Asthma intro Flashcards
Asthma definition
reversible increases in airway resistance, involving bronchoconstriction and inflammation
Characteristics of asthma
reversible decreases in FEV1:FVC
variations in PEF which improve with β2 agonist
decreases in FEV1, reversed by β2 agonist
What is COPD
chronic obstructive pulmonary disease
blanket term for chronic bronchitis and emphysema
obstructed airflow form the lungs
Chronic bronchitis
increased mucus, airway obstruction, intercurrent infections, airways permanently narrowed
Characteristics of COPD
FEV1 reduced, difficult to reverse
little variation in PEF
Clinical features of asthma
wheezing
SoB
tight chest
cough (chronic, worse at night/exercise)
What would be seen on a normal and asthmatic lung function test graph?
y axis: volume (L)
x axis: time (s)
normal - steep increase, plateau
asthma - steep increase which begins to plateau sooner but gradually rises to same level of normal line
Cause of asthma symptoms
stimulus causes mast cells and mononuclear cells in the lungs to release mediators:
spasmogens - immediate, bronchospasms
chemotaxins - later phase, inflammation
Examples of spasmogens
histamine
from arachidonic acid in the membrane: leukotrienes and prostaglandins
platelet activating factor
Examples of chemotaxins
leukotriene B4, PAF
What do chemotaxins do?
attract leukocytes (especially eosinophils and mononuclear cells) to lungs causes inflammation and airway hyper-reactivity
Types of medication to treat asthma
- bronchodilators - ‘relievers’
2. preventers - may be anti-inflammatory
Preferred short acting bronchodilator
salbutamol (Ventolin)
β2-adrenoceptor agonist
Action of salbutamol
bind to β2-adrenoceptors on smooth muscle
adenyl cyclase -> cAMP
relaxation
Effect of salbutamol
short acting
reduces parasympathetic activity
increases FEV1
prolonged use may lead to receptor down-regulation
What is a LABA?
long acting β agonist
eg. salmeterol
given for long-term prevention and control (ie.overnight)
preventer
What are xanthines?
bronchodilators, 2nd line use
phosphodiesterase inhibitors
taken orally
Example of xanthine
theophylline
Action of xanthines
inhibit PDE, inhibiting breakdon of cAMP , therefore effect of salbutamol is enhanced and relaxation increased
Give an example of a muscarinic M-receptor antagonist
ipratropium
Action of ipratropium
block parasympathetic bronchoconstriction on muscarinic receptors
How is ipratropium used?
inhaled to prevent antimuscarinic side effects (blurred vision, constipation)
asthma: only in emergency
mostly used in COPD
Example of corticosteroid
beclometasone
What are corticosteroids?
anti-inflammatory agents
preventers
Action of corticosteroids
activate intracellular receptors, leading to altered gene transcription
decrease in cytokine production and production of lipocortin
Action of lipocortin
protein which inhibits synthesis of prostaglandins and leukotrienes
(chops up membrane so reduced arachidonic acid)
Pros and cons of prescribing steroids
\+ given with β2 agonists, reduces receptor down -regulation
- side effects: throat infections, hoarseness (inhalation)
adrenal suppression (oral)Example of leukotriene receptor antagonist (LTRA)
montelukast
Action of LTRAs
preventative and bronchodilator
antagonise actions of leukotrienes
Example of monoclonal antibodies
omalizumab
Action of omalizumab
prevents free IgE from binding to immune cells, preventing allergen-induced mediator release in allergic asthma
Describe stepped care
short acting β2 agonist and regular inhaled steroid
trial of LABA (or LTRA or xanthine)
increased dose of inhaled steroid
add oral steroid
How to know when to step up treatment from initial
if salbutamol is used more than twice a week
Use of spacer devices
patients with poor technique
reduce steroid impactation on back of throat, reduces side effects
How to take medication
bronchodilator before steroid - helps to get steroid to lungs
rinse mouth out after steroid - reduce side effects
Treatment for COPD
advice: stop smoking
bronchodilators (β2 agonists + ipratropium)
antibiotics for intercurrent infections
oxygen therapy
What are NSAIDs
non-steroidal anti-inflammatory drugs
Example of NSAIDs
aspirin, ibuprofen
How can NSAIDs affect asthmatics?
may provoke asthma by increasing LT production as PTGs inhibited
How can β blockers affect asthmatics and people with COPD?
can cause bronchoconstriction due to non-selectivity and bind to β2 adrenoceptors
therefore are contrindicated for asthma and caution in COPD
