ABSTRACT
Objective To determine the optimum dose of bupivacaine for spinal anesthesia with epidural volume extension (EVE) in patients undergoing cesarean delivery.Methods A total of 100 parturients,weighing 55-100 kg,with body height of 155-170 cm,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,scheduled for elective cesarean delivery,were included and randomized to receive bupivacaine at 5 different doses (A,B,C,D,and E groups) using a random number table,with 20 patients in each group.In A,B,C,D,and E groups,bupivacaine 6.75,7.50,8.25,9.00 and 9.75 mg were injected into the subarachnoid space,respectively,and the volume was all 1.5 ml.After successful spinal anesthesia,an epidural catheter was placed,and normal saline 10 ml was given through the catheter to perform EVE.A successful spinal block was defined as attainment of sensory block of at least T5 within 15 min after EVE along without requirement for additional local anesthetics within 60 min after EVE.The rate of successful spinal anesthesia,time to reach sensory block of T5,the maximum level of sensory block,and the first requirement for local anesthetics were recorded.The occurrence of hypotension,tachycardia,bradycardia,nausea,vomiting,chest distress,dyspnea,shivering,and referred pain and consumption of metaraminol were recorded during spinal anesthesia.Apgar scores at 1 and 5 min after birth were recorded.Results With the increasing doses of bupivacaine,the efficacy of spinal anesthesia was enhanced,and the occurrence of adverse reactions was increased.Compared with group C,the rate of successful spinal anesthesia,and the maximum level of sensory block were significantly increased,the time to reach sensory block of T5 was shortened,and the incidence of hypotension and nausea and consumption of metaraminol were increased in group E;the time to reach sensory block of T5 was significantly shortened,Apgar scores at 1 min after birth were increased (P＜0.05),and no significant change was found in the rate of successful spinal anesthesia,the first requirement for local anesthetics,the rate of time to reach sensory block ofT5≤ 15 min,and the maximum level of sensory block in group D (P＞0.05).Compared with group D,the time to reach sensory block of T5 was significantly shortened,the incidence of nausea and consumption of metaraminol were increased (P＜0.05),and no significant change was detected in the rate of successful spinal anesthesia,the first requirement for local anesthetics,the rate of time to reach sensory block of T5 ≤ 15 min,and the maximum level of sensory block in group E (P＞0.05).Conclusion The optimum dose of bupivacaine for spinal anesthesia with EVE is 9.00 mg in patients undergoing caesarean delivery.
ABSTRACT
Objective To determine the median effective effect-site concentration (EC50 ) of remifentanil inhibiting responses to laryngeal mask airway insertion when combined with propofol in elderly male patients . Methods Thirty ASA physical status Ⅰ or Ⅱ male patients ,aged 65>yr ,with body mass index <30 kg/m2 , scheduled for elective transurethral resection of bladder tumor or prostate under general anesthesia ,were enrolled in this study .Anesthesia was induced with target-controlled infusion of propofol with a target plasma concentration (Cp) of 3 μg/ml .When Observer′s Assessment of Alertness/Sedation (OAA/S ) score ≤1 ,remifentanil target-controlled infusion was started with the initial target Cp set at 4.0 ng/ml . The concentration of propofol was adjusted until BIS value reached 55-65 ,and then the laryngeal mask airway was inserted .Modified Dixon’s up-and-down method was used to determine the Cp of remifentanil . Each time the Cp of remifentanil increased/decreased in the next patient depending on whether or not the response to laryngeal mask airway insertion occurred . The ratio of the two successive Cps was 1.2 .The response to laryngeal mask airway insertion was defined as development of coughing ,laryngospasm and/or body movement during insertion or within 3 min after insertion .The number of patients in whom inhibition of responses to insertion was effective/ineffective was recorded .The EC50 of remifentanil required to inhibit responses to laryngeal mask airway insertion and the 95% confidence interval when combined with propofol were calculated .Results The EC50 (95% confidence interval ) of remifentanil required to inhibit responses to laryngeal mask airway insertion was 1.86 (1.64-2.12) ng/ml when combined with propofol in elderly male patients .Conclusion The EC50 of remifentanil required to inhibit responses to laryngeal mask airway insertion is 1.86 ng/ml when combined with propofol in elderly male patients .