title: Ropivacaine plasma levels following high-dose local infiltration analgesia for total knee arthroplasty.
abstract: We measured total and free plasma concentrations of ropivacaine following high-volume, high-dose local infiltration analgesia in 28 patients aged 65 years or over undergoing unilateral total knee arthroplasty. Patients received infiltration of ropivacaine 400 mg followed by infusion at 20 mg.h(-1) through an intra-articular catheter. Total and free plasma levels of ropivacaine were measured at specified time intervals during a 24-h period after tourniquet release. Patients were monitored for symptoms and signs of local anaesthetic toxicity. Total levels of plasma ropivacaine varied from 0.147 to 3.093 μg.ml(-1) (mean (SD) 1.105 (0.518) μg.ml(-1) ). Free levels of plasma ropivaca-ine varied from 0.001 to 0.104 μg.ml(-1) (mean (SD) 0.037 (0.020) μg.ml(-1) ). Six samples had total plasma ropivacaine levels greater the toxic threshold of 2.2 μg.ml(-1) . No samples reached the toxic threshold for free venous ropivacaine concentration. We conclude that the use of high-dose ropivacaine infiltration and catheter infusion for total knee arthroplasty in an elderly population does not result in free plasma ropivacaine levels previously associated with toxicity but that raised total plasma levels may be observed.
authors.affiliation: Department of Orthopaedic Surgery, Golden Jubilee National Hospital, Glasgow, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: Brydone
authors.affiliation: Department of Anaesthesia, Golden Jubilee National Hospital, Glasgow, UK.
authors.forename: R
authors.initials: R
authors.lastname: Souvatzoglou
authors.affiliation: Institute of Pharmacy and Biomedical Sciences, Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Strathclyde, UK.
authors.forename: M
authors.initials: M
authors.lastname: Abbas
authors.affiliation: Institute of Pharmacy and Biomedical Sciences, Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Strathclyde, UK.
authors.forename: D G
authors.initials: DG
authors.lastname: Watson
authors.affiliation: Department of Anaesthesia, Golden Jubilee National Hospital, Glasgow, UK.
authors.forename: D A
authors.initials: DA
authors.lastname: McDonald
authors.affiliation: Department of Rehabilitation, Golden Jubilee National Hospital, Glasgow, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Gill
mesh_terms: D000368:Aged; D000577:Amides / Q000097:blood*; D000698:Analgesia / Q000379:methods*; D000779:Anesthetics, Local / Q000097:blood*; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D006801:Humans; D008297:Male; D010149:Postoperative Pain / Q000188:drug therapy*; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine