Summary

COPD is an umbrella term for several diseases characterised by airflow obstruction, most commonly chronic bronchitis and emphysema, but also including bronchial asthma and brochiectasis.
COPD is distinguished from restrictive pulmonary disease, a group of disorders characterised by decreased lung capacity due to either chest wall or skeletal abnormalities, where FEV1 and FVC are both decreased proportionately, resulting in a normal FEV1:FVC.
  • In COPD the FEV1:FVC ratio is <70%

General info

Epidemiology

  • Prevalence is approximately 1.5 million and mortality is 23,000/year in the UK
  • By 2020 it is likely to be the 3rd highest cause of death worldwide
  • Smoking accounts for 90-98% of all cases
  • Number of cases has stabilised in men, but is rising among women
  • Most commonly seen in ex-smokers > 35 years of age
  • COPD is unlikely to develop with a smoking history less than 10 pack years
  • Low socioeconomic status and low birth weight are predisposing factors

Causes

  • Smoking
  • Coal mining
  • Genetic, i.e. α1 –antitrypsin deficiency causes emphysema

Signs and symptoms

  • Tachypnoea
  • Use of accessory muscles of respiration
  • Hyperinflation caused by gas trapping
  • Reduced cricosternal distance , <3cm
  • Reduced chest expansion
  • Resonant chest sounds
  • Quiet breath sounds over areas of emphysematous bullae
  • Wheeze
  • Cyanosis
  • Cor pulmonale
  • Prolonged expiration
  • Pursed lip breathing
  • Dyspnoea
  • Cough, productive or non-productive
  • Regular exacerbations
  • Weight loss – a sign of very poor prognosis

Investigations

  • Lung function  – FVC<80% predicted; FEV1/FVC<0.7; increased residual volume
  • CXR – possibly hyperinflation, but often normal; flat hemidiaphragms; large central pulmonary arteries, decreased peripheral vascular markings; bullae; cylindrical heart
  • ECG– right atrial and ventricular hypertrophy suggestive of cor pulmonale, leading to large p waves on ECG p pulmonale
  • ABG – in advanced disease decreased Pa O2, increased PaCO2
  • Tests for α1-antitrypsin – haematocrit >45; normocytic normochromic anaemia; HB and PCV may be raisedsecondary polycythaemia
  • Gas transfer – reduced
  • Spirometry– varies from ≥80% in mild disease to <30% in very severe disease

Complications

  • Respiratory failure
  • Cor pulmonale

Treatment of acute exacerbation

  • Give controlled O2 therapy beginning at 24%, increasing to 28% if after 20 minutes ABGs demonstrate a steady or decreased PaCO2.
  • If PaCO2 has risen > 1.5kPa give doxapram or assisted ventilation.
  • Give nebulised salbutamol and ipratropium, and if measures are unsuccessful consider non-invasive ventilation.
  • Also give a 5-7 day course of prednisolone 40mg.
  • Treat the cause, which is usually a chest infection most commonly caused by Streptococcus pneumonia or Haemophilus influenza, i.e. give antibiotics if 2 or more of the Anthonisen criteria are met.

 

Management of long-term disease

  • Smoking cessation
  • Long-term oxygen therapy – give 2L via nasal prongs for at least 15 hours per day
    • Known as LTOT – long term oxygen therapy
  • Nebulizer –  salbutamol, ipratropium
  • Surgery, i.e. bullectomy in those who have large emphysematous bullae, or lung transplant in those with end-stage emphysema.
  • Exercise training
  • Diet – to promote weight gain if weight loss experienced

Chronic bronchitis

This is defined as cough and sputum production on most days for at least 3 months during the last two years.

Pathology

  • Hypersecretion of mucus due to marked hypertrophy of mucus-secreting glands and hyperplasia of goblet cells
  • Initially small airways are affected and this initial inflammation is reversible, whereas in later stages larger airways become affected and the process is no longer reversible
  • Epithelial layer becomes ulcerated and squamous epithelium may be replaced by columnar cells, resulting in increased gas diffusion distance

Emphysema

Emphysema is enlarged airspaces distal to the terminal bronchioles, with destruction of the alveolar walls causing decreased elastic recoil. 

