title: Dexmedetomidine Does Not Affect Evoked Potentials During Spine Surgery.
abstract: BACKGROUND
  The effect of dexmedetomidine on evoked potentials (EPs) has not been elucidated. We aimed to investigate the effect of dexmedetomidine on somatosensory, motor, and visual EPs.
  
  
  METHODS
  After IRB approval, 40 adult patients scheduled for elective spine surgery using total IV anesthesia with propofol and remifentanil were randomly assigned to receive either dexmedetomidine (n = 20) or placebo (n = 20) in a double-blind, placebo-controlled trial. After obtaining informed consent, positioning, and baseline EPs recording, patients were randomly assigned to either IV dexmedetomidine 0.6 μg/kg infused over 10 minutes, followed by 0.6 μg/kg/h, or a corresponding volume of IV normal saline (placebo). EP measures at 60 ± 30 minutes after initiation of study drug were defined as T1 and at 150 ± 30 minutes were defined as T2. Changes from baseline to T1 (primary end point) and from baseline to T2 (secondary end point) in EP latencies (milliseconds) and amplitudes (microvolts) were compared between groups. Data presented as mean ± SD (95% confidence interval).
  
  
  RESULTS
  Data from 40 patients (dexmedetomidine: n = 20; age, 54 ± 3 years; 10 males; placebo: n = 20; age, 52 ± 2 years; 5 males) were analyzed. There was no difference between dexmedetomidine versus placebo groups in primary end points: change of somatosensory EPs at T1, latency: 0.01 ± 1.3 (-0.64, 0.65) vs 0.01 ± 1.3 (-0.64, 0.65), P = 0.43 (-1.24, 0.45); amplitude: 0.03 ± 0.14 (-0.06, 0.02) vs -0.01 ± 0.13 (-0.07, 0.05), P = 0.76 (-0.074, 0.1); motor EPs amplitude at T1: 65.1 ± 194.8 (-35, 165; n = 18) vs 109.2 ± 241.4 (-24, 243; n = 16), P = 0.57 (-113.5, 241.57); visual EPs at T1 (right eye), amplitude: 2.3 ± 3.6 (-0.4, 5.1; n = 11) vs 0.3 ± 6.0 (-3.3, 3.9; n = 16), P = 0.38 (-6.7, 2.6); latency N1: 2.3 ± 3.6 (-0.4, 5.1) vs 0.3 ± 6.0 (-3.3, 3.9), P = 0.38 (-6.7, 2.6); latency P1: -1.6 ± 13.4 (-11.9, 8.7) vs -1.4 ± 8.1 (-6.3, 3.5), P = 0.97 (-9.3, 9.7) or secondary end points. There were no differences between right and left visual EPs either at T1 or at T2.
  
  
  CONCLUSIONS
  In clinically relevant doses, dexmedetomidine as an adjunct to total IV anesthesia does not seem to alter EPs and therefore can be safely used during surgeries requiring monitoring of EPs.
authors.affiliation: From the *Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington; †Department of Veterans Affairs, Puget Sound Health Care System, Seattle, Washington; ‡Department of Neurosurgery and Rehabilitation Medicine, University of Washington, Seattle, Washington; §Department of Anesthesiology and Pain Medicine and Neurosurgery, University of Washington, Seattle, Washington; and ∥Department of Anesthesiology and Pain Medicine, Neurosurgery and Pediatrics, University of Washington, Seattle, Washington.
authors.forename: Irene
authors.initials: I
authors.lastname: Rozet
authors.forename: Julia
authors.initials: J
authors.lastname: Metzner
authors.forename: Marcia
authors.initials: M
authors.lastname: Brown
authors.forename: Miriam M
authors.initials: MM
authors.lastname: Treggiari
authors.forename: Jefferson C
authors.initials: JC
authors.lastname: Slimp
authors.forename: Greg
authors.initials: G
authors.lastname: Kinney
authors.forename: Deepak
authors.initials: D
authors.lastname: Sharma
authors.forename: Lorri A
authors.initials: LA
authors.lastname: Lee
authors.forename: Monica S
authors.initials: MS
authors.lastname: Vavilala
mesh_terms: D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D020927:Dexmedetomidine / Q000008:administration & dosage* / Q000009:adverse effects; D004311:Double-Blind Method; D005071:Evoked Potentials / Q000187:drug effects*; D019054:Evoked Potentials, Motor / Q000187:drug effects; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects; D005074:Evoked Potentials, Visual / Q000187:drug effects; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage* / Q000009:adverse effects; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D010880:Piperidines / Q000008:administration & dosage; D015742:Propofol / Q000008:administration & dosage; D011930:Reaction Time; D000077208:Remifentanil; D013131:Spine / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors
chemical_list: D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D010880:Piperidines; D020927:Dexmedetomidine; D000077208:Remifentanil; D015742:Propofol