BRONCHIAL ASTHMA. Prof. Vatutin N.T. Definition.
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Prof. Vatutin N.T.
Asthma is a chronic inflammatory disease of the airways which develops under the allergens influence, associates with bronchial hyperresponsiveness and reversible obstruction and manifests with attacks of dyspnea, breathlessness, cough, wheezing, chest tightness and sibilant rales more expressed at breathing-out.
According to epidemiological studies asthma affects 1-18% of population of different countries.
Only in 2006 more than 300 million patients suffered from asthma all over the world, 250 thousands of patients die of asthma. The incidence of asthma is higher in countries with increased air pollution.
The allergens are divided into:Etiology
The most important occupational allergens are dust of stock buildings, mills, weaving-mills, book depositories etc.
Natural allergens are represented by plant pollen (especially ambrosia, wormwood and goose-foot pollen) and different respiratory, particularly viral, infections.
hair and fur
House-dust mites which live in carpets, mattresses and upholstered furniture
Dust of book depo-sitories
Food components (stabilizers, genetically modified products)
Pharmacological agents (enzymes, antibiotics, vaccines, serums)
Trigger-factors, which provoke bronchospasm, are: a simultaneous penetration of a large quantity of allergen, viral respiratory infection, hyperventilation, physical exertion, emotional stress, becoming too cold, adverse weather conditions, administration of some medicines (aspirin, b-blockers).
Asthma pathophysiology is quite difficult and insufficiently studied. Undoubtedly, in most cases the disease is based on 1 type hypersensitivity reaction. The genesis of any allergic reaction may be divided into immune, pathochemical and pathophysio-logic phases.
After involving into the airways allergens activate immunocompetent cells. As a result B-lymphocytes produce antibodies of Ig E class. In case of asthma T-lymphocytes are inhibited, so the activation of B-lympocytes and Ig E production are excessive, exceeding normal needs.
This is a first, immune phase of allergic reaction.
As a result of antigen-antibody reaction the peculiar “explosion” occurs. The membranes of mast cells, basophils and eosinophils of bronchial mucous wreck with output of biologically active substances (histamine, serotonin, chemotaxis factors, heparin, proteases, thromboxane, leukotrienes, prostaglandins),
which induce hyperergic inflammation, mucous edema, spasm of smooth myocytes, glands hypersecretion, viscous exudate formation in bronchial lumen.
The indicated mechanism is specific for atopic (exogenous) asthma genesis. In addition to this,autosensibilization of damaged pulmonary tissue, neuropsychic disturbances, corticoid insufficiency, adrenergic imbalance, impairment of arachidonic acid metabolism, genetic and some other factors probably play a certain role in genesis of nonatopic (endogenous) asthma.
Depending on etiology asthma is divided into exogenous (atopic) and endogenous (non-atopic).Byclinical course asthma is divided into intermittent (beginning, early) and persistent (chronic, late). Depending on frequency of exacerbations, limitations of patient’s physical activity and lung function persistent asthma is divided into mild, moderate and severe (lung function is assessed by forced expiratory volume in 1 second (FEV1) and peak expiratory flow (PEF) and daily variability of these parameters). There are also remission phase and exacerbations.
Daytime asthma symptoms
< 1 /week
2 and < /month
>80% predicted. Daily variability < 20%
1 /week but not daily
> 2 /month
>80% predicted. Daily variability – 20-30%
> 1 /week
> 60 but < 80% predicted. Variability>30%.
Persistent, which limit normal activity
<60% predicted. Variability > 30%.Asthma severity classification
Asthma control is considered as:
Classic signs and symptoms of asthma are:
At theprodromal period:
The severe and prolonged asthma exacerbation with intensive progressive respiratory failure, hypoxemia, hypercapnia, respiratory acidosis, increased blood viscosity and the most important sign is blockade of bronchial b2-receptors.
Stages:1st- refractory response to b2-agonists (may be paradoxical reaction with bronchospasm aggravation)
2nd - “silent” lung because of severe bronchial obstruction and collapse of small and intermediate bronchi;
3rd stage – the hypercapnic coma.
acute or subacute cor pulmonale
Persistent asthma causes:
small bronchi deformation and obliteration
chronic respiratory failure
chronic cor pulmonale.Asthma complications
Asthma in childhood leads to growth inhibition
and thoracic deformation.
Eosinophilia, moderate leukocytosis in blood count as well as increased serum level of Ig E can be found in patients with asthma, especially at asthma exacerbations.
Inflammatory cells, Curschmann's spirals (viscous mucus which copies small bronchi) and Charcot-Leyden crystals (crystallized enzymes of eosinophils and mast cells) can be observed in sputum.
especially in case of severe, persistent asthma, shows hypertrophy of right heart chambers.
Right axis deviation,
Rs type complex in V1 lead,
low amplitude R in V5-V6 leads
The diagnosis and severity assessment of asthma is based mainly on parameters of lung function.The most important of them are:
forced expiratory volume in 1 second (FEV1) and peak expiratory flow (PEF), which
FEV1 and PEF directly depend on bronchial lumen size and elastic properties of surrounding lung tissue.
Typical clinical manifestations and lung function assessment are sufficient for diagnosis of asthma.
Asthma is to be differentiated with a number of diseases manifesting with dyspnea – cardiac, uremic, hysteric asthma, systemic vasculitis, broncho-carcinoma, carcinoid and chronic obstructive lung diseases.
the signs of severe heart disease and pulmonary congestion can be found.
1. Avoiding the contact with allergen. If it is impossible, the specific hyposensitization with standard allergens should be performed. It is rather effective in case of monoallergy, in intermittent and mild persistent asthma, in remission phase.
2. Elimination of trigger factors (rational job placement, changing the residence, psychological and physical adaptation, careful drug using) is the second condition for successful asthma treatment.
3. Optimally selected medical care is the base of asthma management.
cell membrane stabilization
inhibition of inflammatory mediators
restoring the sensivity of b2-receptors.
Inhaled corticosteroids (beclamethazone, inhacort, budesonide, flixotid, fluticazone, asmacort, asthmanex) are the most effective and safe and considered to be the first line drugs for asthma treatment. Systemic are used during short courses, mainly in case of severe persistent asthma or asthmatic status.Corticosteroids
(cromolyn sodium – intal, and nedocromil – tiled)
stabilize cell membranes,
used mainly in pediatric practice (in childhood)
in case of intermittent or mild persistent asthma.
Leukotriene receptor antagonists
have the moderate intiinflammatory activity
used in case of aspirin-induced asthma and
asthma of physical exertion.
receptors of bronchi
Preservation of the environment, healthy life-style (smoking cessation, physical training) – are the basis of primary asthma prophylaxis. These measures in combination with adequate drug therapy are effective for secondary prophylaxis.