title: Is there any need for expanding the perineural space before catheter placement in continuous femoral nerve blocks?
abstract: OBJECTIVE
  There is debate regarding the benefit of perineural space expansion before catheter placement in continuous femoral nerve block. This question is addressed in this prospective, comparative, and randomized study.
  
  
  METHODS
  Sixty patients scheduled for total knee replacement were randomly assigned to receive continuous femoral nerve block with or without perineural space expansion using 10 mL dextrose 5% in water (D5W) flush before stimulation-guided catheter placement. Femoral block was initiated with a 5-mL bolus followed by an infusion of 5 mL/h ropivacaine 0.2% during the 2-hour surgery. The number of attempts before successful placement of the stimulating catheter and the resistance during its insertion were assessed. Patients also received obturator nerve blocks by using ropivacaine 0.75% (10 mL) and sciatic nerve blocks (20 mL). The number of boluses of ropivacaine 0.2% needed to achieve zero VAS scoring was recorded in the postanesthesia care unit during the 2-hour stay. Images of the contrast spread were also studied.
  
  
  RESULTS
  There were 30 patients in each group. The number of successful catheter placements at the first attempt was higher with expansion than without (22 vs. 8, P = .007). The resistance felt during insertion was lower with than without expansion (P = .01). More boluses of ropivacaine were required postoperatively without expansion (P = .03). No difference between groups was found regarding the images of the contrast spread.
  
  
  CONCLUSIONS
  Expansion of the perineural space with D5W is useful for catheter placement in continuous femoral nerve block.
authors.affiliation: Pôle Anesthésie-Réanimations, CHU Nantes, France. charles.phamdang@chu-nantes.fr
authors.forename: Charles
authors.initials: C
authors.lastname: Pham Dang
authors.forename: Jérôme
authors.initials: J
authors.lastname: Guilley
authors.forename: Lyndia
authors.initials: L
authors.lastname: Dernis
authors.forename: Cécile
authors.initials: C
authors.lastname: Langlois
authors.forename: Chantal
authors.initials: C
authors.lastname: Lambert
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Nguyên
authors.forename: Michel
authors.initials: M
authors.lastname: Pinaud
mesh_terms: D000328:Adult; D000368:Aged; D002404:Catheterization; D005260:Female; D005267:Femoral Nerve; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D011446:Prospective Studies