OVERVIEW

What is bronchial asthma?

"Bronchial asthma," commonly referred to as asthma, is a chronic inflammatory disease of the airways characterized by hyperresponsiveness. It is a common respiratory condition^[1,2]. Asthma attacks can occur suddenly or gradually, with most cases presenting as episodic wheezing, shortness of breath, chest tightness, and/or coughing. Some patients may only experience irritative coughing, while a few severe cases can be life-threatening during an attack.

What are bronchi?

The "bronchi" refer to the branching airways that extend from the trachea. The first-level bronchi, the left and right main bronchi, branch downward repeatedly. With each division, their total cross-sectional area increases by approximately 20%. From the main trachea to the terminal branches, there are typically 23–25 levels of branching, forming the bronchial tree. Thus, the bronchi resemble an inverted tree—starting with a single trunk, splitting into two main branches, and progressively dividing into finer structures, ending in the "leaves" (which can be likened to the alveoli).

Trachea and bronchial tree: The lower end of the trachea divides into the left and right main bronchi, leading to the left and right lungs, respectively. Within the lungs, the bronchi continue branching into smaller airways, becoming progressively narrower and thinner-walled^[3].

How prevalent is bronchial asthma?

It is estimated that around 300 million people worldwide currently have asthma, accounting for 5% of the global population. Asthma prevalence varies across regions, with childhood asthma rates ranging from 3.3% to 29% (meaning 3 to 29 out of every 100 children globally may have asthma) and adult asthma rates ranging from 1.2% to 25.5% (meaning 3 to 29 out of every 100 adults globally may have asthma). In China, the adult asthma prevalence is 1.24% (approximately 1 in 100 Chinese adults), while the urban childhood asthma prevalence has reached 3.02% (approximately 3 in 100 Chinese children), with a rising trend^[1,4,5]. By 2025, the global number of asthma patients is projected to exceed 400 million.

What are the classifications of bronchial asthma?

Asthma can be classified in various ways. Traditional classifications include:

• Extrinsic asthma: Triggered by external allergens such as pollen, pet dander, or dust;
• Intrinsic asthma: Caused by non-allergic factors like bacterial or viral infections, often seasonal;
• Mixed asthma: Involving both extrinsic and intrinsic factors.

Recent classifications based on triggers include:

• Allergic asthma: Induced or triggered by allergens (e.g., dust mites, pollen, pet dander, mold);
• Infectious asthma: Caused by bacterial or viral infections;
• Exercise-induced asthma: Triggered by physical activity;
• Drug-induced asthma: Resulting from drug allergies (e.g., aspirin, antibiotics);
• Occupational asthma: Caused by exposure to workplace irritants;
• Cardiac asthma: Episodic wheezing due to left heart failure or acute pulmonary edema, with symptoms resembling bronchial asthma;
• Psychogenic asthma: Asthma exacerbated or triggered by emotional stress;
• Special types: Such as menstrual asthma and pregnancy-induced asthma.

Clinically, there are also atypical forms of asthma without wheezing:

• Cough-variant asthma: Coughing as the sole symptom, without typical asthma symptoms like wheezing or shortness of breath, common in children^[1,4];
• Chest tightness-variant asthma: Chest tightness as the only symptom^[1].

SYMPTOMS

Where does bronchial asthma occur?

It primarily occurs in the bronchi (especially the large airways). Allergen stimulation in the bronchi leads to increased airway reactivity, bronchospasm, and airflow limitation. The airflow limitation caused by asthma is reversible. However, if asthma attacks recur over a long period, it may lead to chronic obstructive pulmonary disease (COPD), gradually affecting the small airways and resulting in irreversible airflow limitation.

What are the symptoms of a bronchial asthma attack?

Typical bronchial asthma presents with recurrent symptoms such as chest tightness, wheezing, difficulty breathing, and coughing. Before an attack, prodromal symptoms like nasal congestion, sneezing, and itchy eyes often occur. In severe cases, significant difficulty breathing may develop. Sometimes, coughing is the only symptom, and worsening at night or early morning is one of the characteristic features of asthma. Asthma symptoms can develop within minutes. Some mild cases may resolve on their own, but most require active treatment^[1,2,5].

Why do lung sounds occur during a bronchial asthma attack?

During an asthma attack, the airways narrow, restricting airflow. When breathing (especially exhaling), air passing through these narrowed passages produces sounds, medically termed wheezing^[1]. Doctors can accurately hear these sounds using a stethoscope. In some severe cases, the wheezing may be loud enough to be heard without a stethoscope.

What symptoms should raise strong suspicion of bronchial asthma?

