Lecture 8: COPD Flashcards
What is the definition of COPD?
COPD is predominantly caused by smoking and is characterised by airflow obstruction that is not fully reversible
The airflow obstruction (AFO) does not change markedly over several months but is usually progressive in the long term
Exacerbations often occur, when there is a rapid and sustained worsening of the patient’s symptoms beyond normal day-to-day variations
In COPD, where are the sites of AFO?
Large Airway damage - bronchitis
Small airway damage - small airways disease obstruction ‘The silent zone’
Alveolar damage - emphysema
What is chronic bronchitis?
Defined by symptoms
Epidemiological definition
- Sputum production for 3 months per year
- For at least two consecutive years
Histological correlate
- Hyperplasia of mucus glands
- Squamous metaplasia
What is emphysema?
Defined by pathology
Destruction of alveoli distal to terminal bronchiole
Loss of elastic supporting tissue
Gas exchange affected as well as AFO
What is a bulla?
All sacs broken down – big airspace – would likely have this surgically removed
What are the causes of COPD?
Smoking
Second Hand Smoke, especially in childhood
Globally: smoke inhalation from biomass fuels
Alpha-1 antitrypsin deficiency
Occupational: rail workers, coal miners, welders, painters, cleaners (but smoking is the main cause of COPD in all occupational groups)
What is a1-antitrypsin?
Alpha-1 antitrypsin (AAT) is aproteinthat is produced mostly in theliver
Its primary function is to protect thelungsfrom neutrophil elastase
Neutrophil elastase is an enzyme that normally serves a useful purpose in lung tissue - it digests damaged or aging cells and bacteria to promote healing
What is a1-antitrypsin deficiency?
Autosomal recessive inheritance
Homozygous PiZZ ~1 in 5,000
Not all develop emphysema
Smoking as co-factor, esp <40 years
~2% of all emphysema in UK
Minority also have liver disease
Heterozygotes not usually at risk if do not smoke
What are the typical symptoms of COPD?
Exertional breathlessness
Chronic cough
Regular sputum
Frequent winter bronchitis
Wheeze
Progressive SOB
Little/no reversibility
Constant symptoms
What are the risk factors of COPD?
> 35 years
Significant smoking history
What spirometry result would suggest COPD?
Post-bronchodilator FEV1/FVC < 70%
What FEV1 % of predicted suggests mild (stage1) COPD?
> 80%
What FEV1 % of predicted suggests moderate (stage2) COPD?
50-79%
What FEV1 % of predicted suggests severe (stage3) COPD?
30-49%
What FEV1 % of predicted suggests very severe (stage4) COPD?
<30
What are the physiological effects of COPD?
Increased work of breathing
Reduced exercise tolerance
Impaired gas exchange
- hypoxia
- hypercapnia
- raised pulmonary artery pressure
- salt and water retention, RV dilatation
- loss of Fat Free Mass
What is first line pharmacological treatment for COPD?
SABA or SAMA
If symptoms persist use combinations
What is the pulmonary rehabilitation scheme?
- Supervised exercise training
- Comprehensive educational programme
- Psychosocial support
2 per week for 6 weeks
What are the benefits to pulmonary rehabilitation?
Dyspnoea
Reduced SOB for a given amount or intensity of activity
Increased exercise capacity
Improved Health Related Quality of Life
Why are ICSs only used for COPD as last choice?
ICS associated with increased incidence of CAP
What are the benefits to inhaled therapy in COPD?
Reduce airflow obstruction
Reduce dynamic hyperinflation
Reduce symptoms
Reduce rate of exacerbations
When is LTOT indicated for COPD?
LTOT is indicated in patients with COPD who have a pO2 < 7.3 kPa when stable
OR
pO2 7.3 – 8kPa and have one of:
- secondary polycythaemia
- nocturnal
- hypoxaemia
- peripheral oedema
- pulmonary hypertension
