Asthma
of asthma Latin meaning "breathing", is a respiratory disease affecting the upper airway including the two bronchi, defined as difficulty breathing at the end. The disease can be explained by three mechanisms General:
* Inflammation with swelling of the bronchial epithelium;
* Bronchoconstriction;
* A bronchial hyper-activity (chronic or not) manifested by an increased secretion of mucus, especially due to remodeling of the upper respiratory tract.
History
Asthma is a disease known since antiquity. Aretaeus around the first century, refers in one of his works. Moses Maimonides in the twelfth century also mentions the disease.
The Treatise of the Asthma John Floyer (1649-1734), published in 1698 and based in part on his own experience. Is the first medical textbook addressing fully asthma.
The French writer Marcel Proust was suffering from asthma since childhood disease affecting up to his work.
Epidemiology
In France, a national survey conducted by the Caisse Nationale d'Assurance Maladie (CNAM) in year 2007 on all patients from 5 to 44 years treated for asthma, found that 900 000 people were receiving regular treatment with three or more prescriptions for asthma medications. Of these 900 000 patients, 27%, mostly in the age group 20-29 years had asthma inadequately controlled, and require at least four times a year to use a medicine only intended to address the crisis. In France, there are approximately 15 000 hospitalizations annually for asthma, and 1 000 deaths.
Types of asthma and clinical manifestations
The bronchi have particular role to protect the lungs from foreign agents or external aggression, including the restriction of the diameter bronchique.L 'asthma is manifested by an overreaction of the bronchi in relation to his environment. The airways of asthma are inflammation and their diameters are reduced. The mucus produced in response to inflammation has further reduced the diameter of the bronchi, making the difficult end, we speak of expiratory airflow obstruction. The causes of inflammation and especially the conditions of events can establish three main types of asthma.
Although each patient correspond to one or other of the profiles of asthma, it is only a manifestation of general disease, it is not uncommon for a chronic asthmatic known attacks of 'allergic asthma or exercise induced asthma and vice versa.
In all types of asthma found the following symptoms:
* Difficulty breathing or shortness of breath;
* Chest tightness (feeling of heaviness in the chest)
* A tachypnea or conversely a bradypnea, that is to say an increase or decrease in respiratory rate;
* A whistle at the end (known as sibilant breathing);
* A decrease in saturation of hemoglobin oxygen mainly in severe attacks;
* Tachycardia;
* A random crisis severe;
* A cough that may be chronic or dominate the night.
* Crises that may occur after exercise (known then induced asthma or more precisely of broncho-spasm, post-exercise)
Only the intensity, duration and causes of these symptoms vary from one type to another.
Chronic Asthma
This is a hyper-activity chronic bronchial little subject to external agents. Chronic inflammation is often slow and gradual installation. Usually this since childhood, it can occur in early childhood by repeated attacks of asthma or chronic bronchitis sibilants. In this case, there is a worsening of the asthmatic syndrome, which is a chronic (when it existed until that trigger an exacerbation). Because of the slow and gradual installation of inflammation, it may go unnoticed, especially because the patient has time to get used to breathing and gene gradually lose the notion of "normality" breathing up that the discomfort becomes too invasive in the patient's life. Untreated this form of asthma usually develops in respiratory failure.
Although the real causes remain to this day debatable, a predominant hypothesis is that this form of asthma is caused by an autoimmune reaction. This means that the patient's immune system attacks its own lungs, and maintaining over time the inflammation.
Allergic asthma
Generally characterized by the occurrence of one or more crises caused by an overreaction of the bronchi of the patient to an external agent (usually allergenic). This is the form of the asthma worse in the short term, the degree of bronchial response may be particularly important and sometimes fatal.
The allergic asthma manifested by a sudden obstruction and rapid progression of bronchial voice, the patient in crisis choking suffocation (inability to breathe properly to prevent a new inspiration) and lack of oxygen in the blood (inability to breathe preventing oxygen (due to the inspiration) and saturating CO2 in the body).