Pathology

  • Abnormal dilation of air spaces with destruction of alveolar walls
  • Inflammation and scarring, reducing size of lumen of airways and reducing lung elasticity
  • Hypersecretion of mucus, again reducing lumen size and increasing distances for gas diffusion

See also Restrivtive vs Obstructive Lung Disease

 

More Information

COPD is a chronic airways disease with little or no reversibility. The airflow limitation is usually progressive and is associated with an abnormal inflammatory response of lung tissues to certain particles. It does not change markedly over several months – i.e it is slowly progressive.
It is an umbrella term for several diseases, mostly chronic bronchitis and emphysema.

Textbook definitions

  • COPD – Cough and sputum production on most days for at least 3 months during the last two years.
  • Emphysema – Enlarged airspaces distal to the terminal bronchioles, with destruction of the alveolar walls.
Symptoms will improve in 90% of cases if the patient stops smoking!

Differentiating COPD and asthma

COPD
Age of onset >35
Age of onset <35
No diurnal variation in FEV1
Diurnal variation in FEV1
Non-reversible
Reversible
Chronic dyspnoea
Acute episodes
Sputum produced
No sputum produced
History of many years of smoking
(generally patients too young to have this)
Neutrophil infiltrate
Eosinophil infiltrate
CD8 mediated
CD4 mediated

Epidemiology

  • Prevalence of about 1.5m in the UK
  • Mortality is 23,000 /year in the UK
  • It is severely under-diagnosed. Airway obstruction affects 10% off the UK population, but only about 4% of these are diagnosed with COPD – thus it is likely to be under-diagnosed.
  • By 2020 likely to be the 3rd highest cause of death world wide.
  • Smoking accounts for 90-98% of cases
  • Number of cases is stable in men, and rising in women
  • The number of deaths from COPD each year has been greatly reduced from 200 per 100 000, to 70 per 100 000 in the last 25 years
  • It is responsible for 1 in 8 hospital admissions
  • 25% of patients will die within the first 5 years of diagnosis
  • Most commonly seen in ex-smokers >35
  • You are unlikely to develop COPD with a smoking history of less than 10 pack years
  • Low socio-economic status, and low birth weight (because this prevents you attaining the maximum lung function in later life) are predisposing factors.

Causes

  • Smoking – between 10-20% of smokers will go on to develop COPD.
  • Coal miners
  • Cotton mills – more contentious – it is not known if this really does have an effect or not.
  • Genetic – α1-antitrypsin deficiency.

Pathology

Chronic Bronchitis

In this, there is:
  • An enlargement in mucus secreting glands (hypertrophy)
  • An increased number of goblet cells (hyperplasia)
particularly in the larger airways. In extreme cases, the bronchial tissue itself may become inflamed, and these may be pus excreted into the lumen.
the main cell involved in this reaction is the NEUTROPHIL in asthma, the main inflammatory cell involved is the eosinophil. The main leukocyte infiltrate is CD8+ in COPD, as opposed to CD4 in asthma.
After events of inflammation, there will be scarring and fibrosis of the tissue. This thickens the walls of the airway, and thus reduces the size of the lumen (thus decreasing the amount of air you can get into and out of the lungs quickly (FEV1),and also increasing the distance that gasses have to travel in order to diffuse properly.
Also remember that the inflammatory process will also cause bronchoconstriction – thus in some cases of COPD where bronchoconstriction is a factor, bronchodilators, such as salbutamol may be of some use for symptom relief.
Initially, the small airways are affected by chronic bronchitis, and this initial inflammation is reversible if smoking is stopped soon enough. Later, the larger airways become affected, and the process is no longer reversible.
In the later stages there will be fibrosis, and squamous cell metaplasia, further narrowing the bronchial lumen.
The epithelial layer can become ulcerated, and when the ulcer heals, the squamous epithelium may be replaced by columnar cells.

