secondary INFECTIONif present, or when the cause
of the pneumonitis is bacterial infection. Elimina-
tion of irritants, when known, prevents the pneu-
monitis from recurring. Most people recover fully
and without complications after the inflammation
subsides. Chronic pneumonitis may result in scar-
ring (fibrosis) and permanent damage to pul-
monary structures, however.
See also ASTHMA; HYPOXIA; MULTIPLE CHEMICAL SEN-
SITIVITY SYNDROME; PLEURISY; PNEUMOCONIOSIS; PNEU-
MONIA.
pneumothorax A circumstance in which air gets
in the pleural space (membrane space between
the pleural linings of the lung and the thoracic
cavity). Pneumothorax results in collapse of a por-
tion of, or the entire, lung. Doctors identify differ-
ent kinds of pneumothorax. They include
- spontaneous pneumothorax, in which the
pneumothorax occurs for no identifiable reason
or as a consequence of severe lung disease such
as CHRONIC OBSTRUCTIVE PULMONARY DISEASE
(COPD) orTUBERCULOSIS - simple pneumothorax, in which air enters the
pleural space and part of all of the lung col-
lapses but there is no pressure on surrounding
structures - tension pneumothorax, in which the pneu-
mothorax occurs and pressure continues to
build in the pleural space, putting pressure on
the heart and causing potentially life-threaten-
ing cardiovascular collapse - traumatic pneumothorax, in which air enters
the pleural cavity as a result of injury or sur-
gery
Symptoms include DYSPNEA (shortness of
breath) and sudden, sharp PAINthat worsens with
deep BREATHINGor coughing. Some people develop
CYANOSIS(bluish hue to the lips and SKIN) that indi-
cates the body is not receiving enough oxygen.
TACHYCARDIA(rapid HEART RATE), TACHYPNEA(rapid
breathing), and HYPOTENSION(low BLOOD PRESSURE)
are also common. The diagnostic path includes
AUSCULTATION, which often reveals reduced or
absent BREATH SOUNDS, and chest X-RAY, which
shows the area of lung collapse.
A pneumothorax that involves only a small
portion of the lung often heals itself. A larger
pneumothorax requires insertion of a chest tube
(done with local ANESTHESIA) to remove the air and
allow the lung to reinflate. Most people who
require such treatment stay in the hospital until
the affected lung returns to normal function and
the doctor can safely remove the chest tube.
About half of people who have one episode of
spontaneous pneumothorax have a subsequent
episode, though most people do not experience
any permanent lung damage. People who are tall
and thin are most vulnerable to spontaneous
pneumothorax. Spontaneous pneumothorax is
also more common among people who smoke.
See also BRONCHIECTASIS.positive airway pressure Methods to maintain
higher than normal air pressure against the inner
walls of the bronchi and TRACHEA during
BREATHING. Positive airway pressure may be a treat-
ment for ATELECTASIS(collapsed lung), chronic RES-
PIRATORY FAILURE, andSLEEP APNEA. Positive airway
pressure is also an important aspect of MECHANICAL
VENTILATION.
The most common method of positive airway
pressure is continuous positive airway pressure
(CPAP), in which a small pump pushes a steady
flow of air through a face mask to maintain
enough pressure against the airways to keep them
open and unobstructed during sleep. CPAP is a
common and an effective treatment for sleep
apnea. Bilevel positive airway pressure, or BiPAP,
is a flexible variation of CPAP. The conventional
CPAP device maintains a constant airway pressure
for inhalation and exhalation. BiPAP provides
additional pressure or support during inspiration
to aid inhalation.
See also BRONCHUS; OXYGEN THERAPY; SLEEP APNEA.postural drainage See CHEST PERCUSSION AND POS-
TURAL DRAINAGE.pulmonary edema Abnormal fluid accumulation
within the alveoli and the interstitial tissues of the
LUNGS, typically resulting from CARDIOVASCULAR DIS-
EASE(CVD) such as HEART FAILUREor CARDIOMYOPATHY.
PNEUMONIA, ACUTE RESPIRATORY DISTRESS SYNDROMEpulmonary edema 223