| The liver is both the heaviest internal organ and the largest gland in the human body. The liver has a wide range of functions, including detoxification of various metabolites, protein synthesis, and the secretion of biochemicals necessary for digestion system. The various functions of the liver are carried out by the liver cells. The sum of all function of liver cells represents the hepatic functional potential, and clinically called hepatic functional reserves. Once the liver was injuried by hepatectomy or various pathogenic factors, the liver cell must be damaged and liver functions will be changed, such as the number of liver cells, hepatocyte mitochondrial function, and liver blood perfusion. So the hepatic functional reserves reduced directly. Therefore, before the hepatectomy, the accurate evaluation of hepatic functional reserve is an very important basis for the size of the liver resection, selecting reasonable treatment methods and estimating prognosis. Reserches show that the regular monitoring of hepatic functional reserve is conducive reveal restrictions in liver or splanchnic perfusion at an early stage. And real-time monitoring for hepatic functional reserve is an important measure to avoid the occurrence of accidents such as liver failure for patients in intensive care.For a long time,traditional artificial blood spectrophotometric, as the “gold standard” clinical method, treates indocyanine green(ICG) as the indicator and measure the concentration change of it. Some parameter of hepatic functional reserve such as ICG plasma disappearance rate(ICG-PDR) and ICG retention rate at 15 min(ICG-R15) was measured in this method. But this method is invasive, non realtime, complex operated and not suitable for continuous dynamic bedside monitoring.Currently, an invasive and real-time hepatic functional reserve automating analytic system developing, which based on dye dilution and discharge test, becomes a deeply requirement of medical scientific research and clinical application.The paper aims at optoelectric detection method for hepatic functional reserves based on ICG densitogram analysis and implementation of the system. Started with the detection theory and technological method of ICG concentration signal, experimental method and processing algorithm of Dye Densitogram, hepatic functional reserve parameters are quantitative evaluated based on both pharmacokinetics of indicator and ICG densitogram to design an optoelectric detection system of hepatic functional reserves.The research includes the following contents:1、 Study on the multi-wavelength pulse indicator densitometry: In the light of Lambert-Beer’s law, human peripheral arterial absorpsion spectrum is sampled, by which the method of multi-wavelength pulse indicator densitometry is built. This method can eliminate the absorption of blood dispersion and other tissue components, and ICG densitogram can be measured noninvasively and continuously.2、 The processing and feature component extraction of pulse indicator density signals: Utilizing Empirical Mode Decomposition(EMD) sparse reconstruction algorithm, the pulse indicator density signals are processed in a rather relativily high signal-noise ration. And then, the adaptive recognition a separation algorithm is used to extract the feature component ICG densitogram.3、 Study on the anti-fluctuate blood oxygen saturation method of ICG indicator densitometry: Through the study of mutual interference between the blood oxygen saturation and ICG indicator densitometry. By the oxygen calibration formula and detection principle of multi-wavelength pulse indicator densitometry, anti-fluctuate blood oxygen saturation mathematical model of ICG indicator densitometry is built. The ICG densitogram is measured accurately, continuously and in real time.4、 The calculating and evaluation of hepatic functional reserves: The hepatic functional reserve evaluation parameters are implemented on the basis of atrioventricular theory model. After analysis of ICG primary and secondary circulation curve, least squares method is adopted to obtain the indicator linear regression equation, and derive the ICG-PDR, ICG-R15, as well as effective hepatic blood flow(EHBF).5、 The design and implementation on detection system of the hepatic functional reserve: the system platform consists two parts: three wavelength measurement platform of pulse indicator density and the dynamic analysis system of hepatic functional reserve. The attenuation signal detected by the three wavelength transmission type photoelectric sensor, after AC/DC extraction separation, multi-stage amplifying and filtering the signal and then transmitted to the upper computer; the liver function reserve dynamic analysis system implemented by Lab VIEW, including serial data reception, data read and stored in real time invoke SQL Server database, signal denoising and anti oxygen fluctuation algorithm, user interface design, and display the calculation parameters and evaluation of hepatic functional reserve.Conclusion: According to the multi-group subjects’ comparisons test to the "gold standard", which is the artificial blood spectrophotometric methed. Utilizing medical professional software “Medcalc” the correlation and consisitency analysising indicated that the experimental aquired ICG-PDR、ICG-R15 and EHBF were very correlated and consistent to golden standard proving that the optoelectric detection system for hepatic functional reserves based on ICG densitogram analysis meet measurement accuracy of application(￡5%).In summary, present work take the advantage of multi-wavelength indicator densitometry theory and test results to make a meaningful attempt to address some key issue in hepatic functional reserve evaluation. A noninvasive hepatic functional reserve measure and auto analysis system was developed. Under this circumstance of no time division and repeatedly blood sampling, ICG densitometry、ICG-PDR、ICG-R15 and other hepatic functional reserves parameters are in vivo detected percutaneously and continuously. |
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