tion, the decrease triggers actions in the body
designed to slow the breathing. Key among these
is temporary loss of consciousness (fainting),
which returns breathing to the involuntary con-
trol of the brainstem and restores normal breath-
ing patterns. People who are hyperventilating
often feel as if they were not getting enough oxy-
gen, though in fact they are getting plenty. Most
often hyperventilation results from emotional
stress, panic, or anxiety. Rarely, cardiovascular or
pulmonary disturbances cause a similar breathing
pattern. Chest X-RAY, blood tests, and ELECTROCAR-
DIOGRAM(ECG) can quickly determine whether this
is the case.
The standard treatment for an active episode of
hyperventilation is breathing slowly and purpose-
fully. Breathing through only one nostril (holding
the other nostril closed with the fingers) helps
focus conscious intent on the breathing as well as
reduce the amount of air entering the LUNGS.
Though once a common remedy for
hyperventilation, BREATHING into a
paper bag may allow carbon dioxide
levels in the blood to rise too much.
Doctors no longer recommend this
method.Once breathing returns to normal the
oxygen–carbon dioxide balance in the blood does
the same and symptoms such as dizziness or light-
headedness fade. Stress management methods
such as MEDITATIONand YOGAhelp lower overall
anxiety levels, which reduces hyperventilation
episodes. BREATHING EXERCISES are also helpful.
Hyperventilation without underlying cardiovascu-
lar or pulmonary disease is not harmful to health.
See also HYPOXIA.
hypoxemia See OXYGEN SATURATION.
hypoxia Inadequate oxygen perfusion of the tis-
sues. Hypoxia occurs when the BLOOD cannot
deliver adequate oxygen, which may result from
pulmonary dysfunction, cardiovascular dysfunc-
tion, STROKE, TRAUMATIC BRAIN INJURY(TBI), disorders
of the blood such as ANEMIAthat affect erythro-
cytes (red blood cells) or HEMOGLOBIN, and BREATH-
ING disturbances such as APNEA. Hypoxia may
involve only a defined organ or area, such as a
region of the BRAINaffected by STROKE, or involve
the entire body. Permanent tissue damage or tis-
sue death results when hypoxia persists. Symp-
toms of hypoxia may include CYANOSIS(bluish hue
to the lips and SKIN), tiredness, and DYSPNEA(short-
ness of breath or difficulty breathing). Most
hypoxia requires supplemental oxygen with addi-
tional treatment that targets the underlying cause.
See also ALTITUDE SICKNESS; DECOMPRESSION SICK-
NESS; OXYGEN SATURATION; OXYGEN THERAPY; POLY-
CYTHEMIA VERA.interstitial lung disorders A broad term for
chronic conditions that restrict the ability of the
LUNGSto function properly, encompassing more
than 150 diseases. Interstitial lung disorders, also
called interstitial lung disease as a collective term,
are typically obstructive, fibrotic (involve SCARfor-
mation), and progressive. Many arise from
occupational exposures such as to asbestos
(ASBESTOSIS), silica (SILICOSIS), and coal dust
(miner’s PNEUMONOCONIOSIS). A variant form that
more commonly occurs later in life, idiopathic
pulmonary fibrosis (IPF), has no identifiable cause
and tends to be more severe in its progression.
The general symptoms, diagnostic paths, and
treatment approaches are similar for interstitial
lung disorders. Common symptoms include
COUGH, DYSPNEA(shortness of breath or difficulty
BREATHING), and frequent INFECTION. Treatment tar-
gets slowing the progression of the disease, reliev-
ing symptoms, and preventing infections. Lung
transplantation is sometimes a treatment option
for severely progressive IPF. However, many peo-
ple who have interstitial lung disorders are able to
manage their symptoms for years to decades,
allowing satisfactory QUALITY OF LIFE.
See also CHRONIC OBSTRUCTIVE PULMONARY DISEASE
(COPD); CYSTIC FIBROSIS AND THE LUNGS; LIVING WITH
CHRONIC PULMONARY CONDITIONS.interstitial lung disorders 205