Chronic obstructive pulmonary disease

Contributed by Dr Jon Miles, consultant pysician at North Manchester General Hospital

1. EPIDEMIOLOGY AND AETIOLOGY

COPD is an umbrella term for chronic undertreated asthma, emphysema and chronic bronchitis. It is estimated that three million people have COPD, of whom just under one third may be accurately diagnosed.

Exposure to cigarette smoke is the most important factor in the development of COPD. Cigarettes and other irritants activate macrophages in the respiratory tract, which facilitate the breakdown of lung parenchyma and stimulate mucus hypersecretion.

COPD definitions demand the demonstration of airway narrowing that is not fully reversible, and therefore objective measurement of airway calibre is an essential part of the diagnostic process. COPD should be suspected in patients over the age of 35 who smoke and who have symptoms of cough, wheeze or breathlessness.

Patients with chronic COPD and hyperinflation may have an increased antero-posterior chest diameter.

The major diagnostic difficulty surrounds the distinction between asthma and COPD. The box above gives some important distinctions.

COPD is characterised by airflow obstruction that varies little over several months. Spirometry is the necessary measurement required to support the diagnosis. Recent guidelines have classified COPD into mild, moderate and severe on the basis of spirometric measurement.

COPD is a systemic disease, and exercise and nutrition are therefore important.

COPD vs asthma   
   
 COPD  Asthma 
Smoker or ex-smoker Nearly all Possibly 
Symptoms under age 35 Rare Common 
   
Chronic productive cough Common Uncommon 
Breathlessness Persistant and Progressive Variable 
Night-time waking with breathlessness or wheeze Uncommon Common 
Significant diurnal or day-to-day variability of symptoms Uncommon Common 

2.MILD TO MODERATE COPD

Patients with mild COPD will predominantly present with symptoms of breathlessness, wheeze or cough.

COPD is defined as mild if the FEV1 is 50-80 per cent of that predicted, or moderate if the FEV1 is 30-40 per cent predicted.

The key issues in management are to quantify the symptoms, encourage cessation of smoking (if still an issue) and to treat symptoms with bronchodilator drugs.

The MRC dyspnoea scale (see box below) is increasingly being recognised as an important tool in quantifying patients' breathlessness.

Smoking cessation
Smoking cessation is an integral part of COPD management and there is an increasing number of options for patients, including bupropion or nicotine replacement therapy (unless contraindicated). The key to the success of interventions, however, is for patients to have access to a dedicated smoking cessation service and quit under the supervision of an appropriately trained smoking cessation counsellor.

Acute exacerbations
All patients with COPD are prone to exacerbations, usually as a consequence of viral or bacterial infection. Guidance is now available to assist in the decision-making process of whether to manage such exacerbations at home or in hospital and an increasing number of areas have dedicated teams for managing patients at home, either throughout their exacerbation, following initial hospital assessment, or as part of an early discharge scheme.

Patients with moderate COPD are likely to experience regular exacerbations and so the focus of management is on both symptomatic control and exacerbation prevention.

Bronchodilator therapy
The symptomatic drug treatment of COPD focuses on bronchodilator therapy. Current practice suggests using short-acting beta-agonist and anticholinergic medication first, before moving on to long-acting preparations.

In patients with moderate to severe COPD who have had more than two exacerbations in the previous year, a number of studies have demonstrated the ability of long-acting beta-agonists with inhaled corticosteroids to prevent exacerbations.

It is possible to administer the two preparations separately, but more convenient for the patient to receive them together.

Long-acting anticholinergics
There is also evidence that long-acting anticholinergic preparations can reduce exacerbations of COPD.

NICE advises that a long-acting bronchodilator should be prescribed if a patient has two or more exacerbations a year.

Anti-mucolytics
Some patients with COPD appear to have particular difficulty expectorating sputum, and antimucolytics have been shown to improve this and reduce exacerbations as a result.

All patients with COPD should have both the influenza and pneumococcal immunisations.

MRC DYSPNOEA SCALE 
 GradeDegree of breathlessness related to activities 
 1Not troubled by breathlessness except on strenuous exercise. 
 2Short of breath when hurrying or walking up a slight hill.
 3Walks more slowly than contemporaries on level ground because of             breathlessness, or has to stop for breath when walking at own pace. 
 4Stops for breath after walking about 100m or after a few minutes on             level ground. 
 5Too breathless to leave the house, or breathless when dressing or undressing. 

3.SEVERE COPD

Patients with severe COPD are particularly prone to the more systemic effects of the condition and the psychological consequences. Depression is common in this group and it may be worthwhile considering routine use of the hospital anxiety and depression (HAD) score.

Patients should be weighed regularly and given dietary advice depending on their weight.

Patients with severe COPD are also prone to pulmonary hypertension and hypoxic cor pulmonale. All healthcare professionals managing patients with severe COPD should have access to pulse oximetry and should be referring patients for oxygen assessment if resting saturations fall below 92 per cent.

Most patients with stable severe COPD do not need regular hospital review, but rapid access to hospital should be available.

Pulmonary rehabilitation
A six- to eight-week exercise programme supplemented with educational discussion minimises exacerbations of COPD. Pulmonary rehabilitation should be available to all patients with symptomatic COPD (MRC dyspnoea level 3 or above and especially those with exacerbations.

End-stage COPD
While there is no accepted definition of end-stage COPD, there are patients with COPD for whom palliative and supportive care is most appropriate. Many such patients are unnecessarily shunted between home and hospital, as access to palliative care services for COPD is limited.

This is one of the key areas for development highlighted in the Healthcare Commission report on chronic lung conditions in 2006.

Chronic disease management
The 10-year NHS plan and the DoH report ‘Commissioning a patient-led NHS' are having considerable impact in the area of chronic disease management, and its potential to affect the care of patients with COPD is no exception.

Many patients with COPD could be managed exclusively outside the hospital setting for all aspects of their condition other than those involving respiratory failure.

Referral centres
A dedicated centre for COPD patients is now being constructed in Rotherham to act as a referral centre for patients with COPD.

Patients will be able to be assessed and undergo diagnosis, assessment and management of COPD, with a focus on pulmonary rehabilitation and including oxygen assessment

(visit http://visit www.rotherhampct.nhs.uk/breathingspace).

Should such centres prove successful, they could act as templates for the delivery of services to these patients.

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