title: Comparative efficacy of ultrasound-guided and stimulating popliteal-sciatic perineural catheters for postoperative analgesia.
abstract: OBJECTIVE
  Perineural catheter insertion using ultrasound guidance alone is a relatively new approach. Previous studies have shown that ultrasound-guided catheters take less time to place with high placement success rates, but the analgesic efficacy compared with the established stimulating catheter technique remains unknown. We tested the hypothesis that popliteal-sciatic perineural catheter insertion relying exclusively on ultrasound guidance results in superior postoperative analgesia compared with stimulating catheters.
  
  
  METHODS
  Preoperatively, subjects receiving a popliteal-sciatic perineural catheter for foot or ankle surgery were assigned randomly to either ultrasound guidance (bolus via needle with non-stimulating catheter insertion) or electrical stimulation (bolus via catheter). We used 1.5% mepivacaine 40 mL for the primary surgical nerve block and 0.2% ropivacaine (basal 8 mL·hr(-1); bolus 4 mL; 30 min lockout) was infused postoperatively. The primary outcome was average surgical pain on postoperative day one.
  
  
  RESULTS
  Forty of the 80 subjects enrolled were randomized to each treatment group. One of 40 subjects (2.5%) in the ultrasound group failed catheter placement per protocol vs nine of 40 (22.5%) in the stimulating catheter group (P = 0.014). The difference in procedural duration (mean [95% confidence interval (CI)]) was -6.48 (-9.90 - -3.05) min, with ultrasound requiring 7.0 (4.0-14.1) min vs stimulation requiring 11.0 (5.0-30.0) min (P < 0.001). The average pain scores of subjects who provided data on postoperative day one were somewhat higher for the 33 ultrasound subjects than for the 26 stimulation subjects (5.0 [1.0-7.8] vs 3.0 [0.0-6.5], respectively; P = 0.032), a difference (mean [95%CI]) of 1.37 (0.03-2.71).
  
  
  CONCLUSIONS
  For popliteal-sciatic perineural catheters, ultrasound guidance takes less time and results in fewer placement failures compared with stimulating catheters. However, analgesia may be mildly improved with successfully placed stimulating catheters. Clinical trial registration number NCT00876681.
authors.affiliation: Department of Anesthesiology, University of California San Diego, 200 West Arbor Drive, San Diego, CA 92103-8770, USA. emariano@stanford.edu
authors.forename: Edward R
authors.initials: ER
authors.lastname: Mariano
authors.forename: Vanessa J
authors.initials: VJ
authors.lastname: Loland
authors.forename: NavParkash S
authors.initials: NS
authors.lastname: Sandhu
authors.forename: Michael L
authors.initials: ML
authors.lastname: Bishop
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Lee
authors.forename: Alexandra K
authors.initials: AK
authors.lastname: Schwartz
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Girard
authors.forename: Eliza J
authors.initials: EJ
authors.lastname: Ferguson
authors.forename: Brian M
authors.initials: BM
authors.lastname: Ilfeld
mesh_terms: D000328:Adult; D000368:Aged; D000577:Amides / Q000008:administration & dosage; D000698:Analgesia / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage; D002406:Catheterization, Peripheral / Q000379:methods*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control*; D011446:Prospective Studies; D000077212:Ropivacaine; D012584:Sciatic Nerve; D013997:Time Factors; D018084:Ultrasonography, Interventional / Q000379:methods*; D055815:Young Adult
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D008619:Mepivacaine