Clinical Study Of Target-Controlled Infusion Midazolam And Small-Dose Ketamine Anesthesia During Sacral Block In Children

Objective The purpose of the present study is(1) to examine the feasibility and safety of target-controlled infusion(TCI) midazolam during sacral block for children.(2) to evaluate the interaction between midazolam and ketamine in children.(3) to assess the value of heart rate variability(HRV) on monitoring the depth of midazolam-ketamine anesthesia and the efficiency of predicting movement during the surgery.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 incorporated into a computer-controlled infusion pump for intravenous anesthesia with midazolam. Sixty children(3 to 4 years old) with ASA gradeâ… andâ…¡,scheduled for elective surgery,were randomly assigned to two groups(30 cases in each group) according to anesthesia methods.Both groups received sacral block,then,The Group M were intravenously received TCI midazolam alone and Group MK were received TCI midazolam with small-dose ketamine,respectively.All the cases were monitored with electrocardiogram(ECG),heart rate(HR),non-invasive blood pressure(BP),pulse oxygen saturation (SpO₂),HRV:low frequency area(LF),high frequency area(HF) and total power(TP).Normalized unit power was derived as follows:low frequency area(nuLF):LF/TP×100%,high frequency area(nuHF):HF/TP×100%.The active movement was observed during anesthesia.Results In the observing processes,both groups can maintain circulation and respiratory system stabile,the hemodynamic changes were infinitesimal. The incidence of hypoxemia(SpO₂＜95%)after anesthesia induction were 6.6% and 0 in group M and MK,respectively.The median effective concentration of midazolam for sedation(EC₅₀) for skin incision was 173.02 ng/ml in group M and 63.01ng/ml in group MK.The levels of TP and LF decreased(P＜0.05), nuHF increased from(32.89±0.22)%to(46.74±0.18)%,nuLF decreased from (38.64±0.22)%to(25.07±0.09)%in group M(P＜0.05).While in group MK,the TP and HF decreased(P＜0.05),nuLF and nuHF no changes.The pre-incision LF and LF/HF of movers were statistically different from the non-movers in both groups.Logistic regression analysis showed that LF/HF was a significant predictor of incision movement.Conclusions These results documented that the TCI midazolam is satisfactory during sacral block for children,the hemodynamics maintains stabile and respiratory depression rarely occurs.Ketamine may markely reduce the EC₅₀ of midazolam.Heart rate variability can assess the alterations in autonomic activity caused by anaesthesia.LF/HF seems to be a useful pedictor of patient movements during surgery incision in children.