Types of Asthma; Causes, Symptoms, Diagnosis

Types of Asthma; Causes, Symptoms, Diagnosis

Types of Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include episodes of wheezing, coughing, chest tightness, and shortness of breath. These episodes may occur a few times a day or a few times per week. Depending on the person, they may become worse at night or with exercise.

Asthma is a common chronic disorder of the airways that is complex and characterized by variable and recurring symptoms, airflow obstruction, bronchial hyperresponsiveness, and an underlying inflammation [Rx]. The interaction of these features of asthma determines the clinical manifestations and severity of asthma [Rx] and the response to treatment.

Asthma is a common chronic disorder of the airways that involves a complex interaction of airflow obstruction, bronchial hyperresponsiveness and an underlying inflammation. This interaction can be highly variable among patients and within patients over time. This section presents a definition of asthma, a description of the processes on which that definition is based—the pathophysiology and pathogenesis of asthma, and the natural history of asthma.

Types of Asthma

  • Allergic (extrinsic) – Your doctor may refer to asthma as being “extrinsic” or “intrinsic.” A better understanding of the nature of asthma can help explain the differences between them. Extrinsic, or allergic asthma, is more common and typically develops in childhood. Approximately 70%-80% of children with asthma also have documented allergies. Typically, there is a family history of allergies. Additionally, other allergic conditions, such as nasal allergies or eczema, are often also present. Allergic asthma often goes into remission in early adulthood. However, in many cases, the asthma reappears later.
  • Nonallergic (intrinsic) asthma – Intrinsic asthma represents a small amount of all cases. It usually develops after the age of 30 and is not typically associated with allergies. Women are more frequently affected and many cases seem to follow a respiratory tract infection. Obesity also appears to be a risk factor for this type of asthma. Intrinsic asthma can be difficult to treat and symptoms are often chronic and year-round.

Or

Depending on the type of trigger, doctors classify asthma as being either allergic or non-allergic.

  • Allergic asthma – is also called “extrinsic asthma” because the trigger comes from outside the body and is breathed in with the air. Different people may have reactions to very different types of triggers, including cigarette smoke (active and passive smoking), plant pollen, animal fur, dust mite excrement, and some kinds of food as well as cold air, perfume, exhaust fumes and certain chemicals.
  • Non-allergic asthma –  (also called “intrinsic asthma”) is caused by triggers that come from inside the body. These triggers include bacterial and viral inflammations of the airways in particular. Sometimes taking certain kinds of painkillers causes asthma. These painkillers include acetylsalicylic acid (ASA, the drug in medicines like Aspirin) and other non-steroidal anti-inflammatory drugs (NSAIDs). In some people, physical or emotional stress that makes them breathe faster can also trigger asthma symptoms.

According to the severity

  • Mild intermittent – This includes attacks no more than twice a week and nighttime attacks no more than twice a month. Attacks last no more than a few hours to days. Severity of attacks varies, but there are no symptoms between attacks.
  • Mild persistent – This includes attacks more than twice a week, but not every day, and nighttime symptoms more than twice a month. Attacks are sometimes severe enough to interrupt regular activities.
  • Moderate persistent – This includes daily attacks and nighttime symptoms more than once a week. More severe attacks occur at least twice a week and may last for days. Attacks require daily use of quick-relief (rescue) medication and changes in daily activities.
  • Severe persistent – This includes frequent severe attacks, continual daytime symptoms, and frequent nighttime symptoms. Symptoms require limits on daily activities.

