Effects of Crystalloid versus Colloid and the α-2 Agonist Brimonidine versus Placebo on Intraocular Pressure during Prone Spine Surgery
Bibliographic record
Abstract
BACKGROUND: Volume replacement with colloid solution and topical α-2 agonists may each moderate the progressive increase in intraocular pressure (IOP) during prone surgery. The authors tested the hypotheses that during prolonged prone surgery, IOP increases less with goal-directed intravenous administration of 5% albumin than with goal-directed administration of lactated Ringer's solution, and with topical α-2 agonist brimonidine than with placebo eye drops. METHODS: Patients having complex prone spine surgery were factorially randomized to albumin and topical placebo (n = 15); albumin and topical brimonidine (n = 16); lactated Ringer's solution and topical placebo (n = 13); and lactated Ringer's solution and topical brimonidine (n = 16). IOP was measured with a pneumotonometer. The primary outcome was time-weighted average intraoperative IOP. RESULTS: Prone positioning increased IOP a mean ± SD of 12 ± 6 mmHg. IOP increased to 38 ± 10 mmHg at the end of anesthesia (approximately 5.5 h). Time- weighted average intraoperative IOP in the brimonidine group was 4 (95% CI: 1, 8) mmHg lower than in the placebo group (P = 0.023), but no different in the crystalloid and albumin groups (mean difference (95% CI) of -2 (-5, 2) mmHg (P = 0.34). There was no interaction between the two randomized factors. CONCLUSIONS: Brimonidine slightly reduced the primary outcome of intraoperative time-weighted average IOP, whereas there was no significant difference between goal-directed albumin or crystalloid administration. Brimonidine thus helps reduce IOP during spine surgery, but maintaining adequate blood pressure might play a more important role.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".