If a patient exhibits the following symptoms, asthma should be highly suspected:

• Recurrent nighttime or early morning coughing;
• Worsening cough after physical activity;
• Persistent cold symptoms lasting over 10 days;
• Long-term coughing after a cold, accompanied by throat itching;
• Frequent colds with runny nose, nasal congestion, sneezing, or skin itching;
• Poor sleep at night, frequent rubbing of the nose or eyes during the day, and a similar family history^[1].

How can bronchial asthma patients self-assess the severity of their condition?

Asthma patients and their families can preliminarily evaluate the severity of the condition based on symptoms and physical endurance.

• Mild: Shortness of breath while walking or climbing stairs, able to lie flat, can speak in full sentences, good mental state;
• Moderate: Shortness of breath with mild activity, worse when lying flat, needs to sit up to breathe normally, speaks in fragments, generally stable mental state, occasional anxiety or irritability;
• Severe: Shortness of breath even at rest, requires sitting upright to breathe (orthopnea), can only speak in words or short phrases, poor mental state, obvious anxiety and irritability;
• Critical: Unable to speak, drowsy, or confused^[1].

What serious complications can bronchial asthma cause?

Acute Complications

• Sudden death: The most severe complication of bronchial asthma, often occurring without obvious warning signs, making timely rescue difficult;
• Lung infection: About half of asthma cases are triggered by upper respiratory infections. Impaired respiratory immunity increases the risk of secondary lung infections;
• Fluid, electrolyte, and acid-base imbalances: Due to hypoxia, inadequate food intake, and dehydration during asthma attacks, these imbalances significantly impact treatment efficacy and prognosis;
• Pneumothorax and mediastinal emphysema: Air trapping in alveoli during asthma attacks increases lung pressure, potentially causing bullae rupture and leading to pneumothorax or mediastinal emphysema;
• Respiratory failure: Severe asthma-induced hypoventilation, infections, or pneumothorax can trigger respiratory failure, complicating treatment;
• Multiple organ failure: Severe asthma often leads to dysfunction or failure of other organs.

Long-term Complications

• Growth retardation and chest deformities: Childhood asthma can cause growth retardation and chest deformities due to factors like malnutrition, hypoxia, and endocrine disorders;
• Chronic obstructive pulmonary disease (COPD), pulmonary hypertension, and chronic cor pulmonale: Long-term, recurrent asthma attacks may eventually lead to COPD, pulmonary hypertension, and cor pulmonale^[1].

CAUSES

What are the causes of asthma?

The exact cause of asthma is not fully understood, but contributing factors include genetic and environmental influences.

• **Genetic factors:** Most asthma patients have an allergic predisposition, and genetic factors play a role in many cases. For example, a significant proportion of patients have a family history of asthma or other allergic diseases (such as allergic rhinitis or atopic dermatitis)^[1,6].
• **Environmental factors:** Common airborne allergens (dust mites, pollen, pet dander, mold, etc.), certain foods (nuts, milk, peanuts, seafood, etc.), bacterial or viral infections, weather changes, exercise, and medications can all act as asthma triggers^[1].

Who is more likely to develop bronchial asthma?

Generally, children have a higher incidence rate than young adults, with those aged 1–6 being particularly susceptible^[4]. Additionally, the prevalence among elderly populations is increasing, possibly due to weakened immunity.

Is bronchial asthma contagious?

Asthma itself is not contagious. However, certain triggers for asthma, such as viral infections, may be transmissible.

Is bronchial asthma hereditary?

As mentioned earlier, asthma is linked to genetic factors^[1]. Bronchial asthma has a complex genetic background, with a heritability of approximately 80% (meaning that out of 100 patients with a family history of asthma, about 80 may develop bronchial asthma). It is classified as a polygenic genetic disorder^[6].

DIAGNOSIS

What tests are needed if bronchial asthma is suspected?

• Lung function tests: Clinically, the ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) and peak expiratory flow rate (PEFR) are used to assess airflow limitation. An FEV1/FVC ratio < 80% indicates airflow limitation. If FEV1 increases by 15% or more (with an absolute increase of over 200 ml) 15–20 minutes after inhaling a bronchodilator, it suggests reversible airflow limitation. If FEV1 > 80%, a bronchial provocation test may help diagnose cough-variant asthma. Allergen testing: Intradermal tests with various allergens can identify suspected allergens. Additionally, serum allergen-specific IgE testing is valuable, but total serum IgE testing has no diagnostic significance.
• Complete blood count: Eosinophil levels may increase during an asthma attack, though some patients show no increase. If infection is present, total white blood cell count and neutrophil count may rise.
• Sputum examination: Sputum is typically thick and white, but may appear yellow if infection is present. Eosinophils in the sputum may also increase.
• Blood gas analysis: In the early stages of an asthma attack, patients often show no significant blood gas abnormalities. As the condition progresses, hypoxia may occur, indicated by decreased alveolar oxygen partial pressure (PaO2). Hyperventilation can lead to a drop in arterial carbon dioxide partial pressure (PaCO2), causing pH to rise, resulting in respiratory alkalosis. If the condition worsens further, hypoxia and CO2 retention may occur, leading to increased PaCO2 and decreased pH, manifesting as respiratory acidosis.
• Chest X-ray: Most asthma patients show no significant abnormalities on chest X-rays. Some may exhibit signs of emphysema, such as increased lung translucency. Chest X-rays are primarily used to rule out other lung diseases^[1].