Others Types of Asthma

Asthma exacerbation

 
Near-fatal High PaCO2, or requiring mechanical ventilation, or both
Life-threatening
(any one of)
Clinical signs Measurements
Altered level of consciousness Peak flow < 33%
Exhaustion Oxygen saturation < 92%
Arrhythmia PaO2 < 8 kPa
Low blood pressure “Normal” PaCO2
Cyanosis
Silent chest
Poor respiratory effort
Acute severe
(any one of)
Peak flow 33–50%
Respiratory rate ≥ 25 breaths per minute
Heart rate ≥ 110 beats per minute
Unable to complete sentences in one breath
Moderate Worsening symptoms
Peak flow 50–80% best or predicted
No features of acute severe asthma
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An acute asthma exacerbation is commonly referred to as an asthma attack. The classic symptoms are shortness of breath, wheezing, and chest tightness. The wheezing is most often when breathing out. While these are the primary symptoms of asthma, some people present primarily with coughing, and in severe cases, air motion may be significantly impaired such that no wheezing is heard.In children, chest pain is often present.

Signs occurring during an asthma attack include the use of accessory muscles of respiration (sternocleidomastoid and scalene muscles of the neck), there may be a paradoxical pulse (a pulse that is weaker during inhalation and stronger during exhalation), and over-inflation of the chest. A blue color of the skin and nails may occur from lack of oxygen.

In a mild exacerbation the peak expiratory flow rate (PEFR) is ≥200 L/min, or ≥50% of the predicted best. Moderate is defined as between 80 and 200 L/min, or 25% and 50% of the predicted best, while severe is defined as ≤ 80 L/min, or ≤25% of the predicted best.

  • Acute severe asthma previously known as status asthmaticus, is an acute exacerbation of asthma that does not respond to standard treatments of bronchodilators and corticosteroids. Half of cases are due to infections with others caused by allergen, air pollution, or insufficient or inappropriate medication use.
  • Brittle asthma – is a kind of asthma distinguishable by recurrent, severe attacks. Type 1 brittle asthma is a disease with wide peak flow variability, despite intense medication. Type 2 brittle asthma is background well-controlled asthma with sudden severe exacerbations.
  • Exercise-induced – Exercise can trigger bronchoconstriction both in people with or without asthma.It occurs in most people with asthma and up to 20% of people without asthma. Exercise-induced bronchoconstriction is common in professional athletes. The highest rates are among cyclists (up to 45%), swimmers, and cross-country skiers. While it may occur with any weather conditions, it is more common when it is dry and cold.Inhaled beta2-agonists do not appear to improve athletic performance among those without asthma, however, oral doses may improve endurance and strength.
  • Occupational – Asthma as a result of (or worsened by) workplace exposures is a commonly reported occupational disease. Many cases, however, are not reported or recognized as such. It is estimated that 5–25% of asthma cases in adults are work-related. A few hundred different agents have been implicated, with the most common being: isocyanates, grain and wood dust, colophony, soldering flux, latex, animals, and aldehydes. The employment associated with the highest risk of problems include: those who spray paint, bakers and those who process food, nurses, chemical workers, those who work with animals, welders, hairdressers and timber workers.
  • Aspirin-induced asthmaAspirin-exacerbated respiratory disease, also known as aspirin-induced asthma, affects up to 9% of asthmatics. Reactions may also occur to other NSAIDs. People affected often also have trouble with nasal polyps. In people who are affected, low doses paracetamol or COX-2 inhibitors are generally safe.
  • Alcohol-induced asthma – Alcohol may worsen asthmatic symptoms in up to a third of people.This may be even more common in some ethnic groups such as the Japanese and those with aspirin-induced asthma. Other studies have found improvement in asthmatic symptoms from alcohol.
  • Nonallergic asthma – Nonallergic asthma, also known as intrinsic or nonatopic asthma, makes up between 10 and 33% of cases. There is negative skin test to common inhalant allergens and normal serum concentrations of IgE. Often it starts later in life, and women are more commonly affected than men. Usual treatments may not work as well

Phenotypes

Owing to the heterogeneity of the disease, a number of different phenotypes can be described. Distinguishing between them can be particularly relevant to the therapy in severe cases:

  • Allergic asthma
  • Nonallergic asthma
  • Pediatric asthma/recurrent obstructive bronchitis
  • Late-onset asthma
  • Asthma with fixed airflow obstruction
  • Obesity asthma
  • Occupational asthma
  • Asthma in the elderly
  • Severe asthma

Classifications by other professional associations (ERS/ATS, European Respiratory Society/American Thoracic Society) tend to focus more on a combination of clinical and pathophysiological aspects (e. g., eosinophilic/neutrophilic asthma, severe allergic asthma etc.)

