cause of a disease
1. Genetic factors
Individual allergic constitution and the influence of external environment are the risk factors of the disease. Asthma is related to polygene inheritance, and the prevalence rate of relatives of asthma patients is higher than that of the population, and the closer the kinship, the higher the prevalence rate; The more serious the patient's condition, the higher the prevalence rate of his relatives.
2. Allergens
(1) Indoor and outdoor allergens? Dust mite is the most common and harmful indoor allergen, and it is an important cause of asthma worldwide. Dust mite exists in secretions such as fur, saliva, urine and feces. Fungi are also one of the allergens in indoor air, especially in dark, humid and poorly ventilated places. Common outdoor allergens: pollen and grass powder are the most common outdoor allergens that cause asthma attacks, and other specific and non-specific inhalants such as animal dander, sulfur dioxide and ammonia.
(2) Occupational allergens? Common allergens include grain flour, flour, wood, feed, tea, coffee beans, silkworm, pigeon, mushroom, antibiotics (penicillin, cephalosporin), rosin, reactive dyes, persulfate, ethylenediamine and so on.
(3) medicine and food? Aspirin, propranolol and some non-corticosteroid anti-inflammatory drugs are the main allergens of drug-induced asthma. In addition, fish, shrimp, crabs, eggs, milk and other foods can also induce asthma.
3. Triggering factors
Common air pollution, smoking, respiratory tract infection, such as bacteria, viruses, protozoa, parasites and other infections, pregnancy, strenuous exercise and climate change; A variety of nonspecific stimuli, such as inhaling cold air and distilled water droplets, can induce asthma attacks. In addition, mental factors can also induce asthma.
clinical picture
Episodic dyspnea with wheezing or paroxysmal cough and chest tightness. In severe cases, people are forced to sit or breathe in an upright position, dry cough or cough a lot of white foam sputum, and even cyanosis, and sometimes cough is the only symptom (cough variant asthma). Some adolescent patients have chest tightness, cough and dyspnea during exercise as their only clinical manifestations (exercise asthma). Asthma symptoms can occur within a few minutes, and after several hours to several days, they can be relieved by bronchodilators or spontaneously. Some patients can have another attack after several hours of remission. Attack and aggravation at night and in the early hours of the morning are often one of the characteristics of asthma.
check
1. Physical examination
During the attack, the chest was inflated, the chest was swollen, and the percussion was unvoiced. Most of them had a wide range of wheezing sounds dominated by exhalation, and the exhalation sounds were prolonged. Severe asthma attacks often have signs such as dyspnea, sweating, cyanosis, abnormal movement of chest and abdomen, increased heart rate, and strange pulse. There may be no abnormal signs in remission.
2. Laboratory and other inspections
(1) Routine blood examination? Some patients may have increased eosinophils during the attack, but most of them are not obvious. If complicated with infection, the number of white blood cells may increase, and the proportion of classified neutrophils may increase.
(2) Sputum examination smear? More eosinophils can be seen, such as respiratory tract bacterial infection. Gram staining of sputum smear, cell culture and drug sensitivity test are helpful for the diagnosis and treatment of pathogenic bacteria.
(3) lung function examination? The pulmonary ventilation function in remission stage is mostly in the normal range. At the time of asthma attack, due to the limitation of expiratory flow rate, the expiratory flow rate indexes all decreased significantly, which showed the forced expiratory volume in the first second (FEV 1), the rate in the first second (FEV1/FVC%) (the ratio of forced expiratory volume to forced vital capacity1sec), the maximum mid-expiratory flow rate (MPEFR) and the expiratory rate of 50%. Lung capacity indicators can include decreased forced vital capacity, increased residual volume, increased functional residual volume and total lung volume, and increased percentage of residual gas in total lung volume. After treatment, it can gradually recover. If the lesion is prolonged and recurrent, its ventilation function can gradually decrease.