Emphysema

This is essentially enlargement of the alveolar spaces with destruction of the elastin walls. In this you lose the natural elastic recoil of the lungs, and you may also have collapse of the small airways.
There are several different types of emphysema that can be identified anatomically, but this may not be of that much use, as often several different types co-exist to different degrees.
About 1/3 of lung tissue has to be destroyed before the clinical consequences of emphysema are seen. You should also note that after the age of 25, an individual will naturally lose 30ml of functional lung capacity each year – the process of COPD just massively accelerates this!
Emphysematous bullae will often form, which are essentially just large closed off air spaces with trapped air inside them.
The three main pathological effects in COPD:
  1. Loss of elasticity of the alveoli
  2. Inflammation and scarring – reducing the size of the lumen, as well as reducing elasticity
  3. Mucus hypersecretion – reducing the size of the lumen and increasing the distance gasses have to diffuse.
Centrilobular and panlobular are the most common types of emphysema.
 

Α1-antitrypsin deficiency

α 1 antitrypsin is an enzyme that destroys other enzymes! It destroys several proteases, including trypsin, elastases and collagenases. In the deficiency, these enzymes aren’t destroyed, and they are allow to happily eat away at the lung tissue, leading to COPD.
The condition is genetic, and is autosomal dominant. You need to be homozygous to have clinical effects, and about 1/5000 people are. 1/10 are carriers of the gene.
The deficiency accounts for about 2% of cases of emphysema in the UK.
The proteinases that act in the lung are often released by inflammatory cells, such as macrophages. Thus, in smoking, there are more of these around, and the effect becomes exaggerated. This also explains the mechanism of emphysema in a normal individual who smokes.

Pink Puffers and Blue Bloaters

  • Pink Puffers – have a near normal PaO2, and a normal or low PaCO2 (due to hyperventilation). They ‘puff’ to increase their alveolar ventilation – and by doing so they are able to keep their blood gas values normal. These patients generally have emphysema or at least a higher degree of emphysema than bronchitis. These are likely to enter type I respiratory failure.
  • Blue Bloaters – these have decreased alveolar ventilation. They have a low PaO2 and a high PaCO2. They are cyanosed but not breathless (because their respiratory centre has become sensitised). They rely on hypoxic drive to maintain adequate ventilation. They often go on to develop cor pulmonale. These patients are more likely to be type II respiratory failure. ‘Bloater’ – due to cor pulmonale.

Types of respiratory failure

Type one

This is hypoxaemia without hypercapnia. The CO2 level will tend to be normal or low. It is caused by a VQ mismatch. Common causes include:
  • Pneumonia
  • Pulmonary oedema
  • PE
  • Asthma
  • Emphysema
  • Fibrosing alveolitis
  • ARDS

Treatment

  • Treat the underlying cause
  • Give O2 (35-60%) by face mask to correct the hypoxia
  • If PaO2 does not rise above 8kPa then give assisted ventilation

Type two

This is hypoxaemia with hypercapnia. It is a result of alveolar hypoventilation. There is not VQ mismatch. Common causes include:
  • Pulmonary disease (COPD, asthma, pulmonary fibrosis, obstructive sleep apnoea)
  • Reduced respiratory drive – can be a result of sedentary drugs, trauma or CNS tumour
  • Neuromuscular disease – e.g. cervical cord lesion, diaphragmatic paralysis, polio, myasthaenia gravis
  • Thoracic wall disease

Treatment

In type II failure, the respiratory centre is likely to have become desensitised to CO2 levels, and hypoxia will now be its main driving force, thus oxygen therapy should be given with care! However, don’t leave the hypoxia untreated!
  • Give controlled oxygen therapy, starting at 24% O2
  • Recheck the ABG after 20 minutes – if the PaCO2 is steady or lower, then you can increase the O2 to 28%.
    • If the PaCO2 has risen >1.5kPa– then consider giving a respiratory stimulant such as doxapram (1.5-4mg/min IV) or assisted ventilation.
    • You can also see CO2 retention as physical signs – the patient will become drowsy and confused
    • If this fails consider intubation / ventilation

