COPD Flashcards
What is COPD?
Chronic obstructive pulmonary disease (COPD) is a non-reversible, long term deterioration in air flow through the lungs caused by damage to lung tissue.
This lung damage is almost always the result of smoking.
Big difference between asthma and COPD
Unlike asthma, this obstruction is not significantly reversible with bronchodilators such as salbutamol. Patients are susceptible to exacerbations during which there is worsening of their lung function.
Exacerbations are often triggered by infections and these are called infective exacerbations.
Symptoms
Long term smoker with:
- Shortness of breath
- Cough
- Sputum production
- Wheeze
- Recurrent resp infections esp winter
COPD does not cause clubbing, coughing up blood unusual
What is the 5 point NICE scale used to assess impact of breathlessness?
Grade 1 – Breathless on strenuous exercise
Grade 2 – Breathless on walking up hill
Grade 3 – Breathless that slows walking on the flat
Grade 4 – Stop to catch their breath after walking 100 meters on the flat
Grade 5 – Unable to leave the house due to breathlessness
How to diagnose
Based on clinical presentation + spirometry
Spirometry will show an “obstructive picture”
Therefore in COPD:
FEV1/FVC ratio <0.7
The obstructive picture does not show a dramatic response to reversibility testing with beta-2 agonists such as salbutamol during spirometry testing. If there is a large response to reversibility testing them consider asthma as an alternative diagnosis.
COPD Severity using FEV1
Stage 1: FEV1 >80% of predicted
Stage 2: FEV1 50-79% of predicted
Stage 3: FEV1 30-49% of predicted
Stage 4: FEV1 <30% of predicted
Other investigations
Chest xray to exclude other pathology such as lung cancer.
Full blood count for polycythaemia or anaemia. Polycythaemia (raised haemoglobin) is a response to chronic hypoxia.
Body mass index (BMI) as a baseline to later assess weight loss (e.g. cancer or severe COPD) or weight gain (e.g. steroids).
Sputum culture to assess for chronic infections such as pseudomonas.
ECG and echocardiogram to assess heart function.
CT thorax for alternative diagnoses such as fibrosis, cancer or bronchiectasis.
Serum alpha-1 antitrypsin to look for alpha-1 antitrypsin deficiency. Deficiency leads to early onset and more severe disease.
Transfer factor for carbon monoxide (TLCO) is decreased in COPD. It can give an indication about the severity of the disease and may be increased in other conditions such as asthma.
Step Two Management - No asthma
If they do not have asthmatic or steroid responsive features they should have a combined long acting beta agonist (LABA) plus a long acting muscarinic antagonist (LAMA).
“Anoro Ellipta”, “Ultibro Breezhaler” and “DuaKlir Genuair” are examples of combination inhalers.
Step Two Management - Asthma
If they have asthmatic or steroid responsive features they should have a combined long acting beta agonist (LABA) plus an inhaled corticosteroid (ICS). “Fostair“, “Symbicort” and “Seretide” are examples of combination inhalers.
If these don’t work then they can step up to a combination of a LABA, LAMA and ICS. “Trimbo” and “Trelegy Ellipta” are examples of LABA, LAMA and ICS combination inhalers.
Severe cases treatment:
Nebulisers (salbutamol and/or ipratropium)
Oral theophylline
Oral mucolytic therapy to break down sputum (e.g. carbocisteine)
Long term prophylactic antibiotics (e.g. azithromycin)
Long term oxygen therapy at home
When is long term oxygen therapy used?
Long term oxygen therapy is used for severe COPD that is causing problems such as chronic hypoxia, polycythaemia, cyanosis or heart failure secondary to pulmonary hypertension (cor pulmonale). It can’t be used if they smoke as oxygen plus cigarettes is a significant fire hazard.
What triggers exacerbation of COPD?
It is usually triggered by a viral or bacterial infection.
What is respiratory acidosis?
Remember that CO2 makes blood acidotic by breaking down into carbonic acid (H2CO3). Low pH (acidosis) with a raised pCO2 suggests they are acutely retaining (not able to get rid of) more CO2 and their blood has become acidotic. This is a respiratory acidosis.
What does raised bicarbonate indicate?
Raised bicarbonate indicates they chronically retain CO2 and their kidneys have responded by producing more bicarbonate to balance the acidic CO2 and maintain a normal pH.
In an acute exacerbation, the kidneys can’t keep up with the rising level of CO2 so they become acidotic despite having a higher bicarbonate than someone without COPD.
What are the different types of respiratory failure?
Low pO2 indicates hypoxia and respiratory failure
Normal pCO2 with low pO2 indicates type 1 respiratory failure (only one is affected)
Raised pCO2 with low pO2 indicates type 2 respiratory failure (two are affected)
