title: The efficacy of automated intermittent boluses for continuous femoral nerve block: a prospective, randomized comparison to continuous infusions.
abstract: OBJECTIVE
  To determine whether an automated intermittent bolus technique provides enhanced analgesia compared with a continuous infusion for femoral nerve block.
  
  
  METHODS
  Prospective, single-blinded, randomized controlled trial (ClinicalTrials.gov Identifier: NCT01226927).
  
  
  METHODS
  Perioperative areas and orthopedic surgical ward of a university hospital.
  
  
  METHODS
  45 ASA physical status 1, 2, and 3 patients undergoing unilateral primary total knee arthroplasty.
  
  
  METHODS
  All patients received single-injection sciatic and femoral nerve blocks plus femoral nerve catheter placement for postoperative analgesia. Patients were randomly assigned to an automated intermittent bolus (5 mL every 30 min with 0.1 mL/hr basal rate) or a continuous infusion (10.1 mL/hr) delivery method of 0.2% ropivacaine.
  
  
  METHODS
  Consumption of intravenous patient-controlled analgesia (IV-PCA) and visual analog scale (VAS) pain scores were assessed postoperatively at set intervals until the morning of postoperative day (POD) 2.
  
  
  RESULTS
  The mean (SEM) cumulative IV-PCA dose (mg of hydromorphone) for the 36-hour postoperative interval measured was 12.9 ± 2.32 in the continuous infusion rate group (n = 20) and 7.8 ± 1.02 in the intermittent bolus group [n = 21, t(39) = 2.04, P = 0.048; a 39 ± 14% difference in total usage]. Pain scores were statistically significantly lower in the intermittent bolus group in the afternoon of POD 1 (t(39) = 2.47, P = 0.018), but were otherwise similar.
  
  
  CONCLUSIONS
  An automated intermittent bolus infusion technique for femoral nerve catheters is associated with clinically and statistically significantly less IV-PCA use (ie, an opioid-sparing effect) than a continuous infusion technique.
authors.affiliation: Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, Charleston, SC 29425-2400, USA.
authors.forename: M Gabriel
authors.initials: MG
authors.lastname: Hillegass
authors.forename: Larry C
authors.initials: LC
authors.lastname: Field
authors.forename: Scott R
authors.initials: SR
authors.lastname: Stewart
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Borckardt
authors.forename: Luke
authors.initials: L
authors.lastname: Dong
authors.forename: Peggy E
authors.initials: PE
authors.lastname: Kotlowski
authors.forename: Harry A
authors.initials: HA
authors.lastname: Demos
authors.forename: H
authors.initials: H
authors.lastname: Del Schutte
authors.forename: Scott T
authors.initials: ST
authors.lastname: Reeves
mesh_terms: D000368:Aged; D000577:Amides / Q000008:administration & dosage; D016058:Analgesia, Patient-Controlled / Q000379:methods; D000701:Analgesics, Opioid / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage*; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001331:Automation; D016503:Drug Delivery Systems; D005260:Female; D005267:Femoral Nerve; D006801:Humans; D004091:Hydromorphone / Q000008:administration & dosage; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control*; D011446:Prospective Studies; D000077212:Ropivacaine; D016037:Single-Blind Method
chemical_list: D000577:Amides; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D000077212:Ropivacaine; D004091:Hydromorphone
keywords: Continuous femoral nerve block; Regional anesthesia; Total knee arthroplasty