Asthma and COPD Flashcards
What should be prescribed to asthmatic patients even if they are not experiencing symptoms
Inhaled SABA (for acute relief when needed) Inhaled corticosteroids
Symptoms of Asthma
Wheeze
Cough
dyspnea
Chest tightness
What are symptoms of asthma like
Intermittent; worse at night and when it’s cold
Type 1 hypersensitivity Mechanism
- Sensitization - first encounter of allergen
2. Allergic stage - re-encounter of allergen
Sensitization stage of type 1 hypersensitivity
- Neutrophils phagocytose and break down the proteins of the pathogen into small peptides and present it on MHC II molecules
- Specific CD4+ T cells become activated and differentiated into TH2 and TFH
- B cell bind to the antigen and TFH binds to the B cell, which fully activates the B cell
- TH2 cell release IL-4 and IL-13 to stimulate B cell to differentiate into plasma cells that produce IgE
- B cell proliferates and differentiates into plasma cells that produce IgM and IgE (mainly IgE)
- TH2 also release IL-5 to cause eosinophilia
- Allergen is cleared, remaining IgE binds to Fc receptors of mast cells and basophils
Allergic stage of type 1 hypersensitivity
- Re-encounter of allergen
- Allergen binds to IgE on mast cells and basophils, causing them to degranulate and release histamine and leukotriene
- Histamine and leukotrine both cause inflammatory response
In asthma, histamine causes
Bronchoconstriction
Mucous production
Mucosal oedema
In asthma, leukotrine causes
Attract eosinophils
Mucous production
Bronchoconstriction
Increase vascular permeability
Type 1 hypersensitivity features
eosinophilia
involvement of IgE
Treatment of asthma
Inhaled SABA for acute relief when needed
Inhaled corticosteroids as prophylaxis
Inhaled corticosteroid + inhaled LABA (if ICS is ineffective in controlling asthma attacks)
Increase dosage of ICS before adding leukotriene modifier
Omalizumab if still inadequately controlled
Drug treatment for acute asthma attacks
Inhaled SABA
Inhaled SABA + SAMA
oral prednisolone for severe attacks
Consider oxygen if hypoxic
Chronic inflammation of asthma attacks can cause
Remodeling of the airways
- smooth muscle hypertrophy
- collagen deposits
- thickening of basement membrane
Diagnosis of asthma
History - pets / family history of atopy
Spirometry - FEV1/FVC < 75%
Peak flow rate - less than 50-75% than expected
If suspect asthma, prescribe the patient 6months of inhaled corticosteroids. Measure the peak flow rate or spirometry before and after the drug treatment. If there is improvement, confirm diagnosis
Management of asthma
Remove pets (allergen)
Weight loss if needed
stop drugs such as NSAID /beta blockers
Triggers of asthma
Allergen Drugs (NSAID; aspirin /beta blockers) Alcohol Exercise Smoking
SABA
short acting beta agonists
acts on beta 2 receptors, causing bronchodilation
Examples of SABA
salbutamol
Albuterol
Terbutaline
Side effects of SABA
tremor (most common) tachycardia dry mouth cardiac dysrhythmia hypokalaemia
Uses of SABA
Acute relief for asthma attacks and COPD
Examples of inhaled corticosteroid
Beclomethasone dipropriate
fluticasone
Example of oral corticosteroid
prednisolone
methylprednisolone
COPD includes
chronic bronchitis
emphysema
chronic bronchitis
Excess mucus secretion
Mucociliary dysfunction
Bronchoconstriction
smooth muscle hypertrophy
Emphysema
destruction of alveolar attachments - these kept bronchioles patent
destruction of alveolar epithelium - reduce gas exchange
-alveolar sacs become larger -> reduce SA
COPD symptoms
Progressive breathlessness Persistent cough + sputum wheeze may be hypoxic frequent chest infections breathlessness on exertion
COPD mechanism
- Breathe in noxious gas / pollutants
