Effects of PEEP Ventilation on Liver Metabolism
Bibliographic record
Abstract
OBJECTIVE: To study the influence of positive endexpiratory pressure (PEEP) ventilation on metabolic parameters with specific regard to liver metabolism. DESIGN: Prospective experimental study on the effects of PEEP ventilation on hemodynamic and gas exchange as well as metabolic parameters, i.e. hepatic glucose production, arterial, hepatic and portal venous insulin, glucagon, free fatty acid (FFA), glycerol, beta-hydroxybutyrate and lactate concentrations. SETTING: Experimental Laboratory Unit of the University Hospital. ANIMALS: 10 Labrador Beagle dogs (18-22 kg) were studied. INTERVENTIONS: Animals were ventilated with PEEP of 0, 7.5, 15, and 0 mm Hg, each level lasting 2 h. RESULTS: PEEP 15 significantly increased heart rate from 110(70) to 220(55) beats/min and decreased cardiac output from 2.5 (2.0) to 1.5 (0.8) l/min. This was associated with significant increases in mean pulmonary artery pressure, pulmonary artery occlusion pressure, portal and hepatic venous pressure, whereas mean systemic pressure did not change. While whole-body oxygen consumption and respiratory quotient remained constant, whole-body oxygen delivery significantly decreased from 456(266) to 294(168) ml/min during PEEP 15 concomitant to augmented whole-body oxygen extraction (from 27(34) to 51(33)%). Oxygen extraction from the splanchnic organs increased from 41(31) to 81(30)%. Hepatic venous oxygen tension (PhvO2) and hemoglobin oxygen saturation (ShvO2) during PEEP 15 decreased from 41(18) to 28(47) mm Hg and from 60(31) to 18(66)%, respectively. Hepatic glucose production was significantly stimulated from 3.44(1.44) to 3.92(1.83) mg/kg/min at PEEP 15. Arterial and portalvenous glucagon/insulin ratios did not change. FFA and glycerol concentrations depending on PEEP levels were significantly higher in the hepatic artery and portal vein than in the hepatic vein. Compared to portal venous and arterial hepatic concentrations, hepatic venous beta-hydroxybutyrate significantly increased with rising PEEP levels. CONCLUSIONS: Low values of PhvO2 and ShvO2 during PEEP 15 gave evidence for hypoxia of the liver. This was associated with a stimulated hepatic glucose production rate accompanied by enhanced hepatic uptake and utilization of FFA serving as fuel substrates. As the rate of gluconeogenesis is a major determinant of hepatic oxygen consumption these metabolic effects of PEEP ventilation have to be considered during states of critical illness.
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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 | 0.001 |
| 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) | 0.001 | 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".