Anaesthesia for MEP use intraoperatively R3 鄭淳心

Case: A 27y/o male was a case of C7-T1 intramedullary spinal tumor, and he was scheduled for spinal tumor excision via posterior approach. Transcranial stimulation motor evoked potentials was used intraoperatively. Past history: nothing particular

Intubation Prone position Monitor Free from pressure: eyes, nose, ear, genitalia Endo fixation Spinal surgery:

EP (Evoked potentials) SSEP(somatosensory evoked potentials ) Wake-up test Motor evoked potentials (false positive results)

Evoked potentials Anesthetics Temperature Hypotension Hypoxia Anemia Pre-existing neurological lesions

Temperature EMG response decrease 8.0%/C muscle 4.1%/C skin no correlation keep the same temperature

Anesthetic agents Inhalation agents IV-agents Propofol Etomidate Methohexital Thiopental Ketamine-based anesthesia With or without propofol

Propofol inhibits motor-evoked potentials induced by transcranial electrical stimulation in a dose- dependent manner If a train of pulses is used for transcranial stimulation, propofol can be effectively used as a supplement to ketamine- based anesthesia during intraoperative monitoring of myogenic motor-evoked potentials Addiction of propofol significantly reduced the ketamine-induced psychedelic effect including unpleasant dreaming and hallucination.

Formula 1 Ketamine 1-2 mg/kg/hr Fentanyl 50% nitrous oxide in oxygen Vecuronium 0.04 mg/kg/hr Propofol 1-3 mg/kg/hr Nicardipine if SBP>150mmHg

Formula 2 ( ’ 96 BJA) Methohexitone 2mg/kg for hypnosis 0.1mg/kg/min for 30 min mg/kg/hr Alfentanil 50 ug/kg 300ug/kg/hr for 15min 60ug/kg/hr Ketamine 1.2 mg/kg/hr for 1hour 0.84 mg/kg/hr muscle relaxant bolus

our formula Ketamine 2mg/kg/hr Alfentanil 20ug/kg/hr Esmeron 6mg/hr Propofol 75mg/hr (1.5mg/kg/hr)

Maintain anesthesia depth (microsurgery) BP control: nicardipine

Thank you for your attention !!