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Questions and Answers
Which demographic group has the highest prevalence of asthma?
What is a primary risk factor for chronic obstructive pulmonary diseases (COPD)?
In the classification of extrinsic asthma, which type of hypersensitivity is involved?
What role does IL-4 play in the sensitization process of allergic reactions?
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Which treatment is commonly used for acute exacerbations of COPD caused by bacterial infections?
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Which endogenous factor is associated with increased susceptibility to bronchial asthma?
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Which of the following triggers is least likely to cause an exacerbation of asthma symptoms?
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What role do mast cells and basophils play in the pathophysiology of asthma?
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Which environmental factor is considered a significant asthma trigger?
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Which inflammatory mediator is NOT typically associated with asthma?
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What is the primary goal of asthma treatment?
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What does a reduction of FEV1 by more than 20% during a methacholine challenge indicate?
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Which of the following is NOT a component of complete control in asthma management?
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Which of the following tests is primarily used to diagnose atopy rather than asthma?
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What should be checked before initiating drug treatment for asthma?
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What are Curschmann's spirals associated with in histological changes related to asthma?
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Which indoor environmental exposures are major contributors to asthma morbidity?
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Which of the following strategies is considered as effective as asthma controller medications for reducing asthma symptoms?
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Which condition may indicate that a patient with asthma is nearing respiratory failure?
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What is the significance of thickened basement membranes in the context of asthma?
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What is indicated when peak flows are diminished in a patient with asthma?
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What type of measurement does a methacholine challenge provide regarding a well patient?
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What role do Charcot-Leyden crystals play in the evaluation of asthma?
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Which component primarily involves bronchial hyper-reactivity and inflammatory mediator release?
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What is the preferred medication for managing intermittent asthma symptoms?
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Which combination of medications is recommended for moderate persistent asthma?
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Which drug class is considered the first choice for long-term control in asthma management?
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In the stepwise management of asthma, what should be checked first when considering a step-up in therapy?
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What is the role of bronchodilators in asthma management?
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Which of the following conditions is NOT typically associated with airway inflammation in asthma?
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What is the main reason for considering a step down in asthma treatment?
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What role does Omalizumab play in asthma management?
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Which of the following is NOT a commonly used method of inhaled therapy for asthma?
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Study Notes
Asthma Diagnosis
-
Labs
- Arterial blood gas (ABG) may reveal respiratory alkalosis in early stages
- Normal CO2 levels suggest imminent respiratory failure
- Elevated CO₂ (respiratory acidosis) is a serious sign and may require intubation
-
Pulmonary function tests
- Peak flows are decreased
- An obstructive pattern may be observed when symptomatic (↓ FEV1/FVC), which improves with bronchodilator administration
- High airway resistance is characteristic
-
Methacholine challenge
- Provocative measure of hyperactivity in an otherwise healthy individual
- Functions as a muscarinic cholinergic agonist
- Reduction of FEV1 by >20% is diagnostic of asthma
-
Skin testing
- May identify hypersensitivity response to allergens when presented into skin (indicates atopy, not necessarily asthma)
-
Histological changes
- In the terminal bronchioles, mucus plugs containing:
- Curschmann's spirals: Trapped epithelial cells killed by eosinophil-produced major basic protein
- Charcot-Leyden crystals: Aggregated eosinophils
- An increase in mucus-producing cells
- In the bronchi:
-
Thickened basement membrane
- Unique to asthma
- Hypertrophy of submucosal glands and smooth muscle
- Also observed in other lung disorders, like chronic bronchitis
- Increased immune cell presence
-
Thickened basement membrane
- In the terminal bronchioles, mucus plugs containing:
Chronic Obstructive Pulmonary Diseases (COPD)
- Includes chronic bronchitis and emphysema
- Chronic bronchitis: Cough associated with inflammation of the bronchioles
- Emphysema: Permanent destruction and enlargement of the airspaces distal to the bronchioles
- COPD results in airway obstruction, dyspnea, ↓ blood O₂ concentrations and ↑ blood CO₂ concentrations
- Risk factors for COPD: Smoking and old age
- Treatment: Bronchodilators, long-term oxygen therapy. Antibiotics can be used for acute exacerbations caused by bacterial infections.
Asthma classification
-
Extrinsic asthma
- Typically seen in children with a genetic predisposition
-
Type I hypersensitivity to an inhaled allergen
- Proceeds in specific stages:
-
Sensitization:
- CD4 TH2 cells produce cytokines (IL-4 and IL-5) when initially stimulated by an allergen.
- IL-4 induces antibody isotype switch to IgE.
- IL-5 induces eosinophil activation.
