COPD Flashcards
Define emphysema. What are the pathological features?
Pathological destruction of terminal bronchioles and distal airspaces leading to a loss of alveolar surface area and impaired gas exchange
- development of large, redundant airspaces (bullae)
(reduced diffusion capacity) - destruction of supporting tissue surrounding small airways due to increased mucus secretion & cilia dysfunction due to smoke
(so airways close during expiration -> airflow obstruction) - loss of elastic tissue due to inflammation (lungs cannot resist expansion of rib cage during inspiration, causing hyperinflation of lungs —> reduced diffusion capacity)
What is the definition of chronic obstructive pulmonary disease?
Disease characterised by airflow obstruction that is progressive, not fully reversible, and does not change markedly over several months.
Predominantly caused by smoking.
Encompasses emphysema and chronic bronchitis.
Define chronic bronchitis. What are the clinical features?
Chronic inflammation of bronchioles leading to chronic mucus hypersecretion
(inflammation -> proliferation of goblet cells -> excessive mucus secretion)
Results in remodelling and narrowing of the airways, causing airflow obstruction (fibrosis + inflammatory infiltrate + mucus)
- chronic productive cough
- frequent upper resp. tract infections
Give some examples of causes of COPD.
SMOKING (15% of smokers get COPD - even after stopping smoking)
- alpha-1-antitrypsin deficiency (chemical protective against neutrophil elastase)
- occupational exposure e.g. coal dust
- pollution
+ low birth weight
+ adenovirus/HIV infection
What are the key signs and symptoms of COPD?
Older patient, onset of symptoms in later life
- cough & sputum production
- breathlessness (persistent & progressive & associated with exacerbations e.g. infection)
- “purse lip” breathing (increases pressure within airways, so reduces/delays airway closure)
- tachypnoea
- use of accessory muscles (including neck muscles)
- barrel chest (hyperinflation of lungs)
- wheeze/quiet breath sounds on auscultation
- advanced: cyanosis, O2 retention, right heart failure (cor pulmonale), oedema
How is the degree of breathlessness assessed?
Breathlessness graded via MRC dyspnoea score:
- Not breathless except on strenuous exercise
- Short of breath when hurrying/walking up a slight hill
- Walks slower on level ground or has to stop for breath
- Stops for breath after ~100m/few minutes on level ground
- Too breathless to leave the house/breathless when dressing
How is COPD diagnosed?
!Measurement of airflow obstruction necessary for diagnosis!
- FEV1 < 80% = limitation of flow of air during expiration + collapse of airways
- FEV1/FVC < 70%
note: FEV1 decline can be slowed by stopping smoking
note: symptoms not always worsen with reduced FEV1
- CXR (to exclude other causes)
- HRCT (high resolution computed tomography): assess the degree of macroscopic alveolar destruction in emphysema - helpful when considering surgery
- ABG (assess resp. failure)
- alpha-1-antitrypsin blood test (young patient with symptoms to check for deficiency)
What is the management for stable COPD?
- SMOKING CESSATION
- pulmonary rehabilitation (exercise, nutritional advice, education, peer support)
- bronchodilators (symptomatic relief by reducing hyperinflation)
- antimuscarinics e.g. ipratropium, tiotropium
- steroids (reduce inflammation)
- mucolytics e.g. carbocysteine (reduce thickness of sputum so it is easier to clear airways)
- methylxanthines e.g. theophylline, aminophylline: inhibit phosphodiesterases (increased c.AMP causes bronchodilation, increased resp. drive, increased strength of resp. muscles, anti-inflammatory)
- education on inhaler technique
- long term O2 therapy (non-smokers who do no retain CO2)
- surgery: lung transplant (if <60yrs), lung volume reduction
Give some examples of some side-effects of beta-2-agonists.
Tachycardia (atrial beta-2 receptors) Tremor (skeletal beta-2 receptors) Anxiety Palpitations Hypokalaemia (K+ uptake in skeletal muscle)
Give some examples of side-effects of anticholinergics.
LOCAL: dry mouth/cough, sore throat, pharyngitis, upper resp. tract, infection, bitter taste, nausea, acute glaucoma
SYSTEMIC: supraventricular tachycardia, AF, urinary difficulty/retention, constipation
Give some examples of side effects of methylxanthines.
Tachycardia, supraventricular tachycardia, nausea, seizures
measure conc. of drug in blood when using
Give some examples of side effects of steroids (above 800ug/oral).
Thin skin, bruising, cataracts, adrenal insufficiency (reset of adrenal axis -> prevent by slowly reducing steroid dose instead of stopping completely), osteoporosis, diabetes, fluid retention, mental disturbance, GI symptoms, proximal myopathy
What is deconditioning in the context of COPD?
Breathlessness -> avoid exercise -> weakened muscles -> increased breathlessness -> depression -> avoid exercise etc.
Hence why pulmonary rehabilitation is so important
What are the diagnostic criteria for prescribing long term O2 therapy for COPD?
Only improves survival if pO2<8kPa + cor pulmonale
Only for non-smokers (O2 canister is combustible)
Prevents cardiac & renal damage due to extended hypoxia
Reduces independence & activity
What is the management for acute exacerbation of COPD?
O2 therapy to increase O2 sat. to 88%-92% Bronchodilators Oral/IV steroids Antibiotics (if caused by infection) ?IV aminophylline Repeat ABG ?BIPAP
