ABSTRACT
Objective:To investigate the predictive efficacy of global inhomogeneity (GI) index based on pulmonary electrical impedance tomography (EIT) in postoperative pulmonary infection of patients with craniocerebral trauma.Methods:A total of 90 patients with emergency craniocerebral trauma underwent surgery under general anesthesia in Suzhou Science & Technology Town Hospital. According to the complication of pulmonary infection at the 3rd day after operation, they were divided into the pulmonary infection group (P3 group) and non-pulmonary infection group (NP3 group), and according to the complication of pulmonary infection at the 7th day after operation, they were divided into the P7 group and NP7 group. The average GI index within 5 min before anesthesia induction (T 0) and 5 min after endotracheal intubation (T 1) and other clinical data in the perioperative period were collected. The prevalence of pulmonary infection at the 3rd and 7th days after operation was recorded. Receiver operating characteristic (ROC) curve was used to evaluate the predictive value of preoperative GI index for pulmonary infection at the 3rd and 7th days after operation. Results:A total of 88 patients were included. Among them, 26 patients developed pulmonary infection within 3 days after operation, and the prevalence rate was 29.5%. Pulmonary infection occurred in 38 patients within 7 days after operation, and the prevalence rate was 43.2%. Within 3 days after operation, the preoperative Glasgow Coma Scale score in the P3 group was significantly lower than that in the NP3 group ( P < 0.05). Within 3 days after operation, GI index in the P3 group increased significantly at T 1 when compared with the NP3 group ( P< 0.001). Within 7 days after operation, GI index in the P7 group increased significantly at T 1 when compared with the NP7 group ( P < 0.05). GI index at T1 accurately predicted pulmonary infection within 3 days after operation (AUC = 0.857, P < 0.001), and the best intercept value was ≥0.4225 (sensitivity: 0.846, specificity: 0.823). GI index at T 1 predicted pulmonary infection within 7 days after operation (AUC = 0.667, P < 0.005), and the best intercept value was ≥0.4225 (sensitivity: 0.579, specificity: 0.780), but the prediction efficiency was poor. Conclusions:The average GI index within 5 min after endotracheal intubation can be used as an effective predictor of pulmonary infection within 3 days after operation.
ABSTRACT
Objective To study a method for monitoring multichannel electrode-scalp contact impedances in electrical impedance tomography (EIT), and to provide support for exploring the impact of contact impedances on imaging and the suppression method.Methods A reference electrode was introduced for the system,placed on the back of the neck or the top of the head. In the spare time of boundary voltage signal acquisition phase, the method of two electrodes was adopted to measure the electrical impedance between each imaging electrode and reference electrode, which was used to analyze the characteristics of multichannel contact impedances.Based on the existing EIT hardware system,the module for monitoring multichannel contact impedance was implemented.Results The calibration board test showed that the measurement error of this method was less than 1‰,and the maximum relative fluctuation of the measurement result within 10 hours was less than 1‰. Preliminary human test indicated that this method had the ability to obtain two kinds of information about spatial consistency and temporal stability of 16-channel contact impedances. Conclusion This method has high accuracy and stability,so it meets the requirements of monitoring multichannel contact impedances in brain EIT.
ABSTRACT
Objective·To find out the optimal positive end expiratory pressure (PEEP) by electrical impedance tomography (EIT) for better lung recruitment and ventilation distribution in patients undergoing off pump coronary artery bypass grafting surgery (OPCAB). Methods?·?105 patients underwent OPCAB from Jan. 2017 to Dec. 2017 were analysed. Patients were randomly divided into two groups, i.e. experiment group (54 cases) and control group (51 cases). Four regions of interest (ROI) were recorded by EIT. PEEP were 3?cmH2O in control group while PEEP were increased stepwise by 2?cmH2O from 0?cmH2O to 14?cmH2O in experiment group. The optimal PEEP for lung recruitment was applied in experiment group. Postoperative oxygenation index (PaO2/FiO2) and pulmonary complication were compared between two groups. Results?·?The overall mortality was 2 (1.90%). The incidence of postoperative pulmonary complication, pulmonary infection, atelectasis, pleural effusion were 18.10%, 2.86%, 18.10%, 18.10%, respectively. The optimal PEEP zone was 6-9?cmH2O. PaO2/FiO2was significantly increased with the optimal PEEP in experiment group (P=0.00). There were significant differences in postoperative pulmonary complication between two groups (P=0.02). Conclusion?·?EIT can directly monitor ventilation distribution and titrate suitable PEEP for better lung recruitment in patients undergoing OPCAB. It can significantly reduce postoperative pulmonary complication, improve oxygenation, and decrease ICU stay and ventilation duration.