Signs and Symptoms

Signs
  • Tachypnoea
  • Use of accessory muscles of respiration
  • Hyperinflation
  • Reduced cricosternal distance (<3cm) – this is the distance between the cricoid cartilage and the sternal angle – this is reduced because of hyperinflation – thus the thorax is raised in relation to the cricoid cartilage.
  • Reduced chest expansion
  • Resonant chest sounds – suggestive of hyperinflation
  • Quiet breath sounds – over areas of emphysematous bullae
  • Wheeze – this is an abnormal high pitched or low pitched breath sound heard on expiration. Often a wheeze is polyphonic- this means it is made up of many different notes, and thus this shows it is caused by many abnormal airways. Wheeze is normally caused by abnormal small airways. A monophonic wheeze is caused by a single airway obstruction, and is more likely to be cancer.
  • Stridor is the name for a wheeze heard on inspiration. It is caused by abnormal large airways – and thus not normally heard in COPD. It is more likely to be heard in cancer.
  • Cyanosis
  • Cor pulmonale
  • Prolonged expiration – because their FEV1 is low, they have to have a prolonged expiratory phase to allow for adequate respiration.
  • Pursed lip breathing – This is a technique that many COPD patients adopt by themselves, but it is also taught in pulmonary rehab clinics. It will reduce the respiratory rate, as well as helping some areas of trapped air in the lungs. There is evidence to suggest it reduces dyspnoea. The respiratory rate is reduced because it just physically reduces the opening of the airway to a small size, and thus exchange of air across the opening is a slow process. This also creates an area of high pressure at the pursed lips themselves, and this high pressure will mean that the dynamic closure point is moved to a more distal area of the lung. In COPD, some of the airways will collapse at a point proximal to many of the alveoli – this point is known as the dynamic closure point. I presume this occurs due to the destruction of elastin tissue that occurs in emphysema. Anyway, pursed lip breathing keeps the pressure in the lungs higher, and thus the closure point is kept open, and thus ventilation can occur in a greater number of alveoli (more alveoli are ‘recruited’), and the VQ mismatch is reduced.
 
As we can also see, COPD leads to gas trapping – which causes an increase in dead space and leads to hyperinflation. This is not only a problem in its own right as it reduces the amount of air exchanged with outside air with each breath, but it also reduced chest wall compliance.
Hyperinflation is particularly a problem during exercise as the time for expiration is reduced, and hyperinflation is exaggerated.

Symptoms

  • Breathlessness (dyspnoea)
  • Cough – may or may not be productive (just normal sputum)
  • Regular exacerbations

Weight loss and COPD

This is a bad prognostic sign. It is thought to be caused by the increased energy needs of the body as a result of the massive amount of energy needed for respiration. A small contributory factor may also be that patients find it hard to eat because they are too breathless!

Complications

Patients will either basically get respiratory failure or cor pulmonale.

Respiratory Failure

  • Cardiac output will be normal or slightly increased
  • Salt and fluid retention will occur as a result of renal hypoxia
  • Technically, respiratory failure occurs when the PaO2 <8kPa, or the PaCO2 >7kPa.
  • See above (pink puffers/blue bloaters section) for treating respiratory failure.

Cor pulmonale

  • This is right sided heart failure, as a result of pulmonary hypertension
  • The patient is likely to be cyanosed – look at the hands!
  • They are also likely to have ankle oedema and ascites due to fluid retention
  • Likely to have severe breathlessness
  • There may be an especially loud pulmonary heart sound, and there may be a diastolic murmur, as a result of incompetence of the pulmonary valve.

Tests

Lung function

  • FVC <80% predicted
  • FEV1/FVC <0.7
  • Increased RV (residual volume)

CXR

  • You may be able to see >6 anterior ribs above the level of the diaphragm in the mid-clavicular line. This suggests hyperinflation. In the normal individual there are normally only 5 visible.
  • However – CXR is very often normal
  • Flat hemidiaphragms
  • Large central pulmonary arteries
  • Decreased peripheral vascular markings
  • Bullae
  • Cylindrical heart due to hyperinflation of lungs – heart appears like a small line down the middle of the chest

ECG

  • Right atrial and ventricular hypertrophy (cor pulmonale)
  • Cor pulmonale lead to large p waves on the ECG – p pulmonale

ABG

These are often normal, but in advanced disease, there may be:
  • Decreased PaO2
  • Increased PaCO2

Test for α1 anti-trypsin

  • Polycythaemia – measure the haematocrit – >45ish
  • Normocytic normochromic anaemia of chronic disease – prevalence of up to 20%.
  • HB and PCV may be raised

Blood tests

  • HB and PVC may often be raised – as a result of persistent hypoxaemia – which causes a secondary polycythaemia.

