Nitrous Oxide-Induced Increased Homocysteine Concentrations Are Associated with Increased Postoperative Myocardial Ischemia in Patients Undergoing Carotid Endarterectomy
Bibliographic record
Abstract
UNLABELLED: Nitrous oxide anesthesia causes increased postoperative plasma homocysteine levels. Acute increases in plasma homocysteine are associated with impaired endothelial function and procoagulant effects. This nitrous oxide-induced plasma homocysteine increase may therefore affect the risk of perioperative cardiovascular events. This prospective, randomized study was therefore designed to evaluate the effect of nitrous oxide anesthesia and postoperative plasma homocysteine levels on myocardial ischemia in patients undergoing carotid endarterectomy. After institutional review board approval and written informed consent, 90 ASA Class I-III patients presenting for elective carotid endarterectomy were randomized to receive general anesthesia with or without nitrous oxide. Prior to induction, on arrival in the postanesthesia care unit, and after 48 h, blood samples were obtained for homocysteine analysis. Three hours prior to induction and for 48 h postoperatively patients were monitored by a three-channel, seven-lead Holter monitor. Postoperatively in the postanesthesia care unit and at 48 h the nitrous oxide group had increased mean plasma homocysteine concentrations of 15.5 +/- 5.9 and 18.8 +/- 14.7 when compared with the nonnitrous group of 11.4 +/- 5.2 and 11.3 +/- 4.0 micromol/L, P: < 0.001. The nitrous oxide group had an increased incidence of ischemia (46% vs. 25%, P: < 0.05), significantly more ischemia (63 +/- 71 vs. 40 +/- 68 min, P: < 0.05), had more ischemic events (82 vs. 53, P: < 0.02), and had more ischemic events lasting 30 min (23 vs. 14, P: < 0.05) than the nonnitrous group. This study reconfirmed that intraoperative nitrous oxide is associated with postoperative increases in plasma homocysteine concentration. This was associated with an increase in postoperative myocardial ischemia. IMPLICATIONS: Use of nitrous oxide during carotid artery surgery induces increases in postoperative plasma homocysteine concentration and is associated with increases in postoperative myocardial ischemia.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".