title: Adding clonidine to the induction bolus and postoperative infusion during continuous femoral nerve block delays recovery of motor function after total knee arthroplasty.
abstract: We evaluated the effects of adding clonidine for continuous peripheral nerve infusions. Sixty patients undergoing total knee arthroplasty under combined single-injection sciatic block and continuous femoral infusion were randomly allocated to three groups: block induction with 0.75% ropivacaine followed by 0.2% ropivacaine (group control; n = 20); block induction with 0.75% ropivacaine and 1 microg/kg clonidine followed by 0.2% ropivacaine (group cloni-bolus; n = 20), and block induction with 0.75% ropivacaine and 1 microg/kg clonidine followed by 0.2% ropivacaine with 1 microg/mL clonidine (group cloni-infusion; n = 20). After surgery, continuous femoral infusion was provided with a patient-controlled infusion pump (basal infusion rate, 6 mL/h; incremental dose, 2 mL; lockout time, 15 min). The median (range) onset time of surgical block was 15 min (5-30 min) in group control, 10 min (5-35 min) in group cloni-bolus, and 10 min (5-30 min) in group cloni-infusion (P = 0.07). No differences were reported among groups in the degree of pain measured with the visual analog scale. The total consumption of local anesthetic solution after a 24-h infusion was 170 mL (144-220 mL) in group control, 169 mL (144-260 mL) in group cloni-bolus, and 164 mL (144-248 mL) in group cloni-infusion (P = 0.51); after the second day of infusion, total consumption was 168 mL (144-200 mL) in group control, 156 mL (144-288 mL) in group cloni-bolus, and 150 mL (144-210 mL) in group cloni-infusion (P = 0.48). Hemodynamic profiles and sedation were similar in the three groups. Motor function impairment after 48 h of infusion was observed in 27% of cloni-infusion patients but in only 6% of both the control and cloni-bolus groups (P = 0.05). We conclude that adding clonidine 1 microg/mL to local anesthetic for continuous femoral nerve block does not improve the quality of pain relief but has the potential for delaying recovery of motor function.
authors.affiliation: *Department of Anesthesiology, University of Parma, Parma, Italy; †Department of Anesthesiology, Vita-Salute University of Milano, Milano, Italy; and ‡Department of Anesthesiology, University School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Andrea
authors.initials: A
authors.lastname: Casati
authors.forename: Federico
authors.initials: F
authors.lastname: Vinciguerra
authors.forename: Gianluca
authors.initials: G
authors.lastname: Cappelleri
authors.forename: Giorgio
authors.initials: G
authors.lastname: Aldegheri
authors.forename: Guido
authors.initials: G
authors.lastname: Fanelli
authors.forename: Marta
authors.initials: M
authors.lastname: Putzu
authors.forename: Jacques E
authors.initials: JE
authors.lastname: Chelly
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000762:Anesthesia Recovery Period; D000779:Anesthetics, Local / Q000494:pharmacology; D019645:Arthroplasty, Replacement, Knee; D003000:Clonidine / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D005267:Femoral Nerve / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D010149:Postoperative Pain / Q000188:drug therapy*; D011446:Prospective Studies
chemical_list: D000779:Anesthetics, Local; D003000:Clonidine
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