Bronchial Anatomy
Anatomical familiarisation of the bronchial tree requires practice. However, there are several tips which should assist you in mastering this area:
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Keep the posterior wall of the trachea at the bottom of the screen and the bronchoscope in the centre of the lumen - this will help to orient you and avoid mucosal trauma
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The tracheal carina is the only truly universally identified structure in the lower airways - if you get lost, retreat to this position
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The right middle lobe and lingula are anatomically anterior
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The apical segments of the lower lobes are anatomically posterior
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Anatomical variation is common (up to 25%), most commonly in the right lower and upper lobes [35].
There is a degree of symmetry in the anatomical orientation of bronchopulmonary segments between the right an left lung. In general, there are ten segments per lung:
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The upper lobes contain three segments - Apical, Posterior, Anterior
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The middle lobe / lingula contain two segments - Medial & Lateral (Middle Lobe), and Superior & Inferior (Lingula)
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The lower lobes contain five segments - Superior (Apical), and the four basal segments - Medial, Anterior, Lateral, and Posterior
The important caveat is that, on the left, the heart occupies an anteromedial location which removes the medial basal segment completely, and distorts/rotates the lingula into superior and inferior orientation (as opposed to lateral and medial of the RML). Finally, the left upper lobe's apical and posterior segments are fused to form an apicoposterior segment, while it still retains an anterior segment. Therefore, there are only eight segments in the left lung.
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This is quite challenging to remember at first, and exposure to the procedure under guidance improves familiarity over time. This mnemonic may assist your recall (segments are in order from most superior to most inferior):
A PALM SEED MAKES A LITTLE PALM
A PALM SEED IS STILL A LITTLE PALM
The Bronchoscope
The flexible bronchoscope (FB) is available in both reusable and disposable forms. Traditional, reusable FBs contain a long fibreoptic system that attaches to a light source and transmits video from the tip to display on a screen. Disposable systems are cheaper as, instead of fibreoptic cables, they house an LED and a distal camera which is transmitted via a cable. They offer convenience and complete sterility, however compromise video quality.
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Other considerations when selecting a bronchoscope and preparing for the procedure are [36]:
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External diameter (slim 2.8-3.8mm, standard 4.4-5.5mm, therapeutic or ultrasound equipped 5.9-6.9mm) - require an endotracheal tube of ≥ 2mm internal diameter size.
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Working channel (slim 1.2mm, standard 2.0-2.2mm, therapeutic 2.8mm) will affect degree of suction power available
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Adequate sedation and analgesia, with consideration to paralysis if avoidance of coughing is desired (note topical plain lignocaine 2% applied via the bronchoscope in a “spray and go” approach may significantly reduce the amount of sedation required for tolerance)
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Ventilator settings - volume control, increase pressure alarm limit to maximum, and set FiO2 to 100%
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Ensure adequate staffing and monitoring, and retain situational awareness during the procedure