What Is the Relationship Between the Respiratory System and Asthma?

Asthma is also called bronchial asthma. Bronchial asthma is a chronic airway inflammation involving multiple cells and cell components. This inflammation is often accompanied by an increase in airway responsiveness, which causes recurrent wheezing, shortness of breath, chest tightness, and / or cough. It occurs at night and / or in the early morning. Such symptoms are often accompanied by extensive and variable airflow obstruction, which can be reversed on its own or through treatment.

Basic Information

nickname

Bronchial Asthma

English name

asthma

Visiting department

Respiratory Medicine

Multiple groups

Allergic

Common causes

Caused by allergens, etc., triggered by environmental, drug and physiological factors

Common symptoms

Sudden wheezing, shortness of breath, tightness in the chest, cough, often at night or early in the morning

Causes of asthma

Genetic factor

Asthma is a disease with complex traits and a multi-gene hereditary tendency. It is characterized by: explicit incompleteness, genetic heterogeneity, polygene inheritance, synergy.

Allergen

Probably the most important trigger for asthma is inhaled allergens.

(1) Indoor allergens House mites are the most common and most harmful indoor allergens, and they are an important cause of asthma worldwide. There are four common species: house dust mites, dust mites, cosmic dust mites, and hairy mites. More than 90% of mites are present in house dust. House dust mites are the most important mites in persistent humid climates. The main antigens are DerpI and Derp, and the main components are cysteine protease or tyrosine protease. Pets raised in the home, such as cats, dogs, and birds release allergens in their fur, saliva, urine, and feces. Cats are the most important sensitizers in these animals. The main allergen component feldl, which is present in the fur and sebum secretions of cats, is the main risk factor for acute attacks of asthma. Cockroaches are common indoor allergens in Asian countries; common asthma-related cockroaches are American cockroach, German cockroach, Oriental cockroach, and black-breasted cockroach. Black-chested cockroach is the most common in China. Fungi are also one of the allergens that exist in indoor air, especially in dark, humid and poorly ventilated places. Penicillium, Aspergillus, Alternaria, Mycospora, and Candida are common. Alternaria alternata has been identified as a risk factor for asthma. Common outdoor allergens: Pollen and grass powder are the most common outdoor allergens that cause asthma attacks. Woody plants (tree pollen) often cause asthma in spring, while grass and yarrow pollen of grasses often cause autumn asthma. Ragweed pollen is mainly in the eastern part of China; Artemisia spp. Is mainly in the north.

(2) Occupational allergens can cause occupational asthma common allergens Original cereal flour, flour, wood, feed, tea, coffee beans, silkworm, pigeons, mushrooms, antibiotics (penicillin, cephalosporin) isocyanate Salt, phthalic acid, rosin, reactive dyes, persulfate, ethylenediamine, etc.

(3) Drugs and food additives Aspirin and some non-corticosteroid anti-inflammatory drugs are the main allergens of drug-induced asthma. Food additives such as salicylate, preservatives and stains can also cause acute attacks of asthma. Royal jelly oral solution is widely used as food for health care in China and countries and regions in Southeast Asia. Royal jelly has been shown to cause acute exacerbations of asthma in some patients and is an allergic reaction mediated by IgE.

3. Trigger factors

(1) Air pollution Air pollution (SO ₂ , NO) can cause bronchoconstriction, transient airway reactivity and increase the response to allergens.

(2) Smoking Cigarette smoke (including passive smoking) is the main source of indoor triggering factors and an important asthma triggering factor, especially for asthmatic children whose parents smoke, often causing asthma attacks due to smoking.

(3) Respiratory virus infection Respiratory virus infection is closely related to asthma attacks. Infant bronchial virus infection is of particular concern as the initiating cause of asthma. Common respiratory infections are respiratory syncytial virus (RSV), adenovirus, rhinovirus, influenza virus, parainfluenza virus, coronavirus, and some enteroviruses. Rhinoviruses and influenza viruses are the main viruses associated with adult asthma; respiratory syncytial virus, parainfluenza virus, adenovirus and rhinovirus are closely related to childhood asthma attacks. Syncytial virus is the main pathogen in the first year after birth, accounting for 44% of infectious asthma under 2 years of age and more than 10% of asthma in older children. It has been reported that nearly 100% of patients with asthma or bronchiolitis after RSV infection have IgE attached to the epithelial cells. Ten years later, 42% of children hospitalized for acute RSV infection develop asthma.

