Preoperative cognitive impairment predicts deep anaesthesia and higher postoperative pain in elderly patients: an observational study
Bibliographic record
Abstract
BACKGROUND: The prevalence of cognitive impairment and its associated risks under general anaesthesia increases with age. This necessitates careful observation and mitigation of anaesthetic risk in elderly patients. While deeper anaesthetic states are hypothesised to predispose patients to postoperative delirium, the causal mechanisms remain unclear, particularly concerning age-related sensitivity to anaesthetics and cognitive deficits. METHODS: This study aimed to investigate the relationship between preoperative cognitive impairment and variability in anaesthetic sensitivity. Additionally, it evaluates the potential of electroencephalogram parameters as markers for identifying cognitive impairment. 84 patients aged ≥ 65 years who underwent elective urological surgery lasting ≥ 60 min were included in this exploratory observational study. Preoperative cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). Cardiovascular and respiratory parameters, anaesthetic concentrations, electroencephalogram indices, and burst suppression ratios were recorded digitally. The primary outcome was the correlation between MoCA scores and deep anaesthesia levels. Secondary outcomes included quantitative electroencephalogram analysis, postoperative pain, and incidence of delirium. RESULTS: Of the 84 patients screened, 67 were included (median age: 70 [67 to 74] years; median total procedure time: 200 [166 to 247] minutes). The mean MoCA score was 24.3 (± 3.2) points. Cognitive impairment (MoCA score < 26) was identified in 64.2% of the patients. Lower MoCA scores correlated with prolonged periods of deep anaesthesia (ρ=-0.27; P = 0.027). Severe cognitive impairment was associated with longer durations of deep anaesthesia (20.1% vs. 1.1% of the monitoring window; P = 0.006). Burst suppression occurred in 31.3% of the patients but showed no association with MoCA scores. Cognitive impairment was linked to increased postoperative pain requiring treatment (P = 0.001), but not to delirium incidence. CONCLUSIONS: Severe preoperative cognitive impairment was associated with prolonged episodes of deep anaesthesia despite comparable anaesthetic dosages, suggesting heightened sensitivity in these patients. Further studies are needed to determine whether these findings can serve as markers for identifying cognitive impairment in preoperative assessments.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 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".