Mechanism of Increased Spinal Cord Blood Flow due to Noradrenaline Administration Using Vascular Resistance: An Experimental Study Using a Canine Model
Bibliographic record
Abstract
Background: During thoracoabdominal aortic surgery, the spinal cord is placed under ischemic conditions. Elevation of systemic blood pressure is thus recommended as a method of increasing the blood supply from collateral networks. This study examined the mechanisms by which noradrenaline administration increases spinal cord blood flow (SCBF) by elevating systemic blood pressure. Methods: In beagles ( n = 7), the thoracoabdominal aorta and L2-L7 spinal cord segmental arteries (SAs) were exposed and a distal perfusion bypass was created to simulate clinical practice. SCBF was measured by laser flowmetry at the L5 dura mater and spinal cord perfusion pressure (SCPP) was measured inside the clamped aorta. The six pairs of SAs from L2 to L7 were clamped, and mean systemic blood pressure (mSBP), SCBF, and SCPP were measured before and after clamping and after starting continuous infusion of noradrenaline at 0.5 µg/kg/min. Rates of change in systemic vascular resistance (SVR) and spinal cord vascular resistance (SCVR) were calculated from the measured values. Results: With no SA clamping (control), the rate of increase in SCVR was 0.74 times the rate of increase in SVR (y = 0.2 + 0.74x, r = 0.889, r 2 = 0.789; P < 0.01). When all six pairs of SAs were clamped, a weak correlation was evident between rate of change in SCVR and rate of change in SVR, and the rate of increase in SCVR was lower than the rate of increase in SVR (y = 0.39 + 0.07x, r = 0.209, r 2 = 0.039; P < 0.01). When all six pairs of SAs were clamped in the absence of distal perfusion, a weak correlation was also evident between rate of change in SCVR and rate of change in SVR, and the rate of increase in SCVR was lower than the rate of increase in SVR (y = 0.19 + 0.08x, r = 0.379, r 2 = 0.144; P < 0.01). Conclusions: The rate of increase in SCVR induced by noradrenaline administration was lower than the rate of increase in SVR in the control group with no spinal cord SA clamping and in both experimental groups with clamped SAs (with and without distal perfusion), creating an environment conducive to spinal cord flow distribution. Cardiol Res. 2023;14(2):115-122 doi: https://doi.org/10.14740/cr1478
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| 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".