(4) Perinatal environment of the fetus The fetal thymus of the 9th week of pregnancy can already produce T lymphocytes, and at the 19th to 20th weeks, B lymphocytes have been produced in all organs of the fetus. As the placenta is mainly produced throughout the pregnancy, auxiliary II Type T cell (Th2) cytokines, so in the lung microenvironment, the response of Th2 is dominant. If the mother has a specific constitution and is exposed to a large amount of allergens (such as milk cells in milk) during pregnancy Protein, egg protein in eggs or mite's DerpI, etc.) or repeated infection by respiratory viruses, especially syncytial virus, may aggravate its Th2 regulated allergies, and increase the possibility of postnatal allergies and asthma.

In addition, the amount of polyvalent unsaturated fatty acids ingested in the third trimester will affect the production of prostaglandin E and may be related to the allergic regulation of Th2 cells. A mother's smoking during pregnancy will definitely affect the fetal lung function and the susceptibility to wheezing in the future.

(5) Other strenuous exercise, climate change, and various non-specific stimuli such as: inhalation of cold air, distilled water mist, etc. In addition, mental factors can induce asthma.

Clinical manifestations of asthma

Asthma is manifested by paroxysmal cough, chest tightness, and dyspnea. Some patients sputum, more than when the onset tends to ease, if there is no co-infection, it is often white sticky sputum, tough, sometimes rice-shaped or mucus columnar. The severity and duration of the onset varies greatly from person to person, with mild chest urgency lasting only a few minutes, and severe cases with extreme difficulty breathing for several weeks or longer. The symptom is characterized by reversibility, that is, it can be relieved within a short period of time after treatment, and part of it will be naturally relieved. Of course, a small part will be sustained without remission. Seizures are often caused by certain factors. Many patients have obvious biological laws. Seizures or exacerbations occur at 2-6 am every day. They usually occur during the transfer in spring and summer or in winter. Some women (about 20%) have pre-menstrual or Asthma attacks or exacerbations. Pay attention to atypical asthma patients. Some patients often have paroxysmal cough as the only symptom, which is often easily misdiagnosed as bronchitis clinically; some adolescent patients have chest tightness and tightness during exercise as the only clinical manifestations.

Asthma check

Physical examination

There may be no abnormal signs during the remission period. During the onset, the thoracic bulge, hyperpercussion was percussive, and most of them had extensive wheezing based on expiratory gas and prolonged exhalation. Severe asthma attacks often have signs such as strenuous breathing, sweating, cyanosis, abnormal movements of the chest and abdomen, increased heart rate, and odd pulses.

2. Laboratory and other inspections

(1) Routine blood test Eosinophils may increase during the onset, but most of them are not obvious. If there is a concurrent infection, there may be an increase in the number of white blood cells, and the proportion of classified neutrophils will increase.

(2) Sputum examination Under the microscope, there are more eosinophils in the smear, and sharp crystals, mucus plugs and transparent asthma beads (Laennec beads) formed by the degradation of eosinophils. If combined with respiratory bacterial infections, sputum smear Gram staining, cell culture and drug sensitivity tests can help diagnose and guide treatment of pathogenic bacteria.

(3) Pulmonary function examination Most of the pulmonary ventilation functions during remission are in the normal range. At the onset of asthma, due to the limited expiratory flow rate, it manifests as forced expiratory volume in the first second, one-second rate, maximum expiratory flow rate, maximum expiratory flow when exhaling 50% and 75% of vital capacity, and peak expiratory flow Are reduced. It can be used to reduce vital capacity, increase residual capacity, increase functional residual capacity and total lung capacity, and increase the percentage of residual gas in total lung capacity. It can gradually recover after treatment.

(4) Blood gas analysis When asthma is severe, there may be hypoxia, PaO ₂ and SaO ₂ decrease. PaCO ₂ decreases due to excessive ventilation, and the pH value rises, showing respiratory alkalosis. Such as severe asthma, further development of the condition, severe airway obstruction, hypoxia and CO ₂ retention, PaCO ₂ rise, showing respiratory acidosis. If hypoxia is obvious, metabolic acidosis can be combined.

