Asthma

Question 1

What is asthma? (2 elements)

Answer 1

• chronic inflammation of the airways, which makes them hyper-responsive
• recurrent, reversible episodes of airway obstruction due to inflammation and smooth muscle hyperactivity/bronchospasm

Question 2

What is asthma frequently linked to?

Answer 2

• allergic disorders

Question 3

What causes asthma?

Answer 3

complex trait/multifactoral

Question 4

What causes episodes of asthma?

Answer 4

hypersensitivity to stimuli:

• allergens
• airway irritants
• exercise
• strong odours
• cold air

Question 5

What is one of the underlying problems thought to be a cause of asthma?

Answer 5

normally, bronchoconstriction occurs via alpha adrenergic receptors and bronchodilation occurs via beta adrenergic receptors

normally cAMP mediates between the two

it is thought that people with asthma have a lack of beta adrenergic receptor stimulus

Question 6

What is the pathology during an acute-phase response in asthma?

Answer 6

• there is prior sensitization (not first exposure to allergen)
• at subsequent exposure, the allergen binds to mast cells with IgE, causing degranulation, releases mediators (leukotrienes, prostaglandin, interleukins, histamine) causing inflammation and bronchoconstriction
• intracellular junctions open - the allergens move into the submucosa and affect the muscle
• there is an increase in permeability and mucus secretion
• there is edema of airways
• there is PNS stimulation causing bronchospasm
• dyspnea and wheezing
• airway constriction (compensatory, doesn’t want allergen to get in)
• lasts up to 1 hour

Question 7

What is the pathology during a late-phase response in asthma?

Answer 7

• peaks in 4-8 hours
• manifestations of acute phase persist
• self-sustaining cycle of exacerbation
• can last days-weeks
• influx of inflammatory cells causes epithelial damage, decreases mucociliary function, hyper-responsive airway (will respond to new triggers)

Question 8

What are the manifestations of asthma?

Answer 8

• dyspnea
• wheezing
• immobilization?
• bronchospasm and coughing
• increased respiratory effort
• ventilatory compromise (altered respiratory status and ABGs)

Question 9

How is asthma diagnosed?

Answer 9

• exclude infection, COPD
• history, presentation
• labs
• pulmonary function tests
• inhalation challenge test (inhale allergens)

Question 10

How is asthma treated?

Answer 10

• avoid triggers, smoking
• drugs:
  1) inhaled short-acting bronchodilators PRN
  2) add inhaled steroid
  3) add long acting bronchodilator to the steroid
  4) short course steroids and a 3rd drug, a leukotriene receptor antagonist or theophylline