Monitor oxygen saturation probe refers to the probe finger fixed to the patient's finger, the use of fingers as a transparent container containing hemoglobin, the use of the wavelength of 660nm red and 940nm near-infrared light as the incident light source, measured through the tissue bed Light transmission intensity, to calculate the hemoglobin concentration and oxygen saturation.

By SpO2 monitoring, you can get SpO2, pulse rate, pulse wave. Used in a variety of patient oxygen monitoring, usually the other end is connected to the ECG monitor.

Functional principle

SpO2 SpO2 refers to the percentage of blood oxygen and blood oxygen capacity. As a noninvasive, rapid, safe and reliable continuous monitoring indicator, SpO2 has been recognized. It is currently used extensively in anesthesia, surgery and PACU and ICU. According to the spectroscopic properties of HbO2 and Hb in the red and infrared regions, it can be seen that the absorption of HbO2 and Hb in the red region (600-700 nm) is very different. The degree of light absorption and the light scattering The degree depends greatly on the oxygen saturation; and in the infrared spectral region (800 ~ 1000nm), the absorption difference is large, the degree of light absorption and the degree of light scattering mainly hemoglobin content, so the content of HbO2 and Hb different absorption The spectra are also different, so blood in the blood oxygen saturation meter can accurately reflect the blood oxygen saturation based on the contents of HbO2 and Hb, whether arterial or venous blood.

The blood reflects the change of oxygen saturation most sensitively around the wavelength of 660nm and around 900nm (ρ660 / 900). The clinical general oximeter (such as Taijia Saturation instrument, pulse oximeter) This ratio is also used as a variable. In the photoconductive route, in addition to arterial hemoglobin to absorb light, other tissues (such as skin, soft tissue, venous blood, and capillary blood) can also absorb light. However, when the incident light passes through the finger or earlobe, the light can be absorbed by pulsatile blood and other tissues at the same time, but the light intensity absorbed by both is different. The light intensity (AC) absorbed by pulsating arterial blood changes with the change of arterial pressure wave And change.

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The light absorption ratio R in two wavelengths is shown. R = (AC660 / DC660) / (AC940 / DC940). R and SpO2 was negatively correlated, according to the value of R, from the standard curve can be derived from the corresponding SpO2 value.