- Early activation: Mast cells are activated by cross-linking of IgE, releasing immune activating substances (histamine, leukotrienes, and acetylcholine) upon re-exposure to the allergen.
-
Sensitization:
- Proceeds in specific stages:
Bronchial asthma
-
Etiology:
- Endogenous factors: Genetic predisposition, atopy, airway hyperresponsiveness, gender, ethnicity, obesity, early viral infections
- Environmental factors: Indoor and outdoor allergens, occupational sensitizers, passive smoking, respiratory infections
- Triggers: Allergens, upper respiratory tract viral infections, exercise, hyperventilation, cold air, sulfur dioxide, drugs (beta-blockers, aspirin), stress, irritants (household sprays, fumes)
Pathophysiology of asthma
- IgE, allergen, sensory nerve activation and plasticity, mast cells/basophils, macrophages/dendritic cells, cytokine chemokines, Th2 cells, eosinophils
- Inflammation: leukotrienes, prostaglandins, purines, histamine, proteases, PAF, protons, etc.
- Asthma is a chronic disease with no cure, the aim of treatment is to control the disease.
Underlying principles of management
-
Before initiating drug treatment, check:
- Compliance with existing treatment
- Inhaler technique
- Elimination of trigger factors
Controlling Indoor Allergens
- Indoor environmental exposure to allergens (e.g., dust mites, mold, rodent, cockroach, pet allergens) and pollutants (e.g., nitrogen dioxide from gas stoves, secondhand smoke) are significant contributors to asthma morbidity, especially in children.
- Environmental control strategies, including allergen source eradication, HEPA air purifiers, and allergen-proof mattress and pillow covers, can be as effective as asthma controller medications in reducing symptoms and flare-ups.
Aim of management
- The goal of asthma management is to control the disease.
-
Complete control is defined by:
- No daytime symptoms
- No night-time awakening due to asthma
- No need for rescue medication
- No asthma attacks
- No limitations on activity, including exercise
- Normal lung function (FEV1 and/or PEF > 80% predicted or best)
- Minimal side effects from medication.
Asthma is a two-component disease
- Smooth muscle dysfunction: Bronchoconstriction, bronchial hyper-reactivity, hyperplasia, inflammatory-mediator release
- Airway inflammation/remodelling: Inflammatory cell infiltration/activation, mucosal oedema, cellular proliferation, epithelial damage, basement-membrane thickening
Stepwise Approach for Managing Asthma in Adults
- Intermittent Asthma
- Persistent Asthma: Daily Medication
| Intermittent | mild persistent | moderate persistent | severe persistent | severe persistent | severe persistent | |
| Step 1 | Step 2 | Step 3 | Step 4 | Step 5 | Step 6 | |
| Preferred | SABA (prn) | Low dose ICS | Low dose | Medium dose | High dose | High dose |
| ICS + LABA | ICS + LABA | ICS + LABA | ICS + LABA + oral | |||
| OR | corticosteroid | |||||
| Alternative | Cromolyn, * | Low-dose ICS | Medium-dose ICS | Medium-dose ICS | ||
| LTRA, | + either LTRA, | + either LTRA, | ||||
| or Theophylline | Theophylline or | Theophylline or | ||||
| Zileuton | Zileuton | |||||
| AND | AND | |||||
| Consider | Consider | |||||
| Omalizumab for | Omalizumab for | |||||
| patients who have | patients who have | |||||
| allergies | allergies | |||||
| Step up if needed | Step up if needed | |||||
| 1ª check adherence | 1ª check adherence | |||||
| environmental control | environmental control | |||||
| & comorbid conditions | & comorbid conditions | |||||
| Assess control | Assess control | |||||
| Step down if possible | Step down if possible | |||||
| & asthma is well controlled | & asthma is well controlled | |||||
| at least 3 months | at least 3 months |
Drugs Used In Asthma
-
Bronchodilators
-
B₂ agonists
- SABA
- LABA
-
Methylxanthines
- Degranulation Inhibitors
- Muscarinic antagonists
-
B₂ agonists
-
Anti-inflammatory agents
- Leukotriene modifiers
-
Corticosteroids
- ICS
- Oral
- Antibodies
- Lipoxygenase inhibitors
- Receptor blockers
-
Oxygen (for low Po2)
-
SABAs are the preferred drugs for acute asthma flare-ups
-
ICS are the drugs of first choice for maintenance treatment, reducing the need for frequent use of SABAs.
Inhaled therapy is the cornerstone of asthma treatment.
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Explore the different methods for diagnosing asthma, including laboratory tests, pulmonary function tests, and skin testing. Learn about key indicators such as arterial blood gas results and histological changes that are crucial for accurate diagnosis and treatment of asthma.
