Objective To investigate the effectiveness of evoked potential in monitoring cerebral perfusion during carotid endarterectomy by a retrospective cohort study.Methods A retrospective cohort survey of clinical data of 59 patients,who underwent carotid endarterectomy in our hospital from September 2013 to December 2016,was performed.All patients were monitored by transcranial doppler ultrasonography (TCD) and somatosensory evoked potential (SEP),motor evoked potential (MEP) for changes of cerebral blood flow;the monitoring of TCD was defaulted as "gold standard",recording monitoring results at different time points.By drawing the four table,the sensitivity,specificity,positive predictive value,negative predictive value of SEP and MEP during cerebral hypoperfusion were calculated,and correlation analyses between SEP and TCD,and between MEP and TCD were performed.Through receiver operating characteristic (ROC) curve,SEP monitoring threshold of cerebral hypoperfusion was predicted.Results The sensitivity,specificity,positive predictive value,and negative predictive value of SEP in predicting intra-operative cerebral hypoperfusion were 60.00％,91.84％,60.00％,and 91.84％ when SEP amplitude declined beyond 50％;the sensitivity,specificity,positive predictive value and negative predictive value of SEP in predicting intra-operative cerebral hypoperfusion were 70.00％,93.88％,70.00％ and 93.88％ when SEP latency extended beyond 10％.The sensitivity,specificity,positive predictive value,and negative predictive value of MEP in predicting intra-operative cerebral hypoperfusion were 30.00％,97.96％,75.00％,and 87.27％ when MEP amplitude declined beyond 50％.Decline of SEP and MEP amplitudes and extension of SEP latency have positive correlations with TCD.ROC indicated that the amplitude of somatosensory evoked potentials could predict intraoperative hypoperfusion when it decreased by 51.0％ than the baseline monitoring value after carotid artery occlusion,with sensitivity of 100.0％,specificity of 89.8％ and area under the curve of 0.918 (95％CI:0.846～0.990,P=0.024).ROC also showed that the latent phase of somatosensory evoked potentials could predict intraoperative hypoperfusion when it was prolonged ＞9.8％ compared to the baseline monitoring value after carotid artery occlusion,with sensitivity of 100.0％,specificity of 92.9％and area under the curve of 0.941 (95％CI 0.878～0.995,P=0.014).Conclusion Evoked potentials can real-time monitor intra-operative cerebral hypoperfusion continuously in carotid endarterectomy,enjoying high sensitivity and specificity;in addition,decline of SEP amplitude and extension of SEP latency have higher sensitivity than MEP.

Objective:To investigate the changes of reactive oxygen species (ROS) in pancreatic cancer cells under the effect of pulsed electric fields (PEF).Methods:Murine-derived pancreatic cancer cells Panc02 were treated with PEF at electric field strengths of 0, 250, 500, 750, and 1 000 V/cm, respectively. The intracellular ROS generation patterns under the different field strengths and at different times after the PEF were investigated in vitro by flow cytometry and immunofluorescence, meanwhile exploring the apoptosis of murine and human pancreatic cancer cells under different field strengths. Twenty 6- to 8-week-old male C57BL/6 SPF mice were prepared as orthotopic pancreatic cancer models and divided into five groups of four mice each: 250 V/cm PEF group, 500 V/cm PEF group, 750 V/cm PEF group, 1 000 V/cm PEF group, and sham operation group. ROS expression in the residual tumor tissues of mice in each group was detected by immunofluorescence.Results:Under the 500 V/cm, 750 V/cm and 1 000 V/cm electric field strength, the proportion of cells with intracellular ROS expression was decreased after 6 h, 12 h, 24 h and 48 h of the PEF compared with 2 h after the PEF, and the differences were statistically significant (all P<0.05). Compared with 0 V/cm PEF group, ROS expression increased in Panc02 cells treated with 500 V/cm and 750 V/cm PEF groups, and the differences were statistically significant (all P<0.05). Compared with 250 V/cm PEF group under the same time, ROS in Panc02 cells treated with 500 V/cm and 750 V/cm electric field strengths increased, and the differences were statistically significant (all P<0.05). The proportions of apoptosis of both Panc02 cells and MIA-PaCa-2 cells increased with rising field strength and peaked at the field strength of 750 V/cm. Compared with the sham-operated group, the expression of ROS was increased in pancreatic cancer tissues of mice in the 500 V/cm PEF-treated group (16.65±6.01 vs. 2.38±1.21, t=-6.53) and 750 V/cm PEF-treated group (16.54±4.41 vs. 2.38±1.21, t=-6.48), and the differences were statistically significant in both cases (both P<0.001). Conclusion:PEF treatment was able to increase the level of ROS in both pancreatic cancer cells and tissues, and more ROS were produced when the electric field strength was 500 and 750 V/cm.