Jörg Hutter

The Effect of Acute Normovolemic Hemodilution (ANH) on Myocardial Contractility in Anesthetized Dogs

The influence of severe acute normovolemic hemodilution (ANH) on myocardial contractility (MC) was investigated in 14 splenectomized, anesthetized dogs.MC was assessed by the maximum rate of left ventricular pressure increase (LVdp/dtmax), end-systolic elastance (Ees), and preload recruitable stroke work (PRSW) (conductance catheter, left ventricular pressure-volume relationship). Measurements of myocardial perfusion and oxygenation (radioactive microsphere technique) assured comparability of the model to previously performed studies. Global and regional myocardial blood flow increased significantly upon hemodilution with preference to midmyocardium and subendocardium. This resulted in preservation of both myocardial oxygen delivery and consumption after ANH. Myocardial oxygen extraction as well as coronary venous PO2 were unaffected by ANH, while coronary venous lactate concentration decreased, indicating that myocardial oxygen need was met. LVdp/dtmax decreased significantly after hemodilution (2278 +/- 577 vs 1884 +/- 381 mm Hg/s, P < 0.01), whereas Ees and PRSW increased significantly (1.76 +/- 0.54 vs 2.15 +/- 0.75 mm Hg/mL, P < 0.05, for Ees and 33 +/- 14 vs 45 +/- 14 mm Hg centered dot mL, P < 0.05, for PRSW). While the decrease of LVdp/dtmax most likely reflects ANH-induced changes of ventricular pre- and afterload, the increase of Ees and PRSW indicates a true increase of myocardial contractility during ANH in anesthetized dogs. (Anesth Analg 1996;83:451-8)

Diaspirin crosslinked hemoglobin enables extreme hemodilution beyond the critical hematocrit

BackgroundNormovolemic hemodilution is an effective strategy to limit perioperative homologous blood transfusions. The reduction of hematocrit related to hemodilution results in reduced arterial oxygen content, which initially is compensated for by an increase in cardiac output and oxygen extraction ratio. To increase the efficacy of hemodilution, a low hematocrit should be aimed for; however, this implies the risk of myocardial ischemia and tissue hypoxia. ObjectiveTo assess whether hemodilution can be extended to lower hematocrit values by the use of a hemoglobin-based artificial oxygen carrier solution. DesignProspective, randomized, controlled. SettingAnimal laboratory of a university hospital. SubjectsTwelve anesthetized, mechanically ventilated pigs. InterventionsIsovolemic hemodilution was performed with either 10% diaspirin crosslinked hemoglobin (DCLHb Baxter Healthcare, Boulder, CO; n = 6) or 8% human albumin solution (HSA, oncotically matched to DCLHb, Baxter Healthcare; n = 6) to a hematocrit of 15%, 8%, 4%, 2%, and 1%. Measurements and Main Results In both groups, measurements were performed at baseline at the previously mentioned preset hematocrit values and at the onset of myocardial ischemia characterized by critical hematocrit (significant ST-segment depression >0.1 mV and/or arrhythmia). To determine peripheral tissue oxygenation and myocardial perfusion and function, the following variables were evaluated: total body oxygen transport variables, tissue oxygen partial pressure (tPo2, MDO-Electrode, Eschweiler Kiel, Germany) on the surface of the skeletal muscle, coronary perfusion pressure, left ventricular (LV) end-diastolic pressure, global and regional myocardial contractility (maximal change in pressure over time, LV segmental shortening, microsonometry method), LV myocardial blood flow (fluorescent microsphere technique), LV oxygen delivery, and the ratio between LV subendocardial and subepicardial myocardial perfusion. In the HSA group, critical hematocrit was found at 6.1 (1.8)% (hemoglobin, 2 g·dL−1), whereas all DCLHb-treated animals survived hemodilution until hematocrit 1.2 (0.2)% (hemoglobin, 4.7 g·dL−1) was achieved without signs of hemodynamic instability. Although arterial oxygen content was higher in the DCLHb group at 1.2% hematocrit than in the HSA group at critical hematocrit (i.e., hematocrit, 6.1%; hemoglobin, 2 g·dL−1) neither oxygen delivery and oxygen uptake nor median tPo2 and hypoxic tPo2 values on the skeletal muscle were different between groups. In contrast, subendocardial ischemia was absent in DCLHb-diluted animals until 1.2% hematocrit was achieved. This was attributable to a higher coronary perfusion pressure (65 (22) mm Hg vs. 19 (8) mm Hg;p < .05), higher subendocardial perfusion (4.1 (2.6) mL·min−1·g−1 vs. 1.2 (0.4) mL·min−1·g−1), and subendocardial oxygen delivery (5.7 (2) mL·min−1·g−1, p < .05) in DCLHb-diluted animals, resulting in superior myocardial contractility reflected by maximal change in pressure over time (3829 (1914) vs. 1678 (730);p < .05) and higher regional myocardial contractility (11 (8)% vs. 6 (2)%;p < .05). An increased LV end-diastolic pressure reflected LV myocardial pump failure in HSA-diluted animals but was unchanged in DCLHb-diluted animals. In the DCLHb group, systemic vascular resistance index remained at baseline values throughout the protocol, whereas coronary vascular resistance decreased. In contrast, both variables decreased in HSA-diluted animals. ConclusionDCLHb as a diluent allowed for hemodilution beyond the hematocrit value, determined “critical” after hemodilution with HSA (6.1% (1.8)%). Even at 1.2% hematocrit (hemoglobin, 4.7 g·dL−1) myocardial perfusion and function were maintained, although at the expense of peripheral tissue oxygenation. This discrepancy in regional oxygenation might be caused by a redistribution of blood flow favoring the heart, which is related to a disproportionate decrease of coronary vascular resistance index during hemodilution with DCLHb.

