ASTHMA

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ASTHMA

• A. K. Nayyar

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Definition

• It is a syndrome characterized by AIRFLOW
  OBSTRUCTION that varies markedly, both
  spontaneously and with treatment.
• Narrowing of the airways is usually reversible,
  but in some patients with chronic asthma there
  may be an element of irreversible airflow
  obstruction

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Cont.

• It is characterized
• pathologically by bronchial inflammation with
  prominent eosinophil infiltration
  physiologically by bronchial hype-reactivity,
  and
• clinically by variable cough, chest tightness and
  wheeze

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Epidemiology

• It affects approximately 10-15 of children and
  5-10 of adults
• Prevalence is greater in industrialized countries
• Prevalence is increasing world-wide

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Pathology of asthma

• Infiltration with inflammatory cells (esp.
  eosinophils and T-lymphocytes)
• Patchy epithelial shedding
• Airway smooth muscle thickening
• Subepithelial fibrosis
• Mucus gland and goblet cell hyperplasia
• widespread mucus plugging in fatal asthma

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Mechanisms of asthma

• Inflammation underlies airway hyperresponsiveness
• The inflammation is of characteristic pattern and
  it involves interaction between many inflammatory
  cells
• This results in the release of multiple
  inflammatory mediators
• Inflammatory mediators result in
  bronchoconstriction, mucus secrition, exudation
  of plasma and airway hyperresponsiveness

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Cont.

• Neural mechanism may amplify the asthmatic
  inflammation
• Structural changes may occur with subepithelial
  fibrosis, airway smooth muscle hyperplasia and
  new vessel formation. These changes may underlie
  irreversible airflow obstruction

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Types of asthma

• Allergic (extrinsic) asthma
• Non-allergic (intrinsic) asthma
• Occupational asthma
• Aspirin induced asthma
• Asthma of infancy(lt2 yr of age)

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Allergic asthma

• Onset usually in childhood
• May persist into adulthood
• Remission in adolescence is common
• Associated with allergic rhinitis and atopic
  dermatitis in variable combination

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Intrinsic asthma

• Onset in adults
• No external inciter is recognized
• Often associated with perennial non-allergic
  rhinitis
• Accounts for approx. 10 of adult asthma

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Occupational asthma

• Due to exposure to chemical sensitizers at work
• Unrelated to atopic status
• Some occur in atopics due to allergen exposure at
  work

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Aspirin induced asthma

• Special type of intrinsic asthma
• It is a metabolic, pharmacological disorder
• acute asthma attacks on first and subsequent
  exposure to aspirin and NSAID

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Asthma of infancy

• Recurrent bouts of significant airflow limitation
  in small airways from viral infections
• Often remits as child gets older
• not associated with atopy
• Sometimes called wheezy bronchitis

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Clinical features

• Symptoms
• Triggers
• Physical signs

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Symptoms

• Wheeze-- intermittent, worse on expiration,
  chracteristically relieved by an inhaled ß2-
  agonist
• Cough-- usually unproductive
• Chest tightness
• SOB
• Prodromal symptoms may precede an attack

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Triggers

• Allergens (house dust mite, pollen, animal
  dander, moulds)
• Irritants (tobacco smoke, air pollutants, strong
  odours, fumes)
• Physical factors (exercise, cold air,
  hyperventillation, laughter, crying)
• Upper respiratory tract viral infections
• Emotions
• Occupational agents (chemical sensitizers,
  allergens)
• Drugs (beta blockers,NSAID)
• Food additives (metabisulphite,tartrazine)
• Change in weather
• Endocrine factors (menstrual cycle,
  pregnancy,thyroid disease)

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Physical signs

• Expiratory ronchi- widespread
• Hyperinflation of chest
• Use of accessory muscles
• Associated signs nasal polyps, flexure eczema

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Features suggestive of asthma in young children

• Symptom free intervals
• Nocturnal cough
• Coughing after exercise
• Coughing when laughing or crying
• Good response to correctly inhled or nebulized
  bronchodilators
• Personal or family history of atopic disease
• Onset unrelated to respiratory syncytial virus
  infection

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Features suggestive of alternative diagnosis in
young children

• Failure to thrive(? Cystic fibrosis,
  immunodeficiency)
• Absence of symptom free interval
• Sudden onset of persistent symptoms
• Persistent URTI/ otitis (? ciliary dyskinesia)
• Vomiting / recurrent pneumonia(? Acid reflux,
  aspiration)
• Premature birth (?bronchopulmonary dysplasia)
• Onset in RS virus season(?Post RSV broncholitis)

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DD in adults

• Mechanical obstruction of airways
• COPD
• Heart failure
• PE
• Vasculitides
• Carcinoid syndrome with hepatic secondaries

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Principles of treatment

• Educate patients to develop a partnership in
  asthma management
• Assess and monitor severity with objective
  measurement of lung function
• Avoid or control asthma triggers
• Establish medication plans for chronic management
• Establish plans for managing exacerbations
• Provide regular follow-up care

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Clinical evaluation of severity

• Number of daytime attacks lasting more than 24
  hrs and needing extra medication
• The presence of completely symptom-free intervals
  lasting more than 4 weeks without medication
• The frequency of waking at night due to asthma
  symptoms
• The amount of absence from work or school because
  of asthma
• The ability of the patients to keep up with peers
  in normal physical activity
• The number and type of medications required on
  regular basis
• The frequency of using extra relief medications
  on an as needed basis
• The frequency of hospital admission
• The of life-threatening episodes