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Chapter 3: Occupational lung disease 131

3 Increased pulmonary vascular resistance: The ECG shows right ventricular hypertrophy with
Chronic lung disease such as chronic bronchitis, right axis deviation: Prominent R wave in V 1 , and

emphysema and pulmonary fibrosis partly due to inverted T waves in the V 1 –V 3 .The rightatrial en-
the vasoconstriction associated with hypoxia. largement results in tall peaked P waves.
Chronic pulmonary thromboembolic disease due Underlying causes should be identified wherever pos-

to occlusion of part of the vasculature and hypoxia. sible.
Primary pulmonary hypertension is seen predominantly
in young females. A similar syndrome is associated with Management
sytemic lupus erythematosus, scleroderma and Ray- Treatment is aimed at the underlying cause.
naud’s disease. Congenitalabnormalitiessuchasseptaldefectsshould
be corrected wherever possible, mitral valve disease
Pathophysiology may indicate surgical intervention and left ventricular
Increasedpulmonaryarterialpressurecausesirreversible failure should be treated.
structural changes in the pulmonary vasculature due to Pulmonary hypertension secondary to chronic lung
increasing amounts of smooth muscle. The result is a de- disease may benefit from oxygen therapy to reduce
crease in the lumen of the vessels and hence an increased the vasoconstrictor effect of hypoxia.
afterload on the right side of the heart. Progressive fail- Long-term intravenous infusion of epoprostenol
ure of the right side of the heart occurs which is called (prostacyclin) improves the outcome of patients with
‘cor pulmonale’. primary pulmonary hypertension. The administra-
tion of bosentan (a nonselective endothelin receptor
Clinical features antagonist) may also be beneficial in patients with
Dyspnoea, syncope and fatigue are common. Symptoms primarypulmonaryhypertensionalthoughlong-term
of the underlying cause and of right ventricular failure follow-up data are not yet available.
may also be present. When there are irreversible vascular changes the con-
Signsare aresult of the elevated pressures within the dition is progressive. Heart–lung transplantation is
pulmonary circulation. There is elevation of the JVP recommended in younger patients.
with a prominent ‘a’ wave, a forceful parasternal heave
due to increased right ventricular stroke work, and a
loud pulmonary component to the second heart sound.
Occupational lung disease
Right heart failure leads to peripheral oedema and hep-
atomegaly.
A pulmonary mid systolic ejection murmur and an Introduction to occupational
early diastolic murmur of pulmonary regurgitation may lung disease
be heard (Graham–Steel murmur).
Lung disease resulting from exposure to dusts, vapours
If tricuspid regurgitation develops there will be a pan-
and fumes resulting in five basic patterns of disease (see
systolic murmur and a large ‘v’ wave in the JVP.
Table3.18).Mostpatientswithoccupationallungdisease
are entitled to compensation according to their degree
Microscopy
of disability.
If pulmonary hypertension is long-standing, micro-
scopy reveals hypertrophy of the media of the vessels
with an increase in the amount of smooth muscle. There Definition
is worsening occlusion of the lumen of the vessels. Diseases of the lung related to exposure to asbestos.

Investigations Incidence
Achest X-ray may show right ventricular and right The incidence of asbestos related disease increased dra-

atrialenlargement.Thecentralpulmonaryarteriesare matically in recent decades but appears to have peaked
usually prominent and may be ‘pruned’ peripherally. in the late 1990s, and is expected to gradually decline.