Notes on Internal Medicine Chapter 1: Section 3 Bronchial Asthma

An airway allergic inflammation characterized by eosinophil and mast cell reaction, characterized by airway hyperresponsiveness.

(1) etiology and pathogenesis

1. The etiology is influenced by both genetic factors and environmental factors, mainly including various specific and nonspecific inhalers; Infection, food, drugs, climate change, exercise, pregnancy, etc.

2. The pathogenesis is related to allergic reaction, airway inflammation, increased airway reactivity and nerve interaction.

(2) Clinical manifestations (Q: How to distinguish endogenous asthma from exogenous asthma? Important test sites. )

1. Symptoms are paroxysmal dyspnea with wheezing or paroxysmal chest tightness and cough. In severe cases, people are forced to sit or sit, dry cough with a lot of white foam phlegm, and even cyanosis. Sometimes cough is the only symptom (cough variant asthma). What is severe asthma is an important noun explanation.

2. Physical examination found that the chest was inflated, with extensive wheezing and prolonged exhalation. However, wheezing may not appear in mild asthma or very severe asthma attacks. Severe asthma patients often have symptoms such as increased heart rate, strange pulse, abnormal chest and abdomen movement and cyanosis. Q: Why is there a strange pulse? What other diseases can produce strange pulses? )

3. Laboratory and other inspections

(1) Eosinophils may increase at the beginning of blood test, and the total number of white blood cells may increase when complicated with infection.

(2) There are many eosinophils, sharp crystals, mucus plugs and transparent asthma beads in sputum examination smear under microscope, which is helpful for the selection of antibiotics.

(3) The indexes of respiratory function test related to expiratory flow rate in asthma attack period decreased significantly, and gradually recovered in remission period. (What are the indicators of respiratory function test? What's the clinical significance? )

(4) The arterial blood gas analysis shows that there may be hypoxia during asthma attack, with decrease of PaO2 _ 2, decrease of PaCO2 _ 2 and increase of pH, showing respiratory alkalosis. Severe asthma, the condition further develops, there may be hypoxia and CO2 retention, PaCO2 increases, showing respiratory acidosis. If hypoxia is obvious, it can be combined with metabolic acidosis.

(5) At the early stage of chest X-ray examination, the brightness of both lungs increased during asthma attack, showing an 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 whether there are complications such as atelectasis, pneumothorax or mediastinal emphysema.

(6) Specific allergen complement detection test:

(7) Skin allergy test, skin scratch test or intradermal test of suspected allergen.

(3) Diagnosis

(1) Repeated wheezing, dyspnea, chest tightness or cough are mostly related to contact with allergens, cold air, physical and chemical stimulation, viral upper respiratory infection and exercise.

(2) During the attack, wheezing can be heard in both lungs, which is diffuse and scattered, mainly in expiratory phase, and the expiratory phase is prolonged.

(3) The above symptoms can be relieved by treatment or self-help.

(4) Atypical symptoms should be at least one of the following three positive:

① Positive bronchial provocation test or exercise test; ② Bronchial relaxation test was positive; ③ The daily change rate or daily fluctuation rate of expiratory flow peak is ≥20%.

(5) Eliminate wheezing, chest tightness and cough caused by other diseases.

(4) Differential diagnosis

1. Cardiogenic asthma is common in left heart failure, with various medical histories and signs such as hypertension, coronary atherosclerotic heart disease, rheumatic heart disease and mitral stenosis. Paroxysmal cough, often coughing up pink foam sputum, extensive moist rales and wheezing can be heard in both lungs, the left cardiac boundary is enlarged, the heart rate is increased, and the pentium rhythm can be heard in the apex of the heart. When the condition permits chest X-ray examination, the heart enlargement and pulmonary congestion can be seen. You can inject aminophylline first to relieve the symptoms. Avoid using adrenaline or morphine to avoid danger.

2. Asthmatic chronic bronchitis is more common in middle-aged and elderly people, with a history of chronic cough, wheezing for many years and aggravating period. There are signs of emphysema and blisters can be heard in both lungs.

3. Bronchial stenosis with infection or carcinoid syndrome caused by central lung cancer can cause wheezing or asthma-like dyspnea. The dyspnea and wheezing symptoms of lung cancer are getting worse gradually, often without inducement. Cough can have blood sputum, and cancer cells can be found in sputum. Chest x-ray, CT or MRI examination or fiberoptic bronchoscopy can often make a definite diagnosis.

4. Allergic lung infiltration has a history of pathogen contact, and pathogens include parasites and pollen occupational dust. Symptoms are mild, patients often have fever, and chest X-ray examination can show multiple, one after another, weak plaque infiltration shadows, which can disappear or recur on their own. Lung biopsy is also helpful for differentiation.

(5) Complications

① Pneumothorax, mediastinal emphysema and atelectasis may occur during the attack; ② Long-term recurrent attacks and infections or chronic bronchitis, emphysema, bronchiectasis, interstitial pneumonia, pulmonary fibrosis and cor pulmonale.

(6) treatment

1. Eliminate allergens and eliminate causes.

2. Drug therapy

(1) bronchodilator

①β2 adrenoceptor agonists, such as salbutamol and terbutaline, can be inhaled by hand-held quantitative atomization (MDI), orally or intravenously. Inhalation and injection are often used for severe asthma.

② Theophylline, anti-inflammatory, stably inhibits mast cells, eosinophils, neutrophils and macrophages, and antagonizes bronchospasm. The usual dose generally does not exceed 0.75g per day.

③ The commonly used anticholinergic drugs are atropine, scopolamine, 654-2 and ipratropium bromide.

(2) Anti-inflammatory drugs

① Glucocorticoids can be divided into inhalation administration, oral administration and intravenous administration.

② Sodium crotonate can stabilize the mast cell membrane, inhibit the release of mediators and reduce AHR.

(3) leukotriene modulators of other drugs.

3. Treatment of acute attack

(1) Slightly inhale short-acting β2 receptor agonists such as salbutamol. When the effect is not good, long-acting beta-agonist controlled-release tablets or a small amount of theophylline controlled-release tablets can be added orally, and long-acting beta-agonist can be inhaled or taken orally for asthma at night. Inhale glucocorticoid or add anticholinergic drugs regularly every day.

(2) Moderate regular inhalation of beta agonists or oral long-acting beta agonists.

(3) Continuous atomizing inhalation of β -receptor agonist or intravenous infusion of salbutamol or aminophylline. Maintain the acid-base balance of water and electrolyte, oxygen therapy, etc. Comprehensive treatment such as prevention of lower respiratory tract infection is an effective measure to treat severe and critical asthma at present.

4. The main purpose of non-acute attack treatment of asthma is to prevent asthma from having another acute attack.

(1) According to the individual differences of control symptoms, inhalation of β -agonists or oral administration of β -agonists is intermittent to mild. Small doses of theophylline can also achieve curative effect. You can also consider inhaling a small dose of glucocorticoid every day.

(2) Inhale the β -adrenoceptor agonist as needed, and take the controlled-release tablets orally when the effect is not good. Besides taking the small dose of aminophylline orally, leukotriene antagonists and anticholinergic drugs can be added. Quantitative inhalation of glucocorticoid (200 ~ 600 mg/d) every day.

(3) In severe cases, β _ 2 receptor agonist should be inhaled regularly, or β _ 2 receptor agonist or theophylline controlled-release tablets should be taken orally, or β _ 2 receptor agonist combined with anticholinergic drugs or leukotriene antagonists should be taken orally. The daily intake of glucocorticoid is more than 600mg. If symptoms persist, you should take prednisone or prednisolone orally regularly.