The Effect of Sevoflurane on Cerebral Autoregulation in Young Children as Assessed by the Transient Hyperemic Response
Bibliographic record
Abstract
In Brief The transient hyperemic response (THR) test is a simple, noninvasive technique to evaluate cerebral autoregulation using transcranial Doppler. It has not yet been used in studies involving children. In this study we evaluated this response in children undergoing general anesthesia using sevoflurane. Twenty ASA physical status I children undergoing elective urological surgery sequentially received sevoflurane at 0.5, 1.0, and 1.5 MAC in a randomized order. Analgesia was solely provided by caudal anesthesia. The right middle cerebral artery flow velocities before (F1), during (F2), and after (F3) a 10-s ipsilateral carotid artery compression were recorded. The THR ratios (THRR) (± sd) for 0.5 MAC, 1.0 MAC, and 1.5 MAC were 1.24 ± 0.11, 1.16 ± 0.09, and 1.13 ± 0.07, respectively. The THRR was significantly different between 0.5 MAC versus 1.0 and 1.5 MAC, respectively (P < 0.05). However, no difference was detected between 1.0 and 1.5 MAC. A THRR of more than 1.09 has previously been accepted as the lower limit of a positive response. The results in this study suggest that THR is affected by sevoflurane in a dose-dependent fashion but is maintained at up to 1.5 MAC. This suggests cerebral autoregulation is preserved in children anesthetized with up to 1.5 MAC sevoflurane. IMPLICATIONS: The transient hyperemic response test can be used in young children. The transient hyperemic response is preserved in children undergoing sevoflurane anesthesia at clinically relevant concentrations, suggesting preservation of cerebral autoregulation under these conditions.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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".