(4) Blood gas analysis? In severe asthma attack, the airway obstruction and uneven ventilation distribution, and the imbalance of ventilation/blood flow ratio can cause the alveolar-arterial oxygen partial pressure difference (A-aDO2) to increase. There may be hypoxia, PaO2 _ 2 and SaO2 _ 2 decrease, because hyperventilation can make PaCO2 _ 2 decrease and pH value increase, showing respiratory alkalosis. For example, severe asthma, with further development and severe airway obstruction, may have hypoxia and CO2 retention, and PaCO2 _ 2 increases, showing respiratory acidosis. If hypoxia is obvious, it can be combined with metabolic acidosis.
(5) chest x-ray examination? In the early stage of asthma attack, the transparency of both lungs increased, showing an over-inflated state; There was no obvious abnormality in remission period. If complicated with respiratory tract infection, increased lung texture and inflammatory infiltration shadow can be seen. At the same time, we should pay attention to complications such as atelectasis, pneumothorax or mediastinal emphysema.
(6) Detection of specific allergens? Asthma patients are mostly accompanied by allergies and are sensitive to many allergens and irritants. The measurement of allergic indexes combined with medical history is helpful to the etiological diagnosis of patients and to get rid of the contact with allergic factors. However, allergic reactions should be prevented.
(7) others? Skin allergen test, inhalation allergen test and specific IgE of patients can be detected in vitro as appropriate.
diagnose
For patients with typical symptoms and signs, except for wheezing, shortness of breath, chest tightness and cough caused by other diseases, clinical diagnosis can be made; For atypical cases, bronchodilation or provocation test should be done, and those who are positive can be diagnosed.
differential diagnosis
1. wheezing dyspnea caused by left heart failure
More common in the elderly. The reasons are: hypertension, coronary atherosclerosis, mitral stenosis or chronic nephritis, etc., and paroxysmal attacks are more common at night. Symptoms are chest tightness, shortness of breath and difficulty, cough and wheezing, severe cyanosis, gloomy complexion, cold sweat, nervous and fearful, similar to acute asthma attack. In addition to wheezing, patients often cough up a lot of thin watery or foamy sputum or pink foamy sputum, and have typical wet rales at the bottom of the lungs, heart enlargement to the left, heart valve murmur, irregular heart sounds and even galloping rhythm. Chest X-ray shows that the cardiac shadow may be enlarged, and the left atrial appendage is often enlarged in patients with mitral stenosis. There are signs of pulmonary edema in the lungs and blurred blood vessel shadows. Because of pulmonary edema, the interlobular septa become wider, and the interlobular septa line can move down to the basal lobe, which is helpful for differentiation.
2. Chronic obstructive pulmonary disease
It is more common in middle-aged and elderly people, with a history of chronic cough, wheezing all the year round and aggravating period. Most patients have a long history of smoking or exposure to harmful gases, signs of emphysema, and wet rales may be audible in both lungs. However, it is sometimes very difficult to strictly distinguish chronic obstructive pulmonary disease from asthma in clinic. It may be helpful to make a therapeutic diagnosis with bronchodilators, oral or inhaled hormones, and sometimes both can coexist.
3. Allergic pulmonary infiltration
This is a group of diseases with pulmonary eosinophilic infiltration, including simple eosinophilic pneumonia, persistent eosinophilic pneumonia, asthmatic eosinophilic pneumonia, tropical pulmonary eosinophilia and pulmonary necrotizing vasculitis, all of which may have asthma symptoms, especially asthmatic eosinophilic pneumonia. The disease can be seen at any age, and most of them are related to bacterial infection of lower respiratory tract. The patient is allergic to Aspergillus, so it is also called allergic bronchopulmonary aspergillosis. Patients often have fever, and chest X-ray examination shows multiple, one after another, faint patches infiltrating shadows, which can disappear or recur on their own. Lung biopsy is helpful for differentiation.
