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How hot are you on... COPD?

Test your knowledge for the nMRCGP with this little GEM from GPnotebook

Test your knowledge for the nMRCGP with this little GEM from GPnotebook

Chronic obstructive pulmonary disease (COPD) is a chronic, slowly progressive disorder characterised by airways obstruction (FEV1 < 80% predicted and FEV1/FVC ratio < 70%) which does not change markedly over several months. The impairment of lung function is largely fixed but is partially reversible by bronchodilator or other therapy. Environmental pollution and smoking contribute to the increasing incidence. COPD is an important cause of activity limitation in the population.

In which patients should the diagnosis of COPD be suspected?

NICE states that clinicians should consider a possible of diagnosis of COPD in patients who are :

• over 35

• smokers or ex-smokers

• have any of these symptoms:

– exertional breathlessness

– chronic cough

– regular sputum production

– frequent winter ‘bronchitis'

– wheeze

Clinical features suggestive of asthma rather than COPD include:

• onset under age 35

• chronic productive cough is uncommon

• breathlessness is variable

• night-time waking with breathlessness and/or wheeze

• significant diurnal or day-to-day variability of symptoms.

What is FEV1?

FEV1 is the volume of air expelled in the first second of maximal forced expiration from a position of full inspiration.

FEV1 is reduced in obstructive respiratory disease (for example asthma,COPD) and restrictive respiratory disease, for example pulmonary fibrosis. FEV1 correlates with maximal exercise capacity. In normal subjects the fraction of the forced vital capacity (FVC see below) which can be expelled in one second is >80 % predicted value.

What is FVC?

Forced vital capacity (FVC) is the volume of air expelled by a forced maximal expiration from a position of full inspiration. The value may be slightly less than for vital capacity (VC).

The FVC is:

• usually 3-6itresl, varying with age, gender and height

• reduced in obstructive and restrictive defects

• correlated with disability in chronic respiratory disease

The FVC is reduced in both obstructive and restrictive respiratory disease:

• in patients with airways obstruction the FEV1 is disproportionately reduced compared with the FVC, resulting in a low FEV1/FVC ratio

• in patients with restrictive pulmonary disease the FEV1 and FVC fall proportionately, resulting in normal values for FEV1/FVC

How is COPD diagnosed and classified?

If COPD seems likely, perform spirometry. Patients with COPD have airflow obstruction which is defined as:

• FEV1 < 80% predicted

• and FEV1/FVC < 0.7

If there is still diagnostic doubt, consider the following pointers:

• clinically significant COPD is not present if FEV1 and FEV1/FVC ratio return to normal with drug therapy.

Asthma may be present if:

• there is a >400ml FEV1 response to bronchodilators

• serial peak flow measurements show significant diurnal or day-to-day variability

• there is a >400ml FEV1 response to 30mg prednisolone daily for two weeks.

COPD is classified as mild, moderate or severe based on the patient's FEV1 compared to predicted result:

• mild; 50-80% (% of predicted FEV1), patient exhibits no clinical signs; may have little or no breathlessness; may have smoker's cough

• moderate; 30-49% (% of predicted FEV1), moderate exertion results in breathlessness (+/- wheeze); cough (+/- sputum); variable clinical signs (presence of wheezes, reduction in breath sounds)

• severe; <30% (% of predicted FEV1), breathlessness at rest or on any exertion; cough and wheeze often prominent; clinical signs include lung overinflation usual with cyanosis, peripheral oedema and polycythaemia in advanced disease, particularly during acute exacerbations.

This series is based on GPnotebook Educational Models (GEMs) – the full version is available via GPnotebook Plus, a service free to UK medics. Register at

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