This form of asthma may develop in chronic asthma, particularly if the allergen exposure is constant and long duration.
The asthma attack is always a medical emergency life-threatening and requires special handling.
The exercise-induced asthma
This is an asthma manifested by crisis occurring during physical exertion. The cause is defined as an effort traumatic for the bronchi. That is an effort seeking particularly the bronchi and / or carried out in conditions that make the lungs work harder. The effort is typically a cardio-training (requesting the cardiac system in particular so breathing). Environmental factors such as aggravating asthma, are the cold, wind and an environment with poor ventilation. The cold and wind, promoting airway inflammation, also promotes the crisis.
This type of asthma is often isolated or sometimes associated with chronic asthma or allergic, becoming a complication of type-induced asthma.
* Asthma could be facilitated by intense stress. Indeed, the stress effect of accelerating the heart rate and develop a syndrome of hyperventilation, facilitating or exacerbating asthma.
The asthma crisis are also classified as follows:
Intermittent asthma is arbitrarily defined as the occurrence to a maximum of two brief seizures per week and / or two nightly episodes per month, and PEF greater than 80%.
The persistent asthma is defined when there are more than two episodes per week and / or more than two nocturnal episodes per month, with impact on daily activities. It can be mild, moderate or severe.
The severe asthma that involves life-threatening. It requires urgent treatment in hospital (for example, in France about 2 000 people a year die from asthma, or 3.2 cases per 100 000 population). Clinically, there is at least one of the following signs:
* Unusual feeling of crisis;
* Difficulty speaking (spoke a word at a time)
* Cyanosis
* Increased heart rate (tachycardia CF> 120/min)
* Impaired consciousness (confusion, coma)
* "Auscultatory silence" (absence of breath sounds on auscultation);
* A decrease of PEF (peak expiratory flow or Peak Flow) halved compared with the best score of the patient, or its theoretical value, the DEP is the only objective way to evaluate the intensity of asthma
* Resistance to treatment of the crisis (rapid-acting bronchodilator);
* Respiratory rate than adults 25/mn, 30/mn in children over 5 years 50/mn among children 2 to 5 years, even with low breathing pauses in breathing
* Hypotension
It is advisable to separate the infant asthma, defined by the appearance of at least three episodes of wheezing before the age of three. Asthma in infants disappears usually before age five.
Recent expansion of asthma
There has been a rapid expansion of disease for 40 years in developed countries. It occurs mainly in countries with heavy industrialization, and industrialization in developing fast, there is such little known in sub-Saharan Africa. In 1999 researchers at the International Study of Asthma and Allergies in Childhood has quantified some data on asthma by measuring the percentage of asthma and allergies among 13-14 years in different countries:
- Sweden and Finland between 10% and 20%;
- Albania, Romania, Russia, Georgia and Uzbekistan: <6%;> 30% (asthma is the second leading cause of death)
Monitoring trends in incidence in France is conducted by the sentinel network of Inserm.
Diagnosis
* Examinations of lung function or spirometry;
* Test for responsiveness to a bronchodilator (expiratory flow before and after salbutamol);
* Bronchial provocation test.
* Measurement of exhaled NO (diagnostic aid but also evaluating the effectiveness of treatment)
Treatment
Chronic Asthma
Steroids used to treat chronic inflammation, whereas the bronchodilator used to relieve the patient daily.
The first line of treatment is a beta-2 agonist short duration of action. (For example Ventolin is salbutamol).
In just the second treatment with inhaled cortico-steroids (eg Flixotide is fluticasone propionate) + beta-2 agonist short duration of action in case of crisis.
Third, if the consumption of beta-2 agonist short duration of action (Ventolin) aerosol dispenser above a year (or 2 uses per week), should be treated with inhaled cortico-steroid + a beta-2 mimetic long duration of action. (For example Seretide is fluticasone propionate + salmeterol).
