Effect of Low-Dose Ketamine on Voltage Requirement for Transcranial Electrical Motor Evoked Potentials in Children
Bibliographic record
Abstract
STUDY DESIGN: Randomized controlled trial. OBJECTIVE.: To determine the effect of low-dose ketamine on the voltage needed to elicit maximal amplitude of the motor-evoked response to transcranial electrical stimulation during propofol/remifentanil anesthesia in children undergoing scoliosis surgery. SUMMARY OF BACKGROUND DATA: Motor-evoked potentials (MEPs) are increasingly used to assess the integrity of motor pathways during surgery. Whereas most general anesthetics depress MEP amplitude, the effect of ketamine has been variable, ranging from little or no reduction to an increase in amplitude, suggesting that ketamine may be useful as an agent to facilitate MEP monitoring. We tested the hypothesis that low-dose ketamine would reduce the voltage required to elicit maximal amplitude of the motor-evoked response to transcranial electrical stimulation during propofol/remifentanil anesthesia. METHODS: Thirty-four patients 12 to 16 years of age undergoing posterior instrumentation for correction of idiopathic scoliosis were randomly assigned to receive low-dose ketamine (0.5 mg/kg bolus, followed by 4 microg/kg/min infusion) or an equal volume of saline. Anesthesia was maintained using a mixture of 30% oxygen in air, continuous infusion of propofol at a rate of 100 to 150 microg/kg per min, and continuous infusion of remifentanil. Myogenic motor-evoked responses to transcranial electrical stimulation of the motor cortex were recorded. The minimum voltage required to elicit maximal amplitude of the MEP response was determined. Voltage requirements were compared using the Mann-Whitney U rank sum test. P < 0.05 was considered statistically significant. RESULTS: No significant difference was found in the minimal voltage needed to elicit maximum amplitude of the MEP response. Median (range) voltage requirements in the ketamine and control groups were 227 V (range, 160-350 V) and 215 V (range, 150-300 V), respectively. CONCLUSION: Addition of low-dose ketamine to propofol/remifentanil anesthesia does not significantly reduce the voltage needed to elicit maximum amplitude of the motor-evoked response to transcranial electrical stimulation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.004 | 0.002 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".