血清胱抑素C预测非急性肾功能不全脓毒症患者入住重症监护室的价值

目的明确入院血清胱抑素C(Cystatin C,Cys-C)对非急性肾功能不全脓毒症患者入住重症监护室(intensive care unit,ICU)及不良预后的预测价值.方法回顾性分析2015年7月至2016年6月四川大学华西医院急诊科非急性肾功能不全脓毒症患者的人口学资料、生命体征、实验室检查、入院诊断等资料及28天入住ICU率、28天机械通气率、7天病死率和28天病死率.采用Logistic回归分析入院时Cys-C和非急性肾功能不全脓毒症患者28天入住ICU率的相关性.结果多因素Logistic回归分析显示,入院时Cys-C是非急性肾功能不全脓毒症患者28天入住ICU的独立危险因素[优势比为1.202,95%CI(1.030,1.401),P=0.019],在1.59mg/L时预测患者入住ICU的效能最大.入院时Cys-C>1.59 mg/L患者比Cys-C≤1.59 mg/L患者具有更高比例的28天入住ICU率(63.7%vs.30.8%,P<0.05)、28天机械通气率(60.7%vs.35.0%,P<0.05)、7天病死率(19.4%vs.8.1%,P<0.05)和28天病死率(34.8%vs.16.5%,P<0.05),Cys-C>1.59 mg/L组患者序贯器官衰竭评分(SOFA)及急性生理和慢性健康状况评分系统Ⅱ(APACHEⅡ)均高于Cys-C≤1.59 mg/L组(P<0.05).入院时高Cys-C浓度是患者具有更高28天入住ICU率[优势比为1.441,95%CI(1.237,1.679),P=0.000]、28天机械通气率[优势比为1.279,95%CI(1.115,1.467),P=0.000]、7天病死率[优势比为1.234,95%CI(1.067,1.428),P=0.005]和28天病死率[优势比为1.209,95%CI(1.063,1.376),P=0.004]的独立危险因素.结论入院时Cys-C可用于预测非急性肾功能不全脓毒症患者预后,有助于指导脓毒症患者早期干预及医疗资源分配;入院时高Cys-C浓度是非急性肾功能不全脓毒症患者不良预后的危险因素.

Intelligent prediction on air intake flow of spark ignition engine by a chaos radial basis function neural network

To ensure the control of the precision of air-fuel ratio(AFR)of port fuel injection(PFI)spark ignition(SI)engines,a chaos radial basis function(RBF)neural network is used to predict the air intake flow of the engine.The data of air intake flow is proved to be multidimensionally nonlinear and chaotic.The RBF neural network is used to train the reconstructed phase space of the data.The chaos algorithm is employed to optimize the weights of output layer connection and the radial basis center of Gaussian function in hidden layer.The simulation results obtained from Matlab/Simulink illustrate that the model has higher accuracy compared to the conventional RBF model.The mean absolute error and the mean relative error of the chaos RBF model can reach 0.0017 and 0.48,respectively.