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Marcos Intaglietta - One of the best experts on this subject based on the ideXlab platform.

  • Acute Hemodilution/exchange transfusion.
    2013
    Co-Authors: Makena C. Hightower, Beatriz Salazar Y. Vázquez, Seetharama A. Acharya, Shankar Subramaniam, Marcos Intaglietta
    Abstract:

    Expression of (A) MCP-1, (B) MIP-1α, and (C) MIP-2 chemokines, 0.5 and 2 hrs post exchange transfusion of individual plasma expanders, 6% Hetastarch, Ringer’s Lactate, Dextran 70, or EAF PEG-Alb. EAF PEG-Alb was the only plasma expander to cause expression to exceed control levels at either the 0.5 or 2 hr assessment point following Hemodilution.

  • microcirculatory effects of intravenous fluids in critical illness plasma expansion beyond crystalloids and colloids
    Current Opinion in Anesthesiology, 2009
    Co-Authors: Nivaldo Ribeiro Villela, Beatriz Salazar Y. Vázquez, Marcos Intaglietta
    Abstract:

    Purpose of review: Plasma expanders are reviewed to determine their ability to restore microvascular function as a means for extending the transfusion trigger and delaying the use of blood transfusions. This outcome is currently achievable because of the emergence of a new understanding of optimal tissue function that prioritizes maintenance of functional capillary density, which results from the normalization of blood viscosity via the increase in plasma viscosity with new viscogenic colloids. Recent findings: Use of viscous plasma expanders in experimental models of extreme Hemodilution, hemorrhagic shock and endotoxemia shows that the limiting factor in anemia is not oxygen-carrying capacity but the decline of microvascular function due to the lowering of functional capillary density. In support of this hypothesis, we find that viscogenic colloids including high-molecular-weight starches, dextrans, polyvinylpyrrolidone, keratin and polyethylene glycol-conjugated albumin maintain or restore microvascular function in extreme Hemodilution, polyethylene glycol-conjugated albumin yielding the best results. Summary: Preclinical studies show that polyethylene glycol-conjugated albumin at concentrations in the range of 2-4% extends the transfusion trigger, providing the more extended and complete microvascular and systemic recovery from hemorrhagic shock, extreme Hemodilution and endotoxemia, postponing the need of reestablish intrinsic blood oxygen-carrying capacity to hemoglobin concentrations lower than those associated with accepted transfusion triggers.

  • microvascular benefits of increasing plasma viscosity and maintaining blood viscosity counterintuitive experimental findings
    Biorheology, 2009
    Co-Authors: B Salazar Y Vazquez, Pedro Cabrales, Judith Martini, Chavez A Negrete, A G Tsai, Marcos Intaglietta
    Abstract:

    The circulation is adapted to specific levels of blood viscosity resulting in a balance that simultaneously sets peripheral vascular resistance, blood pressure and cardiac output, factors in part mediated by the production of nitric oxide by the endothelium. Although it is generally perceived that decreasing blood viscosity is beneficial for cardiovascular function, small increases of blood viscosity in normal healthy experimental subjects significantly improve cardiovascular function. These changes are within the normal variations of viscosity due to the variations of hematocrit in the healthy population. Hemodilution reduces blood viscosity, which is proposed to be physiologically beneficial. However, in extreme Hemodilution, increased plasma viscosity via the use of viscogenic plasma expanders sustains microvascular and tissue function at significantly reduced levels of oxygen delivery. Studies in hemorrhagic shock resuscitation using oxygen carrying and non-carrying red blood cells show that restoration of blood viscosity is as important as restoration of oxygen carrying capacity. It is concluded that although Hemodilution is indicated for reducing abnormally high blood viscosities, it is beneficial to increase plasma viscosity when hematocrit is reduced. Furthermore small increases in hematocrit may be beneficial due to the related increase in blood viscosity, independently of the increase of oxygen delivery capacity.

