title: Evaluation of analgesic and sedative effects of continuous infusion of dexmedetomidine by measuring somatosensory- and auditory-evoked potentials in the rat.
abstract: OBJECTIVE
  To study, the analgesic and sedative effects of different constant rate infusions (CRI) of dexmedetomidine, in the rat, by measurement of specific electroencephalographic parameters. The recorded parameters were somatosensory-evoked potentials (SEPs) and auditory-evoked potentials (AEPs), which have been shown to be related to analgesia and sedation respectively.
  
  
  METHODS
  Nine male Wistar rats (HsdCpb:Wu, Harlan Netherlands BV, body weight 300-350 g).
  
  
  METHODS
  Somatosensory-evoked potentials were recorded from the primary somatosensory cortex and the vertex location (SI/Vx-SEPs). Auditory-evoked potentials were recorded from the primary auditory cortex and vertex location (AI/Vx-AEPs). Primary somatosensory cortex and vertex location recorded SEPs and AI/Vx-AEPs were recorded alternately, during CRI of dexmedetomidine (4.0, 10.0, 20.0 microg kg(-1) hour(-1)) and a control (saline).
  
  
  RESULTS
  The primary somatosensory cortex-evoked potentials were not affected by the dexmedetomidine CRI, but the other three parameters were significantly affected; although the AI-SEP to a lesser extent than the Vx-SEP and Vx-AEP. A maximum effect on the Vx-AEP was reached at lower doses than on the Vx-SEP.
  
  
  CONCLUSIONS
  Based on the present findings, it is suggested that CRI of dexmedetomidine provided profound sedation at low doses, whereas higher doses are needed to provide concurrent analgesia.
  
  
  CONCLUSIONS
  A constant rate infusion of dexmedetomidine can be a valuable adjunct in the provision of sedation and/or analgesia. However, analgesia cannot be produced without sedation, and sedation is not necessarily accompanied by comparative degrees of analgesia.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Division Anaesthesiology and Neurophysiology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
authors.forename: Naomi D
authors.initials: ND
authors.lastname: Franken
authors.forename: Hugo
authors.initials: H
authors.lastname: van Oostrom
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Stienen
authors.forename: Arie
authors.initials: A
authors.lastname: Doornenbal
authors.forename: Ludo J
authors.initials: LJ
authors.lastname: Hellebrekers
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage* / Q000494:pharmacology*; D000818:Animals; D020927:Dexmedetomidine / Q000008:administration & dosage* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005072:Evoked Potentials, Auditory; D005073:Evoked Potentials, Somatosensory; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018712:Analgesics, Non-Narcotic; D020927:Dexmedetomidine