Regional blood flow during hyperoxic haemodilution

Background:  Ventilation with pure oxygen (hyperoxic ventilation, HV) increases arterial oxygen content (CaO2). However HV induces arteriolar constriction and thus potentially affects O2 supply. We therefore investigated the effects of HV on regional blood flow (RBF) and O2 supply of different vital organs during moderate normovolaemic anaemia.

Milieu-adopted in vitro and in vivo differentiation of mesenchymal tissues derived from different adult human CD34-negative progenitor cell clones.

Adult mesenchymal stem cells with multilineage differentiation potentially exist in the bone marrow, but have also been isolated from the peripheral blood. The differentiation of stem cells after leaving their niches depends predominately on the local milieu and its new microenvironment, and is facilitated by soluble factors but also by the close cell-cell interaction in a three-dimensional tissue or organ system. We have isolated CD34-negative, mesenchymal stem cell lines from human bone marrow and peripheral blood and generated monoclonal cell populations after immortalization with the SV40 large T-antigen. The cultivation of those adult stem cell clones in an especially designed in vitro environment, including self-constructed glass capillaries with defined growth conditions, leads to the spontaneous establishment of pleomorphic three-dimensional cell aggregates (spheroids) from the monoclonal cell population, which consist of cells with an osteoblast phenotype and areas of mineralization along with well-vascularized tissue areas. Modifications of the culture conditions favored areas of bone-like calcifications. After the transplantation of the at least partly mineralized human spheroids into different murine soft tissue sites but also a dorsal skinfold chamber, no further bone formation could be observed, but angiogenesis and neovessel formation prevailed instead, enabling the transplanted cells and cell aggregates to survive. This study provides evidence that even monoclonal adult human CD34-negative stem cells from the bone marrow as well as peripheral blood can potentially differentiate into different mesenchymal tissues depending on the local milieu and responding to the needs within the microenvironment.

The Role of Endothelin-1 in Ischemia-Reperfusion Induced Acute Inflammation of the Bladder in Rats

