| Objective To determine the half effective concentration of sufentanil on propofol to prevent laryngeal mask insertion response in elderly patients. Methods 120 low risk patients undergoing elective surgery under general anesthesia were included in this study. Patients were allocated into A and B groups.There were 30 old patients in group A and group AL,aged 66-70 and 30 patients in group B and group BL,aged 71-75. Propofol was administered by the March pharmacokinetic model TCI system in two stpes.The target effect-site concentration(Ce) of propofol was administered from 1μg/ml to 2μg/ml. The interval between the two concentrations was 2min. Sufentanil was first administered 0.3ng/ml with a target effect-site concentration(Ce). The laryngeal mask was inserted by the same anesthetist after sufentanil achieving the balance of target effect-site concentration and plasma concentration.The next concentration of sufentanil was determined using the modified Dixon’s up-and-down method. The ratio between adjacent concentrations was 1:1.2. The changes in cardiovascular response and BIS were recorded. Modified OAA/S sedation score were measured.Probability analysis was used for calculating EC50 and 95% confidence interval(CI). Results The EC50 cf sufentanil on propofol to prevent laryngeal mask insertion response in elderly patients aged 66-70 was 0.164ng/ml, 95%CI was 0.144~0.182ng/ml. The EC50 cf sufentanil on propofol to prevent laryngeal mask insertion response in elderly patients aged 71-75 was 0.160ng/ml, 95%CI was 0.141~0.179ng/ml. Conclusion The EC50 cf sufentanil on propofol to prevent laryngeal mask insertion response in elderly patients aged 66-70 was 0.164ng/ml, 95%CI was 0.144~0.182ng/ml. The EC50 cf sufentanil on propofol to prevent laryngeal mask insertion response in elderly patients aged 71-75 was 0.160ng/ml, 95%CI was 0.141~0.179ng/ml. There were no difference between the two groups, p>0.05. |
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