A

acute respiratory distress syndrome (ARDS) A
complex of symptoms, formerly called adult respi-
ratory distress syndrome, in which respiratory
distress and RESPIRATORY FAILUREdevelop accompa-
nying severe illness or trauma. ARDS involves the
whole of both LUNGS, as the lungs become
inflamed and fill with fluid. ARDS may develop as
a consequence of injury that directly affects the
lungs (notably blunt trauma to the chest, near
drowning,PNEUMONIA, and smoke inhalation) or
when the injury or illness affects other parts or
systems of the body. Systemic INFECTION (SEPSIS),
DRUG OVERDOSE, and BLOOD TRANSFUSIONmay also
result in ARDS. ARDS can affect people of any age
and is life-threatening. Because people who
develop ARDS are already very ill, ARDS has a
high death rate (about 40 percent). The syndrome
may cause complete respiratory failure or lead to
total system failure, either of which presents sig-
nificant challenge for recovery.

Symptoms and Diagnostic Path

People who develop ARDS have generally sus-
tained severe trauma or infection and most are
already in the hospital when their symptoms begin.
Early symptoms of ARDS include restlessness,
TACHYPNEA(rapid, shallow breathing), and HYPOXIA
(reduced oxygen to the body’s tissues). ARDS pro-
gresses rapidly to full involvement of the lungs.
Chest X-rays show the filling of the lungs with
INFLAMMATIONand fluid (called diffuse infiltration).
Arterial BLOODgases show the decreased percentage
of oxygen in the blood. Doctors often perform tests
on SPUTUMand fluid from the lungs to identify any
pathogens, notably BACTERIA, that may be present.

Treatment Options and Outlook
Immediate oxygen supplementation is essential.
Many people require MECHANICAL VENTILATIONwith

positive end expiratory pressure (PEEP) to

increase the amount of oxygen entering the lungs.

Doctors generally administer sedation while the

person is on mechanical ventilation, to provide

comfort and to prevent the natural tendency to

fight the intervention. Treatment primarily is sup-

portive, including close monitoring of cardiovas-

cular and renal (kidney) functions. Because

infection, either in the lungs or elsewhere in the

body, is often present, many people may also

receive intravenous (IV) ANTIBIOTIC MEDICATIONS.

The outlook for full recovery depends on

numerous factors including the person’s age, gen-

eral health status, and the ability to reverse the

circumstances responsible for the initial develop-

ment of ARDS. Even medical intervention that

begins early in the course of ARDS cannot predict

the success of treatment. About 60 percent of peo-

ple survive the ARDS episode, though the severity

of illness can require extensive recuperation.

Risk Factors and Preventive Measures

The primary risk factors for ARDS are sepsis

(severe infection) and major trauma, either to the

lungs or to the body in general. Though such

infection or trauma alerts doctors to the grave risk

for ARDS, there are no known measures that can

head off the development of ARDS. Public health

measures to minimize the risk factors (trauma and

infection) are critical. Once ARDS occurs, how-

ever, aggressive medical intervention and support

provide the best chance for survival.

See also HEART FAILURE; SEVERE ACUTE RESPIRATORY

SYNDROME(SARS).

aging, pulmonary changes that occur with The

LUNGSand tracheobronchial structures undergo few

but significant changes over the course of the life-

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