How the blood oxygen probe works
1. Function and principle
Pulse oximetry SPO2 refers to the percentage of blood oxygen content versus blood oxygen capacity.SPO2 has been recognized as a noninvasive, responsive, safe and reliable continuous monitoring index.It is widely used in anesthesia, surgery, PACU and ICU.According to the spectral characteristics of oxygenated hemoglobin (HbO2) and reduced hemoglobin (Hb) in the red and infrared light regions, the absorption of HbO2 and Hb in the red region (600-700nm) is very different.In the infrared spectral range (800 ~ 1000 nm), the absorption difference is bigger, the blood level of light absorption and scattering degree is mainly related to hemoglobin content, therefore, HbO2 and Hb content of different absorption spectra are different, so the blood from the blood vessels of blood oxygen saturation meter both arterial blood and venous blood saturation instrument can according to the content of HbO2 and Hb oxygen saturation accurately reflect bleeding.[: the ratio of rho 660/900 of blood reflection around the wavelength of 660nm and 900nm is the most sensitive reflection of the change of bleeding oxygen saturation, which is also used as a variable in general clinical oximetry instruments (e.g. Baxter saturation instrument).In the light transmission pathway, in addition to the arterial blood hemoglobin absorption of light, other tissues (such as skin, soft tissue, venous blood and capillary blood) can also absorb light.But when incident light passes through a finger or ear lobe, it can be absorbed by pulsating blood and other tissues at the same time, but with different intensity.However, the light intensity (DC) absorbed by other tissues does not change with pulse and time. Therefore, the light absorption ratio R in the two wavelengths can be calculated.R = (AC660 / DC660)/(AC940 / DC940).R is negatively correlated with SPO2. According to the R value, the corresponding SPO2 value can be obtained from the standard curve.2. Features and advantages of the probe:
SPO2 instrument includes probe, function module and display part.For most monitors on the market, SPO2 detection technology is mature.Whether the SPO2 value detected by a monitor is accurate or not is largely related to the probe, among which there are many factors that affect the detection of the probe, such as the detection device used by the probe, medical wire and connection technology, etc., all of which will affect the detection results.
1. Detection devices: the light-emitting diode and photodetector for detecting signals are the core components of the probe.It is also the key to determine whether the detection value is accurate or not.Theoretically, when the wavelength of red light is 660nm and the wavelength of infrared light is 940nm, the measured value is relatively ideal. However, due to the complexity of the manufacturing process of devices, the wavelength of red light and infrared light produced is always deviated.The magnitude of the wavelength deviation will affect the values detected.Therefore, the manufacturing process of light-emitting diode and photoelectric detection device is very important.The blood oxygen probe we provide is equipped with forroco detection equipment, which has advantages both in accuracy and reliability.
2. Medical wires: in addition to imported materials (reliable in high elastic strength and corrosion resistance), double layer shielding is adopted in the design, which is more able to suppress noise interference and maintain signal integrity than single layer or no shielding.
3. Cushion: the probe we provided is made of a specially designed cushion (refers to cushion), which is comfortable, reliable and non-allergic in contact with the skin, suitable for patients of different shapes.And the use of the all-enveloping design, can avoid the finger movement caused by light leakage interference.
4. Finger clip: the body finger clip is made of fireproof non-toxic ABS material, which is firm and not easy to damage.In the finger clip is also designed to use a light screen, can better shield the peripheral light source.
5. One of the main reasons for the damage of SPO2 is that the spring is loose, the spring is not enough and the clamping force is not enough. We use high tension electroplated carbon steel spring, reliable and durable.
6. Terminals: in order to ensure the reliable connection and durability of the probe, considering the attenuation in the signal transmission process on the connection terminals with the monitor, gold-plated terminals with special technology are adopted.
7. Connection process: the connection process of the probe is also very important for the detection results. The position of the cushion is calibrated and tested to ensure the correct position of the transmitter and receiver of the detection device.
8. In terms of accuracy, ensure that the error is not more than plus or minus 2% when the SPO2 value is 70%~ 100%, and the accuracy is higher, so that the detection results are more reliable.