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2. WHAT IS HYPOXIA ?

3.  Hypoxia is a condition, which manifests as
the deficient oxygen supply at the tissue
level. It should not be confused with the
term anoxia, which means complete absence
of oxygen. Oxygen is a very important
element for our survival and its deficiency
may lead to death within a matter of
minutes.

4.  Tissues of the lungs extract oxygen from the
inhaled air and pass it on to the blood, which
contains hemoglobin, an oxygen binding
protein. It is mandatory for the oxygen to
combine with hemoglobin in order to travel
via the blood into different tissues.

5.  Hypoxia manifests as the sub-optimal levels
of oxygen at the tissue level. The process of
energy generation in cells is inhibited due to
the decreased oxygen availability. It causes
cellular stress and a wide variety of
complications.

6. What are the Types of Hypoxia?

7.  Hypoxic hypoxia - It mainly occurs due to
the decrease in the pressure of oxygen in the
blood vessels, which carry the oxygenated
blood. The defect usually lies at the level of
lungs.

8. Anemic hypoxia - In this type of hypoxia, the
lungs are working just fine, but the oxygen
carrying capacity of blood is reduced due
to lesser hemoglobin in the body as in the
case of anemia.

10.  Stagnant hypoxia - It occurs due to
the reduced blood flow to the tissues,
which implies that in spite of normal partial
pressure of oxygen and hemoglobin,
sufficient amount of oxygen is not being
delivered to the tissues. It is also called as
ischemic hypoxia.

11.  Histotoxic hypoxia - This type of hypoxia
manifests due to the decreased capability of
the tissues to utilize the oxygen because
they have been poisoned. It must be kept in
mind that this is not at par with the standard
definition of hypoxia, which clearly defines
hypoxia as the condition of inadequate oxygen
supply at tissue level. Thus, strictly speaking,
it is not a true hypoxia and only manifests in
cases of poisoning.

12.  What are the Causes of Hypoxia?

13.  Causes of hypoxic hypoxia:
 Low oxygen pressure in the air we breathe in
at higher altitudes. It is very common in
mountain climbers and is known as altitude
sickness. Breathing in a closed space also
induces hypoxia in mineworkers.

14.  Breathing artificial gas mixture having a low partial
pressure of oxygen also induces hypoxic hypoxia as
in the case of deep-sea divers or scuba divers.
 Paralysis of respiratory muscles as in the case of
poliomyelitis, motor neuron diseases
 Damage to the respiratory centers of brain due to
brain tumors or due to the consumption of toxic
drugs like cocaine and heroin
 Respiratory or lung diseases like
asthma, emphysema, chronic bronchitis,
and bronchiectasis cause an obstruction in the
respiratory passage and leads to a low partial
pressure of oxygen in the blood vessels, which
eventually causes hypoxia.
 Pulmonary edema and pulmonary fibrosis

16.  Causes of anemic hypoxia:
 Excessive internal blood loss in the form of
hemorrhage of any organ
 Excessive external blood loss in accidents,
surgical procedures or child birth
 Anemia of all types
 Carbon monooxide poisoning

17.  Congestive heart failure: the blood pumped
out by heart per minute is reduced, which in
turn leads to decreased blood flow to the
tissues and hence causes stagnant hypoxia.
 Congenital heart defects in children such as
ventricular septal defect, atrial septal
defect, tetralogy of Fallot
 Localized stagnant hypoxia is caused by the
stagnation of the blood supply in any area of
the body, like in the case of Raynaud’s
disease or Buerger’s disease, where the
blood supply to extremities is restricted.

18.  Cyanide poisoning
 Sulphide poisoning
 This condition also exacerbated by the use of
alcohol, tobacco smoking, and excessive
narcotics use

19.  What are the Symptoms and Signs of Hypoxia?

20.  The symptoms and signs of hypoxia depend on
the severity of the condition, the rate at which
the condition is progressing and on the ability of
the body to compensate the oxygen deficit.
Common symptoms and signs are:
Chronic Hypoxia:
 Cyanosis: It is the bluish discoloration of skin
and mucous membranes. It is seen in nails,
earlobes, and tongue.
 Tachycardia: It is the increase in the heart rate
and occurs because of compensatory mechanism
initiated by the heart to pump more blood to the
oxygen-starved tissues.

