Objective To investigate the effect of midazolam on ventilatory response to carbondioxide (CO2) when it is used as sedative supplement to epidural blockade(EB). Methods Fifteen ASAⅠ -Ⅱ patients [age (49±7) years , weight (56±13)kg] undergoing upper abdominal surgery were studied. Patients with respiratory disease were excluded. No patient was addicted to smoking, alcohol,received any sedatives or hypotics within one month before surgery. The patients were premedicated with intramuscular phenobarbital 0. 1g and atropine 0.5mg. Epidural catheter was inserted in a cephala direction for 4 cm into epidural space via the tuohy needle at T9.10. 1% lidocaine and 0.2% pontocaine solution was used for epidural block. The level of block was T3.5. When the level of block was fixed, midazolam 0.1mg/kg was given intravenously. Respiratory rate(RR), tidal volume (VT), end-tidal concentration of CO2 (PETCO2) and pulse oxygen saturation (SpO2) were measured before anesthesia (baseline values), before midazolam when the level of block was fixed and 5 min after midazolam. Measurement of ventilatory response to CO2: the patient was asked to breathe with a closed system without a CO2 absorber. PET CO2 increased to 55 mm Hg in 6-10 min. RR, VT and minute ventilation (MV) were measured at PETCO2 40, 45, 50, and 55 mm Hg. The patient then breathed fresh air and PETCO2 returned to normal. 5 min after midazolam the measurment was repeated. The CO2 ventilatory response curve was obtained by plotting MV against the corresponding PET CO2. Results PET CO2, RR and SpO2 did not change significantly after epidural block and midazolam. There was no significant change in VT after epidural block as compared with the baseline value but VT decreased significantly after midazolam (P<0.01).There was no significant change in the slope of CO2 ventilatory response curve before and after midazolam but MV at different PET CO2 decreased significantly 5 min after midazolam. Conclusions Midazolam 0. 1mg/kg given after epidural block decreases VT but depression of respiratory center is slight and lasts for only a short period of time.[Key Words] Midazolam; Anesthesia, epidural; Carbon dioxide

Objective To investigate the effect of midazolam on ventilatory response to carbon dioxide (CO 2) when it is used as sedative supplement to epidural blockade(EB) Methods Fifteen ASA Ⅰ Ⅱ patients [age (49?7) years , weight (56?13)kg] undergoing upper abdominal surgery were studied Patients with respiratory disease were excluded No patient was addicted to smoking,alcohol,received any sedatives or hypotics within one month before surgery The patients were premedicated with intramuscular phenobarbital 0 1g and atropine 0 5mg Epidural catheter was inserted in a cephala direction for 4 cm into epidural space via the tuohy needle at T 9 10 1% lidocaine and 0 2% pontocaine solution was used for epidural block The level of block was T 3 5 When the level of block was fixed, midazolam 0 1 mg/kg was given intravenously Respiratory rate(RR), tidal volume (V T), end tidal concentration of CO 2 (P ET CO 2) and pulse oxygen saturation (SpO 2) were measured before anesthesia (baseline values), before midazolam when the level of block was fixed and 5 min after midazolam Measurement of ventilatory response to CO 2: the patient was asked to breathe with a closed system without a CO 2 absorber P ET CO 2 increased to 55 mm Hg in 6 10 min RR,V T and minute ventilation (MV) were measured at P ET CO 2 40, 45, 50, and 55 mm Hg The patient then breathed fresh air and P ET CO 2 returned to normal 5 min after midazolam the measurment was repeated The CO 2 ventilatory response curve was obtained by plotting MV against the corresponding P ET CO 2 Results P ET CO 2, RR and SpO 2 did not change significantly after epidural block and midazolam There was no significant change in V T after epidural block as compared with the baseline value but V T decreased significantly after midazolam(P

Objective To evaluate the accuracy of variation of epidural labor analgesia in predicting cesarean section.Methods A total of 1 200 parturients with a single baby who were at full term with a singleton fetus,aged 22-34 yr,weighing 60-85 kg,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,volunteered for epidural labor analgesia for pain relief,were enrolled in the study.Epidural labor analgesia (patient-controlled epidural analgesia) was performed when uterine contraction was regular and cervical dilatation was 2-3 cm.Patient-controlled epidural analgesia solution contained the mixture of 0.1％ ropivacaine and fentanyl 2 μg/ml with a background infusion 9 ml/h,bolus dose 4 ml,lockout interval 15 min.The variation of labor analgesia was defined as the difference between the highest visual analog scale score during labor and the visual analog scale score at 30 min after epidural injection of the initial dose of local anesthetic.The receiver operating characteristic curve was used to evaluate the accuracy of variation of epidural labor analgesia in predicting cesarean section.The optimal cut-off value was determined according to the maximum Youden index.Results The area under the receiver operating characteristic curve of variation of epidural labor analgesia in predicting cesarean section was 0.795,and the maximum Youden index was 53.6％,the sensitivity 87.5％ and the specificity 66.1％ when the cut-off value was 3.Conclusion Variation of epidural labor analgesia produces better accuracy in predicting cesarean section.