Study Of Real-time Blood Oxygen Saturation Monitoring Techniques In Cardiopulmonary Bypass Surgery

Cardiopulmonary bypass is not a physiological state, but a control procedure, going at low temperatures and hemodiluted state. To ensure the safety of patients undergoing cardiopulmonary bypass, it's necessary to monitor their physiological indicators. Mixed venous oxygen saturation can accurately reflect the patient blood perfusion and oxygen supply conditions in time and hematocrit can reflect the degree of blood dilution. These two parameters can give guidance to implanted masters adjusting doses and pressure, etc. Take measures according to them in time can reduce the complications of cardiopulmonary bypass and make patients a speedy recovery.This thesis aims to design a blood oxygen/hematocrit detector which was used during cardiopulmonary bypass. In this paper, the hardware circuits based on MCU MSP430F149 was designed. Further more, functions and circuit implementation of each module were analyzed in detail, and hardware system was debugged successfully. Data collected were transferred to PC via serial port. The processing and computing and the display of monitoring results were finished in the host computer. And real-time curves which reflected the results were drew, and a database for storing results and patient information was established thus physicians can access patients'monitoring information on random.As to signal processing, differential amplifier, low pass filtering were applied. Besides, filtering and linear fitting and digital average algorithm in Matlab were embedded in VC++ program to reduce noise and correct the baseline drift.Experiment of simulated sample was implemented using the detector designed in this thesis, and blood sample was also designed. The results of the experiments verified the sensitivity and accuracy of the system.This research and achievements will play a very active role in promoting the development of clinical health care industry.