Central, Peripheral, and Other Blood Volume Changes During Hemodialysis
Bibliographic record
Abstract
Volume overload is a factor in development of hypertension in hemodialysis patients. Fluid removal by hemodialysis (HD), however, may cause intradialytic hypotension and associated symptoms. A better understanding of the relationships between blood pressure volume status and the pathophysiology of fluid removal during HD are, therefore, necessary to control blood pressure and to eliminate intradialytic hypotension. The objectives of the study were to determine the amount and direction of change of body fluid compartments after ultrafiltration (UF) and to determine whether any correlations exist between mean arterial pressure (MAP), change in circulating blood volume (deltaBV), total body water (TBW), central blood volume (which constitutes the volume of blood in the lungs, heart, and great vessels [CBV]), and intracellular and extracellular fluid volumes (ICF, ECF). The study population included 20 patients on regular HD. Each individual had their CBV, cardiac output, and peripheral vascular resistance (PVR) measured by means of saline dilution technique and deltaBV monitored by an online hematocrit sensor (Crit Line). MAP was calculated from measured blood pressure and ICF and ECF were measured using bioelectric impedance analysis techniques. Measurements were obtained before and after maximum UF measured by deltaBV (reduction of 6-10% by Crit Line). Ten healthy controls also had ECF and ICF values measured by bioelectric impedance analysis. Before HD, MAP correlated with TBW (r = 0.473, p = 0.035) and CBV (r = 0.419, p = 0.066), suggesting that hypertension here may be due to volume overload. Patients were ECF expanded before HD with an ECF:ICF ratio of 0.96, which was significantly higher than the control ratio of 0.74 (p < 0.0001). During UF, fluid was removed from both ECF and ICF, but more from the ECF volume ratio 0.92 post UF, a significant reduction (p < 0.0001). After UF, MAP no longer correlated with TBW or CBV but correlated with peripheral vascular resistance (r = 0.4575, p = 0.043). After UF, deltaBV correlated inversely with PVR (r = -0.50, p = 0.024). Despite the fall in deltaBV (7.11+/-2.49%) with UF, CBV was maintained. CBV were 0.899 L and 0.967 L pre and post UF, respectively. These data suggest that in hemodialysis patients, predialysis volume status influences predialysis blood pressure. UF causes BV to fall, but CBV is preferentially conserved by increasing PVR, which also maintains blood pressure. Failure of a PVR response likely leads to intradialytic hypotension.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 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".