Near-infrared Spectroscopy Measurement And Wavelet Coherence Analysis Of Drivers’ Cerebral Oxygen Signals

Drivers’ brain stroke is becoming a more and more serious situation during the recent years. There are serval reasons leading to drivers’ brain stroke:the bad driving environment, Driver fatigue and mental stress during driving. If brain stroke happened during driving, not only the driver’s health but also the traffic safety was damaged. human’s brain is closely connected to physical activities such as thinking, breathing and moving. Brain, which is the most important organ keeping human’s health, is one of the most actively oxygen metabolism organs. brain stroke would lead to irreversible damage of brain tissue and function losing.The near-infrared spectral imaging technology is a rapidly developing detection technology in recent years. the method based on near-infrared spectral can detect the changing of brain oxygen continuously and noninvasively. The object of this paper is to propose a method based on near-infrared spectral imaging technology to measure the cerebral oxygen and a method based on wavelet coherence to analyze the relationship between NIR signals and blood pressure. This paper aims to propose a method to assess the risk of drivers’ cerebral stroke. The main achievement accomplished by this paper is fellowing:(1)Using a method based on near-infrared spectral imaging technology to measure the cerebral oxygen of two groups of subjects(32elderly subjects, age:70.8±5.2years;19young subjects, age:24±2years).(2)Using a method based on spline interpolation and least-squares fitting to remove the noise of original signals. The de-noised signal is more similar to the real data. Using this method can minimize the deviation caused by environment and equipment.(3)Using coherence analyzing based on continuous wavelet to analyze the relationship between cerebral oxygen and blood pressure in six frequency interval s(I,0.4-2Hz; Ⅱ,0.15-0.4Hz; Ⅲ,0.05-0.15Hz; Ⅳ,0.02-0.05Hz;Ⅴ,0.0095-0.05Hz; Ⅵ,0.005-0.0095Hz). The results show that, In elderly subjects,the Delta [HbO2] and ABP oscillations were significantly wavelet coherent in interval I, and wavelet phase coherent in intervals I, II and IV.(4)Using SPSS to statistical analyze the wavelet coherence and wavelet phase coherence. the results show that the wavelet coherence in interval I was significantly higher (p=0.040), in elderly subjects than in young subjects whereas that in interval V significantly lower (p=0.015). In addition, the wavelet phase coherence in interval IV was significantly higher in elderly subjects than in young subjects (p=0.028). The difference in the wavelet coherence of the elderly subjects and the young subjects indicates an altered cerebral auto regulation caused by aging. This study provides new insight into the dynamics of Delta [HbO2] and ABP oscillations and may be useful in identifying the risk for dynamic cerebral auto regulation processes.