COPD Flashcards
What is COPD?
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.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.
How does COPD present?
chronic shortness of breath, cough, sputum production, wheeze and recurrent respiratory infections, particularly in winter.
differential diagnoses such as lung cancer, fibrosis or heart failure. COPD does NOT cause clubbing. It is unusual for it to cause haemoptysis (coughing up blood) or chest pain.
How is the MRC scale used for dyspnoea?
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 is COPD diagnosed?
- Clinical
- Spirometry
- FEV1/FVC ratio <0.7
-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.
How can we grade the severity of 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
Long term management?
-Short acting bronchodilators: beta-2 agonists (salbutamol or terbutaline) or short acting antimuscarinics (ipratropium bromide).
-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)
- asthmatic or steroid responsive features they should have a combined long acting beta agonist (LABA) plus an inhaled corticosteroid (ICS).
What do you give in severe cases?
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
What happens to ABGs in COPD?
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.
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.
How do we distinguish 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)
Oxygen therapy in COPD?
If retaining CO2 aim for oxygen saturations of 88-92% titrated by venturi mask
If not retaining CO2 and their bicarbonate is normal (meaning they do not normally retain CO2) then give oxygen to aim for oxygen saturations > 94%
Medical treatment in COPD exacerbation?
Prednisolone 30mg once daily for 7-14 days
Regular inhalers or home nebulisers
Antibiotics if there is evidence of infection
In hospital:
Nebulised bronchodilators (e.g. salbutamol 5mg/4h and ipratropium 500mcg/6h)
Steroids (e.g. 200mg hydrocortisone or 30-40mg oral prednisolone)
Antibiotics if evidence of infection
Physiotherapy can help clear sputum
Options in severe cases not responding to first line treatment:
IV aminophylline
Non-invasive ventilation (NIV)
Intubation and ventilation with admission to intensive care
Doxapram can be used as a respiratory stimulant where NIV or intubation is not appropriate
