COPD Flashcards
What is COPD characterised by?
Airflow obstruction Usually progressive Not fully reversible Does not change markedly over several months Predominantly caused by smoking
What is COPD?
An umbrella term encompassing emphysema and chronic bronchitis
Causes of COPD?
Smoking
α-1 antitrypsin deficiency
Occupational eg coal dust
Pollution
What does α-1 antitrypsin do?
Counteracts neutrophil elastase which breaks down alveoli
What is seen in spirometry of emphysema?
Reduced FEV
Reduced FEV1/FVC ratio
What is the pathological process of emphysema?
Destruction of the terminal bronchioles and distal airspaces
Leads to loss of alveolar surface area and therefore impairment of gas exchange
Progresses to bullae
Why is emphysema an obstructive disease?
Get destruction of tissue supporting the small airways
They therefore tend to close during expiration when the pressure outside the airway rises
Why in emphysema do you get hyperinflation of the lungs?
Loss of elastic tissue in the lung causes lungs to hyperinflate because lungs are unable to resist the natural tendancy of the ribcage to expand outwards
What is chronic bronchitis?
Chronic mucus hypersecretion that frequently occurs in smokers
What is the hypersecretion of mucus in chronic bronchitis caused by?
Inflammation in the large airways (normally due to cigarette smoke) leading to proliferation of mucus-producing cells in the respiratory epithelium.
What does the hypersecretion of mucus lead to?
Productive cough
Frequent respiratory infections
Why is chronic bronchitis an obstructive disease?
Get narrowing and remodelling of the airways
Symptoms of COPD?
Cough and sputum production
Progressive breathlessness
Exacerbations associated with increased breathlessness and increased cough and sputum production, often infective
Stages of the dyspnoea score?
- Only breathless on strenuous exercise
- Short of breath when walking uphill
- Walk slower than contemporaries on level ground due to breathlessness, or have to stop for breath when walking at own pace
- Stop for breath after walking 100m/few mins on level ground
- Too breathless to leave the house, breathless when dressing/undressing
Signs of COPD?
Purse-lip breathing
Tachypnoea
Prominent sternocleiodomastoid from accessory muscle use
Hyperinflation
Wheeze/quiet breath sounds on auscultation
Cyanosis and CO2 retention
Right heart failure with oedema in legs
What investigations are done in diagnosing COPD and why?
Spirometry - FEV1, severity of airflow obstruction
CXR to exclude other diagnoses
HRCT scanning to assess degree of alveolar destruction in emphysema
ABG to assess resp failure
α-1 antitrypsin blood test for younger patients
What drugs are used in treatment of COPD?
Bronchodilator - β2 agonists to cause relaxation of smooth muscle
Anticholinergics - synergistic with β2 agonists
Methylxanthines
Inhaled corticosteroids - reduce inflammation
Mucolytics - reduce thickness of sputum aiding airway clearance
How do methylxanthines work?
Inhibit phosphodiesterases which normally break down cAMP
So get increased cAMP -> bronchodilation
Also increase respiratory drive and increase strength of respiratory muscles
Anti-inflammatory
Side effects of β2 agonists?
Tachycardia Tremor Anxiety Palpitations Hypokalaemia
Side effects of anticholinergics?
Dry mouth Cough Sore throat Pharyngitis Upper respiratory tract infection Nausea Supraventricular tachycardia AF Urinary difficulty and retention Constipation
Name some anticholinergics
Atropine
Ipatropium
Tiotropium
Side effects of methylxanthines?
Tachycardia, SVT, nausea, seizures
Why do COPD patients need pulmonary rehabilitation?
They try to avoid physical activity which leads to increased social isolation and inactivity
Makes symptoms worse - deconditioning
What is pulmonary rehabilitation?
6-12 week programme of supervised exercise, unsupervised home exercise, nutritional advice and disease education
Why do some COPD patients require long-term oxygen therapy?
Extended periods of hypoxia can lead to renal and cardiac damage
How many hours a day is long term oxygen therapy (LTOT) required for?
16 hours to see a survival benefit
At what point is LTOT offered?
If pO2 falls below 7.3kPa consistently
Or
Below 8kPa with cor pulmonale
What requirements are there for patients before they can go on LTOT?
Non-smokers
Not retain high levels of carbon dioxide
What are the problems with LTOT?
Loss of independence
Reduced activity
Surgical options for COPD?
Lung volume reduction to reduce hyperinflation
Lung transplant in younger patients
Management of acute exacerbations of COPD?
Oxygen therapy to increase SATS to 88-92% Nebulisers - bronchodilators Oral/IV steroids Antibiotics if infective IV aminophylline Repeat ABG
