How to diagnose asthma with high accuracy?

Asthma is an extremely serious disease. If it is not treated correctly, it is very likely to endanger life safety. Therefore, you must understand its symptoms beforehand to facilitate better diagnosis. Asthma patients may experience coughing, difficulty breathing, etc., and attacks often occur at night. In severe cases, they may also experience increased heart rate.

1. Symptoms. Symptoms associated with asthma include coughing, wheezing, difficulty breathing, chest tightness, and coughing up sputum. The typical presentation is episodic expiratory dyspnea with wheezing. In severe cases, the patient may be forced to sit or breathe in an upright position, have a dry cough or produce large amounts of white foamy sputum, or even develop cyanosis. Asthma symptoms can occur within minutes and resolve over hours to days with the use of bronchodilators or on their own. Most patients in the early stages or with mild symptoms suffer from paroxysmal cough and chest tightness as the main symptoms. These manifestations are uncharacteristic. The characteristics of asthma are: 1. Paroxysmal: when encountering inducing factors, it worsens paroxystonially. ② Time rhythm: often occurs or worsens at night and early morning. ③Seasonality: often occurs or worsens in autumn and winter. ④ Reversibility: Antiasthmatic drugs can usually relieve symptoms and may have a significant period of remission. Knowing these characteristics will help in the diagnosis and differentiation of asthma.

2. Physical examination. There may be no abnormal signs during the remission period. During the attack, the chest is bulging and the percussion sound is too clear. Most people have widespread wheezing, which is mainly in the expiratory phase, and the exhalation is prolonged. Severe asthma attacks often include signs such as labored breathing, profuse sweating, cyanosis, abnormal chest and abdominal movements, increased heart rate, and pulsus paradoxus.

3. Laboratory and other examinations

(I) Routine blood examination may show an increase in eosinophils during an attack, but it is usually not obvious. If there is a concurrent infection, the white blood cell count may increase and the proportion of classified neutrophils may increase.

(ii) Sputum smear examination under the microscope shows a large number of eosinophils, as well as sharp-edged crystals (Charcort-Leyden crystals) formed by the degeneration of eosinophils, mucus plugs (Curschmann spirals) and transparent asthma beads (Laennec beads). If combined with respiratory bacterial infection, sputum smear Gram staining, cell culture and drug sensitivity testing can help diagnose the pathogen and guide treatment.

(III) Pulmonary function tests show that lung ventilation function is mostly within the normal range during the remission period. During an asthma attack, due to limited expiratory flow rate, the forced expiratory volume in one second (FEV1), one-second rate (FEV1/FVC%), maximum mid-expiratory flow rate (MMER), maximum expiratory flow at 50% and 75% of vital capacity (MEF50% and MEF75%), and peak expiratory flow rate (PEFR) are all reduced. There may be a decrease in forced vital capacity, an increase in residual volume, functional residual capacity and total lung capacity, and an increase in the percentage of residual air in total lung capacity. It can gradually recover after treatment.

(IV) Blood gas analysis: Severe asthma attacks may cause hypoxia, decreased PaO2 and SaO2. Hyperventilation may cause a decrease in PaCO2 and an increase in pH, indicating respiratory alkali poisoning. For example, in severe asthma, if the condition progresses further and the airway obstruction becomes severe, there may be hypoxia and CO2 retention, increased PaCO2, and respiratory acidosis. If hypoxia is obvious, metabolic acidosis may occur.

(V) Chest X-ray examination shows increased translucency of both lungs during an asthma attack, indicating hyperinflation; there are usually no obvious abnormalities during the remission period. If complicated with respiratory tract infection, increased lung texture and inflammatory infiltration shadows may be seen. At the same time, attention should be paid to the presence of complications such as atelectasis, pneumothorax or mediastinal emphysema.

(VI) Specific allergens can be detected by measuring specific IgE using the radioallergen adsorption test (RAST). The serum IgE of patients with allergic asthma can be 2 to 6 times higher than that of normal people. During the remission period, skin allergy tests can be performed to identify related allergens, but allergic reactions should be prevented.