Influence of Dexmedetomidine on the Evoked Potentials During Spine Surgery
Condition: Spine Surgery
Study type: Interventional

Summary: 
      The purposes of this study are:

        1. To evaluate the safety and efficacy of Dexmedetomidine as an adjunct for anesthesia
           during spine surgery and

        2. To investigate the influence of Dexmedetomidine on the evoked potentials.
    

Detailed description: 
      Use of evoked potentials can significantly improve neurologic outcome after major spine
      surgery. Modalities of evoked potentials commonly used are Somato-Sensory Evoked Potentials
      (SSEP's), Motor Evoked Potentials (MEP's), and Visual Evoked Potentials (VEP's).

      Dexmedetomidine (DEX) is an alpha-2 agonist and has been FDA approved as an adjunct sedative
      agent to general anesthesia. It has been purported to reduce the amount of anesthetic
      required and potentiate the analgesic effect of opiates. In addition, DEX was shown to have
      minimal effect on SSEP's and VEP's in both rats and humans. Any decrease in the dose of
      general anesthesia that improves the monitoring of evoked potentials, supports DEX as an
      adjunct.

      It is known that all anesthetic agents can interfere with the recording of evoked potentials.
      The choice of anesthetic however, depends on the modality of neurophysiologic monitoring
      planned for the patient. Total intravenous anesthesia (TIVA) and Sevoflurane, a low dose
      inhalational anesthetic are the usual agents for spine surgery. Both have a dose-related
      depressant effect on the quality of evoked potentials. As a result, it is common practice for
      the anesthesiologist to adjust the depth of anesthesia to improve signaling. The use of
      either anesthetic must accompany continuous infusion of Propofol and an opioid, Remifentanil
      or Fentanyl. The anesthesiologist then decides whether DEX should be as an adjunct. In our
      experience, DEX did not impair evoked potentials. In fact, it improved the quality of signals
      in a few patients. Yet, there are no published data of such effects in medical literature.

      We hypothesize that Dexmedetomidine will not influence evoked potentials when used as an
      adjunct to general anesthesia. Our study is prospective, randomized, double-blinded and will
      be carried out on a set of anesthetics. We will first evaluate DEX as an adjunct in TIVA,
      then as an adjunct to Sevoflurane. The probable benefit of DEX may avoid the use of potent
      inhaled anesthetics which would improve VEP's monitoring. Quality recording of evoked
      potentials can enhance our ability to detect iatrogenic injury to the spinal cord and vision.
    

Intervention name(s): Dexmedetomidine; Normal Saline
Intervention type(s): Drug; Drug
Intervention description(s): 10 minutes loading dose of 0.9 mcg/kg
Maintenance dose of 0.6 mcg/kg/hour; 10 minutes loading dose of 0.9 mcg/kg
Maintenance dose of 0.6 mcg/kg/hour
Other intervention name(s): Dexmedetomidine hydrochloride; 0.9% Sodium Chloride
Intervention MeSH terms: Dexmedetomidine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Dexmedetomidine; Evoked potentials; Spine surgery