PURPOSE Endothelin (ET)-1 is causatively involved in ischemia-reperfusion induced acute inflammatory reactions and microcirculatory disturbances in many organs. We investigated the role of endothelin-1 in the microcirculatory consequences of ischemia-reperfusion of the bladder using intravital fluorescence videomicroscopy. MATERIALS AND METHODS Male Sprague-Dawley rats were used in the experiments. The animals were randomly assigned to a sham operated group or to 1 of 2 ischemia-reperfusion groups that underwent 60 minutes of ischemia followed by 30 minutes of bladder reperfusion. In 1 ischemia-reperfusion group the animals were pretreated with BQ 610, a specific ET-A receptor blocker. The bladder was placed on an especially designed stage for intravital fluorescence videomicroscopy measurements. Venular red blood cell velocity, functional capillary density, venular and arteriolar diameter, venular and arteriolar macromolecular leakage, and leukocyte-endothelial cell interactions in postcapillary venules were determined using a computer assisted analyzing system. RESULTS Functional capillary density, red blood cell velocity, venular and arteriolar diameter were significantly decreased and macromolecular leakage was significantly enhanced after bladder ischemia-reperfusion. The number of rolling and adherent leukocytes was significantly increased in postcapillary venules. Pretreatment with BQ 610 was effective for attenuating the effects of ischemia-reperfusion induced inflammation but could not completely prevent microcirculatory failure. CONCLUSIONS Ischemia-reperfusion induced cystitis leads to significant impairment of the microcirculation and ET-1 is suggested to have an important role in this process. Pretreatment with an ET-A receptor antagonist reduces ischemia-reperfusion related microvascular disturbances in the bladder.

Synergistic effects of brain death and liver steatosis on the hepatic microcirculation.

Background. The routine transplantation of steatotic livers could potentially mitigate the donor shortage, but so far is associated with a high rate of graft dysfunction. Steatosis and brain death have been perceived as independent risk factors, but they may synergistically target the hepatic microcirculation. This study compares the effects of brain death on the microcirculation of steatotic and normal livers. Methods. Brain death was induced in obese and lean Zucker rats. Lean and obese sham-operated animals served as controls. Liver microcirculation was investigated using intravital fluorescence microscopy. Serum liver enzyme and reduced glutathione, expression of P-selectin, ICAM-1 and VCAM-1 mRNA in the liver were determined. The ultrastructural alterations were compared by electron microscopy. Results. In nonbrain-dead animals, liver steatosis was associated with smaller sinusoidal diameters, but did not impair sinusoidal perfusion. During brain death, sinusoidal diameter and perfusion were reduced in normal and, to a greater extent, in steatotic livers. Also, more leukocytes were recruited to the microvasculature of steatotic livers than to normal livers in brain-dead state. The highest liver enzyme activities and the lowest hepatic GSH concentrations were measured in brain-dead animals with steatotic livers; only in these organs was endothelial cell swelling regularly observed. In brain-dead state, only the P-selectin mRNA expression was increased in steatotic livers as compared to normal livers. Conclusions. Brain death amplifies the adverse effects of steatosis on the hepatic microcirculation. Our results underline the need for therapeutic intervention in brain-dead state when steatotic livers are to be used for transplantation.

Akute normovolämische Hämodilution (ANH) Effekte der ANH auf die diastolische Funktion des linken Ventrikels

