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114 Chapter 3: Respiratory system

Aetiology as dressing. Expiratory wheeze and cough are present
Virtually confined to cigarette smokers and related to the but the cough is dry.
number of cigarettes smoked each day. There is a strong Signsinbothdiseasesincludeexpiratorywheezeheard
genetic element to both components of COPD. in all lung fields, in chronic bronchitis coarse early in-
α1-antitrypsindeficiencyisarecessivedisorder,which spiratory crackles are also heard. As emphysema be-
causes pan-acinar emphysema and accounts for 5% of comesmoresevereothersignsbecomeevidentinclud-
patients with emphysema. One in 5000 births have a ho- ing tachypnoea, cachexia, the use of accessory muscles
mozygousdeficiencyandmostthesegoontodevelopthe of respiration, intercostal recession, pursed lips on ex-
lung disease. Patients tend to be young (below 40 years) piration, poor chest expansion (a hyperinflated chest
especiallyifsmokers,inwhomthediseaseismuchworse. at rest) and loss of cardiac and hepatic dullness due to
hyperinflation.
The two patterns of pink puffer (always breathless, not

Pathophysiology
cyanosed,cachexic)andbluebloater(obese,cyanosed,
Thereisairwayinflammation,dominatedbyneutrophils
hypoventilating, often with little respiratory effort)
and CD8+ Tcells. There is also hypertrophy and hyper-
describe the extremes of the spectrum of disease man-
plasia of the mucus secreting glands causing plugging
ifest as COPD. The pink puffer is typical of relatively
of airways and luminal narrowing resulting in airway
pure emphysema and the blue bloater is typical of rel-
obstruction. This ‘chronic bronchitis’ co-exists with a
atively pure chronic bronchitis.
greater or lesser degree of emphysema in this patient
group.
Macroscopy
Incentri-acinaremphysemathereisdistensionofalve-

There is secretion of abnormal amounts of mucus caus-
oli and damage of lung tissue concentrated around the
ing obstruction and plugging of the airways. Mucus
respiratory bronchioles whilst the more distal alveolar
gland hypertrophy and hyperplasia can be quantified by
ducts and air spaces tend to be well preserved. The
theReidindexwhichistheratioofglandtowallthickness
alveolar dilatation results from loss of elastic recoil in
within the bronchus.
the terminal bronchioles, as a result of destruction of
lung tissue by neutrophil derived proteases. Smoking
Microscopy
also causes glandular hypertrophy (chronic bronchi-
Both emphysema and chronic bronchitis are inflam-
tis) and has an adverse effect on surfactant favouring
matory diseases of the lung. The inflammatory infil-
over distension of the lung.
trate is dominated by neutrophils and CD8 +ve T cells.
In pan-acinar emphysema destruction involves the

Eosinophilsarealsoseenespeciallyinchronicbronchitis,
whole of the acinus.
in which the predominant pathological features are mu-
cus gland enlargement and airway wall inflammation. In
Clinical features emphysema the predominant feature is destruction of
Chronic bronchitis and emphysema together produce the alveolar septae as a result of neutrophil derived pro-
the clinical picture of COPD (also sometimes called teases. Acute viral or bacterial infections, or chronic bac-
chronic obstructive airways disease (COAD), or chronic terial colonisation exacerbates the inflammation. Squa-
obstructive lung disease (COLD)). In addition there may mous metaplasia is commonly seen.
befeaturesofasthmaassomepatientshaveadegreeofre-
versibleairflowobstruction.Theclinicalfeaturesdepend Complications
on the degrees of chronic bronchitis and of emphysema Airway obstruction and alveolar destruction eventually
contributing to the overall picture. leads to impaired alveolar ventilation and respiratory
Symptoms of chronic bronchitis include cough pro- failure in both conditions. Pulmonary vasculature re-

ductive of sputum, expiratory wheeze and progres- sponds to hypoxia by vasoconstriction which increases
sive shortness of breath. Symptoms of emphysema the arterial pressure, causing pulmonary artery hyper-
are dominated by progressive breathlessness, initially tension, which leads to right heart failure (cor pul-
only on exertion but eventually on mild exertion such monale). There may be secondary polycythaemia due