Does experiencing chest tightness and shortness of breath mean it's bronchial asthma?

While asthma symptoms are well-known, not all asthma-like symptoms indicate asthma. Other conditions must be ruled out, including the following common differential diagnoses:

• Wheezing dyspnea caused by heart failure (cardiac asthma): Often seen in left heart failure due to conditions like hypertension, coronary heart disease, or rheumatic heart disease. Symptoms resemble asthma, but cardiac asthma patients typically have a history of heart disease and may cough up pink, frothy sputum.
• Lung cancer: Central lung cancer causing bronchial narrowing or infection may produce wheezing or asthma-like symptoms. However, dyspnea or wheezing in lung cancer worsens progressively, often without clear triggers, and coughing may involve bloody sputum.
• Tracheal lesions: Conditions like tracheal foreign bodies, tumors, or endobronchial tuberculosis can cause similar symptoms due to tracheal obstruction. A bronchodilator test can help differentiate.
• Pneumothorax: Tall, thin adolescents or patients with lung bullae may experience sudden chest tightness and breathlessness resembling asthma. Medical history and physical examination can distinguish the two. Pneumothorax patients often have a history of strenuous activity or heavy lifting, and physical examination reveals absent breath sounds on one side and tympanic resonance on percussion.
• Neurosis: Some sensitive individuals may experience rapid breathing and subjective dyspnea due to emotional stress. This is easily distinguishable by doctors and generally harmless^[1].

TREATMENT

Which department should I visit for bronchial asthma?

Respiratory Medicine or Immunology/Allergy Department.

What are the treatment goals and principles for bronchial asthma patients?

Treatment goals: To minimize asthma symptoms, reduce the frequency of attacks, prevent irreversible airway obstruction, maintain normal or near-normal lung function, and ensure patients can participate in normal work, study, and daily life^[2].

Treatment principles: Long-term, continuous, standardized, and individualized treatment^[5]. During acute episodes, the focus is on anti-inflammatory and bronchodilator therapy to quickly relieve symptoms. During remission, long-term anti-inflammatory treatment, avoiding triggers, and self-care are essential^[4].

What medications are used to treat bronchial asthma?

Asthma medications can be broadly categorized as follows:

• Corticosteroids (hormones): The first-line treatment for asthma, usually administered via inhalation. Systemic (intravenous) corticosteroids are reserved for severe asthma attacks due to their side effects. Common inhaled corticosteroids include beclomethasone dipropionate and budesonide. Long-term use may increase the risk of oral thrush, hoarseness, or eye discomfort^[5]. Contraindicated in pregnant women and those allergic to these drugs.
• Bronchodilators: β2-agonists quickly relieve airway narrowing and are the preferred choice for acute asthma control. Short-acting β2-agonists (e.g., salbutamol, terbutaline) last 4–6 hours but should not be used long-term or alone due to side effects like palpitations and hypokalemia. Long-acting β2-agonists (e.g., procaterol) last 8–12 hours but are not recommended for prolonged solo use due to reduced efficacy^[1].
• Anticholinergics: These drugs (e.g., ipratropium, tiotropium) block cholinergic receptors and synergize with β2-agonists, especially for nocturnal asthma or patients with excessive mucus. Side effects include dry mouth and bitterness. Contraindicated in glaucoma, prostatic hyperplasia, or allergy^[1].
• Leukotriene receptor antagonists: Montelukast and zafirlukast are alternative controllers but are generally less effective than inhaled corticosteroids. Side effects are mild (e.g., gastrointestinal discomfort, rash)^[1].
• Theophyllines: Slow-release theophylline (12-hour duration) is used for chronic or nocturnal asthma. Side effects include nausea, vomiting, and arrhythmias. Caution in fever, children, elderly, and pregnancy^[1,5].
• Mast cell stabilizers: Sodium cromoglycate inhibits histamine and leukotriene release, reducing airway inflammation. Side effects are rare (e.g., nausea, headache). Caution in renal impairment and pregnancy.
• Others: Immunosuppressants may be considered based on individual conditions.

