Bronchial Obstruction in Children

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However, the main causes of bronchial 
obstruction in children are acute obstructive 
bronchitis and bronchial asthma!

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The pathogenesis of bronchial obstruction
depends on the etiology of the disease. Pathogenetic 
mechanisms can be divided into two groups: 
1. Functional (reversible). It is bronchospasm, 
inflammatory infiltration, edema, violation of mucociliary 
clearance, hypersecretion. 
2. Irreversible (congenital stenosis of the bronchi and 
others).

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• The main factor of the pathogenesis of 1 group BOS is inflammation, 
which can be both infectious and allergic in children . 
• The mediator of the acute phase of inflammation is interleukin-1 (IL-1). 
• It is produced by phagocytic cells and tissue macrophages under the 
action of infection, allergy and promotes the release of first type mediators 
(histamine, serotonin) into peripheral blood. 
• These mediators are constantly present in the granules of mast cells and 
basophils, that ensures very rapid biological effects.

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• Besides histamine, an important role in the pathogenesis of 
inflammation is played by mediators of a second type 
(eicosanoids) generated during the early inflammatory 
response. 
• The source of eicosanoids is arachidonic acid, formed of 
phospholipids of cell membranes. 
• Under the action of cyclooxygenase from arachidonic acid 
prostaglandins, thromboxane and prostacyclin are synthesized, 
and under the action of lipoxygenase - leukotrienes.

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It is due to histamine, leukotrienes and anti-
inflammatory prostaglandins that we observe: 
• enhancement of vascular permeability 
• edema of bronchial mucosa 
• hypersecretion of mucus viscous 
• bronchoconstriction 

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• Damaged tissues have an increased sensitivity of receptors of 
the bronchi to external influences (viral infection, pollutants), 
which significantly increases the risk of bronchospasm. 
• In damaged tissues anti-inflammatory cytokines are 
synthesized, degranulation of neutrophils, basophils, 
eosinophils occurs, thereby increasing the concentration of 
such biologically active substances as bradykinin, histamine, 
oxygen free radicals, which are also involved in the 
development of inflammation.

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• Thus, the disease process assumes the character of 
"vicious circle", predisposes to a long course of 
airway obstruction and superinfection!

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• BOS is accompanied by an increase in the amount of secretion in the 
bronchi and by increase of its viscosity. 
• Activity of mucous and serous glands is regulated by the parasympathetic 
nervous system, and acetylcholine stimulates their activity. 
• Such a reaction is initially of defensive nature. 
• However, the stagnation of bronchial content leads to disruption of 
ventilation and respiratory function of the lungs, and the inevitable 
infection - to the development of endobronchial or bronchopulmonary 
inflammation. 
• Furthermore, thick secretion may cause obstruction of the respiratory tract 
due to the accumulation of mucus in the upper or lower airways. 
• In severe cases, atelectasis may develop. 

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• Edema and hypersecretion of the mucous membrane 
of the respiratory tract is also one of the causes of 
bronchial obstruction. 
• There is a thickening of all layers of the bronchial 
wall, which leads to bronchial obstruction. 
• At recurrent bronchopulmonary diseases the structure 
of the epithelium is disrupted, its hyperplasia and 
squamous metaplasia are marked. 

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• Certainly, bronchospasm, is a major cause of BOS in 
older children. 
• Thus, there are several basic mechanisms of bronchial 
obstruction. 
• The share of each of them depends on the reasons for 
the disease process and the child's age. 

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