It is also recommended to monitor and possibly allergies treated by antihistamine. People with allergic asthma should avoid contact with the most common allergens (cat dander, dust, pollen, etc. ...)
The asthma attack
The therapeutic measure is the administration of a bronchodilator salbutamol (known in France under the trade name of "Ventolin") or terbutaline, causing a "relaxation" of the bronchial muscles and reopening of airways (bronchodilation).
The administration is done mainly by inhalation aerosol dispensers or powders.
The technique of using MDIs must necessarily be known by the patient for maximum efficiency.
The use of specific devices "inhalation room" greatly facilitates the administration of the MDIs, particularly in children but also adults.
Any crisis that does not yield quickly to the medication should be treated as a medical emergency.
The acute attack
A transfer medicalized and immediate hospitalization is necessary. The first line of treatment is based on a high oxygen flow (6 to 8 liters / min), associated with the use of beta 2-stimulating short-acting inhaled at high dosages, and administration of oral steroids or IV. Indeed, the main risk is by asphyxiation.
Moreover, as in several cases of difficult ventilation, permissive hypercapnia is an approach advocated by several authors.
The therapeutic management
Adapted in asthma crisis, it is based on the following steps before to prevent the occurrence but also intensity of crises:
* Rehabilitation training (adapted physical activities) to push the threshold of exercise intensity causing the onset of broncho-spasm, post-exercise; minimize ventilatory adaptation necessary for a given intensity (less breathlessness on exercise ) to fight against the deconditioning of a population that minimizes their physical activities for fear of the crisis.
* To address the question of whether asthma is allergic, either by carrying out the eviction (= separation) of the allergen, either by attempting a desensitization to the allergen. The results are good with mites, pollen - less good with animals.
* To prevent seizures, asthma can use a device (peak flow) to measure their peak expiratory flow, control of bronchial obstruction and adapt their treatment outcome (taking bronchodilator d ' Quick action by example or change basic treatment in collaboration with the physician.)
* The method of thoracic manipulation called "Method Gesret practiced in several countries since 1995.
Genetics
In recent years researchers have demonstrated that the airways of patients with chronic asthma are either permanently altered by the disease, or - possibly - will develop differently in the womb. Stephen Holgate, a researcher on asthma in Great Britain, published in the journal Nature the results of a five-year research involving the gene ADAM33. This is the first gene discovered for asthma, and monitor how the muscle grows in the airway. Holgate also believe that environmental factors could influence things much earlier than previously thought in the development of the disease: they may influence the expression of genes in the developing fetus, thereby contributing to genetic modification favoring disease . Holgate and his team have already shown the alteration of the ADAM33 gene by tobacco smoke in cultures of mouse lung tissue. In October 2005 they published a report showing that when the tissues of asthmatic airways are inflamed, they produce a molecule called TNF alpha, or tumor necrosis factor alpha. But the ADAM33 gene, implicated in asthma, behaves very similar to the ADAM17 gene responsible for production of TNF alpha. We also find that molecule TNF alpha in inflamed tissue of patients with other chronic respiratory diseases such as rheumatoid arthritis (?) Or Crohn's disease. After six years of struggle with the pharmaceutical industry to perform these tests, Holgate was able to convince them to endorse an experience that goes against the general tendency to take for asthma disease allergenic. In October 2004, he and his team injected 15 volunteers with etanercept, a soluble receptor for TNF alpha intercepts this molecule and prevents it from binding with the cells of tissues and irritate the lungs. The results are so far very satisfactory, with clear and persistent improvements in each of 15 volunteers. To this date November 2005 three of these patients had used any steroids from 12 weeks of weekly injections just over twelve months ago.
Other genes are associated with asthmatic disease. A mutation in the gene encoding the protein YKL-40 (a chitinase) and significantly increases the risk of developing asthma.
Read also Allergic Rhinitis
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