Can bronchial asthma be treated surgically?

Beyond medications, bronchial thermoplasty (BT) is an innovative procedure using the Alair system to reduce airway smooth muscle and alleviate severe asthma symptoms^[7]. It is suitable for adults (18+) with uncontrolled severe persistent asthma despite corticosteroid/long-acting β2-agonist therapy. BT reduces hospitalization rates but may cause temporary coughing or wheezing^[7].

What is desensitization therapy for bronchial asthma?

Desensitization involves injecting gradually increasing doses of allergens (e.g., pollen, dust mites) to build tolerance, reducing or preventing allergic reactions^[1]. It is effective for asthma, allergic rhinitis, and other IgE-mediated conditions.

How can asthma patients avoid treatment pitfalls?

Avoid neglecting tests: Pulmonary function and allergen testing are crucial for accurate diagnosis and management.

Do not stop treatment prematurely: Abrupt discontinuation may worsen symptoms or cause irreversible lung damage.

Distinguish anti-inflammatory from anti-infective therapy: Asthma inflammation is non-infectious; corticosteroids are key. Antibiotics are only needed for infection-triggered exacerbations.

Do not overestimate side effects: Inhaled corticosteroids are safe with proper use (e.g., rinsing post-inhalation).

Avoid self-adjusting medications: Unsupervised dose changes may cause adverse effects (e.g., tachycardia). Seek emergency help for severe symptoms.

Reject unverified "cures": Stick to evidence-based treatments under medical supervision.

Can bronchial asthma be cured?

Like hypertension or diabetes, asthma is rarely cured but can be well-controlled. Childhood asthma has a high remission rate (≥80% post-adolescence)^[1].

What to do during an asthma attack?

Use a short-acting β2-agonist (e.g., salbutamol inhaler) immediately. Repeat after 20–60 minutes if needed. Seek medical help if symptoms persist^[2].

How to use inhalers correctly?

1. Metered-dose inhalers (MDIs): Shake well → exhale deeply → seal lips around mouthpiece → inhale slowly while pressing canister → hold breath for 10 seconds.
2. Dry powder inhalers (DPIs): Load dose → exhale gently → inhale forcefully → hold breath for 5–10 seconds^[2].

DIET & LIFESTYLE

Can Patients with Bronchial Asthma Get Pregnant?

Statistics show that 2% to 13% of pregnant women worldwide suffer from asthma, meaning that out of 100 pregnant women, 2 to 13 may be affected by asthma, and the prevalence is increasing year by year^[8]. Currently, it is generally believed that the impact of asthma on pregnancy depends on the severity of asthma and the effectiveness of treatment. Mild asthma mostly does not affect the progress of pregnancy, and moderate to severe asthma, if managed correctly and promptly, may also not affect pregnancy.

For the fetus, mild asthma has little impact, but if the pregnant woman's asthma is poorly controlled, it can lead to hypoxemia and respiratory alkalosis, resulting in serious consequences.

Can Hormones Be Used for Bronchial Asthma Patients During Pregnancy?

Regarding asthma patients during pregnancy, when it comes to drug treatment, including physicians, people have some concerns, worrying that the drugs may harm the fetus. This is not unreasonable, but at the same time, it should be considered that asthma itself has a more adverse effect on fetal growth and development^[8].

In fact, the placenta is most affected by drugs during the early stages of pregnancy (about half a month to two months), after which drugs generally do not cause fetal malformations. The National Asthma Education and Prevention Program (NAEPP) issued guidelines for asthma treatment during pregnancy in 2005, stating that for pregnant women with asthma, using drugs to control asthma is safer compared to experiencing asthma symptoms and exacerbations.

Budesonide is the most commonly used and safe inhaled medication during pregnancy, with no significant harm to humans, making it the preferred inhaled corticosteroid during pregnancy^[8]. Conventional doses have no adverse effects on the fetus.

What Should Bronchial Asthma Patients Pay Attention to in Their Daily Diet?

Patients allergic to coffee should avoid coffee and coffee-containing foods; if there is no allergy, they can consume it.

Reduce the intake of cold drinks, as asthma patients have heightened airway reactivity. Drinking ice-cold water can cause a sudden drop in tracheal temperature, leading to bronchial constriction and triggering asthma.

What Should Bronchial Asthma Patients Pay Attention to in Their Daily Life?

