PURPOSE: Information about the onset time and duration of action of ropivacaine during a combined lumbar plexus and sciatic nerve block is not available. This study compares bupivacaine and ropivacaine to determine the optimal long-acting local anaesthetic for lumbar plexus and sciatic nerve block in patients undergoing total knee arthroplasty. METHODS: Forty adult patients scheduled for unilateral total knee arthroplasty, under lumbar plexus and sciatic block were entered into this double-blind randomized study. Patients were assigned (20 per group) to receive lumbar plexus block using 30 ml of local anaesthetic and a sciatic nerve block using 15 ml of local anaesthetic with either bupivacaine 0.5% or ropivacaine 0.5%. All solutions contained fresh epinephrine in a 1:400,000 concentration. Every one minute after local anaesthetic injection, patients were assessed to determine loss of motor function and loss of pinprick sensation in the L1-S1 dermatomes. The time to request first analgesic was documented from the PCA pump. This time was used as evidence of block regression. RESULTS: Blocks failed in four patients in each group. The mean onset time of both motor and sensory blockade was between 14 and 18 min in both groups. Duration of sensory blockade was longer in the bupivacaine group, 17 +/- 3 hr, than in the ropivacaine group, 13 +/- 2 hr (P < 0.0001). CONCLUSION: We conclude that bupivacaine 0.5% and ropivacaine 0.5% have a similar onset of motor and sensory blockade when used for lumbar plexus and sciatic nerve block. Analgesic duration from bupivacaine 0.5% was prolonged by four hours compared with an equal volume of ropivacaine 0.5% Keywords : administration & dosage,Adult,Aged,Amides,Analgesia,Patient-Controlled,Analgesics,Anesthetics,Local,Arthroplasty,Bupivacaine,Double-Blind Method,drug effects,Epinephrine,Female,Humans,Knee Joint,Lumbosacral Plexus,Male,methods,Motor Neurons,Nerve Block,Neurons,Afferent,Pain Threshold,Ropivacaine,Sciatic Nerve,Sensation,surgery,therapeutic use,Time Factors,, Plexus,Sciatic,Nerve,Block, london spine centre ontario
Date of Publication : 1998 Nov
Authors : Greengrass RA;Klein SM;D’Ercole FJ;Gleason DG;Shimer CL;Steele SM;
Organisation : Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
Journal of Publication : Can J Anaesth
Pubmed Link : https://www.ncbi.nlm.nih.gov/pubmed/10021959
The London Spine Unit : Harley Street UK. Specialists in Cutting Edge Technologies for Spinal Surgery
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