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Tracheal and Bronchial Developmental Abnormalities, and Inflammatory Diseases including Bronchiectasis, Cystic Fibrosis and Bronchiolitis.
Published in Fred W Wright, Radiology of the Chest and Related Conditions, 2022
These segments often have an abnormal blood supply with systemic arteries and veins. The artery may be very large and arise above or below the diaphragm (Illus. SEQUESTRATION, Pts. 1f & 5b). It is important to consider the condition before surgery, to make the surgeon aware of it, so that he may look for abnormal vessels before putting his hand under the lung to elevate and deflate it and thereby avoid damage to the vessels. Although pre-operative demonstration is not essential and only an awareness of the possibility, ultra-sound and CT have been to demonstrate the abnormal circulation. Ultra-sound was used by Kaude and Laurin (1984) and by Thind and Pilling (1985) in infants, CT identification of the supplying vessel was reported by Miller et al. (1982). Rarely the supplying artery may spontaneously rupture to form a haemothorax (Zumbro et al., 1974, & Zapatero et al., 1983) and the condition may be present in association with bronchial and pulmonary isomerism (Mohan et al., 1983). The condition may be bilateral (Karp, 1977 and Wimbish et al., 1983). Occasionally double or bilateral systemic vessels may be found with a sequestrated segment (McDowell et al., 1955 and Ennis et al., 1972). Collateral ventilation has been noted by Culiner and Wall (1965) and has been demonstrated by nuclear medicine ventilation studies (Hopkins et al., 1982). In the inter-lobar type, venous drainage is usually via the pulmonary veins, but in the extra-lobar type it may be to systemic veins.
Functions of the Respiratory System
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
As the lung parenchyma consists of interconnected alveolar walls and interstitial tissues, the surrounding tissues oppose any local distortion of alveoli. Therefore, when a small area of alveoli begins to collapse, the surrounding tissue is stretched and tends to pull the alveoli back open. This phenomenon, called alveolar interdependence, along with surfactant and collateral ventilation via the pores of Kohn, prevents alveolar collapse. The airways and alveoli distal to a single terminal bronchiole make up a functional unit: the pulmonary lobule.
Embryology, anatomy, and histology of the lung
Published in Louis-Philippe Boulet, Applied Respiratory Pathophysiology, 2017
Nonrespiratory bronchioles have a histology similar to bronchi except that their wall is thinner and contains neither cartilage nor glands. The height of the respiratory epithelium gradually decreases as the bronchioles diminish in size, their shape changing from cylindrical to cubo-cylindrical then to cuboid. Concomitantly, the ciliated cells and goblet cells are gradually replaced by Clara cells, which are nonciliated and whose apical cytoplasmic portion is enlarged. Clara cells have a secretory role as they produce a surfactant-like substance. They are also the progenitors of the bronchiolar epithelium. The transition from conduction airways to exchange surfaces occurs in the respiratory bronchioles. Respiratory bronchioles lined by respiratory epithelium begin to have alveoli budding from their wall. In addition to the normal ventilation from the trachea to the bronchi to the bronchioles to the alveoli, three structures allow a collateral ventilation. First, pores of Köhn connect adjacent alveoli. Second, Lambert canals directly connect nonrespiratory bronchioles to alveoli. Third, interbronchiolar communications of Martin occasionally connect a bronchiole to another (Figure 1.8).
Device profile of the Zephyr endobronchial valve in heterogenous emphysema: overview of its safety and efficacy
Published in Expert Review of Medical Devices, 2021
Steven R. Verga, Gerard J. Criner
Target lobe selection was based on 50% destruction score [which is based on percentage of voxels < −910 Hounsfield units (HU) on (high resolution computed tomography (HRCT)] along with heterogenous emphysema defined by difference of 15% ≥ destruction score between the targeted and INL (calculated by Myrian quantitative software) [3,15]. ‘Complete’ fissure integrity (based on high HRCT visual score of ≥ 90% fissure completeness) was essential based on post-hoc analysis of VENT trial to identify potential patients that would benefit from BLVR [9]. Fissure integrity was a marker of collateral ventilation (CV), which would result in incomplete bronchial occlusion of target lobe due to alternative pathways of ventilation via pores of Kohn, bronchioloalveolar communications of Lambert and intrabronchiolar pathways of Martin [22]. With only 1 fissure, the left targeted lobe more likely to have no collateral ventilation [14,15,21,23]. Lobar perfusion aided in targeted lobe selection, for upper lobes <8% of total perfusion compared to lower lobe targets with <13% total perfusion [24].
Lung volume reduction with endobronchial valves in patients with emphysema
Published in Expert Review of Medical Devices, 2018
Marieke C. Van Der Molen, Karin Klooster, Jorine E. Hartman, Dirk-Jan Slebos
Collateral ventilation can be measured by means of the Chartis system (PulmonX, CA, USA). To measure collateral ventilation of the target lobe, a Chartis balloon is inserted through the bronchoscope and inflated in front of the ostium of the target lobe to block the airflow. This balloon enables the measurement of expiratory air flow. If no collateral ventilation is present, expiratory air flow declines and thereby qualifies the patient for EBV treatment (Figure 4). In case of an undetectable airflow in the target lobe, alternative measurements in the ipsilateral lobe can be performed. Of note is that if the oxygen saturation drops during the assessment of collateral ventilation, the assessed lobe should be avoided from treatment since it may indicate a significant role in the gas exchange.
Chronic obstructive pulmonary disease
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2020
Jean Bourbeau, Sebastien Gagnon, Bryan Ross
Interventions for Severe Emphysematous COPD: In severe emphysematous patients, lung-volume-reduction surgery (LVRS) can reduce symptoms and increase physical capacity; however, strict selection criteria and high morbidity risk limit this treatment option. Bronchoscopic lung volume reduction (BLVR) was proven to be a promising alternative in patients with heterogeneous emphysema and absence of collateral ventilation following the publication of two recent positive phase III studies.19,20 After one year, one third of patients experienced a FEV1 improvement of ≥15%. However, BLVR did lead to higher incidence of pneumothorax and mortality was consequently elevated, yet remained lower with BLVR than with LVRS.