Dexmedetomidine on Intraoperative Somatosensory and Motor Evoked Potential Monitoring During Neurosurgery in Pediatric Patients
Condition: Tethered Spinal Cord; Brain Tumor; Cranio Cervical Compression
MeSH terms: Brain Neoplasms
Study type: Interventional

Summary: 
      The investigators want to know if using the study drug dexmedetomidine will improve nerve
      wave readings during neurosurgery. These readings are done many times during surgery while
      the patient is asleep. The readings look at how nerves are working and let the operating team
      know if nerves are hurt during surgery. If the readings tell that nerves are not working
      correctly, the surgeons can help while changing the way of operating.

      The study drug will be used in addition to the general anesthesia that a patient is given.
      The nerve readings that the investigators get while using the study drug will be compared
      with nerve readings that the investigators get while not using the study drug.

      The study hypothesis is that dexmedetomidine does not change nerve readings.
    

Detailed description: 
      Somatosensory evoked potential (SSEP) and motor evoked potential (MEP) have become an
      integral component in intraoperative care of patients and have resulted in a high degree of
      sensitivity in predicting neurologic outcomes. According to Padberg, Nuwer and Ecker ,SSEP
      and MEP monitoring allows surgical interventions to occur early and thus decreases the
      incidence of postoperative neurologic deficits.

      These measurements are done during surgery under general anesthesia and it is known that
      anesthetic agents have a dose-dependent adverse effect on the ability to record evoked
      potential responses. All anesthesia agents seem to interfere with the measurements especially
      in higher doses.

      In 1999, dexmedetomidine, a highly specific and selective alpha-2-adrenergic agonist with
      sedative, anxiolytic and analgesic effects, got FDA approved for adult patients for sedation.
      Since then, it has also been widely used off-label in various settings; it is described as a
      successful adjunct for surgical procedures in adolescents and adult populations where SSEP/
      MEP monitoring is beneficial. Several small and retrospective studies have shown that
      dexmedetomidine does not appear to interfere with neurophysiological monitoring when used in
      FDA approved doses.

      In pediatric patients, dexmedetomidine is also used off-label and has been shown to be
      beneficial. In fact, at Doernbecher Childen's Hospital, the use of dexmedetomidine has become
      a standard in pediatric procedures involving SSEP and MEP measurements. To the best of our
      knowledge, prospective studies in pediatric patients with SSEP monitoring while using
      dexmedetomidine have not been completed.

      If dexmedetomidine does not interfere the SSEP/MEP reading, it might be an advantageous
      adjunct to use in these settings. Propofol has a small risk of a serious side effect called
      propofol infusion syndrome. Propofol infusion syndrome is potentially life threatening, with
      the development of a profound lactate acidosis. It is seen when large doses of propofol
      (usually from a prolonged infusion) are given in the pediatric population.
    

Intervention name(s): Isoflurane, Propofol, Dexmedetomidine
Intervention type(s): Other
Intervention description(s): We will include following general anesthesia techniques:
Fentanyl 1 - 2 mcg/kg/hr, Propofol 150 - 250 mcg/kg/min, Isoflurane 0.6% expiratory With this general anesthesia technique we will do our first SSEP/MEP measurements after 30 minutes.
After 30 minutes we will stop isoflurane and will wash out the inhalational anesthetic with high flow air/oxygen and provide:
Fentanyl 1 - 2 mcg/kg/hr, Propofol 150 - 250mcg/kg/min. This technique will be held for 30 minutes. SSEP/ MEP measurements will be done after 30 minutes.
After the measurements dexmedetomidine will be added with a loading dose of 0.5 mcg/kg over 10 minutes and continuous infusion of 0.5 mcg/kg/hr for 30 minutes.
Fentanyl 1 -2 mcg/kg/hr, Propofol 100 - 250mcg/kg/min, Dexmedetomidine 0.5 mcg/kg/hr.
Intervention MeSH terms: Dexmedetomidine; Propofol; Isoflurane
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: SSEP measurements; MEP measurements; Pediatric Patients; Neurosurgery; General Anesthesia