COPD Flashcards
Describe COPD
Chronic obstructive pulmonary disease
Characterised by airflow obstruction
Obstruction is usually progressive, not fully reversible and does not change markedly over several months
Umbrella term for emphysema and chronic bronchitis
Describe emphysema
Pathological destruction of terminal bronchioles and alveoli
Loss of alveolar SA, impairs gas exchange
Often progresses to development of large, redundant air spaces (bullae)
Destruction of supporting tissue (collapse during expiration)
Loss of elastic tissue (tend to hyperinflate - Barrel chest)
Describe chronic bronchitis
Chronic mucus hypersecretion Frequently in smokers Inflammation in the large airways Proliferation of mucus producing cells Chronic productive cough Frequent resp infections Air flow obstruction due to remodelling
Name some causes of COPD
Smoking (commonest)
Alpha 1 antitrypsin deficiency
Occupational exposure (coal, dust)
Pollution
Approximately what percentage of smokers develop COPD?
15%
What are the symptoms of COPD?
Cough
Sputum production
Breathlessness
What is the MRC dyspnoea score?
Grade of breathlessness
Describe the stages of the MRC dyspnoea score
- Not troubled except on strenuous exercise
- Short of breath when hurrying or walking up a slight hill
- Walks slower on level ground because of breathlessness or has to stop for breath when walking at own pace
- Stops for breath after walking about 100m or after a few minutes on level ground
- Too breathless to the leave the house or breathless when dressing/undressing
What are the signs of COPD?
Purse lip breathing Tachypnoea Using accessory muscles Hyperinflation Wheeze/reduced breath sounds Advanced = cyanosis, CO2 retention, RH failure with oedema
Why does a COPD patient purse their lips on breathing?
Protective manoeuvre that increases pressure within the airways
Reduction/delay in closure therefore easier to breathe out
What is essential for diagnosing COPD?
A measurement of airflow obstruction
Spirometry
How is spirometry performed and what does it measure?
Blow out as hard and as much as possible into a sealed tube
FEV1 and FVC measured
Obstruction in COPD leads to a FEV1/FVC ratio of …
< 70%
What ratio from spirometry would suggest mild obstruction?
50-80% predicted
What ratio from spirometry would suggest moderate obstruction?
30-49% predicted
What ratio from spirometry would suggest severe obstruction?
<30% predicted
What features of a Hx are most suggestive of COPD?
Smoker/ex-smoker
Older patient (>40 years)
Chronic productive cough
Breathlessness that is persistent and progressive
How is a COPD Hx different to asthma?
Likely to be smoker Rare to get it <40 years Chronic productive cough Progressive and persistent breathlessness Unlikely to wake you up at night No diurnal variation
What investigations would we do for COPD?
CXR (mandatory to rule out other diagnoses)
CT - detailed assessment of degree of destruction
ABG - assess for resp failure
Alpha 1 antitrypsin blood test (younger people)
Describe the COPD care bundle (Mx)
Smoking cessation Pulmonary rehab Bronchodilators Antimuscarinics Steroids Mucolytics Diet supplements Supportive things eg. Flu vaccine
What do we consider as management for severe COPD patients?
Long term oxygen therapy
Lung volume reduction (surgery)
Describe how beta 2 agonists work in obstructive diseases
Bind to beta 2 adrenoreceptors Activates adenyl cyclase Increased production of cAMP Activates PKA Phosphorylation of targets Inhibits SM contraction Relaxation of SM occurs
What are some of the adverse side effects of beta 2 agonists?
Tachycardia/palpitations
Tremor
Anxiety
Hypokalaemia
How do methylxanthines work?
Bronchodilation
Increased respiratory drive
Anti-inflammatory effects
Inhibition of phosphodiesterase to promote SM relaxation
Give some side effects of long term steroid use
Thin skin/easy bruising Cataracts Adrenal insufficiency GI symptoms Oestoporosis Diabetes Increased weight Mental disturbance
What is pulmonary rehabilitation?
Exercise programme run at hospital 6 weeks All supervised Be able to walk further and easier Give advice on disease Peer support
Describe deconditioning
A viscous cycle of increasing social isolation and inactivity leading to worsening of symptoms
When would we offer long term oxygen therapy for COPD?
If partial pressure oxygen consistently < 7.3 kPa
Non-smokers
Not retain high levels of carbon dioxide
How long do you need to be on oxygen per day to confer a survival advantage?
At least 16 hours/day
What is the management for acute exacerbation of COPD?
Bronchodilators via nebulisers Steroids Abx if infective features Consider IV aminophylline Repeat ABG to check improvement
When would we use non-invasive ventilation (BIPAP) in COPD?
Useful for acute exacerbation
With type 2 resp failure
And mild acidosis
Why is the BIPAP machine not always a good option?
Patient must be conscious to use it
Need to breathe in sync with the machine
Name some contraindications of non-invasive ventilation
Untreated pneumothorax (can make worse) Impaired conscious level (GCS<8) Upper airways secretions +++ Constant cough Facial injury Vomiting Agitated Life threatening hypoxia
