What is SPO2?

Survival signs are numbers measured using different devices and techniques to assess the basic functions of the body. There are 4 traditional signs of survival including pulse, temperature, breathing rate and blood pressure. However, many researchers have now mentioned a fifth sign of survival, the SpO2 index.

1. What is spo2 index?

Oxygen gas is essential for human life. When we breathe, oxygen enters the lungs. Blood and hemoglobin (the most important component of the blood) will transport oxygen from the lungs to everywhere in the body to ensure the maintenance of life. This transport is carried out when hemoglobin (Hb) in combination with oxygen forms HbO2.

A hemoglobin molecule can be combined with 4 oxygen molecules, once all 4 oxygen molecules are attached called oxygen saturation. The SpO2 index is also known as oxygen saturation in the blood, which is in account for the ratio of oxygenated hemoglobin to the total amount of hemoglobin in the blood. If all hemoglobin molecules in the blood are attached to oxygen then oxygen saturation is 100%. A normal healthy person, arterial oxygen saturation ranges between 95-100%. The index of oxygen saturation in the blood below 90% is low.

The SpO2 index is considered one of the signs of survival of the body, in addition to other signs of temperature, pulse, breathing and blood pressure. When the body is deprived of blood oxygen, such bodies as the heart, liver, brain,… will quickly suffer negative effects. Therefore, it is necessary to monitor the SpO2 index regularly to promptly intervene if a dangerous situation occurs.

2. Roles and applications of SpO2 indicators

2.1 In emergency resuscitation

SpO2 is the first basic living index in the monitoring of emergency resuscitation patients. Through the SpO2 index displayed by the SpO2 machine, the doctor can assess the health status of the patient, especially for those who have to ventilator or oxygen ventilator.

2.2 Detection of CO gas poisoning

CO is a toxic gas, which is more likely to burn coal. CO replaces oxygen at the iron attachment position on the Hb molecule, so CO poisoning increases COHb (carbon monoxide-attached hemoglobin) and reduces HbO2 (oxygenated hemoglobin). This phenomenon reduces the saturation of oxygen in the blood. The patient's blood will be taken to the laboratory using a SpO2 meter to accurately diagnose if the patient is poisoned with CO gas.

What is SPO2?

SpO2 index meter for accurate diagnosis of patients with CO poisoning

2.3 Diagnosis of low blood pressure

The SpO2 index is an accurate reflection of the low vascular pressure to 30mmHg(low blood pressure). In the event that the result of a SpO2 measurement in the finger is suspected of accuracy, the doctor may use the SpO2 index probe on the patient's forehead as it responds more quickly to a Change in SpO2.

2.4 Diagnosis of anemia

Anemia is a hemoglobin phenomenon in the blood that decreases lower than normal levels. When there is no hypoxia, the circuit-based oxygen meter results in an accurate SpO2 index when the hemoglobin concentration drops to 2 – 3g/dL.

2.5 Detection of decreased througheration

Clinical trials show that the SpO2 index is a sensitive sign for evaluative the condition of ventilation when the patient is breathing normally (not used for evaluation when the patient is breathing oxygen support).

2.6 Support for the treatment of many respiratory diseases

Patients with a SpO2 measurement of less than 93%, rated as hypoxia, should be given oxygen or blood breathing (if the patient cannot breathe on their own). Or, patients are working in a mysterious, oxygen-deprived environment such as factories, inciners, ore mines,… when going into a well-ventilated environment, oxygen will be replenished when breathing and the doctor will adjust the amount of oxygen for the patient to breathe until the SpO2 index is stable at 97 -100%. The oxygen levels used for patients continue to be kept until they breathe steadily again. And this process is not to mention the role of spo2 meters.

SpO2 index plays an extremely important role for each person's health. SpO2 monitoring should be carried out regularly so that the patient understands the amount of oxygen in the blood, knows when more oxygen is needed for the body and takes timely response measures when in a dangerous situation.

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  • What is the SPO2 index in ordinary people?
  • Normal SPO2 index in newborns
  • What are the signs of survival?

About: Minh Quynh

b1ffdb54307529964874ff53a5c5de33?s=90&d=identicon&r=gI am the author of Share99.net. I had been working in Vinmec International General Hospital for over 10 years. I dedicate my passion on every post in this site.


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