  • plasma viscosity regulates capillary perfusion during extreme Hemodilution in hamster skinfold model
    American Journal of Physiology-heart and Circulatory Physiology, 1998
    Co-Authors: Amy G Tsai, Barbara Friesenecker, Hiromi Sakai, Michael A Mccarthy, Marcos Intaglietta
    Abstract:

    Effect of increasing blood viscosity during extreme Hemodilution on capillary perfusion and tissue oxygenation was investigated in the awake hamster skinfold model. Two isovolemic Hemodilution step...

Vance G Nielsen - One of the best experts on this subject based on the ideXlab platform.

  • effects of hextend Hemodilution on plasma coagulation kinetics in the rabbit role of factor xiii mediated fibrin polymer crosslinking
    Journal of Surgical Research, 2006
    Co-Authors: Vance G Nielsen
    Abstract:

    Background Hydroxyethyl starch administration has been associated with decreases in hemostasis and has recently been demonstrated to decrease fibrinogen (FI)-thrombin-(FIIa)-Factor XIII (FXIII) interactions in vitro in human plasma. Thus, the purpose of the present study was to determine the effect of in vivo Hemodilution with Hextend (6% hydroxyethyl starch, mean molecular weight 450 kDa) on plasma coagulation kinetics. Materials and methods Eight male, New Zealand White rabbits were intravenously administered with 20 ml/kg of Hextend. Citrated plasma was obtained before, 1 min after, and 1 h after Hemodilution. Thrombelastographic analyses were performed, with clot initiation (R, sec), clot propagation (α, degrees), and clot strength (shear elastic modulus, G, dynes/cm 2 ) determined over 20 min. Samples were celite-activated and had either with addition or without additions of FI, FIIa or activated FXIII (FXIIIa) to restore protein content to prediluted values. Results There was no significant difference in R values observed before (229 ± 30), 1 min after (241 ± 54), and 1 h after (214 ± 42) Hemodilution. Prediluted α values (75.2 ± 1.9) were significantly decreased 1 min (53.3 ± 5.9) and 1 h after Hemodilution (56.1 ± 10.2). Prediluted G values (1992 ± 434) were significantly reduced 1 min (532 ± 195) and 1 h after (630 ± 297) Hemodilution. FI, FIIa, and FXIIIa addition significantly decreased R values after Hemodilution. α and G values were significantly improved by FI and FXIIIa after Hemodilution. FIIa addition did not significantly affect α or G. Conclusions Hextend Hemodilution in rabbits maintains clot initiation by diminishing both FIIa-FI and FXIIIa-fibrin interactions, whereas clot propagation and strength were reduced by diminished FXIIIa-fibrin interactions.

  • effects of pentalyte and voluven Hemodilution on plasma coagulation kinetics in the rabbit role of thrombin fibrinogen and factor xiii fibrin polymer interactions
    Acta Anaesthesiologica Scandinavica, 2005
    Co-Authors: Vance G Nielsen
    Abstract:

    BACKGROUND Hydroxyethyl starch (HES) administration has resulted in decreased hemostasis and fibrinogen (FI)-thrombin-(FIIa)-Factor XIII (FXIII) interactions. I proposed to determine the hemostatic effect of Hemodilution with PentaLyte (6% HES, mean molecular weight 220 kDa) and Voluven (6% HES, 130 kDa). METHODS Rabbits were intravenously administered 20 ml/kg PentaLyte or Voluven (n = 8 per fluid) over 10 min. Plasma was obtained prior to, 1 min and 1 h after Hemodilution. Thrombelastography was performed, with clot initiation (R, sec), clot propagation (alpha, degrees), and clot strength (shear elastic modulus, G, dynes/cm2) determined over 20 min. Celite-activated samples had either no additions or addition of FI, FIIa or activated FXIII (FXIIIa) to restore protein content to pre-diluted values. RESULTS AND CONCLUSIONS While there were no significant differences between the groups, R significantly decreased 1 h after Hemodilution compared with values observed before and 1 min after Hemodilution, whereas alpha and G significantly decreased 1 min after Hemodilution and then significantly, but only partially, increased 1 h after Hemodilution compared with pre-dilution values. Addition of FI, FIIa and FXIIIa significantly decreased R in both groups. alpha and G 1 min after Hemodilution were significantly enhanced by FI, FIIa, FXIIIa in both groups; however, 1 h after Hemodilution, rabbits administered PentaLyte had alpha and G enhanced only by FI and FXIIIa addition, whereas animals administered Voluven had alpha and G significantly enhanced by FI addition. PentaLyte and Voluven Hemodilution initially diminishes FIIa-FI and FXIIIa-fibrin, but within an hour primarily inhibit FXIIIa-fibrin interactions in the rabbit.