ZusamenfassungIschämiebedingte Veränderungen der linksventrikulären (LV) Relaxationseigenschaften gehen häufig entsprechenden EKG-Veränderungen voraus. Im Rahmen der vorliegenden tierexperimentellen Untersuchung sollte geklärt werden, ob eine durch akute normovolämische Hämodilution (ANH) induzierte Verdünnungsanämie (Hämatokrit, HKT, 20%) mit Veränderungen der diastolischen LV-Funktion einhergeht.Bei Raumluftbeatmung wurde 22 narkotisierten, splenektomierten Beagle-Zuchthunden so lange Vollblut entzogen und simultan durch isoonkotische Hydroxyäthylstärke (6% HÄS 200.000/0,5) ersetzt, bis ein HKT-Wert von 20% erreicht war. Vor und nach ANH wurden das intravasale Blutvolumen (Indozyaningrün-Verdünnungsmethode), die regionale Myokardperfusion (radioaktive Mikrosphärentechnik) sowie folgende Parameter der LV-Diastolenfunktion mittels kontinuierlicher LV-Katheterisierung bestimmt:1) die maximale Druckabfallsgeschwindigkeit im linken Ventrikel, LV dp/dtmin,2) die Beziehung zwischen LV-Druck und Volumen zum Zeitpunkt der Enddiastole bei unterschiedlicher LV-Vorlast (enddiastolic pressure volume relationship – EDPVR; Conductance-Methode) und3) die Relaxationszeitkonstante “τ” des LV-Myokards.Die diastolische LV-Funktion änderte sich nach ANH auf HKT 20% in unserem Modell nicht. Insbesondere die lastunabhängigen Parameter (EDPVR-Steigung und τ) waren nach ANH unverändert. Die Abnahme von dp/dt min (−2724±479 vs. −2388±408 mmHg·s−1; p<0,05) kann als Ausdruck der nach ANH veränderten LV Vor- und Nachlast gewertet werden. Anzeichen einer subendokardialen Minderperfusion traten nicht auf.Eine ANH auf HKT 20% führt bei Hunden mit intakten Koronargefäßen zu keinen Veränderungen der diastolischen LV-Funktion. Eine Gefährdung von myokardialer Perfusion, Oxygenierung und Funktion kann bei diesem Grad der Verdünnungsanämie ausgeschlossen werden.AbstractIschemia-induced changes of diastolic leftventricular (LV) properties commonly precede corresponding ECG-changes. In the present experimental study the consequences of acute normovolemic hemodilution (ANH) induced dilutional anemia (hematocrit, hct 20%) for LV diastolic function were investigated. A total of 22 anaesthetized, splenectomized beagle dogs breathing room air were hemodiluted with isooncotic hydroxyethylstarch solution (6%HAES 200.000/0.5) until a hct value of 20% was reached. Before and after ANH intravascular blood volume (indocyaningreen dilution technique), global and regional myocardial blood flow (radioactive microspheres technique) and the following parameters reflecting LV diastolic properties were ascertained:1) the maximum rate of LV pressure decrease (LVdp/dtmin),2) slope and intercept of the enddiastolic pressure-volume relationship (EDPVR, conductance technique) and3) the time-constant of isovolumic LV pressure decline “τ”.After ANH to hct 20% diastolic LV function was found unchanged. Particularly the load-independent parameters (EDPVR-slope and τ) remained constant. The decrease of LV dp/dtmin (−2724±479 vs. −2388±408 mmHg·sek−1; p<0.05) reflects ANH induced changes of LV pre- and afterload. Signs of subendocardial perfusion mismatch were not encountered.Presumed that the coronary vascular system is intact ANH to hct 20% does not provoque changes of LV diastolic function. Moreover neither myocardial perfusion and oxygenation nor myocardial function are endangered by this degree of dilutional anemia.

Hemodilution and hyperoxia locally change distribution of regional pulmonary perfusion in dogs

In seven anesthetized dogs, the effects of acute normovolemic hemodilution (ANH) to a hematocrit of 20 and 8% and the effects of hyperoxic ventilation (100% oxygen) on distribution of regional pulmonary blood flow (rPBF; radioactive microspheres) were investigated. Normovolemia was monitored with blood volume measurements (indocyanine green dilution kinetics). Before ANH, fractal dimension (D) of rPBF in the whole lung was 1.19 +/- 0.09 (mean +/- SD). Spatial correlation (rho) of rPBF in the whole lung was 0.6 +/- 0.08. D is a resolution-independent measure for global rPBF distribution, and rho is the averaged flow relationship of directly neighboring lung samples. With regard to the entire lung, neither ANH nor hyperoxia changed D or rho. With regard to horizontal, isogravitational planes, ANH induced opposite changes of rPBF heterogeneity depending on the vertical location of the plane and the parameter used. In ventral planes, a change in relative dispersion (SD/mean) indicated decreased homogeneity. However, rho suggested more homogeneous perfusion. Hyperoxia restored baseline rPBF distribution. Our data suggest that ANH causes different alterations of heterogeneity of rPBF depending on location within the lung.In seven anesthetized dogs, the effects of acute normovolemic hemodilution (ANH) to a hematocrit of 20 and 8% and the effects of hyperoxic ventilation (100% oxygen) on distribution of regional pulmonary blood flow (rPBF; radioactive microspheres) were investigated. Normovolemia was monitored with blood volume measurements (indocyanine green dilution kinetics). Before ANH, fractal dimension ( D) of rPBF in the whole lung was 1.19 ± 0.09 (mean ± SD). Spatial correlation (ρ) of rPBF in the whole lung was 0.6 ± 0.08. D is a resolution-independent measure for global rPBF distribution, and ρ is the averaged flow relationship of directly neighboring lung samples. With regard to the entire lung, neither ANH nor hyperoxia changed D or ρ. With regard to horizontal, isogravitational planes, ANH induced opposite changes of rPBF heterogeneity depending on the vertical location of the plane and the parameter used. In ventral planes, a change in relative dispersion (SD/mean) indicated decreased homogeneity. However, ρ suggested more homogeneous perfusion. Hyperoxia restored baseline rPBF distribution. Our data suggest that ANH causes different alterations of heterogeneity of rPBF depending on location within the lung.

