Determination Of The EC₅₀ Of Propofol For Intratracheal Intubation By Lightwand In Female Patients Combined With Sufentanil

Objective:To determinate the median effective concentration(EC50) of propofol for intratracheal intubation by Lightwand in female patients combined with Sufentanil.To calculate the EC50 of propolfol for intratracheal intubation through the intubation response and observe hemodynamic changes and complications.Method: 42 ASA physical statusⅠorⅡclass young female patients, aged 20~45 years, scheduled for surgery under the general anesthesia were randomly divided into group A(combined with sufentanil 0.20 μg/kg) and group B(combined with sufentanil 0.40 μg/kg),with 21 cases in each group. The laryngeal surface anesthesia was performed by spraying the larynx with 1%tetracaine before general anesthesia induction. Three minutes later, anesthesia was induced by propofol with target- controlled infusion(TCI). Six minutes after the effect-side concentration(ESC) was achieved, sufentanil(0.20 μg/kg or 0.40 μg/kg) was infused in one minute. Respiratory depression was observed and recorded. Assisted ventilation was administrated if necessary. Three minutes later, patient was intubated endotracheal tube with Lightwand by an experienced anesthesiologist without knowing the group assignment. And the positive response to endotracheal intubation was determined by the same anesthesiologist. The first patient in group A was tested at a target ESC of 3.20 μg/ml of propofol in accordance with the results of preliminary experiments,and the first patient in group B was tested at 2.80 μg/ml respectively.The concentration gradient of propofol was set to 2.85 μg/ml,3.20 μg/ml,3.59 μg/ml and 4.03 μg/ml in group A according to the geometric series,and 2.55 μg/ml、2.80 μg/ml、3.07 μg/ml,3.36 μg/ml in group B accordingly.Based on Dixon’s up-and-down method,a higher concentration was applied when the previous intubation response was positive;otherwise, a lower concentration was applied. Anesthesia was deepened by the anesthesiologist so as to intubate endotracheal tube smoothly,when a positive response was determined.The number of positive and negative response to intubation was recorded so as to calculate the EC50 of propolfol and 95% confidence interval(95%CI) according to the formula of Dixon’s up-and-down method.Electrocardiogram(ECG), mean arterial pressure(MAP), heart rate(HR) and blood oxygen saturation(SPO2) were put into use regularly for patients’ safe. Surgery durations and haemodynamic data were recorded. All patients were visited in next day, and the incidences of throat sore, respiratory depression, hoarseness and intraoperative awareness were recorded as well.Results: 1 EC50 and 95% CI :The EC50 of propofol in group A was 3.42μg/ml,and 95% CI was 3.23~3.61μg/ml.The EC50 of propofol in group B was 2.90μg/ml,and 95% CI was 2.81~3.00μg/ml. 2 Comparison of haemodynamic data: Compared with those data before intubation, the HR and MAP after intubation in group A increased dramatically(P<0.05),while the HR and MAP after intubation in group B increased inconspicuously( P>0.05).And compared with those data in group A before intubation those data in group B had no significant difference(P>0.05). 3 Complications: No hoarsness and intraoperative awareness occurred in all cases. There were 3 patients reported throat sore, which in group A and B were 1 and 2, respectively. They were treated with psychological comfort and hormone. After the administrating of sufentanil, there were 5 patients showed respiratory depression( 1 patient in group A and 4 patients in group B). All of them were treated and improved by man-assisted ventilation.Compared with these data, the difference between group A and group B was inconspicuous(P>0.05).Conclusions: The propofol effect-site concentration was measured.Combined with sufentanil 0.20 μg/kg,the effect-site concentration of propofol required for successful lightwand intubation in 50%(EC50)and 95% CI of young female patient were 3.42 μg/ml and 3.2~3.61μg/ml,and combined with sufentanil 0.40 μg/kg, EC50 and 95% CI were 2.90 μg/ml and 2.81 ~ 3.00 μg/ml, respectively. Patients in group B experienced more stable hemodynamic responses(P<0.05) without increasing postoperative complications.