Clinical Aspects Of Airway Disease Flashcards
(47 cards)
At what age does asthma occur?
Any
Most common in childhood (3-5yrs)
Is asthma common?
10-15% of UK population
Incidence increasing worldwide
Does asthma have a high mortality?
1000-2000 people/yr die from acute asthma
What 3 factors can bring on asthma?
- Genetic
- Environmental
- Acute
What are the causes and triggers of asthma?
- Environmental allergen e.g. moulds, dust, grass pollen, pet hair
- Viral infections e.g. rhinovirus, parainfluenza virus, RSV
- Cold air
- Emotion
- Irritant vapours & fumes
- Genetic factors
- Drugs e.g. NSAIDs, beta-blockers
- Atmospheric pollution e.g. sulphur dioxide, ozone, particulates
- Exercise
- Occupational sensitizers
What are the 2 types of asthma?
- Extrinsic/atopic: result of inappropriate adaptive immune response to an inhaled Ag so associated with atopy esp. eczema & hayfever (eosinophilic inflammation)
- Intrinsic/non-atopic: triggered by factors not related to allergies so no personal/family history of asthma/atopy (neutrophilic inflammation)
OFTEN OVERLAP
What is the difference between the onsets of the 2 types of asthma?
- Extrinsic/atopic: typical onset in childhood
2. Intrinsic/non-atopic: typical onset in middle age often following an upper airway infection
What are the 2 phases of extrinsic asthma?
Sensitisation
Effector
What is the pathophysiological features of asthma?
Airway obstruction (reversible)
Airway hyperresponsiveness
Airway inflammation
What happens inside the airways in asthma?
- Mucus accumulation due to increased goblet cells in mucosa & hypertrophy of submucosal glands
- Mucus plug with eosinophils & desquamated epithelial cells
- Hypertrophy & hyperplasia of SMCs so muscle layer thickened
- Thickened basement membrane
- Oedema due to dilated blood vessels
- Chronic inflammation due to recruitment of IS cells e.g. eosinophils, macrophages, neutrophils, lymphocytes & mast cells
What nerve reflex is involved in asthma?
Cholinergic reflex
Activated via sensory nerve irritation & causing SM to constrict
What are the 3 phases of asthma pathogenesis?
- Immediate/early: Allergen stimulates IgE production from B cells & IgE-sensitized MCs produce histamine, tryptase, PDG2, LTC4/D4 & PAF which constricts SM
- Late: Th2 cells produce IL-3, IL-5, GM-CSF & TNF whilst eosinophils release ECP + MCP & neutrophils release proteases + PAF -> vascular leak, cell infiltration & mucus secretion
- Re-modelling (chronic): SM hypertrophy, SM/epithelial cell hyperplasia, epithelial damage & BM thickening
What are the main problems of the early/acute and the late/chronic asthma response?
Acute: transient bronchial constriction due to factors released by IgE-sensitized histamine
Chronic: infiltration of inflammatory immune cells like T cells, eosinophils & neutrophils
What is asthma?
Chronic inflammatory condition with often acute exacerbations called “asthma attacks”
Closely associated with ‘atopy’/allergy
What are the symptoms of asthma?
Cough Wheeze Chest tightness SOB Worst at night often
What are signs of asthma during exacerbation?
Difficulty completing sentences Wheeze (audible) Tachypnoea Tachycardia Use of accessory muscles Reduced breath sounds (if severe)
Why do patients with asthma get woken in the morning by wheezing?
Cyclical secretion of steroids i.e. cortisol exacerbate airway narrowing
How is asthma diagnosed?
- Trial of treatment & assess response (can also give irritant e.g. Ag or histamine)
- Reversibility on spirometry before/after salbutamol
- Diurnal variation on peak flow monitoring
- Fractional exhaled NO (FeNO)
BUT NO GOLD STANDARD TEST
Why can a fractional exhaled NO (FeNO) test help to diagnose asthma?
Measures eosinophilic inflammation in airways -> secrete more NO in breath if their is inflammation present at the time
If you are assessing someone for asthma, but symptoms are always present i.e. does not get better/worst, what should you do?
Consider other diagnoses e.g. COPD or lung cancer
What changes can be seen in CO2 in an Arterial Blood Gas (ABG) in asthma?
Normal in mild cases
CO2 drops due to hyperventilation when bronchospasm is not too bad but when airway spasms get bad there is trapping so CO2 starts to rise again becoming normal at some stage (worrying) & eventually high in very severe cases
What are the 3 first line treatments in the management of acute asthma?
- O2 (to maintain sats 94-98%)
- B2-agonist bronchodilators e.g. salbutamol or terbutaline nebulised or MDI via spacer (repeat at 15-30 min intervals) - IV salbutamol may have role in severe cases
- Corticosteroids e.g. prednisolone or hydrocortisone (continue for min 5 days)
What other treatments may you give for acute asthma management?
- Ipratropium bromide as nebuliser when poor initial response to bronchodilators
- Mg sulphate (safe bronchodilator) or IV in acute asthma with poor response OR life-threatening/near-fatal
- Antibiotics in presence of infection
What are the 4 categorized types of acute asthma in terms of severity?
- Moderate acute
- Acute severe
- Life-threatening
- Near-fatal