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Do evoked potentials measure depth of anaesthesia?
P S Sebel1, P Glass, W K Neville
1Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710.
International Journal of Clinical Monitoring and Computing
|January 1, 1988
Summary
Somatosensory evoked potentials (SEPs) reliably indicate anesthetic depth by showing decreased amplitude and increased latency during anesthesia. These neurophysiological monitoring changes reversed upon recovery, suggesting SEPs are a promising tool.
Area of Science:
- Neuroscience
- Anesthesiology
- Clinical Neurophysiology
Background:
- Anesthetic depth monitoring is crucial for patient safety.
- Neurophysiological methods offer objective measures of brain function during anesthesia.
- Somatosensory evoked potentials (SEPs) have been proposed as a potential indicator of anesthetic depth.
Purpose of the Study:
- To evaluate the utility of somatosensory evoked potentials (SEPs) for monitoring anesthetic depth.
- To assess changes in SEP amplitude and latency during balanced anesthesia.
- To investigate the correlation between SEP measures and vital signs.
Main Methods:
- Eight patients undergoing balanced anesthesia were monitored.
- Somatosensory evoked potentials (SEPs) were recorded every 10 minutes.
- Anesthesia was induced with thiopentone and maintained with N2O/O2, supplemented by halothane or fentanyl.
Main Results:
- Anesthesia induction led to a significant reduction in SEP amplitude (4.2 to 1.6 microvolts) and an increase in latency (19.2 to 20.0 msec).
- Changes in SEP measures were consistent with both narcotic and volatile anesthetics.
- No correlation was found between SEP changes and heart rate or blood pressure.
- SEP amplitude and latency returned to baseline values upon recovery from anesthesia.
Conclusions:
- Somatosensory evoked potentials (SEPs) demonstrate consistent and reversible changes reflecting anesthetic depth.
- The observed changes in SEP amplitude and latency suggest this technique is a promising, objective method for monitoring anesthesia.
- Further research is warranted to fully establish SEPs as a standard neurophysiological monitoring tool in anesthesia.