Athsma

Question 1

Asthma

Definition

Answer 1

Reactive airway disease

airways become inflamed, narrow and swell producing extra mucus, which makes it difficult to breathe.

Question 2

Asthma - High morbidity due to:

Answer 2

1. Under diagnosis and inappropriate therapy
2. Limited access to healthcare
3. Inaccurate assessment of severity
4. Delay in seeking help
5. Inadequate medical treatment
6. No adherence to prescribed therapy
7. Increase in allergens in the environment

Question 3

Triggers

Answer 3

Pollens
• Dust
• Dust mites
• Food colouring
• Moulds/fungi
• Animals
• Feathers
• Job-related factors
• Cold/flu viruses
• Stress, emotions
• Change of weather
• Change of season
• Smoke
• Cold air
• Medicines
• Fumes
• Exercise

Question 4

Asthma

Pathophysiology

Answer 4

• Inflammation resulting in hyper responsiveness of the airways is the
major pathological feature of asthma
• The airways respond in an abnormal & exaggerated way to irritants or
allergens (triggers)
• 2 phases:
• Early phase response 30-120 mins
• Late phase response 4 – 8 hours

Question 5

Asthma: Early Phase

Pathophysiology

Answer 5

Exposure to allergens results in
 Triggered when IgE receptors on mast cells under the bronchial wall are
activated
•Begins with mast cell degranulation & the release of inflammatory mediators
• Histamine - Leukotrienes
• Interleukins - Nitric oxide
• Prostaglandins

Mediators cause
• Increased vasodilation & permeability
• This causes increased blood flow to the area which results in
bronchial infiltration by inflammatory chemicals
• These chemicals cause inflammation and tissue damage

• The resulting inflammatory process produces:
• Congestion
• Oedema
• Thick mucous
• Impaired ciliary function
• Thickening of airway walls
• Increased bronchial hyper responsiveness
• Airway obstruction

Question 6

Asthma: Late Phase

Pathophysiology

Answer 6

Characterized primarily by inflammation
• Another wave of mediator release occurs again causing
bronchospasm, oedema & mucuous secretion
• Leading again to airway obstruction.

Airway obstruction impairs exhalation and causes air trapping and
hyperinflation distal to obstructions
• As the obstruction becomes more severe, alveoli become less
perfused and there is a lack of ventilation
• ↑CO2 & respiratory acidosis signals respiratory failure.

Question 7

Factors Causing Expiratory Obstruction

in Asthma

Answer 7

1. Reduction in airway
diameter
2. ↑ in airway resistance
related to mucosal
inflammation
3. Constriction of
bronchial smooth
muscle
4. Excess production of
mucous

Question 8

Asthma

Clinical Manifestations

Answer 8

• Unpredictable and variable
• Chest constriction
• Expiratory wheezing
• Dyspnoea
• Non-productive cough
• Prolonged expiration
• Tachycardia
• Tachypnoea

•Wheezing is an unreliable sign to gauge severity of
attack
• Severe attacks can have no audible wheezing due to
reduction in airflow
•Diminished or absent breath sounds “Silent chest”
may indicate a significant decrease in air movement
•Ominous sign of impending respiratory failure

Examination of the patient during an acute attack usually reveals
signs of hypoxaemia
• Restlessness
• Increased anxiety
• Inappropriate behavior
• Increased pulse and blood pressure

Question 9

Features of Acute Severe Asthma

Answer 9

Unable to complete a sentence in 1 breath
• RR > 25 breaths per min
• Pulse rate > 110 beats per min
• PEFR (peak expiratory flow rate) <50% predicted normal value or pt’s
best-known value

Question 10

Life Threatening Features

Answer 10

• PEFR <33% of predicted normal value or pt’s best known
value
• Silent chest – absence of wheeze
• Diminished respiratory effort
• Bradycardia
• Hypotension
• Exhaustion
• Confusion & agitation due to hypoxia
• Signs of hypercapnia (sweating, red florid complexion,
bounding pulse, peripheral tremors
• Coma

Question 11

Pharmacology: Asthma

Answer 11

Anti inflammatory drugs
• Hydrocortisone, Prednisone
• Bronchodilators
• Salbutamol, Terbutaline
• Theophylline
• Aminophylline
• Anticholinergic drugs
• Atrovent