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Objective To establish the pharmacodynamic model of sevoflurane with bispectral index (BIS) as the effective index in pediatric patients.Methods Thirteen ASA physical status Ⅰ or Ⅱ pediatric patients,aged 4-9 yr,weighing 12-39 kg,undergoing non-cardiac surgery,were selected in the study.The pediatric patients sequentially inhaled 1％,5 ％ and 1％ sevoflurane via a face mask and each concentration was inhaled for 15 min.BIS value,HR,BP and SpO2 were automatically recorded every 10 s.Based on nonlinear mixed effect modeling,the population pharmacodynamic model of sevoflurane was established using NONMEM software.The effect of age on the pharmacodynamic parameters was evaluated using a stepwise forward addition then backward elimination modeling approach.The standard for model improvement was defined as a decrease in the value of the objective function by more than 3.84.Results Twelve pediatric patients,aged 4.0-8.5 yr,weighing 12.8-38.0 kg,with body height of 92-135 cm,were enrolled in this study and the data which were enrolled comprised 2964 effective concentration-time-BIS points.The model was not improved significantly with any covariates (age,body height,and body weight) introduced (P ＞ 0.05).The estimated parameters of the final pharmacodynamic model of sevoflurane were as follows:ke0 =O.516/min ; EC50 (BIS50) =2.11％ ; γ =2.46 ; E0 =74.6 ; EMAx =11.2.Conclusion The pharmacodynamic model of sevoflurane is successfully established with BIS as the effective index in pediatric patients,and the analysis for each parameter of the model indicates that the sensitivity to sevoflurane is lower,but the blood-brain equilibration time of the drug is shorter and the onset and recovery are faster in children than in adults.
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Objective To evaluate the efficacy and safety of parent-controlled analgesia for postoperative pain management in pediatric patients. Methods Five hundred and seven ASA Ⅰ or Ⅱ pediatric patients aged 10 months to 8 yr, weighting 8.5-34.0 kg, undergoing lower limb operations performed under general anesthesia combined with caudal block were assigned into 2 age groups: group PCIA-P ( < 6 yr, n = 308) and group PCIA ( ≥6yr, n = 199). Anesthesia was induced with intravenous midazolam 1 mg/kg, ketamine 2 mg/kg and propofol 2 mg/kg. Laryngeal mask airway (LMA) was introduced or the patients were intubated. After induction, caudal block was performed with 0.25% bupivacaine 2.5 mg/kg with adrenaline 1:400 000. The patients received PCA with morphine after operation. The PCA pump was controlled by parent in group PCIA-P and by patient in group PCIA. The PCA regimen included a background infusion of morphine at a rate of 15μg~(-1)·kg~(-1)·h, a bolus of 15μg/kg and a 10 min lockout interval. The vital signs, pain score, sedation score, number of attempts, morphine dosage and side effects were recorded. Results The two groups were comparable with respect to the rate of satisfactory analgesia, level of sedation, number of attempts, morphine dosage and side effects. The rates of satisfactory analgesia were 72.7% and 80.2% in group PCIA-P vs 77.9% and 78.9% in group PCIA at 24 and 48 h after operation respectively ( P > 0.05) . Conclusion Parent-controlled analgesia could be used safely and effectively in children after orthopedic surgery.