Akute normovolämische Hämodilution (ANH)

ZusamenfassungIschämiebedingte Veränderungen der linksventrikulären (LV) Relaxationseigenschaften gehen häufig entsprechenden EKG-Veränderungen voraus. Im Rahmen der vorliegenden tierexperimentellen Untersuchung sollte geklärt werden, ob eine durch akute normovolämische Hämodilution (ANH) induzierte Verdünnungsanämie (Hämatokrit, HKT, 20%) mit Veränderungen der diastolischen LV-Funktion einhergeht.Bei Raumluftbeatmung wurde 22 narkotisierten, splenektomierten Beagle-Zuchthunden so lange Vollblut entzogen und simultan durch isoonkotische Hydroxyäthylstärke (6% HÄS 200.000/0,5) ersetzt, bis ein HKT-Wert von 20% erreicht war. Vor und nach ANH wurden das intravasale Blutvolumen (Indozyaningrün-Verdünnungsmethode), die regionale Myokardperfusion (radioaktive Mikrosphärentechnik) sowie folgende Parameter der LV-Diastolenfunktion mittels kontinuierlicher LV-Katheterisierung bestimmt:1) die maximale Druckabfallsgeschwindigkeit im linken Ventrikel, LV dp/dtmin,2) die Beziehung zwischen LV-Druck und Volumen zum Zeitpunkt der Enddiastole bei unterschiedlicher LV-Vorlast (enddiastolic pressure volume relationship – EDPVR; Conductance-Methode) und3) die Relaxationszeitkonstante “τ” des LV-Myokards.Die diastolische LV-Funktion änderte sich nach ANH auf HKT 20% in unserem Modell nicht. Insbesondere die lastunabhängigen Parameter (EDPVR-Steigung und τ) waren nach ANH unverändert. Die Abnahme von dp/dt min (−2724±479 vs. −2388±408 mmHg·s−1; p<0,05) kann als Ausdruck der nach ANH veränderten LV Vor- und Nachlast gewertet werden. Anzeichen einer subendokardialen Minderperfusion traten nicht auf.Eine ANH auf HKT 20% führt bei Hunden mit intakten Koronargefäßen zu keinen Veränderungen der diastolischen LV-Funktion. Eine Gefährdung von myokardialer Perfusion, Oxygenierung und Funktion kann bei diesem Grad der Verdünnungsanämie ausgeschlossen werden.AbstractIschemia-induced changes of diastolic leftventricular (LV) properties commonly precede corresponding ECG-changes. In the present experimental study the consequences of acute normovolemic hemodilution (ANH) induced dilutional anemia (hematocrit, hct 20%) for LV diastolic function were investigated. A total of 22 anaesthetized, splenectomized beagle dogs breathing room air were hemodiluted with isooncotic hydroxyethylstarch solution (6%HAES 200.000/0.5) until a hct value of 20% was reached. Before and after ANH intravascular blood volume (indocyaningreen dilution technique), global and regional myocardial blood flow (radioactive microspheres technique) and the following parameters reflecting LV diastolic properties were ascertained:1) the maximum rate of LV pressure decrease (LVdp/dtmin),2) slope and intercept of the enddiastolic pressure-volume relationship (EDPVR, conductance technique) and3) the time-constant of isovolumic LV pressure decline “τ”.After ANH to hct 20% diastolic LV function was found unchanged. Particularly the load-independent parameters (EDPVR-slope and τ) remained constant. The decrease of LV dp/dtmin (−2724±479 vs. −2388±408 mmHg·sek−1; p<0.05) reflects ANH induced changes of LV pre- and afterload. Signs of subendocardial perfusion mismatch were not encountered.Presumed that the coronary vascular system is intact ANH to hct 20% does not provoque changes of LV diastolic function. Moreover neither myocardial perfusion and oxygenation nor myocardial function are endangered by this degree of dilutional anemia.

