branches in the lung by an embolus,
usually after a deep vein thrombosis
(see thrombosis, deep vein). If the em-
bolus is large enough to block the main
pulmonary artery, or if there are many
clots, the condition is life-threatening.
Pulmonary embolism is more likely
after recent surgery, pregnancy, and
immobility. A massive embolus can
cause sudden death. Smaller emboli
may cause severe shortness of breath,
rapid pulse, dizziness, chest pain made
worse by breathing, and coughing up of
blood. Tiny emboli may produce no
symptoms, but, if recurrent, may even-
tually lead to pulmonary hypertension.
A diagnosis may be made by a chest
X-ray, radionuclide scanning, and pul-
monary angiography. An ECG and
venography may also be performed.
Treatment depends on the size and
severity of the embolus. A small one
gradually dissolves and thrombolytic
drugsmay be given to hasten this pro-
cess. Anticoagulant drugsare given to
reduce the chance of more clots. Surgery
may be needed to remove larger clots.
pulmonary fibrosisScarring and thick-
ening of lung tissue, usually as a result
of previous lung inflammation. It may
be confined to an area of the lung affec-
ted by a condition such as pneumonia
or tuberculosis, or it may be widespread
through the lungs (see fibrosing alveoli-
tis). Shortness of breath is a common
symptom. Diagnosis is confirmed by
chest X-ray. Treatment depends on the
cause, but in most cases the fibrosis is
irreversible and treatment aims to pre-
vent the condition from progressing.
pulmonary function testsA group of
procedures used to evaluate lung func-
tion, to confirm the presence of some
lung disorders, and to ensure that
planned surgery on the lungs will not dis-
able the patient. The tests include
spirometry, measurement of lung vol-
ume, assessment of the degree of
bronchospasmwith a peak-flow meter,
and a test of blood gases.
pulmonary hypertensionA disorder
in which the blood pressure in the arter-
ies supplying the lungs is abnormally
high. Pulmonary hypertension develops
in response to increased resistance toblood flow through the lungs. To main-
tain an adequate blood flow, the right
side of the heart must contract more
vigorously than before. Right-sided heart
failuremay later develop.
Causes of pulmonary hypertension may
include chronic obstructive pulmonary
disease (see pulmonary disease, chronic
obstructive), a pulmonary embolism, pul-
monaryfibrosis, and some congenital
heart diseases (see heart disease, con-
genital), but it can also develop without
an obvious cause. Symptoms, which
include enlarged veins in the neck,
enlargement of the liver, and general-
ized oedema, only develop when heart
failure occurs. Treatment is aimed at the
underlying disorder (if known) and the
relief of the heart failure. Diuretic drugs
and oxygen therapymay be given.
pulmonary incompetenceA rare de-
fect of the pulmonary valveat the exit of
the heart’s right ventricle. The valve fails
to close properly, allowing blood to leak
back into the heart. The cause is usually
rheumatic fever, endocarditis, or severe
pulmonary hypertension.
pulmonary oedemaAccumulation of
fluid in the lungs, usually due to left-
sided heart failure. It may also be due to
chest infection, inhalation of irritant
gases, or to any of the causes of gener-
alized oedema. The main symptom is
breathlessness, which is usually worse
when lying flat and may disturb sleep.
There may be a cough, producing frothy,
sometimes pink, sputum. Breathing may
sound bubbly or wheezy.
A diagnosis is made by a physical
examinationand by a chest X-ray. Treat-
ment may include morphine, diuretic
drugs, aminophylline, and oxygen therapy;
artificial ventilationmay also be given.
pulmonary stenosisA heartcondition
in which the outflow of blood from the
right ventricleis obstructed, causing the
heart to work harder to pump blood to
the lungs. The obstruction may be
caused by narrowing of the pulmonary
valveat the exit of the ventricle; by nar-
rowing of the pulmonary artery, which
carries blood to the lungs; or by narrow-
ing of the upper part of the ventricle.
Pulmonary stenosis is usually congeni-
tal, and may occur alone or with a set ofPULMONARY FIBROSIS PULMONARY STENOSISP