• Pay attention to environmental hygiene. Wash bedding, pillows, quilts, and other items at least once a week, preferably with high-temperature washing. Regularly ventilate the room, and direct sunlight exposure is ideal.
• Patients allergic to pollen should avoid keeping flowers and plants. If necessary, avoid flowering plants and opt for green leafy plants.
• Asthma patients allergic to animal dander should reduce contact with pets. It is recommended not to keep dogs to minimize the chance of asthma attacks.
• Engage in appropriate exercise. Swimming is the most suitable exercise for asthma patients. Swimming is possible when there are no attacks, and cold-water swimming in summer is also acceptable.

What Should You Do If You Encounter a Bronchial Asthma Patient Having an Attack?

As a bystander, if you encounter an asthma patient having an attack, you can take the following emergency measures:

• Help the patient maintain a comfortable position, usually sitting with the body slightly leaning forward.
• Comfort the patient and instruct them to take slow, deep breaths.
• If the patient carries an inhaler, such as salbutamol, levalbuterol, or terbutaline, assist them in using it as follows:
• Exhale slowly.
• Press the top of the inhaler and have the patient inhale slowly.
• Hold the breath for 10 seconds, then exhale slowly.
• If the patient does not carry an inhaler, or if symptoms do not improve after using the inhaler, or if this is the patient's first asthma attack, call 120 immediately for emergency assistance.
• If the patient stops breathing, begin cardiopulmonary resuscitation (CPR) immediately.

CPR should be performed as follows:

1. Ensure the surrounding environment is safe.

2. Shout and tap the patient's shoulder to check for consciousness.

3. Lay the patient flat on the ground or a hard surface, loosen heavy clothing, and observe the chest to check for breathing or abnormal breathing. This observation should take 5 to 10 seconds—no less than five seconds and preferably no more than 10 seconds.

4. If the patient is unconscious and not breathing or only has gasping breaths, immediately assign someone to call 120 and try to obtain an AED.

5. Begin CPR with a compression-to-ventilation ratio of 30:2.

   • First, perform 30 chest compressions in the center of the chest, at the midpoint of the line between the nipples (the lower half of the sternum). Each compression should be 5 to 6 cm deep (for adults).
   • Then, open the patient's airway using the head-tilt-chin-lift method and deliver two rescue breaths. Place one hand on the patient's forehead and pinch the nostrils with the thumb and index finger. Use the other hand to lift the chin, tilting the head back to keep the airway open. Take a normal breath, then seal your mouth over the patient's mouth and deliver two one-second breaths. Observe the chest for rising. If the breaths are effective, the chest should rise with each breath. Complete the two breaths within 10 seconds.
   • For infants, use mouth-to-mouth-and-nose breathing. Tilt the infant's head back to open the airway. Take a normal breath, cover the infant's mouth and nose with your mouth, and deliver two one-second breaths. Observe the chest for rising, ensuring the breaths cause visible chest rise without over-ventilation.
   • Thirty chest compressions and two rescue breaths constitute one cycle. Continue CPR until the patient resumes breathing and heartbeat or until professional emergency personnel arrive.

PREVENTION

How Can Bronchial Asthma Patients Avoid Asthma Attacks?

To prevent asthma attacks, the first step is to eliminate triggering factors. There are many causes of asthma attacks—some are obvious, while others are often hidden^[2], requiring joint efforts from doctors and patients to identify. Currently known triggers of bronchial asthma include:

• Allergens: Allergens can be identified in 30%–40% of bronchial asthma patients. Dust mites, pet dander, mold, pollen, milk, eggs, feathers, and fungi are common allergens.
• Infections: Upper respiratory infections (e.g., colds) are the most common asthma triggers, especially in winter, spring, or during weather changes. Respiratory infections, particularly viral ones, are more likely to induce asthma attacks.
• Irritants: Inhaling smoke, dust, gasoline, paint fumes, or cold air can irritate the bronchial mucosa, leading to bronchial smooth muscle spasms in asthma patients.
• Avoid Overexertion: Sudden intense or prolonged physical labor, as well as competitive sports, may trigger asthma.
• Weather Factors: Cold seasons increase the risk of respiratory infections, while sudden weather changes, air pollution, or smog can provoke asthma attacks. Patients should dress warmly in cold weather to prevent colds.
• Occupational Factors: Workers in industries like pharmaceuticals or chemicals may develop allergies to certain drugs or raw materials.
• Humidity: Changes in air humidity also affect asthma. Excessively high or low humidity is harmful; the optimal relative humidity is 60%–70%.

Patients can undergo desensitization therapy under medical guidance based on their attack patterns for early prevention, treatment, and relief. During remission periods, moderate exercise helps boost immunity. Understanding asthma-related knowledge and proper medication use is crucial for prevention^[2].