Ultrasound-guided continuous interscalene block: the influence of local anesthetic background delivery method on postoperative analgesia after shoulder surgery: a randomized trial.

BACKGROUND: Automated bolus delivery has recently been shown to reduce local anesthetic consumption and improve analgesia, compared with continuous infusion, in continuous sciatic and epidural block. However, there are few data on the influence of local anesthetic delivery method on local anesthetic consumption following interscalene blockade. This randomized, double-blind trial was designed to determine whether hourly automated perineural boluses (4 mL) of local anesthesia delivered with patient-controlled pro re nata (PRN, on demand) boluses would result in a reduction in total local anesthesia consumption during continuous interscalene blockade after shoulder surgery compared with continuous perineural infusion (4 mL/h) plus patient-controlled PRN boluses. METHODS: One hundred one patients undergoing major shoulder surgery under general anesthesia with ultrasound-guided continuous interscalene block were randomly assigned to receive 0.2% ropivacaine via interscalene end-hole catheter either by continuous infusion 4 mL/h (n = 50) or as automated bolus 4 mL/h (n = 51). Both delivery methods were combined with 5 mL PRN boluses of 0.2% ropivacaine with a lockout time of 30 minutes. Postoperative number of PRN boluses, 24- and 48-hour local anesthetic consumption, pain scores, rescue analgesia (morphine), and adverse events were recorded. RESULTS: There were no significant differences in either the number of PRN ropivacaine boluses or total 48 hour local anesthetic consumption between the groups (18.5 [11-25.2] PRN boluses in the continuous infusion group vs 17 [8.5-29] PRN boluses in the automated bolus group). Postoperative pain was similar in both groups; on day 2, the median average pain score was 4 (2-6) in the continuous infusion group versus 3 (2-5) in the automated bolus group (P = 0.54). Nor were any statistically significant intergroup differences observed with respect to morphine rescue, incidence of adverse events, or patient satisfaction. CONCLUSIONS: In continuous interscalene blockade under ultrasound guidance after shoulder surgery, automated boluses of local anesthetic combined with PRN boluses did not provide any reduction in local anesthetic consumption or rescue analgesia, compared with continuous infusion combined with PRN boluses.

Perineural clonidine does not prolong levobupivacaine 0.5% after sciatic nerve block using the Labat approach in foot and ankle surgery.

BACKGROUND: There is controversy about the effectiveness of perineural clonidine used as an adjuvant to local anesthetics. This study investigated whether the addition of 150 µg clonidine to 0.5% levobupivacaine used for posterior sciatic nerve block would prolong the duration of analgesia. METHODS: This double-blind, prospective trial compared the analgesic characteristics of 20 mL plain levobupivacaine versus 20 mL levobupivacaine 0.5% plus 150 µg clonidine in a posterior sciatic nerve block (Labat approach) for foot and ankle surgery. Sixty patients were randomized and allocated to receive either levobupivacaine alone or levobupivacaine plus clonidine, to find a 30% prolongation of analgesia with the adjuvant, using the same SD. The onset and duration of the block (time from completion of block administration to first morphine request), the hemodynamic changes during surgery, the need for rescue analgesia, and technical or neurologic complications were assessed over a 24-hour period. RESULTS: The onset of sensory block (in minutes) was similar in the levobupivacaine and levobupivacaine plus clonidine groups (10 [5-20] vs 10 [5-23] minutes, median [interquartile range], respectively), as was the time to first request of pain medication (1215 [920-1530] vs 1275 [1067-1360] minutes, respectively). However, during surgery, statistically significantly more subjects in the levobupivacaine plus clonidine group than the levobupivacaine group experienced a decrease of more than 20% in systolic arterial pressure (50% vs 28% of patients, respectively; P < 0.028). No complications were noted in either group over 24 hours. CONCLUSIONS: Addition of 150 µg clonidine to 20 mL of levobupivacaine 0.5% in posterior gluteal (Labat) sciatic nerve block did not prolong the duration of analgesia but had a slight effect on systolic arterial pressure.

Levobupivacaine 0.5% provides longer analgesia after sciatic nerve block using the Labat approach than the same dose of ropivacaine in foot and ankle surgery.

BACKGROUND: Levobupivacaine and ropivacaine are 2 left enantiomeric molecules frequently used for peripheral nerve blocks because of their safe clinical profile. Levobupivacaine is more lipophilic and theoretically more potent than ropivacaine, but clinical studies show conflicting results in terms of anesthetic and analgesic characteristics. We hypothesized that the pure S-enantiomer of bupivacaine provides longer-lasting analgesia than ropivacaine. METHODS: We compared the analgesic characteristics of 20 mL levobupivacaine versus 20 mL ropivacaine 0.5% in a posterior sciatic nerve block (Labat approach) for foot and ankle surgery. In a double-blind, randomized, prospective design, 80 patients received either substance. We assessed the onset, duration, and success of the block, and the need for rescue analgesia and technical or neurologic complications over 24 hours. RESULTS: The onset of sensory block (minutes) and the success rate were similar in levobupivacaine and ropivacaine groups (onset, 15 minutes [5-40 minutes] vs 15 minutes [5-60 minutes], respectively; success rate, 90% vs 92.5%). The average time for the first request of pain medication provided by 20 mL levobupivacaine 0.5% was significantly longer than with ropivacaine (1605 minutes [575-2400 minutes] vs 1035 minutes [590-1500 minutes], P < 0.001). The need for postoperative rescue analgesia was higher in the ropivacaine group (37 of 40 [92.5%] vs 30 of 40 [75%], P < 0.034). No complications were noted in either group at 24 hours. CONCLUSION: Twenty milliliters levobupivacaine 0.5% in posterior gluteal (Labat) sciatic nerve block provided longer-lasting analgesia after foot and ankle surgery compared with the same dose of ropivacaine.