Neil D Dattani - One of the best experts on this subject based on the ideXlab platform.

  • metoprolol reduces cerebral tissue oxygen tension after acute Hemodilution in rats
    Anesthesiology, 2009
    Co-Authors: Tenille E Ragoonanan, Scott W Beattie, David C Mazer, Howard Leongpoi, David F Wilson, Albert K Y Tsui, Elaine Liu, Gordon Tait, Melissa Noronha, Neil D Dattani
    Abstract:

    Background: Perioperative β-blockade and anemia are independent predictors of increased stroke and mortality by undefined mechanisms. This study investigated the effect of β-blockade on cerebral tissue oxygen delivery in an experimental model of blood loss and fluid resuscitation (Hemodilution). Methods: Anesthetized rats were treated with metoprolol (3 mg · kg -1 ) or saline before undergoing Hemodilution with pentastarch (1:1 blood volume exchange, 30 ml · kg -1 ). Outcomes included cardiac output, cerebral blood flow, and brain (P Br O 2 ) and kidney (P K O 2 ) tissue oxygen tension. Hypoxia inducible factor-1α (HIF-1α) protein levels were assessed by Western blot. Systemic catecholamines, erythropoietin, and angiotensin II levels were measured. Results: Hemodilution increased heart rate, stroke volume, cardiac output (60%), and cerebral blood flow (50%), thereby maintaining P Br O 2 despite an approximately 50% reduction in blood oxygen content (P < 0.05 for all). By contrast, P K O 2 decreased (50%) under the same conditions (P < 0.05). β-blockade reduced baseline heart rate (20%) and abolished the compensatory increase in cardiac output after Hemodilution (P < 0.05). This attenuated the cerebral blood flow response and reduced P Br O 2 (50%), without further decreasing P K O 2 . Cerebral HIF-1α protein levels were increased in β-blocked hemodiluted rats relative to hemodiluted controls (P < 0.05). Systemic catecholamine and erythropoietin levels increased comparably after Hemodilution in both groups, whereas angiotensin II levels increased only after β-blockade and Hemodilution. Conclusions: Cerebral tissue oxygen tension is preferentially maintained during Hemodilution, relative to the kidney, despite elevated systemic catecholamines. Acute β-blockade impaired the compensatory cardiac output response to Hemodilution, resulting in a reduction in cerebral tissue oxygen tension and increased expression of HIW-1α.

Christian Ohrloff - One of the best experts on this subject based on the ideXlab platform.

  • retinal vein occlusion and low dose fibrinolytic therapy r o l f a prospective randomized controlled multicenter study of low dose recombinant tissue plasminogen activator versus Hemodilution in retinal vein occlusion
    Retina-the Journal of Retinal and Vitreous Diseases, 2009
    Co-Authors: Larsolof Hattenbach, Carl Friedrich Arndt, R C Lerche, Inge Scharrer, Holger Baatz, Fabrice Margaron, Gisbert Richard, Wolfgang Behrensbaumann, Christian Ohrloff
    Abstract:

    PURPOSE: To investigate the efficacy of intravenous thrombolysis with low-dose recombinant tissue plasminogen activator (rt-PA) in recent-onset central retinal vein occlusion (CRVO) or branch retinal vein occlusion. METHODS: This was a prospective, randomized, controlled multicenter trial in patients with CRVO or branch retinal vein occlusion, best-corrected visual acuity < or =20/50, and onset of symptoms within 11 days before treatment. In each group, patients were randomized to either Hemodilution or thrombolysis with 50 mg of rt-PA with concomitant intravenous heparinization. The primary clinical outcome measure was improvement in best-corrected visual acuity from baseline at 1 year. RESULTS: Fifty-two subjects were enrolled in the study. Patients with CRVO (n = 41) who were treated with rt-PA exhibited a significant improvement in best-corrected visual acuity compared with those who received Hemodilution (P < 0.0001). At 1-year follow-up, the proportion of eyes with CRVO achieving an improvement in visual acuity of three or more lines was 45% after treatment with rt-PA and 21% after Hemodilution therapy. The median final best-corrected visual acuity among CRVO patients given rt-PA was 20/60 (light perception, 20/15) compared with 20/400 (light perception, 20/20) in the Hemodilution group. There were no significant differences among patients with branch retinal vein occlusion (n = 11). We observed no serious adverse events. No significant differences were found regarding the development of ocular neovascularization. CONCLUSION: Treatment with intravenous low-dose rt-PA improved visual outcome in CRVO. Thrombolysis was not associated with a lower risk of ocular neovascularization, indicating that the mechanisms involved in this process occur at an early stage.

Donat R. Spahn - One of the best experts on this subject based on the ideXlab platform.

  • effect of progressive haemodilution with hydroxyethyl starch gelatin and albumin on blood coagulation
    BJA: British Journal of Anaesthesia, 1997
    Co-Authors: G A Egli, Andreas Zollinger, Burkhardt Seifert, Dragoljub Popovic, T. Pasch, Donat R. Spahn
    Abstract:

    We have compared the effects of progressive (30% and 60%) in vitro haemodilution with hydroxyethyl starch (HES), gelatin (GEL) and albumin (ALB) with haemodilution using 0.9% saline in 96 patients by thrombelastography. Haemodilution with HES, GEL and ALB significantly (P

  • cardiovascular and coronary physiology of acute isovolemic Hemodilution a review of nonoxygen carrying and oxygen carrying solutions
    Anesthesia & Analgesia, 1994
    Co-Authors: Donat R. Spahn, Bruce J Leone, J G Reves, Thomas Pasch
    Abstract:

    Acute isovolemic Hemodilution is used increasingly to avoid the potentially serious side effects of homologous blood transfusions. Cardiovascular physiology during Hemodilution is characterized by a marked increase in cardiac output and organ blood flow to compensate for the decrease in arterial oxygen-carrying capacity. During advanced Hemodilution an increased oxygen extraction is also observed, such that oxygen consumption generally is maintained even during advanced Hemodilution. The increase in cardiac output is related mainly to a decrease in blood viscosity and an enhanced sympathetic tone resulting in stimulation of the heart. The magnitude and the mechanisms involved in the increase depend upon species, state of awareness (awake versus anesthetized), type of anesthesia, type of exchange solution, and condition of the heart prior to Hemodilution. Recent laboratory findings, as well as clinical practice in cardiac surgery, suggest that moderate Hemodilution to hematocrit values of approximately 25% is well tolerated in single vessel coronary artery disease which should thus not be regarded as an absolute contraindication for moderate Hemodilution. An integral concept to minimize homologous blood transfusions consists of preoperative autologous blood donation, preoperative isovolemic Hemodilution, meticulous (asanguineous) surgical technique, and acceptance of minimum hemoglobin levels during the entire hospitalization. The incidence of homologous blood transfusions will be reduced using acute isovolemic Hemodilution. This incidence will be further reduced once hemoglobin solutions become clinically available for specific indications. At present, research activities are concentrated on defining the critical level of Hemodilution in various pathologic conditions and to investigate pharmacology and physiology of the new hemoglobin solutions. Finally, several chemically modified hemoglobin-based oxygen-carrying solutions devoid of renal toxicity will be available in the future. The cardiovascular physiology and pharmacology of these hemoglobin solutions have been studied. Cardiac output is generally constant and oxygen extraction is increased to maintain oxygen consumption during Hemodilution with hemoglobin solutions. In most studies, some vasoconstriction was observed also, which might result from interaction of the hemoglobin molecule with the EDRF/NO system. However, with enhanced purification, chemical modification or microencapsulation of the hemoglobin molecule, vasoconstriction can be limited.