(5) Chest X-ray examination During the early stage of asthma attacks, the transillumination of both lungs can be seen to increase, showing an over-inflated state; there is no obvious abnormality during the remission period. Such as concurrent respiratory infections, increased lung texture and inflammatory infiltrates can be seen. At the same time, attention should be paid to complications such as atelectasis, pneumothorax, or mediastinal emphysema.

(6) Detection of specific allergens Specific radioactive allergen adsorption test can be used to determine specific IgE. The serum IgE of patients with allergic asthma can be 2-6 times higher than that of normal people. During the remission period, skin allergy tests can be used to determine the relevant allergens, but allergic reactions should be prevented.

Asthma diagnosis

For typical symptoms and signs, clinical diagnosis can be made. For atypical cases, the following examinations should be made, and the diagnosis can be confirmed in combination with the response after treatment.

Differential Asthma Diagnosis

As the clinical manifestations of asthma are not unique to asthma, it is necessary to exclude wheezing, chest tightness and cough caused by other diseases while establishing a diagnosis.

Cardiogenic asthma

Cardiogenic asthma is common in left ventricular heart failure. The symptoms at the time of attack are similar to asthma, but cardiogenic asthma often has a history and signs of hypertension, coronary atherosclerotic heart disease, rheumatic heart disease, and mitral stenosis. Coughing frequently, pink foamy sputum often coughing, extensive blisters and wheezing sounds can be heard in both lungs, enlarged left heart boundary, faster heart rate, and rushing heart rhythm. On chest X-ray examination, it can be seen that the heart is enlarged, pulmonary congestion signs, cardiac ultrasound and cardiac function examination are helpful to distinguish. If it is difficult to identify aerosolized selective ₂ agonist or injection of small doses of aminophylline to relieve the symptoms for further examination, avoid using epinephrine or morphine to avoid danger.

2. Bronchial lung cancer

Central lung cancer can cause bronchoconstriction or infection or carcinoid syndrome, and wheezing or asthma-like dyspnea, audible lungs, and wheezing can occur. However, lung cancer's dyspnea and wheezing symptoms are progressively increased, often without inducement, cough may have bloody sputum, sputum can be found in cancer cells, chest X-ray, CT or MRI examination or fiber bronchoscopy often can be clearly diagnosed.

3. Endotracheal lesions

Tumors, endometrial tuberculosis, and foreign body lesions can cause asthma-like symptoms and signs when they cause airway obstruction. By raising awareness and making lung flow-volume curves, tracheal tomography or fiberbronchoscopy in a timely manner, the diagnosis is usually clear.

4. Allergic pulmonary infiltration

Found in tropical eosinophilia, pulmonary eosinophilic infiltration, multi-source allergic alveolitis and so on. The cause of the disease is parasites, protozoa, pollen, chemicals, occupational dust, etc., with a history of contact, mild symptoms, and systemic symptoms such as fever. Multiple x-ray examinations of the chest can reveal multiple symptoms, and the thin patches of infiltrating shadows infiltrate , Can disappear or resend by itself. Lung biopsy can also help with identification.

Asthma treatment

Treatment goal

(1) Control symptoms as much as possible, including nighttime symptoms.

(2) Improve activity and quality of life.

(3) Make the lung function close to the optimal state.

(4) Prevent outbreaks and exacerbations.

(5) Improve self-awareness and ability to deal with acute exacerbations, reduce emergency department or hospitalization.

(6) Avoid affecting other medical problems.

(7) Avoid side effects of drugs.

(8) Prevent death from asthma.

The significance of the goals of the above treatment lies in emphasizing: Treatment should be actively pursued to achieve complete control of symptoms. Protect and maintain lung function as normal as possible. To avoid or reduce the adverse effects of drugs to achieve the above goals, the key is to have a reasonable treatment plan and adhere to long-term treatment.

2. Remission phase treatment

(1) Patients who smoke should first quit smoking. The incidence of chronic bronchitis in smokers is many times higher than that of non-smokers. After quitting, patients' lung function has been greatly improved, and passive smoking must be avoided.

