title: Evaluation of electrical nerve stimulation for epidural catheter positioning in the dog.
abstract: OBJECTIVE
  To evaluate the accuracy of epidural catheter placement at different levels of the spinal cord guided solely by electrical nerve stimulation and resultant segmental muscle contraction.
  
  
  METHODS
  Prospective, experiment.
  
  
  METHODS
  Six male and two female Beagles, age (1 ± 0.17 years) and weight (12.9 ± 1.1 kg).
  
  
  METHODS
  Animals were anesthetized with propofol and maintained with isoflurane. An insulated epidural needle was used to reach the lumbosacral epidural space. A Tsui epidural catheter was inserted and connected to a nerve stimulator (1.0 mA, 0.1 ms, 2 Hz) to assess positioning of the tip at specific spinal cord segments. The catheter was advanced to three different levels of the spinal cord: lumbar (L2-L5), thoracic (T5-T10) and cervical (C4-C6). Subcutaneous needles were previously placed at these spinal levels and the catheter was advanced to match the needle location, guided only by corresponding muscle contractions. Catheter position was verified by fluoroscopy. If catheter tip and needle were at the same vertebral body a score of zero was assigned. When catheter tip was cranial or caudal to the needle, positive or negative numbers, respectively, corresponding to the number of vertebrae between them, were assigned. The mean and standard deviation of the number of vertebrae between catheter tip and needle were calculated to assess accuracy. Results are given as mean ± SD.
  
  
  RESULTS
  The catheter position in relation to the needle was within 0.3 ± 2.0 vertebral bodies. Positive predictive values (PPV) were 57%, 83% and 71% for lumbar, thoracic and cervical regions respectively. Overall PPV was 70%. No significant difference in PPV among regions was found.
  
  
  CONCLUSIONS
  Placement of an epidural catheter at specific spinal levels using electrical nerve stimulation was feasible without radiographic assistance in dogs. Two vertebral bodies difference from the target site may be clinically acceptable when performing segmental epidural regional anesthesia.
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA. garciaf@ufl.edu
authors.forename: Fernando L
authors.initials: FL
authors.lastname: Garcia-Pereira
authors.forename: Robert
authors.initials: R
authors.lastname: Sanders
authors.forename: Andre C
authors.initials: AC
authors.lastname: Shih
authors.forename: Ioana M
authors.initials: IM
authors.lastname: Sonea
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Hauptman
mesh_terms: D000767:Anesthesia, Epidural / Q000379:methods / Q000662:veterinary*; D000818:Animals; D002404:Catheterization / Q000379:methods / Q000662:veterinary*; D004285:Dogs / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D008297:Male
keywords: epidural anesthesia; epidural catheter; nerve stimulation