The Change Of Skin Conductance Was Evaluated In Epidural Anesthesia

Objective:To assess the feature of the basis value and amplitude value of wave of skin conductance (SC) in epidural anesthesia. Methods:Twenty-five ASAⅠ-Ⅱpatients with normal communicating ability undergoing elective surgery were enrolled in this study. The patients were unpremedicated. BP, ECG, HR and SpO2 were monitored during anesthesia. After each patient were carried out an epidural catheter placed at L2-3 interspace, SC were monitored and recorded data in a compute.1% lidocaine 5ml were given through epidural catheter as a test dose. After correct placement of epidural catheter was confirmed five minutes later,0.75% ropivacaine 10ml were injected into epidural space. Three sets of data collected for each patient:the basis value of SC (SC0), the amplitude value of wave in epidural anesthesia plane up(SC1) and down(SC2)by pin prick. Each group collecting seven time points(TP) of data, they are given prior to local anesthestics(TP0),1% lidocaine 5min (TP1),0.75% ropivacaine 5min(TP2), 10min (TP3),15min(TP4),25min(TP5),45min(TP6). The data between the time points and the other time points were analyzed to use repeated measures analysis of variance in SPSS17.0. The data within the time points were analyzed to use paired t test. Receiver operation characteristic (ROC) curve and logistic regression were used to analysis the sensitivity and specificity and predict the accurateness of the plane of sensory block in epidural anesthesia. Results:Compared with the TP0; the mean of SC0, SC1 and SC2 in other group continued to decrease. Each group of SC1 and SC2 have significant difference in blocked and non-blocked areas of epidural anesthesia correspondingly(P<0.05). The area under the ROC curve was in 0.92 and have significance of difference from 0.5 (P<0.01). When the sensitivity and the specificity were 88% and 78% respectively, the Youden Index obtained 0.66 score at the most highness. The total predicting probability was 85% in logistic regression,5%,50%,95% of predicting probability corresponded to 0.105μS,0.841μS,1.577μS in the amplitude value of wave respectively. Conclusion: The basis value of skin conductance decreased continuously after onset of epidural anesthesia. When given the same stimulus in blocked and non-blocked areas, the amplitude value of wave change have significant difference and high accurateness in distinguishing them.