Encyclopedia of Health and Medicine

226 The Pulmonary System
resistance against the blood flowing through the
veins. People who have an increased tendency to
form clots (hypercoagulation) are also at increased
risk of developing a clot or pulmonary embolism.
Research suggests that as many as 80 percent of
people who have DEEP VEIN THROMBOSIS (DVT) experience
frequent pulmonary emboli. About half of
the people who have one pulmonary embolism
experience subsequent episodes.
Prevention often incorporates ongoing ANTICO-
AGULATION THERAPY in people at risk for pulmonary
embolism, including those who have had a previous
episode. Support stockings help the leg muscles
to work more efficiently in massaging blood
through the veins. For someone who has never
had a pulmonary embolism, regular physical
activity and maintaining healthy body weight help
to lower the risk for clot formation. Frequent
stretching of the legs, and getting up to walk for a
few minutes every hour, can maintain effective
circulation and venous return when taking long
air flights or train or automobile trips to lower the
risk for both DVT and pulmonary embolism. Postoperative
recovery and recuperation regimens
incorporate early ambulation (walking within
hours of surgery) as well as progressive ambulation
(walking for longer times and distances as
recovery continues). When the person cannot
ambulate, preventive measures may include compression
stockings and anticoagulant medications.
See also COAGULATION; MYOCARDIAL INFARCTION;
PLATELET AGGREGATION; POSTOPERATIVE CARE; STROKE;
SURGERY BENEFIT AND RISK ASSESSMENT; WEIGHT LOSS
AND WEIGHT MANAGEMENT.
pulmonary fibrosis A condition in which SCAR
tissue replaces normal tissue in the alveoli, reducing
the ability of the LUNGS to oxygenate the
BLOOD. Many conditions of the lungs result in
fibrosis, notably CYSTIC FIBROSIS and occupational
PNEUMOCONIOSIS. Pulmonary fibrosis may also be
idiopathic—that is, develop without an identifiable
cause. Once the process of fibrosis begins in
the lungs, it tends to be progressive. In many people
the progression takes place over decades,
resulting in slow decline of pulmonary function.
Clubbing of the fingers is a characteristic indication
of chronic HYPOXIA (insufficient oxygen reaching
the tissues) such as results from pulmonary
fibrosis.
Symptoms of pulmonary fibrosis include
• persistent dry COUGH
• DYSPNEA (shortness of breath) that worsens with
exertion
• diminishing capacity for physical activity
• fatigue
• chest tightness, discomfort, or PAIN
The diagnostic path includes chest X-RAY, pulmonary
function tests, and arterial blood gases.
The pulmonologist may conduct additional imaging
procedures, such as COMPUTED TOMOGRAPHY (CT)
SCAN, to further assess structural changes in the
lungs. BRONCHOSCOPY and lung biopsy may be necessary
to rule out CANCER or to identify pathologic
changes that characterize specific diseases.
Treatment depends on the underlying cause, if
the diagnostic path can identify one. Generalized
treatment may include CORTICOSTEROID MEDICATIONS
to reduce INFLAMMATION, bronchodilator medications
to relax and open the airways, and cough
suppressants to relieve nonproductive coughing.
These methods control symptoms and improve
BREATHING in many people who have pulmonary
fibrosis, especially in the early and middle stages
of the condition. However, progressive pulmonary
fibrosis typically results in RESPIRATORY FAILURE for
which LUNG TRANSPLANTATION may be the only
viable treatment option.
See also BRONCHIECTASIS; CHRONIC OBSTRUCTIVE
PULMONARY DISEASE (COPD); CYSTIC FIBROSIS AND THE
LUNGS; INTERSTITIAL LUNG DISORDERS; NAILS.