Design Of A System For Detecting Blood Oxygen Saturation Of Weakly Perfused Tissue

Clinically,critically ill patients and patients with respiratory diseases often have low peripheral tissue blood perfusion index,which makes it impossible to accurately monitor blood oxygen saturation.The blood perfusion index can reflect the blood filling condition in the arteries,and the weakly perfused tissues are difficult to collect pulse signals due to the low perfusion index,which directly affects the non-invasive monitoring of blood oxygen saturation.The emergence of portable physiological parameter detection equipment has facilitated the detection and monitoring of patients’ physiological parameters by medical staff.Wearable physiological parameter devices are a further development of portable devices.In the existing portable and wearable blood oxygen saturation detection equipment,the target test population is mainly healthy individuals.For people with low blood perfusion index,the needs in this regard cannot be met.In response to the above-mentioned problems,this article considers the wearable device perspective,proposes a method for detecting blood oxygen saturation based on weakly perfused tissue,and uses a reflective sensor to design a wearable detection method based on the blood oxygen saturation on the back of the finger root at the weakly perfused site system.The theoretical preparations for the system design are as follows: study the principle of non-invasive measurement of blood oxygen saturation;study the literature suitable for the strength of the pulse wave signal of the wearable device.Through the study of the above theoretical knowledge,choose the back of the finger root of the weakly perfused tissue,and design the collection system as a finger ring device model.This system is controlled by the ultra-low power STM32H743VI;the fixed wavelength of the biometric sensor SFH7072 is 660 nm and 940 nm to detect blood oxygen information;the 540 nm wavelength is used as the perfusion index measurement light source;SGM8594 integrated operational amplifier mainly constitutes the signal processing module;AD7691 realizes analog-digital signal conversion function;for the real-time display design of the system,the calculation results are displayed by OLED.After the system design is completed,the pulse signal of the back of the root of the weakly perfusion site is collected,and the value of blood oxygen saturation and perfusion index of the site is calculated.Real-time data comparison between the weakly perfused tissue blood oxygen saturation detection system and Mindray PM-9000 Express standard multi-parameter monitor.Two experiments were performed on 10 volunteers to measure the blood oxygen saturation of the back of the finger roots at room temperature and under room temperature.Each group of experiments obtains 100 sets of data,and a total of 200 sets of experimental data are obtained.The error analysis of the experimental data under different conditions shows that the maximum relative error of the blood oxygen saturation of the finger at room temperature is 3.03%;after the temperature of the finger decreases,the maximum error of the blood oxygen saturation is 3.06%.At the same time,the Bland-Altman consistency analysis was performed on the experimental data under different conditions,and the results showed that all the sample data were within the 95% consistency limit confidence interval.It is concluded that the detection system for blood oxygen saturation of weakly perfused tissues designed in this paper has a maximum relative error of 3.06%,which basically meets the detection requirements within the error range,and has certain reference value for the research on blood oxygen detection of weakly perfused tissues.