The Correlation Analysis Between Cerebral State Index And End-tidal Concentration Of Isoflurane

Objective By observing the change of cerebral state index(CSI)during isoflurane anesthesia,analyze the feasibility of using CSI monitor the depth of isoflurane anesthesia.Methods Seventy-five patients receive general anesthesia and undergo elective surgery.All patients fast from liquids and solids for an average of 8 h.They were premedicated with intramuscular 1mg Penehyclidine Hydrochloride Injection when 30 min before the start of anesthesia.ECG,S p O 2,HR,BP,PI(perfusion index)were monitored.Anesthesia was induced with 0.5?g/kg sufentanil,0.5mg/kg atracurium,1.5-2.0mg/kg propofol.They were carried out endotracheal intubation after induction of intravenous anesthesia.The patients were mechanically ventilated(V T 8-10ml/kg,RR10-12 bpm,I:E 1:2).PE TCO 2 was maintained at 30-40 mm Hg.Anesthesia was maintained with isoflurane inhalation.Isoflurane was started with 2 L/min of fresh gas flow,2% for isoflurane forten minutes.End-tidal concentration of isoflurane was maintained to be around 0.7MAC by adjusting the inhaledconcentration of isoflurane during the procedure.The fresh gas flow was reducedto 1L/min after ten minutes.End-tidal concentration of isofluranewas maintained to be around 0.7MAC by adjustingthe inhaledconcentration of isoflurane.If End-tidal concentration of isoflurane was at 0.7MAC,CSI was above 60 and last for five minutes.End-tidal concentration of isoflurane wasrisen to1.0MAC by adjusting the inhaledconcentration of isoflurane.When End-tidal concentration of isoflurane was at 1.0MAC and CSI was above 60 and last for five minutes,End-tidal concentration of isoflurane was risen to 1.3 by adjusting the inhaledconcentration of isoflurane.During operation Anesthesia was intermittent intravenous injection of atracurium.Continuous target controlled infusion(TCI)of remifentanil was administered at 30 min after anesthesia induction.The target effect-site concentration of remifentanil administered by target controlled infusion(TCI)duringanesthesia: 2-6ng/ml,adjust the target effect-site concentration of remifentanil TCI according to the change of perfusion index(PI),blood pressure and heart rate.The value for CSI and End-tidal concentration of isoflurane were recorded per minute during the phrase of median-flow.To investigate the correlation of CSI and End-tidal concentration of isoflurane by observeing the change in range between the two.The number of the case was recorded when End-tidal concentration of isoflurane was at 0.7 or 1.0 in the meantime CSI was above 60.Awareness of patients during surgery were assessed by questionnaire for explicit memory at 48 h after surgery.Results1.There is a linear correlation between CSI and End-tidal concentration of isoflurane,the correlation coefficient was-0.996(P < 0.001).With the rise of End-tidal concentration of isoflurane,the value for CSI was gradually reduced.2.There were twenty cases whose value for CSI was above 60 while End-tidal concentration of isoflurane was at 0.7MAC.When End-tidal concentration of isoflurane rose to 1.0MAC,the twenty cases' value for CSI were dropped below 60.3.None patient reported awareness in all patients.Conclusion1.CSI may be used as a good indicator formonitoringthe depth of isoflurane anesthesia.2.When ETAC was great than 0.7MAC,it may prevent intraoperative awareness,it may be a indicator for monitoring the depth of inhaled anesthesia.But it is not enough to use it as a monitoring indicator.A protocol that is based on both CSI and MAC alerts would be better than one based on either approach alonein preventing and decreasing intraoperative awareness.