Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a disease state characterised by airflow limitation that is not fully reversible. The airflow limitation is usually both progressive and associated with an abnormal inflammatory response of the lungs to noxious particles or gases.¹ COPD is now the preferred term for patients with airflow obstruction who were previously diagnosed as having chronic bronchitis or emphysema. There are separate articles covering:

• Diagnosing COPD
• Use of Oxygen Therapy in COPD
• Acute Exacerbations of COPD
• Spirometry and the Spirometry Calculator

• The prevalence in the UK is estimated to be 1%, increasing with age to 10% in men older than 75.²
• It is very likely that COPD is under-diagnosed in the UK.
• COPD predominantly affects adults older than 40 who have a history of smoking.
• Other causes include occupational exposure to noxious gases and particles, and hereditary alpha1 antitrypsin deficiency.

• COPD should be considered in any patient older than 35 years with a history of smoking and respiratory symptoms, especially breathlessness on exertion, productive cough with regular sputum production, wheezing or frequent episodes of chest infection.
• COPD may also cause abnormal weight loss, effort intolerance and ankle oedema.

Signs

• Respiratory distress: tachypnoea, breathlessness on exertion, increased use of accessory muscles of respiration, pursed lip breathing.
• Abnormal posture: patients may lean forward and rest their arms on the table to ease breathing.
• Drowsiness, flapping tremor, and mental confusion (these are features of elevated carbon dioxide levels).
• Other signs include underweight, ankle oedema, cyanosis, hyperinflation of the chest, downward displacement of the liver, relatively quiet vesicular breath sounds, wheezing may be audible, prolonged forced expiratory time.

• Asthma: asthma is diagnosed by establishing reversibility or variability of airflow obstruction either by spirometry or peak flow measurements after treatment with a bronchodilator or steroid.
• Other diagnoses to consider are congestive heart failure, bronchiectasis, allergic fibrosing alveolitis, pneumoconiosis, asbestosis or other restrictive conditions, tuberculosis, lung cancer, anaemia or general poor physical condition.

• Spirometry is considered the gold standard test for diagnosing COPD. The diagnostic criteria are:
  • Reduced FEV₁ (<80% predicted) after bronchodilation together with a reduced FEV₁/FVC ratio (<70%).
  • Little or no reversibility of airflow obstruction.
• Other investigations:
  • In younger patients, or in those who are not exposed to cigarette smoke or other factors known to be associated with COPD, consider a genetic cause such as alpha1 antitrypsin deficiency.
  • NICE recommends that all patients with newly diagnosed COPD should have a chest x-ray to exclude other lung diseases such as cancer or tuberculosis.³ It also recommends measuring BMI and a full blood count (to rule out anaemia; chronic hypoxia may cause polycythaemia).

The guidelines from NICE adopt the following classification:³

• 50% to 80% predicted FEV₁ = mild
• 30% to 50% predicted FEV₁ = moderate
• Less than 30% predicted FEV₁ = severe

The GOLD classification of severity is as follows:¹

• Stage 0: at risk; chronic cough and sputum production. Spirometry is normal.
• Stage I: mild COPD; mild airflow limitation (FEV₁/FVC less than 70% but FEV₁ 80% or more than predicted; usually, but not always chronic cough and sputum production.
• Stage II: moderate COPD; worsening airflow limitation (FEV₁ 50-79% predicted) and usually progression of symptoms, with shortness of breath, especially on exertion.
• Stage III: severe COPD; further worsening of airflow limitation (FEV₁ 30-50% predicted), increased shortness of breath, and repeated exacerbations.
• Stage IV: very Severe COPD; severe airflow limitation (FEV₁ less than 30% predicted) or the presence of chronic respiratory failure.

An effective COPD management plan includes prevention (reduction of risk factors, particularly smoking cessation), assessment and monitoring of disease and its progression, management of stable COPD and management of exacerbations of COPD. The overall approach to treating stable COPD involves a stepwise increase in treatment, depending on the severity of the disease.

• Stopping smoking is the most important aspect of treatment for people with COPD because it reduces the rate of decline of lung function.³
• Pulmonary rehabilitation; relieves dyspnoea and fatigue, improves emotional function and enhances patients' sense of control over their condition.⁴
• Referral to a dietitian; low BMI is a poor prognostic sign.
• All patients with COPD should be offered pneumococcal vaccination and an annual influenza vaccination.³

Drugs

No medication for COPD has been shown to modify the long-term decline in lung function that is the hallmark of this disease. Therefore the role of drug treatment is to decrease symptoms and complications.

• The NICE guidelines recommend the following stepwise approach:³
  • Use short-acting bronchodilator (beta agonist or anticholinergic) as required.
  • If symptoms persist, use combined therapy of short-acting beta agonist and short-acting anticholinergic.
  • If symptoms persist, use long acting bronchodilator (beta agonist or anticholinergic).
  • If symptoms persist, consider 4 week trial of combination long acting beta agonist and inhaled corticosteroid. Discontinue if no benefit after 4 weeks.
  • If symptoms persist, consider adding theophylline which can improve FEV₁.
• Tiotropium (long-acting antimuscarinic bronchodilator) has been shown to reduce COPD exacerbations and related hospitalisations compared to placebo and ipratropium.⁵
• Mucolytics may reduce the frequency of exacerbations.
• A recent Cochrane review found support for the use of antibiotics for patients with COPD exacerbations with increased cough and sputum purulence who are moderately or severely ill.⁶
• Oxygen therapy should usually be prescribed only after specialist assessment. Long-term home oxygen therapy improves survival in COPD patients with severe hypoxaemia but not in those with mild to moderate hypoxaemia or in those with only arterial desaturation at night.⁷
• Palliative care for end stage COPD includes opiates to help breathlessness and oxygen when appropriate.

Surgical

A respiratory specialist may refer selected patients with COPD to a cardiothoracic surgeon for consideration for surgery. In general, patients who are still breathless despite maximal medical therapy may be candidates for one of three types of operation:³

• Bullectomy if there is a single large bulla occupying more than one third of a hemithorax.
• Lung volume reduction surgery for patients with upper lobe predominant emphysema.
• Lung transplantation for patients with homogeneously distributed emphysema.

• The practice can produce a register of patients with COPD; 3 points.
  The percentage of all patients with COPD diagnosed after 1st April 2008 in whom the diagnosis has been confirmed by post bronchodilator spirometry; 5 points; payment stages 40-80%
• The percentage of patients with COPD with a record of FEV₁ in the previous 15 months; 7 points; payment stages 40-70%.
• The percentage of patients with COPD receiving inhaled treatment in whom there is a record that inhaler technique has been checked in the previous 15 months; 7 points; payment stages 40-90%.
• The percentage of patients with COPD who have had influenza immunisation in the preceding 1st September to 31st March; 6 points; payment stages 40-85%.

• Cor pulmonale
• Pneumothorax
• Respiratory failure
• Arrhythmias, including atrial fibrillation
• Infection
• Secondary polycythaemia

• The disease is progressive and patients deteriorate but the natural history of the disease varies in different people.
• In patients who stop being exposed to cigarette smoke and other noxious substances the disease may continue to progress but the rate of declining lung function may slowed.¹
• Repeated exacerbations lead to irreversible decline in lung function and efforts should therefore be made to reduce exacerbations.

• Smoking cessation and restriction of other potential risk factors, e.g. occupational dusts and chemicals.
• Reduce risk of exacerbations, e.g. influenza and pneumococcal immunisation.