Asthma – symptoms, causes, prevention, complications

What is Asthma?

Bronchial asthma (asthma) is a chronic airway inflammation involving a variety of cells, especially fat cells, eosinophils and T lymphocytes. It affects the chest area of the body.

Symptoms of Asthma

Some of the main symptoms include recurrent wheezing, shortness of breath, chest tightness and/or cough in susceptible people, mostly at night and/or in the early hours of the morning. The airways are more reactive to multiple stimulus factors. However, symptoms of asthma can be alleviated on their own or with treatment.

Clinical manifestations

Typical bronchial asthma, symptoms are  sneezing, runny nose, cough, chest tightness, etc. If it is not dealt within a timely manner,  then it can worsen. It may cause bronchial obstruction, and in serious cases people may be forced to take a seat to breathe, dry cough or a large number of white foam sputum, and even purple cyanosis.

However, with flat wheezing drugs and other treatment  it’s symptom can be eased out temporally. Some patients can experience re-attack after a few hours of remission. This can even leads to a persistent state of asthma.

In addition, there are clinically atypical manifestations of asthma. Such as cough variant asthma, in which patient may experience cough for more than 2 months without obvious reasons. These cough attacks are frequent during the night and early morning time.  Exercise, cold air and other induced aggravation, indicate high reactivity of airway.

Clinically, exogenous asthma and endogenous asthma are divided into non-allergens and age of onset.

Exogenous asthma often occurs in childhood and adolescence, and has a family history of allergies, which is a type I perverted reaction.

Endogenous asthma doesn’t have known allergen, occur mostly in adults, no obvious seasonality, rare history of allergies, and may be caused by in vivo infection.

Regardless of asthma, mild illness can gradually be self-managed. However, the remission period can be without any symptoms or abnormal signs.


Causes of Asthma

Finding the cause of Asthma is more complex. As, asthma is mostly considered to be a multi-gene genetic disease. It is impacted by genetic factors as well as environmental factors. The formation and recurrence of asthma are often the result of a combination of many complex factors.

Genetic factors of Asthma

The relationship between asthma and genetics needs to be studied in depth to facilitate early diagnosis, early prevention and treatment.

Susceptibility to Asthma

The likelihood of an individual being susceptible to asthma is called susceptibility by a combination of genetic and environmental factors. The size of heredity can measure the role of genetic factors in the onset of the disease. Higher degree of heredity indicates that genetic factors play a greater role in the onset of the disease. Many survey data show that the prevalence of relatives of asthma patients is higher than that of the group, and the closer the kinship, the higher the prevalence rate. In a family, the greater the number of cases, the higher the prevalence of their relatives. The more serious the patient’s condition, the higher the prevalence of his or her relatives.

Hyperactivity of Airways

An important factor in asthma is the presence of airway hyperreactivity. Studies has shown that some genetic factors control the airway’s response to environmental stimuli. Higher the airway responsiveness plays an important role in asthma.

Asthma and air pollutants

There are 2 kinds of inhalation- specific and non-specific two kinds.

Inhaling specific substances like dust mites, pollen, fungi, animal dander, etc.

Nonspecific inhalants such as sulphuric acid, sulfur dioxide, chloramine, etc.

Specific inhalations that lead occupational asthma include toluene diisocyanate, phthalates, acetylamine, penicillin, protease, amylase, silk, animal dander or excreta, etc.,

In addition, non-specific include formaldehyde, tomic acid and so on.

Asthma and infections

Asthma and seizures are related to repeated respiratory infections. In asthma patients, there can be bacteria, viruses, myogens, etc. specific IgE.

If inhaled the corresponding substances described above, then it can stimulate asthma. After the virus infection, it can directly damage the respiratory epithelial. This results in increased respiratory response.

Some researchers believe that interferon and IL-1 produced by viral infections increase the release of histamines by eosinophils. In childhood, respiratory viruses (especially respiratory syncytial viruses) are also present in many people with asthma symptoms. Asthma caused by parasites such as ticks and hookworms is still visible in rural areas.

Asthma and food allergies

Food dietary relationship also plays an important role that can cause asthma attacks. It can be often seen in asthma patients. Especially infants and young children are prone to food allergies, but gradually it decreases with age. The most common foods that cause allergies are fish, shrimp crabs, eggs, milk, etc.

Asthma and season change

Change in temperature, air pressure and/or air ion can induce asthma. It happens frequently during the change of cold winter season or autumn .

Asthma and mental health

Patients who often feel emotional, nervous, angry, etc. , can promote asthma attacks. It is generally caused by the cerebral cortex and vagus nerve reflexes or excessive ventilation of it.

