Hypoxemia . It is an abnormal decrease in the partial pressure of oxygen in arterial blood. Not to be confused with hypoxia , a decrease in the diffusion of oxygen in the tissues.


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  • 1 Symptoms
  • 2 Causes of hypoxemia
    • 1 Alveolar hypoventilation
    • 2 Deterioration of diffusion
    • 3 Ventilation-perfusion, inequality (or ventilation-perfusion)
    • 4 Bypass
  • 3 Treatment
  • 4 Source


Poor mental performance, including memory and the ability to solve mental problems. Staying, for example 5,000 meters high for an hour, reduces mental performance by 50%. Personality disturbances and disorders of consciousness can also occur. The carotid receptors and stimulate aortic, as a result of a decrease in oxygen concentration in blood, hyperventilation and to the increase the respiratory rate increases blood oxygen .

Causes of hypoxemia

  • Alveolar hypoventilation.
  • Impaired diffusion of blood gases through the membrane.
  • Ventilation-perfusion, inequality.

Alveolar hypoventilation

If alveolar ventilation is low, there may be enough oxygen delivered to the alveoli per minute. This can cause hypoxemia, even if the lungs are normal, as the cause may be outside the lungs (for example, obstruction of the airways, depression of the respiratory center of the brain, or muscle weakness).

Impaired diffusion

Impaired blood gas diffusion through the membrane into the lungs can cause hypoxemia. However, this is a very rare cause, as it is only in very unusual circumstances that it actually causes a problem.

Most of the above cases once thought to be due to a diffusion problem are now recognized as due to ventilation-perfusion inequality.

Ventilation-perfusion, inequality (or ventilation-perfusion)

It is a common cause of hypoxemia in patients with lung disease. It is the areas of the lungs with ventilation / perfusion ratios that have less than one (but not zero) that cause hypoxemia by this mechanism. A ventilation / perfusion ratio of zero is considered a shunt.


Blood diversion from the right side to the left side of the circulation (from right to left shunt) is a powerful cause of hypoxemia.

The shunt can be intracardiac or intrapulmonary can be. Traditionally it has been thought that this cause could be easily distinguishable from others as the sole cause that cannot be corrected by administering 100% oxygen.

However, this may be an oversimplification, as some types of intrapulmonary shunts can be closed with 100% O 2 and hypoxemia remedied. Ventilation-perfusion, inequality.


If hypoxemia is caused by being at a high altitude above sea level, you will have to descend to recover. If it is due to some other problem, it will have to be treated.


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