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Causes of Asthma

Asthma triggers are different from person to person and can include:

  • Airborne substances, such as pollen, dust mites, mold spores, pet dander or particles of cockroach waste
  • Respiratory infections, such as the common cold
  • Physical activity (exercise-induced asthma)
  • Cold air
  • Air pollutants and irritants, such as smoke
  • Certain medications, including beta blockers, aspirin, ibuprofen and naproxen 
  • Strong emotions and stress
  • Sulfites and preservatives added to some types of foods and beverages, including shrimp, dried fruit, processed potatoes, beer and wine
  • Gastroesophageal reflux disease (GERD), a condition in which stomach acids back up into your throat
  • Asthma is a chronic inflammatory disorder of the airways. This feature of asthma has implications for the diagnosis, management, and potential prevention of the disease.
  • The immunohistopathologic features of asthma include inflammatory cell infiltration:

    • Neutrophils (especially in sudden-onset, fatal asthma exacerbations; occupational asthma, and patients who smoke)
    • Eosinophils
    • Lymphocytes
    • Mast cell activation
    • Epithelial cell injury
  • Airway inflammation contributes to airway hyperresponsiveness, airflow limitation, respiratory symptoms, and disease chronicity.
  • In some patients, persistent changes in airway structure occur, including sub-basement fibrosis, mucus hypersecretion, injury to epithelial cells, smooth muscle hypertrophy, and angiogenesis.
  • Gene-by-environment interactions are important to the expression of asthma.
  • Atopy, the genetic predisposition for the development of an immunoglobulin E (IgE)-mediated response to common aeroallergens, is the strongest identifiable predisposing factor for developing asthma.
  • Viral respiratory infections are one of the most important causes of asthma exacerbation and may also contribute to the development of asthma.

Sign Symptoms of Asthma

Early warning signs of asthma include. Intermittent and variable (may also be absent, e.g., during symptom-free intervals or in mild disease)

Common signs and symptoms of asthma include

  • Coughing – Coughing from asthma often is worse at night or early in the morning, making it hard to sleep.
  • Wheezing – Wheezing is a whistling or squeaky sound that occurs when you breathe.
  • Chest tightness – This may feel like something is squeezing or sitting on your chest.
  • Shortness of breath. Some people who have asthma say they can’t catch their breath or they feel out of breath. You may feel like you can’t get air out of your lungs.
  • Shortness of breath
  • Trouble sleeping caused by shortness of breath, coughing or wheezing
  • A whistling or wheezing sound when exhaling (wheezing is a common sign of asthma in children)
  • Coughing or wheezing attacks that are worsened by a respiratory virus, such as a cold or the flu
  • Increasing difficulty breathing (measurable with a peak flow meter, a device used to check how well your lungs are working)
  • Exercise-induced asthma, which may be worse when the air is cold and dry
  • Occupational asthma, triggered by workplace irritants such as chemical fumes, gases or dust
  • Allergy-induced asthma, triggered by airborne substances, such as pollen, mold spores, cockroach waste or particles of skin and dried saliva shed by pets (pet dander)

Other symptoms of an asthma attack include

  • Severe wheezing when breathing both in and out
  • Coughing that won’t stop
  • Very rapid breathing
  • Chest pain or pressure
  • Tightened neck and chest muscles, called retractions
  • Difficulty talking
  • Feelings of anxiety or panic
  • Pale, sweaty face
  • Blue lips or fingernails