Exercise-induced asthma

After an intense exercise, about 70% to 80% of asthma patients experienced exercise-induced asthma, or sports asthma. In typical cases within 6 to 10 minutes of exercise they experience it. Bronchospasm is most evident within 1 to 10 minutes after cessation of exercise, and many patients recover on their own within 30 to 60 minutes.

Clinical manifestations include coughing, chest tightness, shortness of breath, wheezing, hearing and snarling. Some patients do not have typical asthma symptoms after exercise. But lung function measurements before and after exercise, can indicate bronchospasm. The disease is most common in teenagers.

According to the relevant research, excessive ventilation after intense exercise causes the loss of moisture and heat in the airway mucous membrane. The concentration of gram molecules temporarily appears in the epithelial of the respiratory tract. This results in the contraction of the smooth muscle of the bronchial tube.

Asthma and drugs

Some drugs can cause asthma attacks, and can impact heart health by blocking beta 2-adrenaline receptors.

About 2.3% to 20% of asthma sufferers have asthma caused by taking aspirin-based drugs, known as aspirin asthma. Patients with nasal polyps and low tolerance to aspirin are also known as aspirin trilogy.

Its clinical characteristics include-  taking aspirin can induce severe asthma symptoms which mostly appear within 2 hours after medication, occasionally as late as 2 to 4 hours. Patients may have cross-reactions to other anti-heat analgesics and nonsteroidal anti-inflammatory drugs. The incidence of asthma in children is mostly before the age of 2 years, but most of them are middle-aged patients aged between 30 to 40 years. There are more women than men. The ratio of men to women is about 2:3.

Menstruation, pregnancy and asthma

Many women with asthma have asthma exacerbation during the first 3 to 4 days of menstruation. This  may be related to the sudden decline of progesterone in premenstrual period. If a patient is required to give it every month and has a small amount of menstruation, progesterone can be injected at the right time, sometimes to prevent severe premenstrual asthma.

The effect of pregnancy on asthma is not regular. Some of the asthma symptoms improve, but can worsen also.  The effect of pregnancy on asthma is mainly manifested due to changes in hormones. If asthma is treated properly, there will be no adverse consequences for pregnancy and childbirth.

Neurological factors

Recent studies have proved that nitric oxide (NO) is the main neurotransmitter that helps to relax airway, smooth muscle control and kill pathogenic microorganisms. It plays important role in the defense support for immune system of the lungs.  Large production of nitric oxide can aggravate airway tissue damage and induce airway hyperactivity. So, it is vital to regulate the formation of airway NO as it may be beneficial for asthma treatment.

Diagnosis of Asthma

(i) Diagnostic criteria

1. Repeated wheezing, breathing difficulties, chest tightness or cough, contact with allergens, viral infections, exercise or certain irritants related symptoms.

2. The seizure of the double lung can be smelled and scattered in or diffuse, to exhale period-based snarling sound.

3. Above symptoms can be treated to relieve or self-remission.

4. The elimination of other diseases that can cause wheezing or breathing difficulties.

5. The symptoms of atypical (if there is no obvious wheezing or signs), should have at least one of the following test positive:

(1) if the basic FEV1 (or PEF) – 80% normal value, inhalation of beta 2 agonists after FEV1 (or PEF) increased by more than 15%.


(3) The bronchial excitation test (or motion excitation test) is positive.

(ii) According to the characteristics of medical history, symptoms, signs and laboratory examination results, asthma is clinically classified as exogenous asthma and endogenous asthma (Table 1).

Differences between exogenous and endogenous asthma

Table 1

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Severity rating

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Asthma Examination

  • The blood routine examination

May be eosinophils increased. If concurrent infection then can increase the total number of white blood cells, the proportion of classified neutrophils increases.

  • Sputum examination

Such as the combination of respiratory bacterial infections, sputum smears, bacterial culture and drug sensitivity tests to help pathogen diagnosis and proper treatment is suggested accordingly.

  • Respiratory function check
  • Blood gas analysis.
  • Chest X-ray examination
  • Special allergen supplement test
  • Skin sensitivity test.

In asthma, the relief period with a suspected allergen for skin scratches or intracutaneous tests, conditional inhalation excitation test, allergen diagnosis can be made. However, it should be noted that highly sensitive patients can sometimes induce asthma and systemic reactions, and even develop anaphylactic shock. It should be closely observed and dealt within a timely manner.

