title: Comparison of procedural times for ultrasound-guided perineural catheter insertion in obese and nonobese patients.
abstract: OBJECTIVE
  Perineural catheter insertion with ultrasound guidance alone has been described, but it remains unknown whether this new technique results in the same procedural time and success rate for obese and nonobese patients. We therefore tested the hypothesis that obese patients require more time for perineural catheter insertion compared to nonobese patients despite using ultrasound.
  
  
  METHODS
  Data from 5 previously published randomized clinical trials comparing ultrasound- and stimulation-guided perineural catheter insertion techniques were reviewed, and patients who received ultrasound-guided catheters were divided into 2 groups: obese (body mass index ≥30 kg/m(2)) and nonobese (body mass index <30 kg/m(2)). A standardized ultrasound-guided nonstimulating catheter technique was used with mepivacaine, 1.5% (40 mL), as the initial bolus via the placement needle for the primary surgical nerve block. The primary outcome was the procedural time for perineural catheter insertion. Secondary outcomes included block efficacy, procedure-related pain, fluid leakage, vascular puncture, and catheter dislodgment.
  
  
  RESULTS
  A sample of 120 patients was identified: 51 obese and 69 nonobese. All obese patients had successful catheter placement compared to 68 of 69 (98%) nonobese patients (P = .388). The time for perineural catheter insertion [median (10th-90th percentiles)] was 7 (4-12) minutes for obese patients versus 7 (4-15) minutes for nonobese patients (P = .732). There were no statistically significant differences in other secondary outcomes.
  
  
  CONCLUSIONS
  On the basis of this retrospective analysis, perineural catheter insertion is not prolonged in obese patients compared to nonobese patients when an ultrasound-guided technique is used. However, these results are only suggestive and require confirmation through prospective study.
authors.affiliation: Department of Anesthesia, University of California, San Diego, California, USA. emariano@stanford.edu
authors.forename: Edward R
authors.initials: ER
authors.lastname: Mariano
authors.forename: Jay B
authors.initials: JB
authors.lastname: Brodsky
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage; D015992:Body Mass Index; D002404:Catheterization / Q000379:methods*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D009765:Obesity / Q000150:complications*; D010147:Pain Measurement; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D013997:Time Factors; D018084:Ultrasonography, Interventional
chemical_list: D000779:Anesthetics, Local; D008619:Mepivacaine