(2) Strengthen physical exercise and strengthen the body's resistance. The amount of exercise depends on your physical condition. Every morning, you can take a walk, punch, jog, etc. This way you can breathe fresh air and promote blood circulation. Winter exercise can improve the adaptability of the respiratory mucosa to cold air.

(3) Reasonably adjust the room temperature to prevent colds, and the indoor temperature should not be too high in winter, otherwise the temperature difference between the room and the outside is large, which is prone to colds. In summer, it is not advisable to be cold, and the temperature of the air conditioner should be moderate, otherwise going out is susceptible to "hot tetanus" and causing bronchitis. In the epidemic season of influenza, try to go to the crowd as little as possible. Changing clothes, the elderly can get flu vaccine to reduce the chance of flu infection.

(4) Select necessary multifunctional treatment and protective measures.

3.Treatment principles and clinical management strategies of bronchial asthma

(1) Those who are atypical in early stage (such as cough variant asthma) or coexist with other diseases (such as chronic bronchitis and asthma) should pass the bronchial provocation test or exercise test, bronchodilator test, PEF monitoring or before and after treatment A series of changes in lung function, a clear diagnosis.

(2) Pay attention to identify obstructive diseases of trachea, such as tracheal endometrial tuberculosis and tumor.

(3) Treatment goals Complete control of symptoms; Prevention of seizures or exacerbations; Pulmonary function close to the optimal value of the individual; Normal mobility; Avoid adverse reactions to drugs; Prevent irreversible airway obstruction; Prevent sudden asthma death.

4. Basic clinical strategies for asthma prevention and treatment

(1) Long-term anti-inflammatory treatment is the basic treatment, and inhaled hormones are preferred.

(2) The drug of choice for emergency relief is the inhaled beta ₂ agonist.

(3) If the disease control is not satisfactory after regular inhalation of hormones, it is advisable to add inhaled long-acting ₂ agonists, or slow-release theophylline, or leukotriene modulators (combined drugs); consider increasing the amount of inhaled hormones.

(4) In patients with severe asthma, intensive treatment may be considered when they have recurrent episodes after long-term treatment. That is, according to the treatment of severe asthma (given a large dose of hormones and other treatments), until the symptoms are completely controlled, the optimal level of lung function is restored, and PEF volatility is normal 2 to 4 days later, the hormone dosage is gradually reduced. Some patients have ideal disease control after intensive treatment.

5. Comprehensive treatment measures

(1) Eliminate the cause and induction.

(2) Prevention and treatment of co-existing diseases, such as allergic rhinitis and reflux esophagitis.

(3) Immunomodulatory therapy.

(4) Regularly check whether the inhaled medicine is used correctly and follow the doctor's order.

Asthma prevention

Allergic factors

Allergens can be detected in 30% to 40% of people with bronchial asthma. Dust mites, scales of animals such as cats and dogs, mold, pollen, milk, poultry eggs, silk, feathers, moths, cotton wool, and fungi are all important allergens.

2. Non-specific physical and chemical factors

Such as inhalation of odors such as smoke, dust and vegetable oil, gasoline or paint, and cold air, can stimulate the sensory nerve endings under the bronchial mucosa, reflexively cause vagus nerve excitement and cough, and cause bronchial smooth muscle spasm on the basis of high airway response.

3. Microbiological infection

Colds and upper respiratory tract infections are the most common causes, especially in winter and spring or when the climate changes. Respiratory infections, especially viral infections, are more likely to cause asthma attacks in children.

4. Overworked

Asthma can be induced by sudden or long-term physical labor and intense competitive sports.

5. Mental factors

Mood swings can be an inducement. Anxiety, such as anxiety, sadness, excessive excitement, and even laughter, can cause asthma attacks.

6. Occupational factors

This involves a wide range, such as workers working in the pharmaceutical industry and chemical companies, allergic to certain drugs or raw materials, and medical personnel allergic to certain drugs.

7. Climatic factors

Cold seasons are prone to cold and cause respiratory infections, or sudden changes in weather or decreased air pressure can trigger bronchial asthma attacks. The focus of prevention of bronchial asthma is on intensive care during the remission period.

To sum up, asthma patients should do the following prevention: physical exercise; breathing adjustment; avoiding inducing factors; dietary maintenance; food and medicine prevention.