The development and application of an analysis system for physiological rhythms

Ten years ago, little was known about short-term rhythms of physiological signals. These rhythms had a period of around 3 to 10 seconds, and were broadly found in blood pressure and heart rate signals. Because of a lack of analytical tools, only a small fraction of physiological laboratories could study them with specially designed computer programs. It was difficult for investigators, as well as the general population, to appreciate the importance of these rhythms. I started research on physiological rhythms in 1990, and designed an analytical system for the computer. The program was constructed in four parts, basic input-output, signal processing, graphical and numerical output and timing control subsystems. The prototype was finished in 1990, and was frequently revised to offer specific features. Power spectral analysis was first incorporated. It separated and quantified periodical variations in arterial pressure, heart rate, electromyogram, electroencephalogram and even neuronal activity. I designed a computer program for transfer function analysis of paired physiological signals and constructed programmable electric stimulators, analog-digital converters and programmable ventilators since 1994. With the applications of the hardware and software, a number of animal experiments were done to explore the frequency-domain relationship of two specific biological signals. In 1996, I started to design a cerebral blood flow analysis program. With the cooperation of clinical investigators, we performed human experiments to test a new protocol to detect the cerebral autoregulation function non-invasively. At the same time, the analysis system was applied in the field of public health. I designed an electrocardiogram (ECG) acquisition device by which ECG signals of 3,000 more people were collected to analyze heart rate variability. Since ten years ago, I had written more than 40,000 lines of program codes, and constructed tens of electric circuits. More than 40 research papers have been derived from this system. More important, my colleagues and I have successfully generalized the knowledge and techniques of physiological rhythms into various fields of biomedical sciences. The analyses of physiological rhythms have provided the following applications: (1) detecting depth of general anesthesia. (2) detecting baroreflex sensitivity. (3) detecting autonomic activities. (4) diagnosis of brain death. (5) outcome prediction of critical illness. (6) detection of rejection of transplanted hearts. (7) evaluation of aging. (8) evaluation of cerebrovascular functions. (9) study of essential hypertension. The underlying mechanisms and potential applications warrant further invstigation.