What does hypoxia mean

Once hypoxia occurs, it will be very dangerous to people's bodies and will directly lead to death. Therefore, you must go to the hospital as soon as you feel that your body is lacking oxygen. Oxygen treatment measures must be taken to allow patients to feel the fresh air they are breathing. In addition, do not let them go to noisy environments and keep the living environment absolutely quiet.

Hypoxia refers to a pathological process in which insufficient oxygen supply or oxygen utilization disorder in tissues leads to abnormal changes in the metabolism, function and morphological structure of tissues. Hypoxia is a very common pathological process in various clinical diseases. Hypoxia of important organs such as the brain and heart is also an important cause of death. In addition, the significant decrease in arterial oxygen content leads to insufficient oxygen supply to tissues, which is also called hypoxemia.

Hypoxia refers to the lack of endogenous oxygen, which is the oxygen bound to cells.

According to the cause of hypoxia and the characteristics of blood gas changes, simple hypoxia can be divided into four types:

2.1 Hypotonic hypoxia Hypotonic hypoxia refers to a significant decrease in Pa O2 resulting in insufficient oxygen supply to tissues. When Pa O2 is lower than 8kPa (60mmHg), it can directly lead to a significant decrease in CaO2 and SaO2, so hypotonic hypoxia can also be called hypotonic hypoxemia.

2.1.1 Reasons

Common causes of hypotonic hypoxia are low oxygen partial pressure of inspired gas, pulmonary dysfunction, and increased mixing of venous blood into arterial blood.

(1) Low oxygen partial pressure of inhaled gas: Hypoxia caused by inhaling gas with too low oxygen partial pressure is also called atmospheric hypoxia.

(2) External respiratory dysfunction: caused by pulmonary ventilation or gas exchange dysfunction, known as respiratory hypoxia. It is common in various respiratory diseases, respiratory center depression or respiratory muscle paralysis, etc.

(3) Venous blood is shunted into the arteries: more common in congenital heart disease.

2.1.2 Characteristics of blood oxygen changes

① The PaO2 decreases due to the low oxygen pressure diffused into the arterial blood. Too low PaO2 can directly lead to a decrease in CaO2 and SaO2;

② If there is no abnormal change in the quality and quantity of Hb, CO2max is normal;

③When PaO2 decreases, 2,3-DPG in red blood cells increases, so blood SaO2 decreases;

④ In case of hypoxia, PaO2 and blood SaO2 decrease, which leads to a decrease in CaO2;

⑤The arteriovenous oxygen difference decreases or changes little. Normally, when 100 ml of blood flows through tissues, about 5 ml of oxygen is utilized, that is, AV d O2 is about 2.23 mmol/L (5 ml/dl). The driving force for oxygen diffusion from blood to tissues is the oxygen partial pressure difference between the two. In case of hypotonic hypoxia, PaO2 and CaO2 are significantly reduced, which slows down the diffusion rate of oxygen. The same amount of blood diffuses less oxygen to tissues, eventually leading to a decrease in AVdO2 and tissue hypoxia. In case of chronic hypoxia, when the tissue's ability to utilize oxygen increases compensatorily, the change in A-Vd O2 may not be obvious.