Diagnosis of Asthma

Basic diagnostic evaluation of bronchial asthma*1

History

  • Sudden onset of symptoms, often at night or in the early morning hours, typical shortness of breath and cough (productive or unproductive), particularly
    • after allergen exposure
    • during (or, more commonly, after) physical exertion or sports (so-called
    • exercise-induced asthma)
    • in the setting of upper respiratory infection
    • on exposure to thermal stimuli, e.g., cold air
    • on exposure to smoke or dust
  • Seasonal variation of symptoms (seasonal elevation of pollen count)
  • Positive family history (allergy, asthma)
  • Precipitants of asthmatic symptoms in the patient’s environment at home, at work, and during leisure activities

Differential diagnosis

The following entities should be considered in the differential diagnosis of bronchial asthma because of their frequency and clinical significance ():

  • Chronic obstructive pulmonary disease (COPD)
  • Hyperventilation
  • Aspiration
  • Laryngeal changes/vocal cord dysfunction
  • Pneumothorax
  • Cystic fibrosis (CF)
  • Cardiac diseases, e.g., left heart failure
  • Pulmonary embolism
  • Gastroesophageal reflux disorder.

In as many as 10% to 20% of cases, a clear-cut distinction between asthma and COPD cannot be drawn.

  • Allergy test – Reasonable because many children show relevant sensitization even under 3 years of age. For example, sensitivity to house-dust mites is associated with increased asthma risk.
  • Lung function diagnostics  Children usually have to be 5–6 years old before spirometry is possible, but it can be attempted earlier with sufficient expertise and time investment. The GINA Guidelines do not make any reference to alternative technologies (forced oscillation, impulse oscillometry, multiple-breath washout etc.). In addition, these techniques currently are only available in specialized centers.
  • Exhaled NO –  Listed as a possible examination (tidal technique) in the GINA Guidelines, but not yet established for young children (apart from scientific applications). As soon as spirometry is possible, the forced expiratory flow maneuver can usually be employed in a defined flow range (“single-breath” method).
  • Further tests – mainly to rule out differential diagnoses: In addition to the lung X‑ray specified in the GINA Guidelines, further examinations (bronchoscopy, sweat test, pH measurement etc.) may be required. However, they are not part of the primary diagnosis.

You may also be given lung (pulmonary) function tests to determine how much air moves in and out as you breathe. These tests may include:

  • Spirometry – This test estimates the narrowing of your bronchial tubes by checking how much air you can exhale after a deep breath and how fast you can breathe out.
  • Peak flow – A peak flow meter is a simple device that measures how hard you can breathe out. Lower than usual peak flow readings are a sign your lungs may not be working as well and that your asthma may be getting worse. Your doctor will give you instructions on how to track and deal with low peak flow readings.
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Additional tests of Asthma

Other tests to diagnose asthma include

  • Methacholine challenge – Methacholine is a known asthma trigger that, when inhaled, will cause mild constriction of your airways. If you react to the methacholine, you likely have asthma. This test may be used even if your initial lung function test is normal.
  • Imaging tests – A chest X-ray and high-resolution computerized tomography (CT) scan of your lungs and nose cavities (sinuses) can identify any structural abnormalities or diseases (such as infection) that can cause or aggravate breathing problems.
  • Allergy testing – This can be performed by a skin test or blood test. Allergy tests can identify allergy to pets, dust, mold and pollen. If important allergy triggers are identified, this can lead to a recommendation for allergen immunotherapy.
  • Sputum eosinophils – This test looks for certain white blood cells (eosinophils) in the mixture of saliva and mucus (sputum) you discharge during coughing. Eosinophils are present when symptoms develop and become visible when stained with a rose-colored dye (eosin).
  • Provocative testing for exercise and cold-induced asthma – In these tests, your doctor measures your airway obstruction before and after you perform vigorous physical activity or take several breaths of cold air.

References

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