1, functions and principles
SPO2 pulse oxygen saturation refers to the oxygen content and oxygen capacity percentage. SPO2 as a noninvasive, rapid response, safe, reliable and continuous monitoring of indicators, has been recognized. Currently in anesthesia, surgery and PACU and ICU, to be widely used. According to oxyhemoglobin (HbO2) and deoxygenated hemoglobin (Hb) in red and infrared spectral characteristics of the region, we can see in the red zone (600 ~ 700nm) HbO2 and Hb absorption vary greatly, the blood level of light absorption and light scattering great extent dependent on the oxygen saturation; while in the IR spectrum area (800 ~ 1000nm), the absorption of large differences in blood levels of light absorption and light scattering and hemoglobin content of the main level, therefore, HbO2, and Hb content of the various absorption spectrum is different, so the blood oximeter catheter in the blood of both the arterial blood saturation or under HbO2 and Hb meter can accurately reflect the content of oxygen saturation. 〕: Blood in the wavelength of 660nm and 900nm in the vicinity near the reflection ratio (ρ660/900) reflect the most sensitive to changes in blood oxygen saturation, clinical general oximeter (such as Baxter saturation meter) also used the ratio as a variable. In the optical transmission channels, with the exception of light absorption of arterial blood hemoglobin, other organizations (such as skin, soft tissue, blood and capillary blood) can also absorb light. But the incident light through the finger or ear lobe, the light can be pulsatile blood and other organizations at the same time, it should absorb the light intensity between the two is different, pulsatile arterial blood absorbed light intensity (AC) with the changes in arterial pressure wave change. And other organizations absorbed light intensity (DC) does not change with the beat and time, thus, can be calculated in two wavelengths of light absorption ratio of R. R = (AC660/DC660) / (AC940/DC940). R was negatively correlated with SPO2, according to R value, the standard curve can be drawn from the corresponding SPO2 value.