COPD Flashcards
What id the definition of COPD? (WHO)
preventable and treatable disease characterised by persistant respiratory symptoms and air flow limitation and/or alveolar abnormalities, usually caused by significant exposuire to noxious particles or gases. Exacerbations and comorbidities contribute to the overall sevcerity in individual patients.
What is the GOLD 2023 definition of COPD?
Chronic obstructive pulmonary disease is a heterogenous lung condition characterised by chronic respiratory symptoms due to abnormalities in the airways (bronchitis, bronchioloitis) and/or alveoli (emphysema) that cause persistant, often progressive airflow obstruction
What chronic respiratory symptoms generally present in COPD?
- dyspnea (medical word for short of breath)
- Cough
- Sputum production
What symptoms prompt initial seekign of medical attention in COPD?
can’t run like before, feeling very breathless from activities that didn’t used to be so difficult, coughing and difficulty expelling mucus. Feeling cold
Clear exacerbations such as frominhaling pollution from cars, second hand smoke etc
What is the prevalence of COPD in the UK?
2% of the population (1.17 million people).
Globally 6%.
What are the missing millions referring to in COPD statistics?
About 2 million people likely to be walking around with COPD who are undiagnosed and have not sought medical treatment
What community and environmental factors directly relate to prevalence of COPD?
Prevalence is directly related to prevalence of risk factors in the community e.g. tobacco smoke, coal dust exposure, use of biomass fuels and age of population being studied.
95% of UK cases due to tobacco smoke exposure and is the most significant risk factor for COPD and is a dose response to duration and quantity smoked.
Unusual to get COPD from less than 10 pack years (1 pack year = 20 cigs/day for a year). There is individual susceptability.
List noted environmental factors for developing COPD?
- indoor air pollution - cooking with biomass fuels in low income countries (i.e. Kyrgyzstan)
- Occupational exposures - coal dust, silica, cadmium
- Low birth weight - may reduce maximally attained lung function in young adult life - there is an established link between COPD and low birth weight.
- Lung growth - childhood infections or maternal smoking may affect growth of lung during childhood = a lower maximally attained lung function in adult life
- Infections - recurrent infection can accelarate decline in FEV1 - persistant adenovirus in lung tissue can alter inflammatory response = predisposing to lung damage; HIV infection is associated with emphysema
- Low socioeconomic status
- Cannabis smoking
What host factors are associated with COPD development?
- Genetics - Alph-1-trypsin deficiency
- Airway hyperreactivity
What are the 2 main conditions under the umbrella term COPD?
- Bronchitis
- Emphysema
What is emphysema?
Destruction of the alveoli leading to abnormal and permanent enlargement of the airspaces distal to the terminal bronchioles, accompanied by the destruction of their walls.
How is chronic bronchitis defined?
a cough and sputum for >3 months in each of 2 consequtive years
What are the names of the 3 enlarged air spaces in COPD?
- Centriacnar
- Panacinar
- Paraseptal
What is a bullae and what impact does it have on breathing?
Bullae = a permanent air filled space within the lung that is >1 cm in diameter.
Results in impaired gas exchange and respiratory failure.
Describe simple pathophysiology of COPD
Pulmonary + systemic components.
The presence of airflow limitation combined with premature airway closure leads to gas trapping and hyperinflation - adversely affects pulmonary and chest wall compliance.
Pulmonary hyperinflation flattens diaphragmatic muscles and leads to an increasingly horizontal alignment of muscles= mechanical disadvantage for breathing ability.
Therefore the work of breathing is increased - initially on exercise when the time for expiration is further shortened and then with disease progression, at rest.
Describe the pathophysiology of Bronchitis
- Irritants enter the airway
- Mucus glands hypertrophy (get bigger)
- Leads to an increase in mucus gland secretion
- Increases polymorphism in the promoter region of inflammatory mediators in the airways
- Airways narrow (especially in bronchioles)
Describe the pathophysiology of Emphysema
- Loss of cell walls of alveoli leading to reduced surface area for gas exchange
- There is a loss of elastic supporting tissue as it starts to disintegrate
- Leads to hyperinflation (barrel shaped chest)
- As a result patients can become very hypoxic
Describe the inflammatory mechanisms involved in COPD
- Irritant enters airways
- Comes into contact with epithelial cells of airways, which activates the CD8 lymphocyte and neutrophils
- CD8 lymphocyte and neutrophil stimulates the destruction of alveolar wall destruction, proteases and fibroblast proliferation
- CD8 inhibits mucus hypersecretion
- The fibroblasts stimulate abnormal tissue repair
- Irritant stimulates macrophage response. Neutrophil chemotactic factors, cytokines and mediators.
- These can also react with oxidants which then inhibit protease inhibitors which inhibits proteases which stimulates alveolar wall destruction , and also stimulates alveloar wall destruction directly as well as mucus hypersecretion
What are some of the consequences of herpinflation in COPD?
- reduced ventilation
- Type 2 respiratory failure = respiratory muscles get stretched so don’t work effectively.
What are some of the consequences of Emphysema in COPD?
- reduced gas exchange
- hypoxia
- Typ1 1 respiratory failure
What are some of the consequences of Bronchitis in COPD?
Airway inflammation causes hyperinflation and sputum production
What are some of the consequences of exacerbations in COPD?
- development of resistant infections due to being on so many antibiotics for infections that they become antibiotic resistant
- hospitalisation
What are some of the systemic consequences of COPD?
- muscle weakness and cachexia
- heart failure
- pulmonary hypertension
- weight changes - excess and weight loss
- Metabolic syndrome
- Cardiovascular disease
- Osteoporosis
- Depression
- Lung Cancer
- Systemic inflammation: Cytokine IL-6 and TNF-alpha
WHat is the difference between type 1 and type 2 respiratory failure?
Type 1 = 1 problem of low oxygen levels (hypoxic)
Type 2 = Type 1 + hypercapnic (high levels of carbondioxide levels circulating)
Describe pulmonary features of COPD
- Pulmonary vascular remodelling and impaired cardiac performance
- Enlargement of mucus-secreting glands (hypertrophy) and an increase in the number of goblet cells, accompanied by an inflammatory cell infiltrate resulting in increased sputum production = leading to chronic bronchitis
- Loss of elastic tissue, inflammation and fibrosis of the airway wall resulting in premature airway closure, gas trapping and dynamic hyperinflation leading to changes in pulmonary and chest wall comliance.
- Unopposed action of proteases and oxidants leading to destruction of alveoli and appearance of emphysema
Describe systemic features of COPD
- Muscular weakness reflecting deconditioning and cellular changes in sekeletal muscles
- Increased circulating inflammatory markers
- Impaired salt and water excretion leading to peripheral oedema
- Altered fat metabolism contributing to weight loss
- An increased prevalence of osteoporosis
How is COPD diagnosed?
- Patient lifestyle and symptom history
- Clinical signs and symptoms
- Sputum test
- Walking test (how far can they walk in a certain time frame) (VO2max)
- Spirometry
What is heamoptysis and what implications does it have on COPD?
Haemoptysis = coughing up of blood.
May complicate COPD exacerbations.