Positive end-expiratory pressure following coronary artery bypass grafting.
Bibliographic record
Abstract
BACKGROUND: Cardiac surgery-related pulmonary complications include alterations in lung mechanics and anomalies in gas exchange. Higher levels of positive end-expiratory pressure (PEEP) have been suggested to benefit cardiac surgical patients. We compared respiratory compliance, arterial oxygenation and time till tracheal extubation in 2 cohorts of patients weaned from mechanical ventilation with different levels of PEEP after elective and uncomplicated coronary artery bypass grafting (CABG). We hypothesized that higher PEEP levels improve pulmonary compliance and gas exchange in the first hours of weaning from mechanical ventilation, but not to shorten time till tracheal extubation. METHODS: Secondary retrospective analysis of 2 randomized controlled trials: in the first trial patients were weaned with PEEP levels of 10 cmH2O for the first 4 hours followed by PEEP levels of 5 cmH2O until tracheal extubation (high PEEP, HP); and the second trial patients were weaned with PEEP levels of 5 cmH2O during the entire weaning phase (low PEEP, LP). The primary endpoint was pulmonary compliance. Secondary endpoints included arterial oxygenation, duration of mechanical ventilation and postoperative pulmonary complications. RESULTS: The analysis included 121 patients; 60 HP patients and 61 LP patients. Baseline characteristics were similar. Compared to LP patients, HP patients had a better pulmonary compliance, 47.2±14.1 versus 42.7±10.2 ml/cmH2O (P<0.05), and higher levels of PaO2, 18.5±6.6 (138.75±49.5) versus 16.7±5.4 (125.25±40.5) kPa (mmHg) (P<0.05). Patients in the HP group were less frequent in need of supplementary oxygen after ICU discharge. These differences remained present during the entire weaning phase, even after reduction of PEEP. However, HP patients had a longer time till tracheal extubation, 16.9±6.1 versus 10.5±5.0 hours (P<0.001). HP patients had longer durations of postoperative infusion of propofol, 4.9 (2.6-7.4) versus 3.5 (1.8-5.8) hours (P<0.05). There were no differences in use of inotropes. Cumulative fluid balances were slightly higher in HP patients. CONCLUSION: Use of higher PEEP levels after elective uncomplicated CABG improves pulmonary compliance and oxygenation but seems to be associated with a delay in tracheal extubation.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".