ABSTRACT
Objective • To find out the optimal positive end expiratory pressure (PEEP) by electrical impedance tomography (EIT) for better lung recruitment and ventilation distribution in patients undergoing off pump coronary artery bypass grafting surgery (OPCAB). Methods • 105 patients underwent OPCAB from Jan. 2017 to Dec. 2017 were analysed. Patients were randomly divided into two groups, i.e. experiment group (54 cases) and control group (51 cases). Four regions of interest (ROI) were recorded by EIT. PEEP were 3 cmH2O in control group while PEEP were increased stepwise by 2 cmH2O from 0 cmH2O to 14 cmH2O in experiment group. The optimal PEEP for lung recruitment was applied in experiment group. Postoperative oxygenation index (PaO2/FiO2) and pulmonary complication were compared between two groups. Results • The overall mortality was 2 (1.90%). The incidence of postoperative pulmonary complication, pulmonary infection, atelectasis, pleural effusion were 18.10%, 2.86%, 18.10%, 18.10%, respectively. The optimal PEEP zone was 6-9 cmH2O. PaO2/FiO2 was significantly increased with the optimal PEEP in experiment group (P=0.00). There were significant differences in postoperative pulmonary complication between two groups (P=0.02). Conclusion • EIT can directly monitor ventilation distribution and titrate suitable PEEP for better lung recruitment in patients undergoing OPCAB. It can significantly reduce postoperative pulmonary complication, improve oxygenation, and decrease ICU stay and ventilation duration.
ABSTRACT
Purpose: To obtain more precise Electrical Impedance Tomography, the conductivity imaging which utilizes the in-formation of magnetic field has been developed as new approaches of EIT. Methods: Analysing the basic theory and develop-ing status of MIT, MD-EIT and MREIT, the Electrical Impedance Imaging by magnetic means was proved to have more bright applicational prospect. Results: Based on different imaging methods, the Electrical Impedance Imaging by magnetic means can give more accurate conductivity distributions. Conclusions: The Electrical Impedance Imaging will be used more widely by magnetic means.
ABSTRACT
Objective To compare the performance of novel Ag/AgCl pulverized electrodes with conventional Ag/AgCl coating electrodes in cerebral application of Electrical Impedance Tomography(EIT).Methods Based on the EIT system developed by our group,raw data were measured on a phantom and an adult volunteer,with Ag/AgCl coating electrodes and pulverized electrodes,respectively.The performances of electrode systems were evaluated in contact impedance and two other figures(the high-frequency SNR,HFSNR;the low-frequency SNR,LFSNR).Results Ag/AgCl pulverized electrode plays a better performance in resisting noise and keeping stabilization.Conclusion Ag/AgCl pulverized electrode develops the needs of imaging and monitoring human brains in EIT more availably.
ABSTRACT
This paper is to build a finite element model of brain with a real brain shapeon which simulation studies of electrical impedance tomography EIT in the brain is based. A curve of a real brain shape is simulated with the curve-fitting methods and EIT in the brain is finished with finite-element methods and Equipotential Lines Back-Projection algorithm.The locationarea and amplitude of the change of the resistivity are reconstructed accurately. But the image quality has to be further improved.This paper provides a basis for clinical applications of EIT in brain.
ABSTRACT
Objective To provide the hardware system of EIT with an excellent direct current(DC) power source. Methods The spectrums of the outputs of DC power source and the driving source were analyzed by means of Spectrum Analyzer- E4408B when EIT system was respectively powered by battery, linear power source and switching power source. Based on the numbers and power levels of the spurs of the three power sources and the numbers and power levels of the interferences within the driving source, the influence of the three power sources on the error of measuring was estimated. Meanwhile the EIT system did data acquisition, the overall signal-to-noise-ratio(SNR) of the three power sources at the 18 frequencies were calculated and the influence of the three power sources on the error of measuring was judged. Results With respect to the numbers and power levels of the interferences within the driving source when EIT was powered respectively by the three power sources, the battery output 6 interferences, the highest power of which achieved -78.25 dBm; the linear power source output 6 interferences, the highest power of which achieved -67.11 dBm; the switching power source output 15 interferences, the highest power of which achieved -35.83 dBm. The overall SNRs of the battery at the 18 driving frequencies were higher than that of the linear power source, and the overall SNRs of the linear power source were higher than that of the switching power source. Conclusion The power mode of battery is the best for the hardware of EIT among the three power sources.
ABSTRACT
The reverse problem of Electrical impedance tomography(EIT) is a highly ill-posed problem.It is concluded that spatial prior information could improve the final image quality.This paper proposes a new method for obtaining prior information.By this method,the inspected cross-section contour and internal structure for EIT can be achieved.
ABSTRACT
It is very important for pulmonary disease treatment to monitor the pulmonary function continuously. In this paper, the hardware of electrical impedance tomography (EIT) system is designed, and simulative model of human thorax is established for image reconstruction based on Landweber pre-iteration method. Compared with linear back projection, the method above results in the better image reconstruction with little trailing and increased speed of real-time reconstruction.
ABSTRACT
A master-slave electrical impedance tomography (EIT) system for body complex impedance based on digital signal processor (DSP) is designed in this paper. Used as the master computer, a PC performs the image reconstruction and display on time, while DSP carries out such tasks as electrode selection, data acquisition and data communication with the master. Based on DDS technique, the signal generator can create the sine wave signals, and it's amplitude, frequency and phase can be continuously adjusted. The designed feedback unit can improve the linearity and the stability of the voltage-controlled current source effectively. Undersampling technology and digital demodulation technology are used in this system in order to attain the information of real and imaginary components of the body complex impedance. Back projection method is adopted to reconstruct the image in this system. Experimental results show that this system improves the data acquisition speed and the image resolution.