Asthma Prevention Tips

  • After identifying allergens, avoid them completely. For example: if it is due to indoor dust or radon induced asthma attacks, then you should keep your room clean, frequent expose the bedding under the sun, often keep your windows open, proper ventilation, and keep the indoor air fresh.
  •  Avoid keeping pets indoors (cats, dogs and other small animals).
  • Pay attention to the child’s activities or habits like physical exercise, use of cold water bath, use dry towel to wipe body etc.
  • Focus on proper nutrition, avoid mental stimulation, avoid colds and excessive fatigue, etc. to prevent asthma attacks as these factors also play an important role.

Complications of Asthma

Acute complications

  1. Sudden death  is the most serious complication of bronchial asthma, because it often has no obvious precursor symptoms. once, it occurred suddenly then it is often too late to rescue and patient dies. The important causes of sudden asthma death can be summarized as: (1) Specific hypersensitivity reaction: When the airway is in highly sensitive state, because of any specific or nonspecific stimulation, then it can cause serious throat, trachea edema and extensive bronchial spasms.As a result, the trachea gets blocked causing suffocation or induce severe arrhythmia or even cardiac arrest and death.
  2.  Closes lung: May be due to widespread sputum it blocks the bronchial or may be due to isopropyl epinephrine side effects. The latter is due to the drug metabolism of the intermediate product 3-methylamphetamine epinephrine, not only it excite β receptors, but also can play a β receptor blocking effect, causing bronchial smooth muscle spasms and goes to ventilation block.
  3. Fatal arrhythmia: can be caused by severe hypoxia, water, electrolyte and acid-base imbalance, can also be caused by  improper drug use, resulting in the concurrent heart failure.
  4. Bronchial asthma outbreaks: Often too late to use drugs and can cause death. However, the mechanism is not clear yet.
  5. Anesthetics or sedatives is not used properly: Narcotic drugs can cause respiratory suppression or even sudden cardiac arrest. Some sedatives have a significant inhibitory effect on the respiratory center. During such situation artificial airways should be established immediately for artificial ventilation of the heart, brain and other important organs.
  6. Lower respiratory tract and lung infections- According to statistics, about half of asthma is caused by upper respiratory tract virus infection. As a result, the immune function of the respiratory tract is disturbed and it is easy to catch secondary lower respiratory and lung infections. Therefore, efforts should be made to improve the immune function of asthma patients, keep the airways open, remove allergens, keep the room clean, and prevent cold etc. Once there are precursors of infection, appropriate antibiotics should be used for treatment based on bacteria and drug sensitivity.
  7. Water electrolyte and acid-base imbalance- Due to asthma attacks, lack of oxygen, lack of food, dehydration, heart, liver, especially respiratory and kidney insufficiency, can often cause concurrent water electrolyte and acid-base imbalance. These are important factors affecting asthma efficacy and prognosis. Efforts should be made to maintain water, electrolytes and acid-base balance. Monitor electrolytes and arterial blood gas analysis, timely detection of abnormalities, so that it can be treated on time.
  8. Gas and chest emphysema – Because of asthma attack some gas gets retained in the alveoli. When the alveoli contains excessive air, the pressure in the lungs significantly increased. This causes chronic asthma with concurrent emphysema that lead to the rupture of the large bubble. The formation of spontaneous gas in the chest can be experienced. When applying mechanical ventilation, the peak pressure of the airways and alveoli is too high, which can easily cause the alveoli to rupture and form a pressure injury, causing the gas chest and even accompanied by emphysema.
  9. Respiratory failure- Severe asthma attack ventilation deficiency, occurrence of  infection, improper medication and treatment, concurrent formation of gas in the chest, lung enlargement and pulmonary edema, are common causes of asthma concurrent respiratory failure. In the event of respiratory failure, asthma treatment is made more difficult due to severe hypoxia, carbon dioxide retention and acidosis.
  10. Multi-organ failure- Due to severe hypoxia, serious infection, acid-base imbalance, gastrointestinal bleeding and drug toxic side effects, severe asthma often cause inefficient functioning of multiple organ or even failure. So, it is important to work on improving the function of the important organs.

Long-term complications

1. Stunted and chest deformity – Asthma among children, often cause stunting and chest malformation. There are many factors such as under nutrition, hypoxemia, endocrine disorders, etc.  Also with the long-term systemic use of corticosteroids in children, report indicates up to  30% of stunted.

2. Pulmonary hypertension and chronic pulmonary heart disease – The incidence of asthma caused by long-term or repeated airway obstruction, serious infection, hypoxia, hypercarbonemia, acidosis and increased blood viscosity.