COPD Flashcards
(30 cards)
What is COPD?
A progressive lung disorder characterised by airflow obstruction:
1. Chronic bronchitis: chronic cough and sputum production on most days for at least 3 months per year over 2 consecutive years
2. Emphysema: pathological diagnosis of permanent obstructive enlargement of air spaces distal to the terminal bronchioles.
What is the prevalence/most commonly affected profile?
Very common (8%) of population, presents in middle age or late, more common in males
Describe aetiology
Chronic inflammation with neutrophilic infiltration and CD8+ T lymphocytes + macrophages
What is chronic bronchitis/emphysema characterised by?
CB:
1. Narrowing of the airways results in bronchiole inflammation (bronchiolitis)
2. Bronchial mucosal oedema
3. Mucous hypersecretion
4. Squamous metaplasia
Emphysema:
1. Destruction and enlargement of alveoli
2. Leads to loss of elasticity that keeps small airway open during expiration
3. Progressively larger air spaces develop known as bullae (>1cm diameter)
What are other causes of lung damage?
- Environmental toxins - predominantly affects upper lobes as they are better ventilated (smoking, air pollution, cadmium, coal etc)
- a1 antitrypsin deficiency - predominantly affects lower lobes (consider in young, never smoked patients with COPD like symptoms of cirrhosis and cholestasis)
What are symptoms of COPD?
Cough, often productive
Dyspnoea
Wheeze
RHF resulting in peripheral oedema
What would be revealed on chest inspection in a COPD patient?
Resp distress
Accessory muscle use
Barrel shaped over inflated chest
Decreased cricosternal distance
Cyanosis
Pursed lip breathing
Tar staining
What can be noticed on chest palpation and percussion?
Palpation:
- Decreased chest expansion
- Parasternal heave due to RV cardiomegaly secondary to cor pulmonale)
Percussion:
Hyper-resonance
Loss of liver/cardiac dullness
What can be noticed on chest auscultation?
- Quiet breath sounds
- Prolonged expiration
- Wheeze
- Rhonchi - rattling sounds caused by secretions in larger airways and obstructions
- Early inspiratory coarse crackles - infective exacerbation
What are signs of CO2 retention?
- Bounding pulse
- Warm peripheries
- Asterixis
- Signs of right heart failure (cor pulmonale) - right ventricular heave, raised jvp, ankle oedema
What are the 4 stages of COPD?
See table
What investigations are done for COPD?
- Spirometry
- ABG: Resp failure (hypoxaemia with or without hypercapnia)
- CXR
- FBC
- ECG
- Serum A1AT
- TLCO
What does a COPD CXR show?
- Flattened hemidiaphragms
- Horizontalisation of ribs
- More than 10 posterior ribs above diaphragm at MCL
Higher prominence of pulmonary vessels if pulmonary hypertension present.
How is COPD treated?
Start with SABA/SAMA
If features of steroid responsiveness present:
1. Graduate to LABA + ICS
2. LABA + LAMA + ICS
If features of steroid responsiveness not present:
1. LABA + LAMA
2. 3 month trial of LABA + LAMA + ICS
Oral theophylline may be used if symptoms not controlled.
What features suggest steroid responsiveness?
Asthmatic features
1. Previous diagnosis of asthma/atopy
2. Raised blood eosinophil
3. Substantial variation in FEV1 over time - 400ml
4. Substantial diurnal variation in PEF - over 20%
What are lifestyle aspects of managing COPD?
- Smoking cessation
- Encourage exercise + pulmonary rehab
- Vaccines - annual flu + one pneumococcal
- Depression screening
- Mucolytics like carbocysteine if chronic sputum production
- Long term oxygen therapy
What are smoking cessation medicines?
Varenicline + Bupropion
What is long term oxygen therapy and evidence for it?
PaO2 of above 8 maintained for 15 hours a day - 3 year survival increased by 50%
Who is long term oxygen therapy considered for?
- Non smoker on maximal treatment with consistent PO2 below 7.3
- Consistent PO2 between 7.3-8.0 with:
- Secondary polycythaemia
- Cor pulmonale
- Peripheral oedema
- Nocturnal hypoxia
What is hypoxic drive?
In someone with healthy lungs, stimulation to breathe comes from detection of high CO2 in the blood. However, in chronically hypercapnic people, body starts to use the hypoxic drive which kicks in when saturations are very low - therefore, usually have sats of around 92%.
What are surgical management options for COPD?
- Lung volume reduction: removes emphysematous tissue and helps the diaphragm contract more effectively to improve ventilation.
- Lung transplant - patients such as those with A1AD
- Bullae removal
What are bullae?
Focal areas of emphysema with smaller ones called blebs. Can encroach on lung tissue and worsen symptoms. May burst and cause pneumothoraces. Can also be caused by connective tissue disease.
What is alpha 1 antitrypsin and why is smoking particularly injurious?
Alpha 1 antitrypsin is made in the liver and breaks down elastase. Elastase damages connective tissue in the lungs (COPD) and liver (cirrhosis). Cigarette smoke inactivates A1AT so people with A1AD even more susceptible to damage from smoking.
Think of this in COPD symptoms, under 40, never smoked
How is alpha 1 antitrypsin deficiency diagnosed?
- Low serum A1AT
- Liver biopsy showing cirrhosis and acid-Schiff-positive staining globules
- Genetic testing for the A1AT gene
- High resolution CT thorax diagnoses bronchiectasis and emphysema
