Hemodilution Induces Stable Changes in Global Cardiovascular and Regional Myocardial Function

Abstract

The cardiovascular responses associated with isovolemic hemodilution have been described. However, the stability of these responses over time remains controversial. We hypothesized that the hemodynamic responses to isovolemic hemodilution are stable over time. Nine fentanyl-midazolam-anesthetized dogs were monitored to follow global cardiovascular and regional myocardial function. Isovolemic hemodilution was performed to a moderate (hemoglobin = 7.5 g%) target hemodilutional state that was maintained for 4 h. Data were obtained at each hemodilutional state and each hour during the 4-h period of sustained moderate hemodilution. During acute hemodilution, cardiac output increased from 2.6 +/- 0.5 L/min to 3.0 +/- 0.5 L/min (P < 0.05) and mean coronary flow increased from 20.8 +/- 2.4 mL/min to 31.4 +/- 5.5 mL/min (P < 0.05). Cardiac output and mean coronary flow remained elevated during the extended hemodilutional period. In addition, norepinephrine increased from 586 +/- 152 pg/mL to 1135 +/- 247 pg/mL (P < 0.05) during acute isovolemic hemodilution and remained at this increased level during extended hemodilution. Epinephrine levels did not change with hemodilution. Compensatory mechanisms such as increases in cardiac output and mean coronary flow observed during acute hemodilution persist during extended periods of hemodilution.

Evidence for a Novel Mechanism Independent of Myocardial Iron in β-Thalassemia Cardiac Pathogenesis

“…In contrast to findings in chronic anemia states [24], [28], [29], the CI in homo-βthal mice rose further and reached a maximum at 10 months of age. Moreover, a persistent increase in LV mass and diameter demonstrate LV remodeling throughout life with progressive deterioration of the homo-βthal cardiac geometry/structure.…”

IV Perflubron emulsion versus autologous transfusion in severe normovolemic anemia: effects on left ventricular perfusion and function

“…However, in previous studies in anesthetized dogs [3,34] elevated norepinephrine levels were already detected after less severe ANH to Hct levels between 19% and 21%. Furthermore the catecholamine-mediated hemodynamic changes following hemodilution could be partially blunted by β-receptor blockade [8,10,11], underlining the catecholaminergic influence during ANH.…”

Anemia of chronic disease: A harmful disorder or an adaptive, beneficial response?

“…5,6 Experiments designed to quantify the cardiovascular response to anemia have generally done so by the acute induction of severe anemia below 80 g/L. [7][8][9] Induced acute anemia is associated with a progressive increase in heart rate and cardiac output; 10,11 however, these changes are not found in patients with stable mild or moderate anemia. Studies involving adults with chronic anemia showed no consistent changes in cardiac output until hemoglobin levels fell below 70 g/L or 50% of normal.…”