notes by dr Claudio Italiano
The asthma ('asthma: short breath) already describes Homer in the epic, in the
verses in which he speaks of Hector, hero wounded in the plain, who gasps with
short breath and emits blood from the mouth.
Today, unlike what happened in the past when we talk about asthma we refer to a
chronic inflammatory disease of the airways, where the bronchial tubes are
affected by the inflammatory process. Do not confuse asthma with cardiac asthma,
that is, with breathlessness or dyspnoea affecting patients with heart failure.
The bronchial tubes are the means of communication through which the air enters
and leaves the lungs during respiratory acts.
When a person has asthma the bronchi are inflamed, and their wall is reddened
and thickened and is overactive, ie the smooth muscles that make up the
respiratory bronchioles is able to contract in an intense and inappropriate way,
thus causing the narrowing of the bronchiole itself, which is called the
phenomenon of "bronchospasm" ..
White blood cells take part in the inflammatory process, which is at the base of
asthma, in particular some families of cells: mast cells, eosinophils and T
lymphocytes (at the blood count such subjects often have the eosinophils
increase in the formula of Arneth) .
This website discussed the role that pollutants play in the genesis of asthma (see
photochemical smog) in subjects predisposed to this inflammation, in which there
are recurrent episodes of wheezing (whistling, dry noises, "having kittens
inside" (!)), difficulty breathing, chest tightness and cough (see chest
auscultation).
Fortunately, these signs are associated with reversible bronchostructure, that
is the bronchiole, with smooth muscle, after contraction, then it is released
and makes the air pass, unlike what happens in chronic bronchitis where the
process is irreversible and 'obstruction of the bronchi resolvable with extreme
difficulty and with intense care, as long as this is possible (cf. care of
chronic bronchitis).
Given the problems associated with increasing pollution in our cities (see
photochemical smog) it is estimated that 100 million people worldwide are
asthmatic, including children and even athletes, for whom sporting is a
fundamental cure.
The causes triggering the asthmatic attack can be multiple and are mainly
represented by the following allergenic substances and conditions:
-allergy: inhalation of aero-allergens, such as pollens (grasses: seasonality of
the events (from May to July with a second peak in September; weeds, for example
Lanciuola, Artemisia, Parietaria: seasonality of the events, from July to
September. : seasonality of events from February to April: -micophytes, molds
Cladosporium, Alternaria: molds that grow in hot-humid environments (present in
homes) The peak of production of fungal spores occurs at the end of
summer-beginning of autumn .
- food allergy triggered by milk protein, egg, sausage preservatives, ex. monosodium glutamate
-Viral infections (respiratory syncytial virus, common cold virus) and bacterial, house dust, dust mites
- Continuous gastroesophageal reflux with regurgitation of material in the airways.
-Chemical substances: photochemical photo smog, isocyanates and epoxy resins:
plastic and polyurethane workers, painters, designers and printers; formaldehyde:
plastic workers, health personnel; ethylendiamine: photographers. wheat and
flour: bakers, millers, farmers; laboratory animals: personnel exposed to mice,
guinea pigs, rabbits, etc; woods (for example oak, mahogany, red cedar, walnut):
carpenters; drugs: factory workers; metals (for example chromium, nickel,
mercury, cobalt): metalworkers, welders.
- systemic stress: situations of strong physical stress, especially in sports
activity can cause bronco constriction
improved hygienic conditions, for example children living at home in aseptic
environments.
- about a third of women in the pre-menstrual period.
When an allergen, be it a pollen, a mold, is inhaled and reaches the respiratory
tree, it happens that this substance is incorporated by some cells called
macrophages, that is "processed", that is reduced in very small infinitesimal
portions that have a function antigenic and is thus presented in this way to
other immunocompetent cells, called lymphocytes; the latter are aware that the
substance is "not self", that is unknown to those belonging to the human body,
and therefore that it must be fought by the activation of the white cells, B
cells, to work of special "missiles" which are proteins called "immunoglobulins".
In the case of the allergic process, these immunoglobulins are called IgE or
reagine (phenomenon of atopy) and are linked to particular sites of the mast
cell itself to be conveyed around the human body. When an allergen binds to
these immunoglobulins, allergy mediators are released, including vasoactive
substances such as histamine.
It acts by determining vasodilatation, edema of the tissues and, therefore, of
the bronchioles, bronco constriction, production of mucus and various secretions
and breathlessness. In addition, other substances are produced, such as basic
proteins that can damage the bronchial epithelium.
Anatomo-pathological changes in bronchial asthma can be summarized as follows:
-infiltration of eosinophils and lymphocytes (cells that cause inflammation);
-description of the epithelium (the surface of the bronchus loses its integrity);
-vasodilation and protein extravasation (the bronchus "swells" and tends to
close);
- increase in the mass of smooth muscle (microscopic muscles surrounding the
bronchus become enlarged and tighten the bronchus, reducing its lumen);
-angioneogenesis (new capillaries are created);
- increase in the number of muciparous cells (the cells that make the mucus);
- deposition of collagen in the region below the epithelium (thickening of the
basement membrane).
It makes use of the visit and of the approach to the patient, which may present
exacerbations of asthma, and must present these signs:
-broncospasmo
- expiratory breath
- snappy
- effortless breathing
But the fundamental examination is spirometry, (also chronic bronchitis) that is
the measurement of the air emitted and the speed with which this is possible at
the first or FEV 1. This measurement is possible with an instrument called a "spirometry
cabin", where a patient is seated who is connected to a tube and must breathe
through it, while a computer measures airflow, and provides information on the
airway obstruction status. . A simple and important test is the so-called "reversibility
test", which consists in performing two spirometries, one of which before and
after the administration of a bronchodilator spray. In asthmatics, this
administration causes changes in spirometry that allow diagnosis.
The D.D. for asthma should be placed with other patients who have dyspnoea:
Those suffering from chronic obstructive bronchitis, typical of mature people
while asthma is generally a problem that afflicts young people.
Heart failure (also called "cardiac asthma") due to insufficient contraction
force of the heart
Acute bronchitis: passing inflammation of the bronchi usually on an infectious
basis.
Asthmatic disease usually requires continuous treatment. It uses drugs in
aerosol sprays or in the form of inhalation powder in order to limit the state
of inflammation of the airways within normal limits and consequently do not
incur the accentuation of the "bronchial hyperreactivity". The most important
drugs for the anti-inflammatory treatment of asthma are the cortisone-based
preparations: beclometasone, budesonide, flunisolide, fluticasone.
One category of anti-inflammatory drugs is the antileukotrienics. These drugs
are currently only taken orally. The so-called "antiallergic vaccines" or, more
correctly, specific immunotherapies do not belong to the "drugs" category.
These products are only indicated in allergic asthma when the causal allergen
has been well identified. They intervene in desensitization towards allergenic
substances and, when properly administered, may be able to gradually reduce
bronchial inflammation within a few years. In case of crisis, however, the
subject can resort to another category of drugs called short bronchodilators (salbutamol)
duration of action which, as the name suggests, dilate the bronchial tubes if an
asthma episode has made them occlude.