Oxygen saturation refers to the percentage of hemoglobin that is saturated with oxygen, that is, the ratio of the oxygen content of hemoglobin to the amount of oxygen bound multiplied by 100. It mainly depends on the arterial oxygen partial pressure (PO2). Oxygen saturation indirectly reflects the magnitude of blood oxygen partial pressure and is an indicator of the degree of hemoglobin oxygen content and the hemoglobin system buffering capacity. It is affected by blood oxygen pressure and blood pH. When the oxygen partial pressure is low, the blood oxygen saturation is also low; when the oxygen partial pressure is high, the blood oxygen saturation is also high. Arterial blood was drawn and measured with a blood gas analyzer.

Basic Information

Specialist classification: Respiratory examination classification: pulmonary function test

Applicable gender: whether men and women apply fasting: not fasting

Tips: Some drugs can affect the pH of the blood. The doctor should inform the doctor about the recent medication before the test. Normal value

Generally, the normal value of SpO2 should be no less than 94%, and below 94% is insufficient oxygen supply. Some scholars have set SpO2 <90% as the standard for hypoxemia, and believe that when SpO2 is higher than 70%, the accuracy can reach ±2%, and when SpO2 is lower than 70%, there may be errors.

Clinically, we have compared the SpO2 values ​​of several patients with the values ​​of arterial oxygen saturation. It is believed that the SpO2 reading can reflect the patient's respiratory function and reflect the changes of arterial oxygen in a certain extent.

In patients with thoracic surgery, except for the clinical symptoms and values ​​of individual cases, blood gas analysis is required. Conventional application of pulse oximetry monitoring can provide meaningful indicators for clinical observation of disease changes, avoiding repeated blood collection by patients and reducing nurses' The workload is worth promoting.

Clinically, it is generally greater than 90%, and of course it is necessary for different departments.

Clinical significance

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

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

In addition, hypoxia and the patient's own disease may have an important impact on the patient's homeostasis.

Low results may be diseases: pediatric respiratory failure, left ventricle double exit, pediatric acute respiratory failure, pediatric alveolar proteinosis, shock, pediatric obstructive sleep apnea, congenital pulmonary arteriovenous fistula

1. Conventional arterial blood should be taken for examination. If venous blood is to be taken, the forearm should be immersed in 45 °C warm water for 20 minutes to make the venous blood arterial. It is not advisable to use a tourniquet when drawing blood.

2. Flush with heparin beforehand in the syringe.

3. Ensure that the needle and needle of the syringe are tightly combined, and there must be no air leakage to ensure that the blood sample does not come into contact with the outside air.

4. Send samples in time.

5, certain drugs can affect the pH of the blood, the doctor should be informed of the recent medication before the test.

Inspection process

The blood of the test subject is taken and measured.

Not suitable for the crowd

Generally there are no special taboos.

Adverse reactions and risks

1, may bring certain blood vessel damage.

2, blood draw has the potential to bring infection.