What Is Blood Oxygen Saturation?

Blood oxygen saturation (SaO2) is the percentage of the capacity of oxygen-bound oxygenated hemoglobin (HbO2) in the blood to the total bindable hemoglobin (Hb, hemoglobin) capacity. Important physiological parameters. The functional oxygen saturation is the ratio of the concentration of HbO2 to the concentration of HbO2 + Hb, which is different from the percentage of oxygenated hemoglobin. Therefore, monitoring arterial oxygen saturation (SaO2) can estimate the oxygenation of the lungs and the ability of hemoglobin to carry oxygen. The oxygen saturation of normal human arterial blood is 98%, and venous blood is 75%.

Blood oxygen saturation

Blood oxygen saturation (SaO2) is the combination of oxygen in the blood

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It is generally recognized that the normal SaO2 should not be less than 94%, and below 94% is insufficient oxygen supply. Some scholars set SaO2 <90% as

Hypoxia is an imbalance between the body's oxygen supply and oxygen consumption, that is, tissue metabolism is in a state of hypoxia. Whether the body is hypoxic depends on the amount of oxygen transported and the oxygen reserve that the tissues accept to meet the needs of aerobic metabolism. The harm of hypoxia is related to the degree, rate and duration of hypoxia. Severe hypoxemia is a common cause of death from anesthesia, accounting for about 1/3 to 2/3 of deaths from cardiac arrest or severe brain cell damage.

Clinically, PaO2 <80mmHg is hypoxia, which is basically equivalent to severe hypoxemia.

Hypoxia has a huge impact on the body. For example, the effects on CNS, liver and kidney function. The first thing that occurs during hypoxia is the acceleration of compensatory heart rate, the increase in heart rate and cardiac output, and the lack of oxygen content in the circulatory system with a high dynamic state. At the same time, blood flow redistribution is generated, and the brain and coronary vessels are selectively expanded to ensure sufficient blood supply. However, in severe hypoxic conditions, due to the accumulation of lactic acid under the endocardium, ATP synthesis is reduced, myocardial depression occurs, resulting in bradycardia, premature contraction, decreased blood pressure and reduced cardiac output, and arrhythmias such as ventricular fibrillation Even stopped.

In addition, hypoxia and the patient's own disease may have a significant impact on the patient's internal environmental homeostasis.