Asthma and COPD Flashcards
what is asthma?
recurrent and reversible (in short term) obstruction to the airways due to an abnormal response to a stimulus
epidaemiology of asthma?
5-10% of population in industrialised countries
common in children
can be genetically predisposed (atopic)
what is the asthma triad?
reversible airflow obstruction
airway hyperresponsiveness airway hyperinflammation.
what changes does lung remodelling in chronic asthma cause?
Increased mucous production Thickening of smooth muscle Accumulation of interstitial fluid Epithelial damage resulting in exposed nerve endings Sub-epi fibrosis
what is the prognosis for untreated asthma?
Bronchoconstriction
Chronic airway inflammation
Airway remodelling
Inflammatory cascade
why does lung remodelling occur in chronic asthma?
chronic inflammation
how does an asthmatic present?
wheeze on expiration struggling to breathe tight chest cough dinural variability
which tests can be used in the diagnosis of asthma?
Spirometry
Challenge tests
Peak flow
Exercise testing
spirometry result of an asthmatic?
FEV1/FVC ratio reduced
FEV1 severly reduced
triggers for asthmatics?
dust, pet dander, hair, smoke cold exercise viral URI BB
describe the immune response in asthma attack
- Antigen
- Dendritic cell phagocystoses antigen and presents MHC-II receptors
- CD4 from Th2 cell interacts with MHC-II and antigen binds to TCR causing Th2 cell to release IL-4 and IL-5
- IL-4 acts on plasma cells to secrete IgE antibodies which trigger mast cells to degranulate (releasing inflammatory mediators)
- IL-5 acts on eosinophils to activate it to release leukotrienes + cytokines (to recruit) + proteases
what does the histamine and leukotrienes produced in the inflammatory response in asthma cause?
NARROWING OF AIRWAY BY:
- bronchoconstriction
- mucous hypersecretion + build up
- inflamed mucosa
- increased vascular permeability (bring more immune cells)
which pulmonary function tests do you use to diagnose an asthmatic when symptomatic vs asymptomatic?
symptomatic: spirometry + bronchodilator to relieve
asymptomatic: challenge tests
describe what you do to diagnose asthma in spirometry and what the results are.
measure FVC and FEV1 and calculate ratio (FEV1 reduced, ratio <80%)
then give bronchodilator and repeat (if FEV1 significantly improved then likely asthma - as shows reversible)
Describe what you would do in a challenge test for asthma.
Test FVC and FEV1
Give a bronchoconstrictor (eg: methacholine)
repeat tests and if worsens a lot then asthma
Treatment progression for asthma
Avoid triggers
- SABA
- ICS (low dose)
- LABA
- (med dose) ICS OR + LTRA
- (high dose) ICS OR + LTRA (if not already added) OR + tiotropium (LAMA) OR + theophylline (methylxanthine)
- monoclonal antibody therapy (rare)
acute asthma attack treatment?
- high flow O2 (60%)
- oral prednisolone (CS)
- nebulised high dose salbutamol (SABA) +/- ipratropium (SAMA)
- +/- IV aminophylline (methylxanthine)
what is COPD?
chronic obstructive pulmonary disorder causing airflow restriction on expiration which worsens over time
what is chronic bronchitis?
chronic inflammation of bronchi and bronchioles
what is emphysema?
loss of elastic recoil due to damage of alveolar sacs (causes hyperinflation)
what causes COPD?
smoking
air pollution
how do COPD patients present?
progressively worsening SOB
productive cough
maybe wheeze
recurrent infections
which investigations are used to diagnose COPD and why/results?
ABG (detect type 2 resp failure) CXR (see hyperinflation) CT scan Spirometry (FEV1/FVC ratio <70% and FEV1 reduced) MRC scale (assess dyspnoea) CAT (assess COPD severity as whole)
Treatment progression of COPD
- Smoking cessation
- Flu vaccine
- Pulmonary rehab
- SABA/SAMA (occasional symptoms)
- LABA/LAMA (1st line)
- +ICS
- PDE4 inhibitor
- macrolides
- O2 therapy
- surgery (lung vol reduction - reduce hyperinflation)
- transplant
