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[Effect of bolus propofol administration on muscle evoked potential (MsEP) during spine surgery]
S Kajiyama1, M Sanuki, H Kinoshita
1Department of Anesthesia and Intensive Care, Hiroshima City Asa Hospital, Hiroshima 731-0293.
Abstract:
Intraoperative monitoring of descending pathways by means of muscle evoked potential (MsEP) is a reliable method to monitor spinal cord motor function, but MsEP is readily affected by anesthetics. We monitored MsEP evoked by repetitive transcranial electrical stimulation of the motor cortex in 30 patients receiving spine surgery. Total intravenous anesthesia was maintained with propofol and fentanyl without any muscle relaxant. Onset latencies and peak to peak amplitudes of MsEP were evaluated before and after the bolus propofol administration. The concentrations of propofol in blood and the effect-site during MsEP monitoring were predicted by computer simulation software. The amplitude of MsEP decreased slightly by bolus propofol administration, but the latencies showed no significant change with propofol under the same condition. We consider that total intravenous anesthesia with propofol and fentanyl without muscle relaxants is compatible with the recording of MsEP evoked by high frequency repetitive electrical transcranial stimulations. When MsEP is monitored during spine surgery, anesthetic condition should be controlled carefully in order to maintain a stable blood concentration of propofol and thus to assure the reliability of MsEP measurements.
Insights
Muscle evoked potentials (MsEP) reliably monitor spinal cord motor function during surgery. Propofol anesthesia minimally impacts MsEP amplitude, ensuring monitoring reliability when anesthetic levels are stable.
Area of Science:
- Neuroscience
- Anesthesiology
- Spinal Surgery
Background:
- Intraoperative monitoring of descending motor pathways is crucial for spinal surgery.
- Muscle evoked potentials (MsEP) are a reliable method for assessing motor pathway integrity.
- Anesthetic agents can significantly affect MsEP, complicating intraoperative monitoring.
Observation:
- This study investigated the effect of propofol-fentanyl total intravenous anesthesia on MsEP during spine surgery.
- MsEP were recorded using repetitive transcranial electrical stimulation of the motor cortex in 30 patients.
- Propofol blood and effect-site concentrations were simulated using computer software.
Findings:
- A slight decrease in MsEP amplitude was observed following bolus propofol administration.
- MsEP onset latencies remained largely unchanged despite propofol administration.
- Total intravenous anesthesia with propofol and fentanyl, without muscle relaxants, is compatible with MsEP monitoring.
Implications:
- Careful control of anesthetic conditions is essential for maintaining stable propofol blood concentrations.
- Stable propofol levels ensure the reliability of MsEP measurements during spine surgery.
- This supports the use of MsEP for intraoperative spinal cord motor function assessment under specific anesthetic protocols.