Asthma Clinical Features Flashcards
No wheeze, no?
Asthma
What are the defining features and epidemiology of asthma?
Defining features: Reversible airway obstruction, bronchoconstriction, and airway inflammation that cause symptoms like wheezing, dyspnea, and coughing.
Epidemiology: Asthma affects both children and adults, with a higher prevalence in children. It is more common in industrialized countries and has a rising prevalence in urban areas. Gender differences show higher rates in boys during childhood, but this reverses in adulthood with higher rates in women.
What are the proven and putative aetiological factors of asthma?
Proven aetiological factors:
Genetic predisposition (family history of asthma or atopy).
Environmental exposures: Allergens (e.g., dust mites, pollen), respiratory infections (especially viral), and air pollution.
Putative aetiological factors:
Lifestyle factors: Urbanization, diet, and obesity.
Environmental exposures: Early-life antibiotic use, and reduced microbial exposure (hygiene hypothesis).
Indoor air pollution (e.g., tobacco smoke).
What are the major pathological features of asthma?
Airway inflammation involving eosinophils, mast cells, and T lymphocytes.
Bronchoconstriction caused by smooth muscle tightening.
Airway remodeling with thickening of the basement membrane, mucus hypersecretion, and increased vascularity.
Increased airway hyperresponsiveness to triggers (e.g., allergens, irritants).
What are the main causes of wheezing illness?
Asthma: Characterized by reversible airway obstruction and inflammation.
Bronchiolitis (viral): Common in infants and young children, caused by RSV or other viruses.
Croup: Viral infection leading to inflammation and narrowing of the upper airway.
Pneumonia: Bacterial or viral infection that can cause wheezing.
Foreign body aspiration: Can cause localized wheezing.
Gastroesophageal reflux disease (GERD): Aspiration of gastric contents can lead to wheezing.
What are the possible reasons for the changing prevalence and severity of respiratory disease with child’s age and its links to adult respiratory disease?
Childhood asthma: Higher incidence in early life due to genetic predisposition and environmental exposures.
Prevalence in adults: Worsening in adulthood due to chronic exposure to environmental triggers, lack of early treatment, or development of comorbidities like obesity.
Long-term effects: Childhood asthma can persist into adulthood and lead to chronic obstructive pulmonary disease (COPD) or airway remodeling.
Hygiene hypothesis: Decreased microbial exposure in early life may contribute to asthma development and increased severity of disease in adulthood.
What are the symptoms and clinical patterns of asthma?
Symptoms: Wheezing, dyspnea (shortness of breath), coughing (especially at night or early morning), and chest tightness.
Clinical patterns:
Intermittent symptoms: Symptoms often triggered by allergens, exercise, or respiratory infections.
Exacerbations: Symptoms worsen, and bronchodilator use increases.
Nocturnal symptoms: Worsening of symptoms at night due to changes in airway tone and inflammation.
What specific features should be included in the clinical history of asthma?
Family history of asthma, atopy, or other respiratory conditions.
Personal history: Early childhood respiratory infections, allergic rhinitis, and eczema.
Exposure history: Contact with allergens (e.g., pets, dust mites, pollen), smoking (active or passive), and air pollution.
Symptom pattern: Timing of symptoms, triggers, and severity (daytime vs nocturnal).
Response to treatment: Effectiveness of bronchodilators, inhaled corticosteroids, and other asthma medications.
What investigations are used to diagnose asthma?
Spirometry: To assess airflow limitation and reversibility (FEV1/FVC ratio < 0.7, and improvement with bronchodilators).
Peak flow measurement: To monitor peak expiratory flow (PEF) variability.
Allergy testing: Skin prick tests or specific IgE blood tests to identify allergen sensitivities.
Chest X-ray: To rule out other conditions, though not typically diagnostic for asthma.
Exhaled nitric oxide (FeNO): To assess airway inflammation (elevated FeNO may indicate eosinophilic inflammation).
Arterial blood gases (ABG): In acute cases to assess hypoxemia or respiratory acidosis during severe exacerbations.
How do you assess the severity of acute, severe asthma?
Clinical assessment:
Severe symptoms: Marked dyspnea, use of accessory muscles, unable to speak in full sentences, tachypnea, tachycardia, and hypoxemia.
Oxygen saturation: Less than 92% on room air suggests significant hypoxemia.
PEF: A peak expiratory flow (PEF) of <50% of predicted value indicates severe obstruction.
Arterial blood gases (ABG): May show hypoxemia, hypercapnia, or respiratory acidosis in severe exacerbations.
Management: Immediate bronchodilators (e.g., nebulized SABA), systemic corticosteroids, and oxygen therapy.