- Activates macrophages which then secretes cytokines to attract neutrophils
- Neutrophils degranulate to release proteins
- elastase
- caspase
- matrix metlloproteinase - these proteins cause destruction of the alveolar wall and mucous hypersecretion
Exacerbation of COPD
Increased sputum production
Increased sputum purulence
dyspnea
Which organism most often cause infective COPD exacerbations
Haemophilus influenza
Diagnosis of COPD
History -smoking / family history of COPD Spirometry -FEV1/FVC < 0.7 -Post bronchodilator spirometry will show some improvements but still <0.7
What may be the cause of COPD in patients that do not smoke
alpha-1 antitrypsin deficiency
Drug treatment of COPD
Inhaled SABA or SABA + SAMA for relief of symptoms
Inhaled LABA + ICS for prophylaxis in patients that have asthmatic features
Inhaled LABA + LAMA for prophylaxis in patients that do not have asthma
Inhaled LABA + LAMA + ICS if still not controlled well
Oral carbocisteine (mucolytic) = easier to cough up mucus to ensure airway clearance
How can COPD lead to cor pulmonale
- Progressive airflow obstruction can lead to V/Q mismatch
- Lack of O2 causes vasoconstriction in pulmonary vessels
- This can cause pulmonary hypertension and increased vascular resistance
- This means that the left ventricle needs to pump harder to push blood into the lungs
- Overtime, it causes left ventricular hypertrophy and eventually cardiac failure
Management of COPD
Vaccination to prevent infective exacerbation
Smoking cessation
Examples of inhaled LABA
Salmeterol
olodaterol
formoterol
Examples of inhaled LAMA
Tiotropium
Aclidinium Bromide
Glycopyrronoium
Examples of SAMA
Ipratropium
LABA
Long acting beta agonist
LAMA
Long acting muscarinic antagonist
Mechanism of SABA and LABA
- Beta 2 agonist binds to Beta 2 receptor on airway muscles
- This causes the B2 receptor to attach to G proteins
- GDP is exchanged for GTP
- Gas + GTP detaches and moves to interact w adenylyl cyclase
- adenylyl cyclase converts ATP to cAMP
- cAMP phosphorylates PKE
- PKE inhibits myosin light chain kinase and stimulates myosin phosphatase to cause bronchodilation
Side effect of LABA
Tremor
Headache
Palpitations
Why is olodaterol only administered once a day
bc it is an ultra LABA
SABA is administered
maximum 4 times a day
Why is ipratropium not ideal to use
Because it is a non-selective muscarinic receptor antagonist
It can bind to M2 receptors on postganglionic neurone which can stimulate mroe secretion of ACh
SAMA binds to
M3 receptor
SAMA mechanism
Prevents bronchoconstriction by preventing ACh from binding to M3 receptors
Usage of corticosteroid
Anti-inflammatory effects and decrease immune response
Why do COPD patients have an increased risk of getting pneumonia when taking ICS
COPD predisposes patients to chest infections due to dysfunction of mucociliary escalator (chronic bronchitis). corticosteroids reduces immune response hence patients are more likely to catch pneumonia.
Long term consequence of COPD
Lack of O2 causes vasocontriction in pulmonary vessels, causing pulmonary hypertension
This makes it harder for right ventricle to pump blood into lungs
Overtime, right ventricle hypertrophy occurs and eventually right heart failure (cor pulmonale)
This can lead to congestion of blood in systemic venous system
leading to pleural transudate
Common side effect of inhaled corticosteroids
Oral candidiasis - oropharynx is erythematous and has white patches
This is because steroids suppress the immune system
Common spirometry finding in asthma attacks
FEV1 / FVC lower than 70%
FEV1 lower than normal
FVC unchanged
Management of acute exacerbation of COPD
Inhaled SABA + SAMA
oral prednisolone or IV hydrocortisone if severe
Antibiotics if infective
