title: Continuous interscalene analgesia with ropivacaine 2 mg/ml after major shoulder surgery.
abstract: BACKGROUND
  In this open, randomized study, the pharmacokinetics, clinical efficacy, and safety of a 48-h continuous interscalene infusion of 2 mg/ml ropivacaine for postoperative pain relief were investigated in patients undergoing open major shoulder surgery.
  
  
  METHODS
  An initial interscalene block with 30 ml ropivacaine, 7.5 mg/ml (225 mg), was performed. After completion of interscalene block, all patients (n = 24) received general anesthesia, and 6 h after interscalene block, a 48-h continuous interscalene infusion of 12 or 18 mg/h using 2 mg/ml ropivacaine was started. Total and unbound plasma concentrations of ropivacaine and 2.6-pipecoloxylidide (PPX; a major active metabolite) were determined during and up to 6 h after the interscalene infusion. Postoperative pain at rest was assessed by a visual analog scale. Supplementary analgesics and adverse events were recorded.
  
  
  RESULTS
  Plasma concentrations of total and unbound ropivacaine were proportional to the total dose. At the end of the interscalene infusion of 9 ml/h, the mean +/- SD plasma concentrations of total and unbound ropivacaine were 1.40 +/- 0.54 and 0.03 +/- 0.01 mg/l, respectively, and of total and unbound PPX were 0.70 +/- 0.38 and 0.30 +/- 0.20 mg/l, respectively. Plasma concentrations of unbound ropivacaine and unbound PPX, added together, remained well below threshold levels for systemic central nervous system toxicity. There were no significant differences between the groups for postoperative pain (median maximum of about 20 mm on the visual analog scale in both groups), analgesic consumption, or quality of pain relief assessed by the patient. No signs or symptoms of systemic local anesthetic toxicity were observed.
  
  
  CONCLUSIONS
  A 48-h continuous interscalene infusion of 6 or 9 ml/h ropivacaine, 2 mg/ml, started 6 h after an initial interscalene block of 30 ml ropivacaine, 7.5 mg/ml, provided satisfactory postoperative pain relief after major shoulder surgery and was well tolerated. Unbound plasma concentrations of ropivacaine and PPX remained well below threshold levels for systemic central nervous toxicity.
authors.affiliation: *Consultant, dagger Professor and Chief of Staff, Department of Anesthesiology, University Clinic of Zurich/Balgrist. double dagger AstraZeneca R&D, Södertälje, Sweden.
authors.forename: Georgios
authors.initials: G
authors.lastname: Ekatodramis
authors.forename: Alain
authors.initials: A
authors.lastname: Borgeat
authors.forename: Gunilla
authors.initials: G
authors.lastname: Huledal
authors.forename: Lennart
authors.initials: L
authors.lastname: Jeppsson
authors.forename: Lars
authors.initials: L
authors.lastname: Westman
authors.forename: Jan
authors.initials: J
authors.lastname: Sjövall
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000577:Amides / Q000493:pharmacokinetics; D000698:Analgesia; D000779:Anesthetics, Local / Q000493:pharmacokinetics; D001711:Biotransformation; D001917:Brachial Plexus; D004305:Dose-Response Relationship, Drug; D005260:Female; D006207:Half-Life; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D019637:Orthopedic Procedures; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy*; D000077212:Ropivacaine; D012782:Shoulder / Q000601:surgery*; D020069:Shoulder Pain / Q000188:drug therapy* / Q000209:etiology
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine