title: Ultrasound-guided saphenous nerve block--within versus distal to the adductor canal: a proof-of-principle randomized trial.
abstract: OBJECTIVE
  Reliable saphenous nerve blockade is a desirable complement to popliteal sciatic nerve blockade for foot and ankle surgery. We compared two promising ultrasound-guided techniques, the supine adductor canal (AC) technique and the prone peri-saphenous branch of the descending genicular artery (Peri-SBDGA) technique, using 8 mL of 2% lidocaine with epinephrine 1:400,000.
  
  
  METHODS
  Following Research Ethics Board approval, we conducted a randomized single-blinded parallel-group trial in 102 patients undergoing foot and ankle surgery at a single centre. The primary endpoint was saphenous nerve ease of visualization (0 = not visible; 1 = visible with difficulty; and 2 = easily visible). Other endpoints included vascular landmark visualization (0 = not visible; 1= visible with colour flow Doppler; 2 = visible without colour flow Doppler), block success, onset, and complications.
  
  
  RESULTS
  Ninety-one patients were eligible for analysis. Saphenous nerve visibility was not different between the groups (visibility score = 2: AC group, n = 24/49 [49%] vs Peri-SBDGA group, 20/42 [48%]; P = 1.00). Vascular landmark visibility was better in the AC group than in the Peri-SBDGA group (visibility score = 2: 41/49 [84%] vs 25/42 [60%], respectively; P = 0.018). Block success rates were similar (AC group, 41/49 [84%] vs Peri-SBDGA group, 34/42 [81%]; P = 0.79), as were median [interquartile range] onset times (AC group, 5 [5-10] min vs Peri-SBDGA group, 8 [5-11] min; P = 0.38).
  
  
  CONCLUSIONS
  In this randomized trial, we found no differences in nerve visibility, block success rate, or onset between the AC and Peri-SBDGA techniques of ultrasound-guided saphenous nerve blockade, although the former technique provided superior vascular landmark visibility. Neither technique produced a sufficiently high success rate to provide reliable surgical anesthesia per se.
authors.affiliation: Department of Anesthesia, St. Paul's Hospital, Providence Level 3, 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada, steevhead@yahoo.ca.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Head
authors.forename: Rochelle C
authors.initials: RC
authors.lastname: Leung
authors.forename: Greg P T
authors.initials: GP
authors.lastname: Hackman
authors.forename: Rachael
authors.initials: R
authors.lastname: Seib
authors.forename: Kevin
authors.initials: K
authors.lastname: Rondi
authors.forename: Stephan K W
authors.initials: SK
authors.lastname: Schwarz
mesh_terms: D000328:Adult; D000368:Aged; D000842:Ankle / Q000601:surgery; D004837:Epinephrine / Q000008:administration & dosage*; D005260:Female; D005528:Foot / Q000601:surgery; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D016037:Single-Blind Method; D018615:Ultrasonography, Doppler, Color / Q000379:methods; D018084:Ultrasonography, Interventional / Q000379:methods*
chemical_list: D008012:Lidocaine; D004837:Epinephrine