The following points highlight the four main types of hypoxia. The types are: 1. Hypoxic Hypoxia 2. Anemic Hypoxia 3. Stagnant Hypoxia 4. Histo-toxic Hypoxia.
Type # 1. Hypoxic Hypoxia:
This is characterized by normal oxygen capacity but diminished oxygen tension in the arterial blood with the result of varying degree of hemoglobin unsaturation.
(a) High Altitude:
Hypoxia is caused by the diminished oxygen content in the atmospheric air and consequently in the alveolar air and blood stream. This leads to respiratory alkalosis.
(b) Rapid, Shallow Respiration:
Shallow breathing is due to insufficient oxygenation of blood. This happens in diseases.
(c) Congenital Heart Disease:
In the congenital cardiac defect a portion of the blood may flow directly form the right to the left side of the heart without passing through the lungs. As a result, the mixture of aerated and non-aerated blood in the systemic circulation causes hypoxic hypoxia.
Type # 2. Anemic Hypoxia:
This is characterized by diminution in the oxygen capacity of arterial blood due to the decrease in the amount of functioning hemoglobin.
Type # 3. Stagnant Hypoxia:
This is due to circulatory insufficiency—the rate of blood flow through the tissues being retarded, with resulting increase in the percentage volume of oxygen removed from the blood in its passage through the capillaries.
Type # 4. Histo-toxic Hypoxia:
In this condition the oxygen supply is normal in every respect but the degree of oxygen utilization by the tissues is diminished because the tissue cells are poisoned in such a way that they cannot use oxygen properly.