4. Lung cancer of trachea and main bronchus
Because cancer oppresses or invades trachea or main bronchus, the lumen of upper respiratory tract is narrow or not completely blocked, and cough or wheezing occurs, even accompanied by wheezing. However, patients usually have no history of asthma attack, expectoration can bring blood, wheezing symptoms are mostly inspiratory dyspnea, or wheezing is limited, and antiasthmatic drugs are ineffective. As long as the disease is considered, it is not difficult to make further chest X-ray examination, CT, sputum cytology and fiberoptic bronchoscopy.
treat
At present, there is no specific treatment, but insisting on long-term standardized treatment can make asthma symptoms well controlled, reduce recurrence or even stop.
1. treatment target
(1) completely control the symptoms;
(2) to prevent the onset or aggravation of the disease;
(3) The lung function is close to the individual optimal value;
(4) Normal mobility;
(5) Improve self-awareness and ability to deal with acute exacerbation, and reduce the probability of emergency or hospitalization;
(6) Avoid adverse drug reactions;
(7) prevent irreversible airway obstruction;
(8) Prevent death caused by asthma.
2. Basic clinical strategies for asthma prevention and treatment.
(1) Long-term anti-inflammatory treatment is the basic treatment, and inhaled hormone is the first choice. Commonly used inhalation drugs include beclomethasone (BDP), budesonide, fluticasone, momethasone, etc. The latter two drugs have stronger biological activity and more lasting effects. It usually takes more than a week to take effect.
(2) Inhalation of β2 agonist is the first choice for emergency relief of symptoms. β _ 2 agonist mainly stimulates β _ 2 receptor in respiratory tract and activates adenylate cyclase, which increases the content of cyclic adenosine monophosphate (cAMP) in cells and decreases free Ca, thus relaxing bronchial smooth muscle. It is the first choice for controlling acute asthma attack.
(3) If the patient's condition is not well controlled after regular inhalation of hormones, it is advisable to add inhaled long-acting β2 agonist, or slow-release theophylline, or leukotriene regulator (combined medication); You can also consider increasing the amount of inhaled hormones.
(4) Patients with severe asthma who have long-term recurrent attacks after the above treatment can consider intensive treatment. That is, according to the treatment of severe asthma attack, high-dose hormone and other treatments are given, and the dosage of hormone is gradually reduced after 2 to 4 days after the symptoms are completely controlled, the lung function returns to the optimal level and the PEF volatility is normal. After intensive treatment, some patients' condition is well controlled.
3. Treatment measures of comprehensive treatment
(1) Eliminate the etiology and induced causes.
(2) Prevention and treatment of coexisting diseases, such as allergic rhinitis and reflux esophagitis.
(3) Immunomodulatory therapy.
(4) Always check whether the inhaled drugs are used correctly and the compliance with the doctor's advice.
prognosis
The prognosis of asthma varies from person to person, which is closely related to the correct treatment plan. Through active and standardized treatment, the clinical control rate of childhood asthma can reach 95%. Mild symptoms are easy to recover, serious illness, obvious increase in airway responsiveness, or other allergic diseases are difficult to control. Long-term attack with chronic obstructive pulmonary disease (COPD) and pulmonary heart disease will lead to poor prognosis.
Education and management of asthma
The education and management of asthma patients is an important measure to improve the curative effect, reduce recurrence and improve the quality of life of patients. Doctors should make prevention and treatment plans for each newly diagnosed asthma patient so that patients can understand or master the following contents:
1. I believe that asthma attacks can be effectively controlled through long-term, appropriate and adequate treatment;
2. Understand the stimulating factors of asthma, and find out their own stimulating factors and ways to avoid them according to everyone's specific situation;
3. Simply understand the essence and pathogenesis of asthma;
4. Be familiar with the premonitory manifestations of asthma attack and the corresponding treatment methods;
5. Learn to monitor and evaluate the changes of illness at home, focus on the use of peak current meter, and record asthma diary if possible;
6. Learn simple emergency self-treatment methods when asthma attacks;
7. Understand the function, correct dosage, usage and adverse reactions of commonly used antiasthmatic drugs;
8. Master the correct usage of different inhalation devices;
9. Know under what circumstances you should go to the hospital;
10. Work out a plan to prevent asthma recurrence and maintain long-term stability with the doctor.