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 potentia

ls ) 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

PropofolEtomidateMethohexitalThiopental

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 hypnosis0.1mg/kg/min for 30 min3-4.5 mg/kg/hr Alfentanil 50 ug/kg300ug/kg/hr for 15min60ug/kg/hr Ketamine1.2 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!!