Clinical Study Of Midazolam And Ketamine Anesthesiausing Target-Contrlled Infusion Technique For Children

Objective: The purpose of the present study is (1). to examine the feasibility and safety of midazolam and ketamine combining anesthesia using target-controlled infusion(TCI) technique for children; (2). to evaluate the influences of midazolam and ketamine on quantitative electroencephalogram(q-EEG) and heart rate variability power spectrum analysis(HRV-PSA) in children; (3). to assess the value of q-EEG and HRV-PSA on monitoring the depth of midazolam and ketamine combining anesthesia.Methods: Software was designed based on the pharmacokinetics and phamacodynamics of midazolam, to achieve and maintain any desired concentration at the site of drug target. The software was input into a computer-controlled infusion pump for intravenous midazolam anesthesia. Sixty-four children (6 to 12 years old) with ASA grade I and II, scheduled for elective surgery, were randomly assigned to four groups according to anesthesia methods. The children in Group K were intravenously received a bolus dose of 2 mg/kg and subsequent infusion of 2 mg/kg · h of ketamine, which was adjusted as required. Cases in Group MK were received midazolam with target concentration of 250ng/ml using TCI technique, accompanied with a bolus dose of 2 mg/kg and subsequent infusion of 2 mg/kg/h of ketamine, which was adjusted as required. The children in Group EM were administered withtarget concentration of 200ng/ml using TCI technique besides epidural block. The children in Group EMK were given midazolam and ketamine in addition of epidural blockade, using same method as in Group KM, but with half of the dose and infusion speed of anesthetics. All the cases were monitored with non-invasive blood pressure (BP), pulse oxygen saturation (SpO2), electrocardiogram (ECG) and electroencephalogram (EEG) during anesthesia.Results: The incidence of hypoxemia (SpO2 <95%) after anesthesia induction was 7.14%, 13.33%, 9.09% and 7.69% in group K, group MK, group EM and group EMK, respectively. The total dosages of ketamine used were 15.34±3.16mg/kg and 8.45±1.59mg/kg in group K and group MK, respectively. The median effective concentration of midazolam for sedation (CP50) was significantly lower in group EMK (85.42±4.69ng/ml) than that in group EM (176.58±19.32ng/ml, p<0.05). The BIS value significantly increased in those cases with body movement to the stress of skin incision in every group. The LF/HF value significantly increased in those cases with body movement in operating.Conclusions: TCI technique is advantageous for the administration of intravenous midazolam anesthesia. Midazolam is able to remarkably reduce the dosage of ketamine used, and ketamine is capable of greatly decreasing the CP50 of midazolam in combining anesthesia. BIS and LF/HF are the useful parameters to monitor and predict anesthesia depth.