Gas Transfer

This is a test to measure the effectiveness of gas transfer across the alveoli. You should test the Hb first, as you need to know this value to work out your transfer value. The patient inhales a known value of carbon monoxide (which has a very high affinity for haemoglobin – higher even than oxygen). In normal patients, the transfer test is a good way of measuring transfer efficiency, but in patients with disease, VQ mismatch will alter the results. To help make the results more accurate, the amount of carbon monoxide inhaled is related to the lung volume.
In emphysema and severe fibrosis, the gas transfer value is reduced.

Diagnosis

This can be done clinically using the GOLD criteria. This just measure the FEV1 as a % of the FVC – thus spirometry is the test needed for clinical diagnosis.
Stage
FEV (%)
Symptoms
0 – at risk
≥80%
None
I – Mild
≥80%
Variable
II – Moderate
50-70%
Mild to moderate
III – Severe
30-49%
Limit exertion
IV – very severe
<30%
Limit ADL’s
  • If there is no history of cigarette smoking then a tentative diagnosis of asthma is usually given instead of COPD. UNLESS, there is also a family history of lung disease suggestive of α1- antitrypsin deficiency.
  • There are no clinical features that are diagnostic. Be wary of giving a diagnosis of emphysema just on the basis of hyperinflation. Asthma may also cause this. Also be aware that in elderly patients, there may appear to be a barrel chest, but in actual fact, it is just curvature of the spine as a result of osteoporosis.

Vaccination

COPD patients should receive an annual flu vaccine, and a one-off vaccine of polyvalent pneumococcal polysaccharide – which provides life-long immunity.

Air travel

Commercial airliners have a cabin pressure equal to an altitude of 2750m. At this level PaO2 will fall from 13.5kPa to 10kPa – and oxygen saturation will fall by 3%. In normal healthy individuals this has no effect, but in patients with even moderate COPD, this can reduce their O2 saturation to around 6.5kPa and oxygen therapy may be needed. As a result, patients with COPD should consult their doctor / airline before travelling.

Exacerbations

These are most commonly caused by:
  • Streptococcus pneumoniae – this is a Gram-positive diplococcus.
  • Haemophilus influenzae – this is a Gram-negative coccobascillus.
Because these two organisms are by far the most common causes, you do not need to take a sputum sample in an exacerbation of a known COPD patient – the first line treatment is amoxicillin 500mg tds for 7 days. Second and third line options are co-amoxiclav and ciprofloxacin respectively. These have almost identical dose regimens as amoxicillin, as does clarithromycin which is given in penicillin allergic individuals.

Treatment

Acute exacerbation

Give controlled oxygen therapy, starting at 24% O2
Recheck the ABG after 20 minutes – if the PaCO2 is steady or lower, then you can increase the O2 to 28%.

  • If the PaCO2 has risen >1.5kPa– then consider giving a respiratory stimulant such as doxapram (1.5-4mg/min IV) or assisted ventilation.
  • You can also see CO2 retention as physical signs – the patient will become drowsy and confused

Give nebulised salbutamol (2.5-5mg in solution), and ipratropium (0.5mg).

  • ‘Nebuliser driver’ – you can ‘drive’ the nebuliser with different gasses – in COPD patients you should just drive it with room air, but in asthma patients you should drive it with 100% O2 – from the wall outlet.

If measures are unsuccessful then consider non-invasive ventilation
Give steroids – 5-7 day course of 40mg prednisolone
Treat the cause – will usually be a chest infection. You should use the ‘Anthonisen criteria’ to determine if antibiotics would be suitable for a particular patient.

Anthonisen criteria
  • Increasing dyspnoea
  • Increasing sputum volume
  • Increasing sputum purulence (thickness)

 

Anthonisen classification
  • Type I – all 3 present
  • Type II – 2 things present
  • Type III – only one factor present
You should use antibiotics when 2 or more criteria are met; i.e. in types I and II of the Anthonisen criteria.
Management on long term disease
  • Smoking cessation – whatever stage the disease is at, this can slow down the progression. Smoking cessation and LTOT are the only two things that can prolong the life expectancy in COPD.