Acute normovolemic hemodilutin (ANH). Effects of ANH on the diastolic function of the left ventricle

ZusamenfassungIschämiebedingte Veränderungen der linksventrikulären (LV) Relaxationseigenschaften gehen häufig entsprechenden EKG-Veränderungen voraus. Im Rahmen der vorliegenden tierexperimentellen Untersuchung sollte geklärt werden, ob eine durch akute normovolämische Hämodilution (ANH) induzierte Verdünnungsanämie (Hämatokrit, HKT, 20%) mit Veränderungen der diastolischen LV-Funktion einhergeht.Bei Raumluftbeatmung wurde 22 narkotisierten, splenektomierten Beagle-Zuchthunden so lange Vollblut entzogen und simultan durch isoonkotische Hydroxyäthylstärke (6% HÄS 200.000/0,5) ersetzt, bis ein HKT-Wert von 20% erreicht war. Vor und nach ANH wurden das intravasale Blutvolumen (Indozyaningrün-Verdünnungsmethode), die regionale Myokardperfusion (radioaktive Mikrosphärentechnik) sowie folgende Parameter der LV-Diastolenfunktion mittels kontinuierlicher LV-Katheterisierung bestimmt:1) die maximale Druckabfallsgeschwindigkeit im linken Ventrikel, LV dp/dtmin,2) die Beziehung zwischen LV-Druck und Volumen zum Zeitpunkt der Enddiastole bei unterschiedlicher LV-Vorlast (enddiastolic pressure volume relationship – EDPVR; Conductance-Methode) und3) die Relaxationszeitkonstante “τ” des LV-Myokards.Die diastolische LV-Funktion änderte sich nach ANH auf HKT 20% in unserem Modell nicht. Insbesondere die lastunabhängigen Parameter (EDPVR-Steigung und τ) waren nach ANH unverändert. Die Abnahme von dp/dt min (−2724±479 vs. −2388±408 mmHg·s−1; p<0,05) kann als Ausdruck der nach ANH veränderten LV Vor- und Nachlast gewertet werden. Anzeichen einer subendokardialen Minderperfusion traten nicht auf.Eine ANH auf HKT 20% führt bei Hunden mit intakten Koronargefäßen zu keinen Veränderungen der diastolischen LV-Funktion. Eine Gefährdung von myokardialer Perfusion, Oxygenierung und Funktion kann bei diesem Grad der Verdünnungsanämie ausgeschlossen werden.AbstractIschemia-induced changes of diastolic leftventricular (LV) properties commonly precede corresponding ECG-changes. In the present experimental study the consequences of acute normovolemic hemodilution (ANH) induced dilutional anemia (hematocrit, hct 20%) for LV diastolic function were investigated. A total of 22 anaesthetized, splenectomized beagle dogs breathing room air were hemodiluted with isooncotic hydroxyethylstarch solution (6%HAES 200.000/0.5) until a hct value of 20% was reached. Before and after ANH intravascular blood volume (indocyaningreen dilution technique), global and regional myocardial blood flow (radioactive microspheres technique) and the following parameters reflecting LV diastolic properties were ascertained:1) the maximum rate of LV pressure decrease (LVdp/dtmin),2) slope and intercept of the enddiastolic pressure-volume relationship (EDPVR, conductance technique) and3) the time-constant of isovolumic LV pressure decline “τ”.After ANH to hct 20% diastolic LV function was found unchanged. Particularly the load-independent parameters (EDPVR-slope and τ) remained constant. The decrease of LV dp/dtmin (−2724±479 vs. −2388±408 mmHg·sek−1; p<0.05) reflects ANH induced changes of LV pre- and afterload. Signs of subendocardial perfusion mismatch were not encountered.Presumed that the coronary vascular system is intact ANH to hct 20% does not provoque changes of LV diastolic function. Moreover neither myocardial perfusion and oxygenation nor myocardial function are endangered by this degree of dilutional anemia.