Obstructive Lung Disorder Flashcards
Male tidal volume
7ml/kg
About 560ml
Inspiratory Reserve
2-3L
Expiratory Reserve
1L
Dead space
Volume of respiratory tree that does not take part in gas exchange
Everything except terminal alveoli
Vital capacity woman
3-3.5L
Peak Flow
Used to monitor effectiveness of treatment
As treatment starts to work, it increases
Normal FEV1/FVC ratio
80-90%
Obstructive Lung Disease FEV1
Reduced due to narrowed airways
Obstructive Lung Disease FVC
Normal or nearly normal
Obstructive Lung Disease FEV1/FVC Ratio
Reduced
FEV1/FVC ratio Asthma
40%
FEV1/FVC ratio Mild obstruction
61-69%
FEV1/FVC ratio Moderate obstruction
45-60%
FEV1/FVC ratio Severe obstruction
<45%
Smoking
Replacement of elastin with collagen
Flow reduced
Reduces FEV1
Asthma essential features
Bronchoconstriction- airflow limitation
Hyper-secretion of mucus- clogs up airways + restricts flow more
Airway inflammation- chronic inflammation + oedema in those not managing asthma well
Asthma Diagnosis
Spirometry
Peak Flow
FEV1/FVC
Asthma Symptoms
Cough especially at night
Cough after exercise
Tightness after allergen exposure
Colds that last more than 10 days
Asthma signs
Wheezing during normal breathing Hyper-expansion of thorax Increased nasal secretions Allergic skin conditions REDUCED PEAK EXPIRATORY FLOW
Peak Expiratory Flow Asthma
Reduced
Substances that Trigger Asthma
Air pollutants Pollens, mites + moulds Animal dander Medication Foods
What causes Asthma
Inhaled particles act as antigens
Get trapped in mucus in airways
Bind to IgG antibodies on APCs
Stimulates CD4+ to release Interleukins 4+5
Interleukins stimulate B cells
B cells produce IgG antibody specific to antigen
Most common Ig
IgG
First Ig to be made
IgM
Ig least common in serum
Ig-E
Binds tightly to basophils + mast cells before interacting with antigen
Asthma Reaction MOA
T Cells release extra Interleukins- IL13
Stimulates B cells to become plasma cells- make IgE as well as IgG
Ig-E attaches to mast cells
Next time that specific antigen is inhaled, mast cells release histamine + pro-inflammatory cytokines (including prostaglandin)
Mast cell secretions cause..
Local inflammation- oedema
Bronchoconstriction
Mucus Secretion
Phosphodiesterase
Enzyme that breaks down cyclic AMP and cyclic GMP
Needed for release of pro-inflammatory mediators
Delayed Asthma Treatment
Repeated exposure- cytokines cause eosinophils + polymorphonuclear neutrophils (PMNs) to migrate into the lung tissue
Eosinophils stimulated- release enzymes that increase inflammation + epithelial damage
Stimulated Eosinophils
More powerful vagally mediated reflex bronchoconstriction
Increased mucus secretion
Damage epithelial cells- less cilia- less mucus moved
Bronchodilators
Beta 2 agonists
Anti-muscarinics
Phosphodiesterase inhibitors
Anti-inflammatory Drugs
Steroids
Leukotriene antagonists
Anti Ig-E agonists
Beta 2 agonists MOA
Mimic effect of adrenaline
Relieve acute symptoms
Short Acting Beta 2 agonists
Salbutamol
Terbutaline
Bitolerol
Fenoterol
Long Acting Beta 2 agonists (LABA)
Fermoterol
Bambuterol
Clenbuterol
Anti-muscarinics MOA
Block parasympathetic bronchoconstriction and mucus hypersecretion
Antagonise M3 muscarinic receptors
Anti-muscarinics examples
Ipratropium
Tiotropium
Phosphodiesterase inhibitors MOA
Prevent formation and release of pro-inflammatory cytokines from mast cells and eosinophils
Phosphodiesterase inhibitors
Theophylline
Aminophylline
Monoclonal Antibody
Omalizumab
Downregulates Ig-E receptors and stabilises mast cells
Used to control severe allergic asthma that doesn’t respond to high doses of corticosteroids
Magnesium
IV in emergencies
Reduces smooth muscle contractility
Antagonist to calcium
Corticosteroids
Reduce bronchoconstriction, oedema + mucus formation
Stimulation of beta-2 gene expression
Suppression of expression of inflammatory genes
Steroids
Help control asthma
Does not cure it
Corticosteroids example
Beclomethasone
Dipropionate
Fluticasone
Spacers
Improve penetration of inhaled drugs into lungs
Nebuilsers
Produce inhaled mist of medication
COPD
Chronic bronchitis + Emphysema combination
Chronic Bronchitis
Presence of chronic productive cough without discernible cause for more than half the time over two years
Chronic bronchitis features
Hypertrophy of bronchial glands
Hypersecretion
Mucous plugs
Infection/inflammation
Chronic bronchitis cause
Exposure to airborne irritants
Chronic bronchitis histology
Squamous cell proliferation
Massive mucous gland enlargement
Emphysema
Enlargement of airspaces distal to terminal bronchioles
Destruction of lung stroma- bullae
Floppy airways- cause obstruction
Smoking + emphysema
Stimulates polymorphonuclear leucocytes (PMN) to release serine elastase
Smoke inactivates elastase inhibitor alpha1-antitrypsin
Allows elastase to destroy elastic tissue of lung
COPD + asthma similarity
Wheezy bronchitis
COPD vs Asthma
COPD- non-reversible- actual damage to lungs
Asthma- reversible- symptoms can be reversed
COPD + flow-volume loops
Same inspiration
But expiration difficult –> top of x line is scooped, but below x is normal
Expiration ends prematurely
Inspiratory capacity reduced
Why is expiration bad in COPD
Expiration usually passive due to elastic recoil
Needs to be forced- much less