Drugs – in many cases these are similar to those used in asthma, despite the fact that on paper, it appears they shouldn’t work. However, in practice, many patients get great symptom relief from these drugs:

  • Short acting beta agonist or anti-cholinergic – i.e. salbutamol – 200μgevery 4-6 hours
  • Long acting beta agonist or anti-cholinergic – i.e. ipratropium – 40μg 4x a day
Exacerbations – if they have 2 or more each year, then they are eligible to try inhaled steroids.
When using these drugs, the change in FEV1 will usually be very small (the whole definition of COPD is that the airway damage is irreversible). Thus, the use of these drugs should be related to the amount of breathlessness the patient experiences.

Steroids – a trial of these is indicated in virtually any patient with symptoms. The trial is typically 40mg prednisolone for 2 weeks. If the trial increases the FEV1 by >15% then you should prescribe a long term inhaled corticosteroid – i.e. beclomethasone – 400μg twice daily. If there is no response in the trial, then there is no point giving the inhaled corticosteroid.

  • The long-term effectiveness of these drugs is yet to be established.

Antibiotics – these should be given promptly during exacerbations, as they reduce the duration of the exacerbation, and prevent hospital admission and further lung damage.

  • Patients are sometimes given their own supply of antiobiotics to keep at home, and instructed to take them as soon as their sputum turns yellow or green. They are NOT FOR PROPHYLAXIS!
    • However – there is some new evidence emerging that long term AB therapy can preserve lung function, as lung function may be lost during exacerbations.
  • Note that about 10-20% of H influenzae is now amoxicillin resistant – although this is not a major problem, as co-amoxiclav is a very useful alternative drug.

Diureticsthese are often also taken by many patients (I presume due to the secondary cor pulmonale)

Things you don’t give in COPD:
  • Moteleucast – this is a leukotriene receptor antagonists, and prevent bronchoconstriction by leukotriene mediated means. In COPD there is very little bronchoconstriction in this manner.
  • Antibiotic prophylaxis – the risk of resistant organisms is too great

Further management in severe disease

LTOT – long term oxygen therapy
This can prolong the life expectancy of COPD patients! Basically, the longer you give it for, the greater the increase in life-expectancy. You should give it @ 2L via nasal prongs for at least 15 hours a day. This aims to keep oxygen saturation above 90%.
  • Only 30% of those not receiving LTOT survive more than 5 years after diagnosis.
  • By giving the LTOT you reduce the pulmonary arterial pressure. Moderate reduction is pressure is achieved after 15 hours, and a larger reduction after 19 hours a day.

Indications for LTOT

  • PaO2 <7.3kPa
  • PaO2 <8kPa, and patient also has polycythaemia, hypoxaemia, peripheral oedema or pulmonary hypertension
Patients should be asses for LTOT when they have:
  • FEV1 30-49% predicated
  • Cyanosis
  • Any of the indications above

Surgery

  • Some patients who have a large emphysematous bullae may benefit form a bullectomy. This enables adjacent areas of collapsed lung to re-expand into the space, and function again. This improves VQ mismatch.
    • Another option – you can put a valve in on bronchoscopy – this will allow air out of an emphysematous bullae, but not allow air in, and this eventually allows the bullae to collapse.
  • Another option is lung volume reduction surgery. This aims to increase the elastic recoil of the lung. Patients have to be carefully selected, and have an FEV1 <1L. it improves symptoms, but does not improve mortality.
  • Lung transplant can be performed on certain patients with end stage emphysema. It has a 3-year survival of 75%, and again, the treatment improves symptoms, but does not really affect quality of life.

Pulmonary rehabilitation

This basically just involves exercise training – and the aim is to improve symptom control. The exercises usually involve walking / climbing stairs, and can be arranged at clinic or in the home. These exercises are often in conjunction with physiotherapy and education classes. Breathing exercises are of little use.
Pulmonary rehabilitation has no effect on life expectancy

Diet

Patients can lose weight – this is a particularly bad prognostic sign – because it shows that they are expending a huge amount of energy trying to breathe – you have to encourage them to try and gain weight – but you can lose muscle mass, and this will make it even more difficult to breathe.

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