The Correlation Between The Oxygen Uptake Monitored By Zeus Anesthesia Machine Automatic Control Anaesthesia System And The Target Effect-site Concentration Of Propofol

Objective:Zeus anesthesia machine emerged in recent years,is the latest generation of the anesthesia system, which first implemented closed circuit breathing system.Therefore, the closed circuit breathing system of Zeus anesthesia machine can monitor the patient's oxygen uptake conveniently and in real-time. At present, the depth of sedation is often evaluated by bispectral index monitoring (BIS) and auditory evoked potentials (AEPI), whether the oxygen uptake is associated with the depth of sedation is not clear. This study will analyze the correlation between the oxygen uptake and the target level of propofol during the target-controlled propofol total intravenous anesthesia.Methods:Twenty-one ASAⅠ-Ⅱpatients,18 to 65 years, BMI 18.5 to 25,and no disease of heart, lung, brain, liver and kidney.Anesthesia was induced with target-controlled infusion of propofol. Routine prohibit drink and food at 8 hours pre—operative.All of patients intravenous driped Ringer's solution(8ml/kg) fastly,then changed the drip transfusion velocity to 8ml/kg/h. Heart rate, electrocardiogram, traumatic arterial pressure, degree of blood oxygen saturation(SpO2) and bispectral index(BIS) were monitored continually during the operation.Recorded heart rate, blood pressure and BIS after 5 minutes,as the baseline. The target effect-site concentration (C_E)was set at 2.5ug/ml,intravenous injected fentany 3ug/kg for anesthesia inducement,and injected rocuronium 0.9mg/kg after loss of eyelash reflex. Closed veil tightly and ventilated to get rid of nitrogen and fill in oxygen, then intubated and connected to Zeus anesthesia machine,using the closed circuit breathing mode.Seted the oxygen concentration of 50%, and tidal volume adjusted according to weight of patients to keep the end-tidal carbon dioxide partial pressure between 30～40.Wait 5 minutes and record heart rate, blood pressure, BIS values, and oxygen uptake.And then set the target concentration to 2.0ug/ml, wait 5 minutes after the level of propofol was achieved effect-site concentration,record heart rate, blood pressure, BIS values, and oxygen uptake.Repeat the same steps,record heart rate, blood pressure, BIS values, and oxygen consumption when the level of propofol was 1.5ug/ml and 1.Oug/ml.During the experiment, if the mean arterial pressure down to 50, give phenylephrine O.lmg iv in bonus, and records the time.After the surgery,appraises whether the intraoperative awareness occured. Using SPSS17.0(Statistical Package for Social Sciences17.0)to analysis the data. Measurement data expressed with Mean±Standard deviation(x±s). each index use multiple comparisons among each target concentration. P<0.05 means statistically significant.Results:In this study,the baseline before anesthesia, BIS was 95.6±2.0, heart rate was 76.1±14.7, arterial blood pressure was (136.2±8.9)/(73.3±9.2). After induction of anesthesia, when the target-controlled propofol concentrations were 2.5ug/ml,2.0ug/ml,1.5ug/ml,1.0ug/ml, correspondingly the oxygen uptake were 82.1±44.4,120.9±44.8,142.9±39.6,170.7±27.6,while BIS were 58.2±10.5,61.6±11.7, 64.9±11.5 and 69.0±10.7. Oxygen uptake and BIS increase with the lower of the propofol-level,the difference was statistically significant, measured with DCT (P <0.05).The correlation coefficients were 0.9389 and 0.9869. When the target concentrations were 2.5ug/ml,2.0ug/ml,1.5ug/ml,1.0ug/ml, correspondingly heart rate were 72.5±14.0,67.8±13.4,67.7±17.5,72.1±20.3,arterial blood pressure were (106.8±17.3)/(58.1±11.4), (99.9±14.4)/(55.5±9.5), (101.5±21.0) /(55.8±11.2),(114.7±28.1)/(63.2±15.4). All the differences of arterial blood pressure and heart rate at different target level of propofol do not have statistical significance measured with DCT (P<0.05).None of patients experienced intraoperative awareness.Conclusion:During the target-controlled propofol total intravenous anesthesia,BIS and oxygen uptake increases with the lower of the target level of propofol,the difference was statistically significant(P<0.05).The correlation coefficients were 0.9389 and 0.9869.Heart rate and arterial blood pressure was not sensitive to change with the target concentration of propofol,when the target concentration change within a certain range,heart rate and blood pressure do not necessarily change. None of patients experienced intraoperative awareness.