title: Continuous blockade of the lumbar plexus after knee surgery: a comparison of the plasma concentrations and analgesic effect of bupivacaine 0.250% and 0.125%.
abstract: In 20 patients a continuous block of the lumbar plexus was administered after knee-joint surgery, and the analgesic effect of two different concentrations of bupivacaine was compared. The same volume of bupivacaine was given to both groups of patients: a bolus dose of 0.4 ml/kg, 0.5% or 0.25%, followed by infusion of 0.14 ml/kg/h, 0.25% or 0.125%, respectively, via a catheter placed in the neurovascular fascial sheath of the femoral nerve according to the "3-in-1 block" technique. The median morphine consumption during the first 16 h postoperatively was 6.0 mg when bupivacaine 0.5/0.25% was used and 9.5 mg when 0.25/0.125% was used. This difference is not significant. The visual analogue pain scores were also similar in the two groups (P greater than 0.05). All plasma concentrations were below 4 micrograms/ml, the highest concentration measured being 3.6 micrograms/ml. It is concluded that when used for a continuous block of the lumbar plexus after knee-joint surgery, bupivacaine in a concentration of 0.125% offers the same pain relief as a concentration of 0.25%, and the risk of toxic reactions is reduced.
authors.affiliation: Department of Anesthesiology, Arhus Amtssygehus, University Hospital, Denmark.
authors.forename: E
authors.initials: E
authors.lastname: Anker-Møller
authors.forename: N
authors.initials: N
authors.lastname: Spangsberg
authors.forename: J B
authors.initials: JB
authors.lastname: Dahl
authors.forename: E F
authors.initials: EF
authors.lastname: Christensen
authors.forename: P
authors.initials: P
authors.lastname: Schultz
authors.forename: P
authors.initials: P
authors.lastname: Carlsson
mesh_terms: D000328:Adult; D002045:Bupivacaine / Q000008:administration & dosage* / Q000097:blood; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008160:Lumbosacral Plexus / Q000187:drug effects*; D008297:Male; D009407:Nerve Block; D010149:Postoperative Pain / Q000517:prevention & control*; D013997:Time Factors
chemical_list: D002045:Bupivacaine