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Effect of Neutrophils on Airway Smooth Muscle Responsiveness
Published in Devendra K. Agrawal, Robert G. Townley, Inflammatory Cells and Mediators in Bronchial Asthma, 2020
Two studies have compared the in vitro responsiveness of canine trachealis with the in vivo responsiveness after ozone exposure and have come to somewhat different conclusions. Walters et al.30 determined the ES and ACh responsiveness of trachealis muscle (stripped of epithelium) from ozone- and air-exposed dogs in which increased airway reactivity was documented. After a 2-h “equilibration” period during which the tissues were washed several times, they found no change in the responsiveness to ACh, but there was potentiation of ES contractions. Jones et al.31 used a 30-min exposure to 3 ppm of ozone and a 1-h equilibration period in tissue bath. They apparently did not use propranolol to abolish any inhibitory effects from the release of norepinephrine. They found that both ES and ACh contractile responses were enhanced in dogs exposed to ozone. They also failed to find the secondary oscillations in membrane potential that had accompanied the ES-induced EJP after U-46619.29 Therefore, they concluded that the effect of ozone was to cause a postjunctional change in the airway smooth muscle. The reasons for the difference between the two studies are unknown.
The respiratory system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
The larynx is supported by a cartilaginous framework, connected by ligaments. The trachea comprises a series of ‘C’-shaped cartilages, joined by fibroelastic membranes to form a hollow tube. Posteriorly lies the trachealis muscle. The midline cervical trachea lies anterior to the oesophagus. Subglottic tracheal lesions may cause oesophageal dysfunction and vice versa. The isthmus of the thyroid gland is anterior to the second, third and fourth rings.
Disorders of larynx, trachea and upper airway
Published in Brice Antao, S Irish Michael, Anthony Lander, S Rothenberg MD Steven, Succeeding in Paediatric Surgery Examinations, 2017
Charles M Myer IV, Charles M Myer III
Complete tracheal rings exist when there is minimal to no trachealis muscle present in the posterior tracheal airway. This airway is less likely to grow commensurate with the patient and often presents during infancy. The condition is associated with various cardiovascular anomalies, most commonly a pulmonary artery sling. A three-dimensional contrast-enhanced chest CT scan will help elucidate any cardiovascular anomalies to be addressed at the time of tracheoplasty, since the majority of patients who require repair will need cardiopulmonary bypass. In addition, a CT scan complements bronchoscopic evaluation in determining the length and extent of tracheal stenosis.
The role of the pediatrician in caring for children with tracheobronchomalacia
Published in Expert Review of Respiratory Medicine, 2020
Manisha Ramphul, Andrew Bush, Anne Chang, Kostas N Prifits, Colin Wallis, Jayesh Mahendra Bhatt
Cholinergic stimulation with muscarinic agonists may improve the tone of the trachealis muscle and a decrease in airway compliance; thereby improving the overall airway mechanics, including the forced expiratory flows [57]. Options include inhaled methacholine, a short acting agent, and bethanechol, a long-acting oral agent. After initiation of bethanechol, half of patients with TBM report an improved quality of life, with an improvement in cough, and a decreased frequency of emergency medical reviews and hospitalizations [59]. Experience from one center suggests that the use of bethanechol in TBM resulted in a decrease in cough frequency and hospital stays [60]. A trial of bethanechol may be considered in children with very troublesome symptoms; however, further research in this field is required to determine which children (if any) are most likely to benefit from bethanechol and this is not routinely used in current practice [11].