21.  Tachypnoea: An increase in the rate of
breathing per minute is known as tachypnea.
 Shortness of breath or dyspnea: It occurs
after physical exertion and exercise. In
severe cases, shortness of breath might occur
even at rest, which calls for emergency
consultation with a doctor.
 Fatigue or tiredness
 Palpitations and development of abnormal
heart rhythm in severe cases

22.  Fulminant hypoxia:
 It is a severe hypoxia, which develops
rapidly within seconds. It might occur in the
cases of accidental loss of cabin pressure in
an aircraft above 20,000 feet with no
supplemental oxygen. It leads
to unconsciousness within 15-20seconds and
brain death may follow in 4-5 minutes.

23.  Acute hypoxia:
 The symptoms of acute hypoxia include:
 Lack of co-ordination
 Slowing of reflexes
 Slurring of speech
 Unconsciousness
 Coma and death might possibly occur in
minutes or hours if the body’s compensatory
mechanisms are insufficient

25. What are the Complications of Hypoxia?

26.  Hypoxia is a serious condition and must be
timely taken into consideration. Ignored
cases of hypoxia might lead to severe and
permanent adverse effects on health or even
cause death. The various complications
include
 Brain damage and paralysis
 Death of body tissues leading to gangrene
and
 Cardiac arrest

27. Howdo you Diagnose Hypoxia?

28.  Hypoxia is usually diagnosed by evaluation of
symptoms and medical history of patient to
identify the cause. The presence and degree
of hypoxia is determined by
 Arterial Blood Gas analysis (ABG
analysis): It gives a brief estimate of the
partial pressure of oxygen in the blood
vessels carrying oxygenated blood and the
amount of hemoglobin that has been
saturated with oxygen

29.  Pulse oximetry: Hypoxia can also be
estimated by a pulse oximeter, which is
placed at the tip of finger and is connected
to the monitor. The percentage of oxygen
saturation is continuously monitored on the
screen.
 Other diagnostic blood tests and imaging may
be done to determine the cause of hypoxia
and institute appropriate treatment.

30. Howdo you Treat Hypoxia?

31.  The main aim of treatment is to restore partial
pressures of oxygen in the blood to normal and
keep the patient comfortable. The cause of
hypoxia has to be identified and treated.
 The treatment of hypoxia is oxygen
administration.
 Supplemental oxygen is administered at
atmospheric pressure of 760 mmHg by a nasal
cannula or simple oxygen facemask connected to
an oxygen reservoir.

33.  Hyperbaric oxygen therapy (inhalation of 100%
pure oxygen at high barometric pressure) is
given in those cases of hypoxia where normal
hemoglobin is not available to carry the oxygen
to the tissues.
 Indications include:
Anemic hypoxia
Wounds with poor blood supply
Carbon monoxide poisoning
Decompression sickness and air embolism in
scuba divers and mountain climbers.

34.  Mechanical ventilation: It is a form of life
support in patients who are very sick and
cannot breathe on their own. The device
used is termed a ventilator, breathing
machine or respirator. It does the work of
breathing by forcing a constant stream of air
into the nasal passages.
 A ventilator is used as a temporary measure
while the patient is on other treatments to
improve the primary condition. Most patients
come off the ventilator in a few hours or
days but some remain sick and continue to
be on life support.

35.  Treating the cause: The underlying cause of
hypoxia has to be treated at the same time.
This may be bronchodilators to treat asthma,
drugs such as steroids to reduce lung
inflammation or transfusing packed cells in
an anemic patient.
 It is important that the underlying cause is
also treated while treating the hypoxia.

36. Howdo you Prevent Hypoxia?

37.  Hypoxia can be prevented by taking
appropriate precaution
 Mountain climbes must take proper training
before hand. It is very important for the
mountain climbers to climb a specific
distance and then camp for 2-3 days to get
acclimatized to the increasing altitude and
its changes on the body.
 Mountain climbers and scuba divers must
always carry oxygen cylinders and face
masks.

39.  It is crucial to recognize the symptoms of
hospitalized patients with impending
hypoxia, and administer at earliest, the
oxygen therapy through nasal cannula and
face masks.
 Patients suffering from asthma should be
regular with their medications