Asthma Flashcards
symptoms of asthma
Wheezing
Coughing
Nocturnal waking
Symptoms of SEVERE asthma
Cyanosis
Tachycardia
Hyperventilation
Summary pathway of asthma
Inflammation»_space; leads to bronchial hyperactivity and airway obstruction»_space; symptoms
What are the environmental factors in asthma?
Allergens:
Smoke
Pets
Air pollution
Drugs:
Aspirin
Beta blockers
NSAID’s
What are the differential diagnoses?
COPD
Cystic fibrosis
Bronchiectasis
What are the treatment goals for asthma?
No daytime symptoms
Minimal side effects
No need for rescue meds
Factors that affect the development of asthma?
Genes predisposing to allergy
Genes affecting beta 2 receptors
Obesity
Gender
What are the causes of airway narrowing?
Smooth muscle contraction ( bronchial hyper reactivity)
Inflammation (eosinophils and TH2 cells)
Airway oedema
Mucus hyper secretion
What is the role of dendritic cells in detecting allergens?
Immature dendritic cells migrate into airway mucosa
They differentiate and form a dynamic network in epithelium
They pick up airborne allergens
Leave epithelium , differentiate further and migrate to lymph nodes
They mature and present allergens to T cells.
What is the pathophysiology of asthma? (After dendritic cells present allergen to T cells)
- dendritic cells present allergens to T and B lymphocytes
- these produce lgE antibodies against allergen
- lgE is inserted onto mast cell surface
- allergen bind lgE’s causing release of inflammatory mediators
- white blood cells attracted to lgE’s and mast cells
- releasing mediators that cause bronchospasm (coughing, wheezing) and mucus production.
What are the roles of mediators released by activated cells?
Histamine: acts at H1 receptors leading to bronchoconstriction
- Drugs: H1 antagonists e.g loratadine
- antihistamines not used to treat asthma due to ineffectiveness in bronchodilation.
Prostaglandins (PGD2) : acts at PG receptors leading to bronchoconstriction.
- Drugs: anti-inflammatory steroids reduce synthesis
- Precursor is arachidonic acid
Leukotrienes (cysLT’S): acts at cysLT receptors leading to bronchoconstriction and eosinophilia
- Drugs: anti-inflammatory steroids reduce synthesis , cysLT receptors antagonists (LTRA’s)
- Precursor: arachidonic acid
What are the benefits of nebulizer?
Patient can inhale their prescribed medication directly into lungs providing fast relief
What are the two types of asthma
Atopic: a form of allergy that is hereditary
Non- atopic
Effects of inflammatory cells released by mast cells in asthma
- Histamine: cause bronchoconstriction by stimulating the H1 receptors on airway smooth muscle by stimulation of afferent vagaries fibres in airways
- leukotrienes: cause constriction and eosinophilia
- prostaglandins: cause constriction through binding of PGD2 to DP2 receptor on immune cells
How does taking NSAID’s and Aspirin lead to worsening of asthma
They block COX enzymes, leading to increased production of 5-LPX (lipoxygenase) and also an increase in leukotrienes which are responsible for inflammation and contraction. (More wheezing and sputum production)
