), narrower, more horizontal
  • Branches
    • Left upper lobe bronchus
      • From the left main bronchus: described as 0900
      • Superior
        • Apicoposterior, anterior
      • Lingular
        • Superior, inferior
      • Left lower lobe bronchus
        • Anterior, posterior, lateral
        • From the left main bronchus: described as 0600

Bronchial circulation

  • Only receives 1% of total blood flow
  • Bronchial arteries: 2x left bronchial arteries (separate origins arising from descending aorta), 1x right bronchial artery (origin from intercostal artery from descending aorta)
  • Venous drainage: 2/3 into pulmonary vein (physiological shunt), 1/3 into systemic circulation via azygos vein

Innervation

  • Vagus (CNX)

Risks and ways to mitigate

Bleeding

  • Avoid vascular lesions

Bronchospasm, laryngospasm

  • Pretreatment – beta agonist
  • Paralysis
  • Deep sedation

Pneumothorax

  • Avoid distal biopsies

Damage to surrounding structures

  • Bronchial perforation

Hypoxaemia

  • Preoxygenation and supplemental oxygen

Loss of surfactant

  • Avoid lavage

Contraindications

  • Concerns for airway compromise during procedure (ie. Unable to maintain patent airway, inadequate oxygenation, or ventilation)
  • Severe haemodynamic instability
  • Active cardiac ishcaemia
  • Severe coagulopathy
  • Life threatening arrhythmias
  • Refractory hypoxaemia

Other

  • Procedural limitations: flexible bronchoscopy can only go to 4/5th order bronchi

Author: Suzanne Luong