COPD

Overview

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterised by airflow obstruction that is not fully reversible. COPD is now the preferred term for patients who were previously described as having chronic bronchitis or emphysema.

Epidemiology

• COPD is the fourth leading cause of death worldwide
• COPD is the second largest cause of emergency admissions
• COPD is often associated with other comorbidities such as cardiovascular disease, lung cancer, depression, and anxiety

Risk Factors

• Cigarette smoking is associated with around 90% of cases
• Occupational exposure e.g. coal, grains, silica
• Air pollution
• Genetics e.g. alpha-1-antitrypsin deficiency
• Asthma
• Problems with lung growth and development 

Presentation

Patients generally have:

• Cough – this is usually the initial presenting complaint
  • This often starts off being worse in the morning but becomes constant as COPD gets worse
  • Usually productive
• Shortness of breath
  • This is usually with exercise initially but can progress to shortness of breath at rest
• Features of hyperinflation may be seen.
  • Hyperinflation occurs when air is trapped in the lungs due to blockages and reduced elasticity leading to the lungs overinflating. These may manifest as:
    • Hyper-resonance on percussion
    • Barrel chest
    • Distant breath sounds on auscultation
• Poor airflow on auscultation
• Wheeze on auscultation
• Coarse crackles – often seen in exacerbations
• Features of cor pulmonale:
  • Distended neck veins
  • Lower limb oedema
  • Hepatosplenomegaly

COPD does not cause clubbing. If clubbing is seen, there may be a related condition present such as lung cancer.

Differential Diagnoses

Asthma

• Symptoms are usually diurnal (vary throughout the day, usually worse at night and first thing in the morning)
• The cough is usually dry
• There is usually a history of associated atopy e.g. allergic rhinitis, eczema, etc. 

Bronchiectasis

• Cough usually brings up copious amounts of purulent and offensive sputum
• Frequent chest infections
• History of childhood chest infection
• Coarse lung crackles

Heart failure

• The patient may have a history of ischaemic heart disease or a myocardial infarction
• There may be oedema, pulmonary crackles, or an elevated jugular venous pressure (JVP) on examination

Occupational asthma

• Symptoms present in an adult
• Symptoms usually improve away from work or while on holiday
• Causative agents may be present e.g. isocyanates

Foreign body/obstruction

• The wheeze may be localised, rather than general

Investigations

All patients

• Spirometry – patients should be given bronchodilators before investigating:
  • Usually shows an FEV₁/FVC ratio <0.70
• Full blood count (FBC):
  • To screen for secondary polycythaemia
• Chest x-ray:
  • To rule out lung cancer
  • May show bullae (air pockets in damaged areas of the lung), and signs of hyperinflation (e.g. a flattened diaphragm, increased intercostal spaces etc.)

Other investigations

The following investigations may need to be considered in specific scenarios:

• Alpha-1-antitrypsin:
  • If the onset of symptoms is relatively early or there is minimal smoking history
• ECG and echocardiography:
  • If there are features of heart disease or pulmonary hypertension
• Sputum culture:
  • If sputum is persistently present/purulent
• Serial peak flow measurement:
  • To exclude asthma if there is diagnostic doubt
• Arterial blood gases (ABG):
  • May show respiratory acidosis, see Acid-Base Disturbances.

Diagnosis

NICE classification of the severity of COPD

• Stage 1: mild – FEV₁ >80% predicted
• Stage 2: moderate – FEV₁ 50-79% predicted
• Stage 3: severe – FEV₁ is 30-49% predicted
• Stage 4: very severe – FEV₁ <30% predicted or FEV₁ <50% + respiratory failure

Management

General management in all patients

• Smoking cessation – the single most important measure to reduce progression
• Annual influenza vaccination and one-off pneumococcal vaccination
• Pulmonary rehabilitation – if COPD is limiting functional ability

Medical therapy

• 1^st-line: short-acting beta₂ agonist (SABA) or short-acting muscarinic antagonist (SAMA)
• 2^nd-line: determine if the patient has asthmatic/steroid-responsive features:
  • If asthmatic/steroid responsive features*: add long-acting beta₂ agonist (LABA) + inhaled corticosteroid (ICS):
  • If non-asthmatic and no steroid-responsive features: LABA + long-acting muscarinic antagonist (LAMA)
    • If the patient is already taking a SAMA, stop this and replace it with a SABA
• 3^rd-line: add whichever option was not added in the second-line step i.e. SABA + LABA + LAMA + ICS
• Consider adding theophylline
• Consider mucolytics in all patients

* Patients are considered to have asthmatic/steroid-responsive features if they have any of the following:

• A previous diagnosis of asthma or atopy
• Raised eosinophil counts
• Variation in FEV₁ over time (at least 400 ml)
• Diurnal vibration (at least 20%)

Antibiotic prophylaxis

• In some patients, specialists may consider antibiotic prophylaxis. The antibiotic of choice is azithromycin.

Oxygen Therapy

Overview

Chronic hypoxia can occur in COPD and this can lead to progressive pulmonary hypertension causing right ventricular hypertrophy and cor pulmonale, and secondary polycythaemia which can increase blood viscosity and lead to a tendency to thrombosis.

Long-term oxygen therapy (LTOT) may be beneficial in some patients and may increase survival. It is generally offered to patients who have any of the following:

• PaO₂ <7.3 kPa when stable or <8 kPa when stable + peripheral oedema
• Secondary polycythaemia
• Pulmonary hypertension

Monitoring

• Patients with mild, moderate, or severe COPD are followed up at least annually
• Patients with very severe COPD are followed up at least twice a year
• Patients with severe COPD requiring interventions such as long-term non-invasive ventilation should have regular reviews with specialists 

Patient Advice

• Patients should stop smoking as this is one of the most important factors for improving survival. They should be offered help regarding this.
• Patients should stay as healthy and active as possible
• Patients should have regular reviews of their medication adherence and the severity of symptoms. Motivational interviewing should be used where necessary when addressing issues with adherence and lifestyle changes.

Complications

• Recurrent pneumonia:
  • This is a frequent cause of COPD exacerbation. This is due to the lung damage caused by COPD itself, or the use of inhaled corticosteroids (due to their immunosuppressive effects).
• Cor pulmonale:
  • Chronic hypoxia can lead to vasoconstriction in the pulmonary arteries (in an attempt to increase oxygenation of the blood) leading to pulmonary hypertension. This leads to more strain on the right side of the heart leading to right ventricular hypertrophy and cor pulmonale. 
• Lung cancer:
  • COPD itself is a risk factor for lung cancer
• Pneumothorax:
  • Bullae can form and rupture leading to the development of pneumothorax
• Respiratory failure:
  • Due to increased airway resistance. Patients may need to have non-invasive ventilation or mechanical ventilation.
• Polycythaemia:
  • Chronic hypoxia can lead to erythropoietin (EPO) release from the kidneys leading to the increased production of red blood cells. This can make the blood more viscous and prone to thrombosis.
• Muscle wasting and cachexia:
  • Due to multiple factors such as breathlessness, anorexia, and increased nutritional requirements
• Anaemia
• Reduced quality of life

Prognosis

• The prognosis varies from person to person, but in general, COPD is a chronic and progressive condition with a gradual decline in lung function and increasing symptoms
• Factors that affect the prognosis are:
  • Severity of COPD on spirometry:
    • A low FEV₁ is associated with a risk of exacerbation and death
  • Smoking:
    • Smoking cessation can reduce the rate of decline
  • Presence of complications
  • Frequency and severity of COPD exacerbations
  • Hospital admissions
  • Multimorbidity and frailty