Objective To evaluate the accuracy of spectral entropy including response entropy(RE)and state entropy(SE)as a new electroencephalographic measure of depth of sedation during general anesthesia.Methods Twenty ASA Ⅰ or Ⅱ patients aged 20-55 yr undergoing elective abdominal surgery were studied.Anesthesia Was induced with intravenous propofol,fentanyl and vecuronium.After tracheal intubation anesthesia was maintained with sevoflurane inhalation and intermittent iv boluses of fentanyl and vecuronium.BP,HR,SpO2,spectral entropy(Datex-Ohmeda)and BIS(Aspect Medical)were monitored during anesthesia.Loss of eyelash reflex and unresponsiveness to verbal stimulus and mild prodding and shaking were considered to be signs of loss of consciousness(LOC).The time of regaining consciousness Was defined as the time when patients started responding to verbal commands.RE,SE and BIS were recorded before anesthesia(baseline),10 min before LOC,immediately after LOC,immediately after tracbeal intubation,1 h after skin incision,10 min before regaining consciousness immediately after consciousness was regained and 10 min after extubation.Results There were sisnificant changes in RE,SE and BIS during the transition from consciousness to LOC.The RE,SE and BIS values for LOC were 76,73 and 68 with sensitivity of 94%,95%and 92%and specificity of 92%,94%and 91%respectively.The accuracy of RE.SE and BIS in predicting LOC was 93%,95%and 94%respectively.The RE,SE and BIS values for regaining consciousness were 82,75 and 70 with sensitivity of 95%,95%and 91%and specificity of 93%,96%and 93%respectively.The accuracy in predicting regaining of consciousness was 98%,96%and 97%respectively.Conclusion Entropy index Can accurately monitor level of sedation during general anesthesia.

0.05).Furthermore,logistic regressive equations of prediction probability and RE,SE,BIS were calculated as ln [Pk/(1-Pk)]=-19.825+0.243x,ln [Pk/(1-Pk)]=-18.012+0.236x and ln [Pk/(1-Pk)]=-21.780+0.316x,respectively.From the perspective of sensitivity/specificity,RE,SE and BIS had threshold values for regaining consciousness of 83,76 and 71 with sensitivity/specificity of 0.90/0.85,0.89/0.80 and 0.88/0.78,respectively.RE was 30s earlier than BIS in predicting regaining consciousness.Conclusion Compared with BIS,entropy index seems to be a more accurate and sensitive electroencephalographic measure,and is promising in clinical application.

0.05),while the entropy index showed significant differences between the two groups(P

Objective In order to explore the effects of trauma on MAC and its mechanism, the changes in MAC of sevoflurane and plasma ? endorphin were investigated in state of trauma. Methods Twenty New Zealand rabbits were randomly divided into control group and trauma group. MAP,CVP, P ET CO 2 and ECG were monitored continuously. The MAC of sevoflurane was measured in the two groups. In trauma group, the left femur of rabbits was fractured combined with parenchyma damage.Plasma ? endorphin concentration was assaied at various times in two groups. Results MAC of sevoflurane was 2 2%?0 2% in control group and 1 7%?0 2% in trauma group. Trauma induced increase of plasma ? endorphin concentration significantly 5min and 30min after trauma,? endorphin concentration increased by 44% and 52% in trauma group, respectively. Conclusions MAC of sevoflurane in rabbits is 2 2%?0 2%.Trauma can reduce MAC of inhalational anesthetic significantly. The endogenous ? endorphin releasing enormously induced with trauma may be one of the mechanisms to decrease MAC of inhalational anesthetics.