CT 10 - Airway Disease Flashcards
what is asthma
chronic inflammatory airway disease characterised by intermittent and reversible (either spontaneously or with treatment) airway obstruction, and hyper-reactivity)
triggers for asthma
viral or bacterial infections, allergens, food additives and chemicals, aspirin, occupational exposures etc)
exercise
cold air
strong emotions
what is the pathophysiology in an acute asthma attack
Early phase = initiated by IgE antibodies produced by plasma cells. Bind to mast cells and basophils and upon exposure to the trigger the cells release cytokines and degranulate. The chemical mediators released such as histamine, leukotrienes and prostaglandins cause contraction of smooth muscle leading to bronchoconstriction
Late phase = immune cells such as eosinophils, basophils and neutrophils migrate to lungs and facilitate further bronchoconstriction and inflammation.
Alongside this there is hypersecretion of mucous and plasma leakage leading to oedema
(dendritic cells present to T cells and produces IL-4 for differentiation of T cells into Th2 cells. tH2 release cytokines which attract eosinophils and promote B cell proliferation. b cells produce IgE which binds to mast cells to release histamine
what is status asthmaticus
severe, prolonged asthma attack that doesn’t respond to standard treatment, and can be life-threatening. Neutrophils are important with this, as they move to the airway, and
change the epithelium, airway tone, and autonomic neural control. This leads to hypersecretion of
mucus, mucociliary function alteration, and increased smooth muscle responsiveness
Risk factors for asthma
FHx
atopic triad
obesity
GORD
allergens
occupational exposures (spray painters, nurses, chemical industry workers, handling animals, hairdressers and timber workers at greatest risk)
S + S of asthma
Shortness of breath
Chest tightness
Dry cough
Wheeze
what drugs can worsen asthma
BB especially non selective like propranolol
NSAIDs
what is FEV1
volume that has been exhaled at the end of the first second of forced expiration
what is FVC
volume that has been exhaled after a maximal expiration following a full inspiration
what happens to FEV1, FVC AND RATIO
FEV1 = reduced
FVC normal
FEV1/FVC = <70%
what investigations for asthma
1) spirometry
2) FeNO ( >50ppb in adults and >35 in children older than 5)
3) reversibility testing: measure baseline. give salbutamol. remeasure, greater than 12% increase in FEV1 is positive
4) peak flow variability diary
5) direct bronchial challenge testing with inhaled histamine or methacholine.
Example of SABA
salbutamol
Normally binding of adrenaline to B2 receptors in the lungs causes smooth muscle relaxation. SABA works as an agonist at b2 receptors.
SE of SABAs
- tremor
- nervousness
- headaches
- palpitations
- muscle cramps
Example of inhaled corticosteroid
beclometasone
Used in patients whose asthma is not controlled by SABA alone
Taken everyday, regardless of whether the patient has symptoms
Side effects include oral candidiasis and stunted growth in children
Example of LABA
salmeterol
formeterol
act in same fashion as SABA but have longer half life.
- taken everyday regardless of symptoms (preventative)
LTRA’s
montelukast
muscarinic antagonists
- tiotropium
- ipratropium
ACh normally binds to M3 receptors within the airway causing SM contraction and secretion of mucus. these drugs act as antagonists at M3 receptors providing relief
what is MART
combined ICS and LABA treatment in which a single inhaler, containing both ICS and a fast-acting LABA, is used for both daily maintenance therapy and the relief of symptoms as required
1st line management for asthma
1) low dose ICS/formoterol combination
OR if severe exacerbation low dose MART
2) Low dose MART
3) mod dose MART
4) if feno or eosinophil count raised refer to specialist.
if not consider LTRA or LAMA in addition to mod dose MART
5) specialist if not under control despite above steps
management of asthma in children aged 5-11
First step
twice-daily paediatric low-dose inhaled corticosteroid (ICS) + short-acting beta2 agonist (SABA) as needed
2nd:
MART pathway or conventional pathway
COPD
- chronic bronchitis = long-term symptoms of a cough and sputum production due to inflammation in the bronchi
- emphysema = involves damage and dilatation of the alveolar sacs and alveoli, decreasing the surface area for gas exchange.
investigations for COPD
The following investigations are recommended in patients with suspected COPD:
post-bronchodilator spirometry to demonstrate airflow obstruction: FEV1/FVC ratio less than 70%
chest x-ray: hyperinflation, bullae, flat hemidiaphragm. Also important to exclude lung cancer
full blood count: exclude secondary polycythaemia
body mass index (BMI) calculation
management of COPD without asthmatic involvement
> smoking cessation advice: including offering nicotine replacement therapy, varenicline or bupropion
annual influenza vaccination
one-off pneumococcal vaccination
a short-acting beta2-agonist (SABA) or short-acting muscarinic antagonist (SAMA) is first-line treatment
add a long-acting beta2-agonist (LABA) + long-acting muscarinic antagonist (LAMA)
signs of severe COPD
very severe airflow obstruction (FEV1 < 30% predicted). Assessment should be ‘considered’ for patients with severe airflow obstruction (FEV1 30-49% predicted)
cyanosis
polycythaemia
peripheral oedema
raised jugular venous pressure
oxygen saturations less than or equal to 92% on room air
