Susceptibility of Motor-Evoked Potentials to Varying Targeted Blood Levels of Dexmedetomidine
Condition: Scoliosis
MeSH terms: Scoliosis
Intervention: low dexmedetomidine, low propofol; high dexmedetomidine, low propofol; Dexmedetomidine; Dexmedetomidin; Dexmedetomidine
Intervention description: Dexmedetomidine loading dose 0.6 MCG/KG,Propofol infusion 100 MCG/KG/M; Dexmedetomidine loading dose 1.1 MCG/KG ,Propofol infusion 100 MCG/KG/M; Dexmedetomidine loading dose 0.6 MCG/KG,Propofol infusion 200 MCG/KG/M; Dexmedetomidine loading dose 1.1 MCG/KG.Propofol infusion 200 MCG/KG/M; Dexmedetomidine loading dose 0.9 mcg/kg,Propofol infusion 140 mcg/kg/min
Intervention MeSH terms: Dexmedetomidine; Propofol
Phase: Phase 1
Study type: Interventional
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: None (Open Label)
Enrollment: 44.0
Sex: All
Minimum age: 10 Years
Maximum age: 25 Years
Healthy volunteers: No
Keywords: dexmedetomidine; neuromonitoring; spine procedures; safe dose; 1- safe dose of dexmedetomidine when used in total intravenous anesthesia for procedures require neuromonitoring; 2- safe dose of propofol when uses in comination with dexmedetomidine in neuromontoring; 3effect of dexmedetomidine on somatosensory evoked potential and motor evoked potentials

Summary:

      Reduction of the spinal cord injuries during scoliosis surgery is a major goal of the
      anesthesia and surgical team. Despite improvement in scoliosis surgery over the years, the
      development of neurological deficits remains the most feared complication of spine surgery.
      During scoliosis surgery it is very important to monitor the spinal cord to detect spinal
      cord injury with surgical manipulation. Continuous or intermittent intraoperative
      electrophysiological monitoring (neuron-monitoring) is used routinely during these procedures
      to provide the surgeon with information concerning the integrity of neurological structures
      at risk. All neuron-monitoring modalities are affected by the anesthetic regimen used. Of the
      various intravenous anesthetic drugs, the combination of propofol, remifentanil and
      dexmedetomidine appear to impact neuron-monitoring the least. The current anesthetic practice
      is to use the three drugs in combination at doses that do not depress the signals but there
      is no data relating targeted dexmedetomidine and propofol blood levels to neuron-monitoring
      signals. The lack of data results in wide variability in dosing with consequent variability
      in patient response.

      Hypothesis: Clinically relevant blood levels of dexmedetomidine will affect the amplitude of
      transcranial motor-evoked potentials (TcMEP) either independently or by interaction with
      propofol in a dose dependent manner.
    

Eligibility criteria:

        Inclusion Criteria:

          -  Subjects must be 10 to 25 years of age

          -  Diagnosis of idiopathic scoliosis is established

          -  Subject's legal authorized representative has given written, informed consent to
             participate in the study and, where appropriate, the subject has given assent to
             participate

          -  American society of Anesthesiology physical status one/two

          -  Patients scheduled for posterior spinal fusion only

        Exclusion Criteria:

          -  • Patients with neuromuscular scoliosis and patients with motor or sensory deficit in
             the lower extremities

               -  Patients with allergy to, or contraindication for the drugs or techniques used in
                  the study

               -  Morbid obesity (Body mass index higher than 40)

               -  History of malignant hyperthermia

               -  Patient with severe cardiopulmonary disease (pulmonary hypertension,
                  cardiomyopathy, mechanical ventilation)