The analgesic effect of dexmedetomidine combined with ropivacaine in single sciatic nerve block after total knee arthroplasty with continuous femoral never block / 实用医学杂志

Objective To evaluate analgesic effect of dexmedetomidine (DEX) combined with ropivacaine in single sciatic nerve block after total knee arthroplasty (TKA) with continuous femoral never block.Meth ods One hundred and twenty patients,ASA physical status Ⅰ ～ Ⅱ,who underwent unilateral TKA were randomly allocated into two groups:group D (DEX with ropivacaine);group R (ropivacaine only).Both groups experienced spinal-epidural anesthesia.Continuous femoral nerve block was performed after operation.Rest and movement visual analogue score (VAS),Ramsay sedation scores were recorded.In addition to the date of the analgesia drug dose,the pressed times of PCA,the mobility of knee joint and the force of quadriceps femoris were obtained at different points of time.Results Rest Pain scores (RVAS) of the group D were lower at time point 8,12,24,36,48 h and Ramsay sedation scores were higher at time point 4,8,12 h than that in the group R (P ＜ 0.05).The analgesia drug dose and the pressed times of PCA reduced in the group D.The range of motion (ROM) was better in the group D at 1 d,2 d after operation (P ＜ 0.05).There was no significant difference in the force of quadriceps femoris in both groups.Conclusion Dexmedetomidine combined with ropivacaine in single sciatic nerve block after TKA provided better analgesia when continuous femoral nerve block was performed.Meanwhile,analgesia lasted longer and did not increase the motor nerve blockade.

Effect of dexmedetomidine administered locally on median effective concentration of ropivacaine for paravertebralnerve block / 中华麻醉学杂志

Objective To evaluate the effect of dexmedetomidine administered locally on the median effective concentration ( EC50 ) of ropivacaine for paravertebral nerve block ( PVNB) . Methods Forty?eight ASA physical status Ⅰ or Ⅱ female patients, aged 20-64 yr, with body mass index<24 kg∕m2 , scheduled for elective unilateral segmental mastectomy under PVNB, were randomly divided into 2 groups ( n=24 each) using a random number table: ropivacaine group ( group R) and ropivacaine mixed with dexmedetomidine group ( group RD) . PVNB was performed at T4 on the operated side guided by ultrasound and nerve stimulator. Ropivacaine 20 ml and a mixture of ropivacaine and 20 μg dexmedetomidine 20 ml were injected locally in group R and group RD, respectively. The concentration of ropivacaine was determined by up?and?down sequential allocation. The initial ropivacaine concentration was set at 0. 35%, and the ratio between the two successive concentrations was 1. 2. The EC50 and 95%confidence interval of ropivacaine were calculated using Dixon?Massey method. Results The EC50 ( 95%confidence interval) of ropivacaine was 0.27% (0.23%-0.30%) and 0.22% (0.18%-0.25%) in group R and group RD, respectively. Compared with group R, the EC50 of ropivacaine was significantly decreased by 19% in group RD. Conclusion Small dose of dexmedetomidine administered locally can significantly enhance the efficacy of PVNB with ropivacaine.

Effect of right stellate ganglion block on heart rate variability in patients with carbon dioxide pneumoperitoneum / 中华麻醉学杂志

Objective To invetstigate the effects of right stellate ganglion block (SGB) on heart rate variability (HRV) in patients with carbon dioxide pneumoperitoneum.Methods Forty ASA Ⅰ or Ⅱ patients of both sexes,aged 39-75 yr,weighing 47-75 kg,undergoing elective laparoscopic cholecystectomy,were randomly divided into 2 groups ( n =20 each):control group (group C) and right SGB group (group SGB).Right SGB was performed with 1％ lidocaine 7 ml at 10 min before induction of anesthesia.The low frequency power ( LF),high frequency power (HF),total power (TP) and LF/HF ratio were recorded before SGB (baseline,To ),at 5 and 30 min of pneumoperitoneum (T1,2),at 5 min after deflation (T3) and at the end of operation (T4 ).The LF in normalized units (LFnu) and HF in normalized units (HFnu) were calculated.Results Compared with the baseline values at T0,LF,LFnu and LF/HF ratio were significantly increased at T1-4,HF was significantly decreased at T3,4,and HFnu was significantly decreased at T2-4 in group C,and HF was significantly increased at T1-4,HFnu was significantly increased at T2-4 and LF/HF ratio was significantly decreased at T1-4 in group SGB ( P ＜ 0.05 or 0.01 ).LF,LFnu and LF/HF ratio were significantly decreased at T1-4,and HF at T1-4 and HFnu at T2-4 were significantly increased in group SGB as compared with group C ( P ＜ 0.05 or 0.01 ).Conclusion Right SGB can not only inhibit the sympathetic activity induced by carbon dioxide pneumoperitoneum,but also increase the vagal tone.

Minimum local analgesic concentration of ropivacaine and bupivacaine in continuous axillary brachial plexus block for postoperative active mobilization of flexor tendon / 中华麻醉学杂志

Objective To determine and compare the minimum local analgesic concentration(MLAC) of ropivacaine and bupivacaine in continuous block of axillary brachial plexus for postoperative active mobilization of flexor tendon. Methods Seventy ASA Ⅰ or Ⅱ patients undergoing relaxation of flexor tendon were randomly allocated into 2 groups (n = 35 each): ropivacaine group (group R) and bupivacaine group (group B). A catheter was inserted into axillary sheath using B. Braun stimulating intraducer, 24-48 h after operation. 30 min before functional exercise 20 ml of ropivacaine or bupivacaine was injected through catheter. The minimum local analgesic concentration of both local anesthetics was determined by up-and-down sequential test. The first concentration of both local anesthetics was 0.1%. The next concentration of local anesthetic was determined by response of the previous patient. The analgesia efficacy was assessed using 100 mm VAS score (0 = no pain, 100 mm = worst possible pain) . Increase/decrease in VAS by 10 mm was defined as effective. An effective result resulted in increase/decrease by 0.01% in the next patient. The motor block was also recorded.Results The two groups were comparable with regard to age, sex, body weight and baseline VAS score. The MLAC of ropivacaine was 0.133% [95% confidence interval (CI), 0.128%-0.138%] and MLAC of bupivacaine was0.121% (95%CI, 0.116%-0.126%). The analgesic potency of ropivacaine was 10% less than that of bupivacaine. The potency ratio of ropivacaine to bupivacaine was 0.91. The degree of motor block is higher with bupivacaine than with ropivacaine. Conclusion The results of our study show that the analgesic potency of ropivacaine is 10% less than that of bupivacaine. The degree of motor block is higher with bupivacaine than with ropivacaine.