Hypervolemic Hemodilution: An Alternative to Acute Normovolemic Hemodilution? A Mathematical Analysis

Singbartl, Kai; Schleinzer, W.; Singbartl, G.

doi:10.1006/jsre.1999.5711

Cited by 22 publications

(32 citation statements)

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“…1 verify that this entire volume remained in the vascular compartment, because the observed dilution closely matched the dilution predicted by a closed-system, one-compartment model. Prior studies in humans and animals that electively used hypervolemia to protect circulatory volume during presurgical hemodilution found no indication that it was deleterious (33,53,59,65).…”

Section: Resultsmentioning

confidence: 99%

Subcutaneous Po₂ as an index of the physiological limits for hemodilution in the rat

Pearce¹,

Waasdorp²,

Hufnagel³

et al. 2005

Journal of Applied Physiology

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Section: Resultsmentioning

confidence: 99%

Subcutaneous Po₂ as an index of the physiological limits for hemodilution in the rat

Pearce¹,

Waasdorp²,

Hufnagel³

et al. 2005

Journal of Applied Physiology

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“…-Based on their results some authors draw conclusions that are difficult to follow [8]. Mathematical modelling (MM) of ANH consistently demonstrates that net saving of rbc mass due to ANH is rather small [9][10][11][12][13][14][15]. With an initial hct of approximately 40% and with 3 units of blood collected (each 500 ml), the minimal hct level accepted has to be (≤)24%, in order to save approximately 140 ml of rbc [14,15].…”

mentioning

confidence: 99%

“…Mathematical modelling (MM) of ANH consistently demonstrates that net saving of rbc mass due to ANH is rather small [9][10][11][12][13][14][15]. With an initial hct of approximately 40% and with 3 units of blood collected (each 500 ml), the minimal hct level accepted has to be (≤)24%, in order to save approximately 140 ml of rbc [14,15]. These data from MM are in very good agreement with findings from clinical studies [16][17][18].…”

mentioning

confidence: 99%

“…MM demonstrate ANH to be beneficial as a blood-saving measure if the (expected) blood loss is ≥2.0-2.5 l (i.e. approximately 50% of the patient's blood volume) [14,15] and if a (very) low minimal hct value / 'transfusion trigger', in the range of ≤20%, is accepted [12,14,15,21]. (… 'if the surgical blood loss fails to exceed a minimum value, hemodilution fails to offer any savings' [20,21]).…”

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Gesellschaftsmitteilungen · Society Bulletins

2000

Transfus Med Hemother

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“…2. The realationship between minimal acceptable hematocrit (Hmi n) and maximal allowable surgical blood loss for HHD, ANH and no hemodilution (HD) with initial hematocrit of 45%, modified from [1].…”

Section: Resultsmentioning

confidence: 99%

Hemodilution: modeling and clinical aspects

Kaya

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Abstract-Hemodilution is defined as the dilution of the concentration of red blood cells and plasma constituents by partially substituting the blood with colloids or crystalloids and it is a strategy to avoid exposure of patients to the hazards of homologous blood transfusions. Several mathematical models and computer simulations have been introduced to validate the efficacy of hemodilution; the amount of maximal allowable blood loss and final postoperative hematocrit or hemoglobin has been calculated. I. INTRODUCTIONNormovolemic hemodilution implies dilution of the normal blood constituents, occurring after injury or blood loss or as a result of plasma replacement or expansion. As a result of acute normovolemic hemodilution (ANH), blood subsequently lost during surgery contains proportionally fewer red blood cells per milliliter, thus minimizing intraoperative loss of autologous erythrocytes and potentially improves tissue perfusion. Preoperative hemodilution was primarily intended to meet the general shortage of homologous (bank) blood during surgery and to avoid its hazards. It is also alternative to the homologous blood due to shortage in blood supply.Instead of simultaneously exchanging the patient's blood versus a cell-free solution as seen in ANH, some studies used acute preoperative volume expansion without any blood removal and considered this technique as hypervolemic hemodilution (HHD).Several mathematical and computer models have been developed to more accurately predict the efficacy of hypervolemic and normovolemic hemodilution. To determine the efficacy of each technique maximal allowable blood l oss and final postoperative hematocrit or hemoglobin and oxygen transport to tissues should be calculated. II. METHODOLOGYSince the red blood cell (RBC) mass is most suitable to reveal changes in the ratio of main blood constituents, the large-vessel hematocrit (normal 36-45% in females and 42-50% in males) is used to define the degree of hemodilution. It is, however, important to note that both the hematocrit and the hemoglobin concentration respectively reflect only the concentration of the vehicle transporting oxygen in blood; they do not represent the clinical parameter in hemodilution, which is oxygen content (CaO 2 ) of arterial blood.The basic prerequisite for preserving tissue oxygenation during hemodilution is adequate oxygen delivery. The determinants of oxygen delivery are summarized in Figure 1.Limited or moderate hemodilution denotes a decrease of hematocrit from the normal value to 30%, or slightly lower, whereas a reduction of hematocrit to or 20% or below is termed extreme or severe hemodilution.To determine the amount of blood that should be removed to reach the desired hematocrit, various formulas and nomograms have been proposed. A simplified formula was presented in 1983 that approximates the logarithmic formula throughout the range of clinical applicability and closely correlates with the observed data:where V L is the allowable blood loss (i.e., the volume of autologous blood withdr...

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Hypervolemic Hemodilution: An Alternative to Acute Normovolemic Hemodilution? A Mathematical Analysis

Cited by 22 publications

References 20 publications

Subcutaneous Po₂ as an index of the physiological limits for hemodilution in the rat

Subcutaneous Po₂ as an index of the physiological limits for hemodilution in the rat

Gesellschaftsmitteilungen · Society Bulletins

Hemodilution: modeling and clinical aspects

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Hypervolemic Hemodilution: An Alternative to Acute Normovolemic Hemodilution? A Mathematical Analysis

Cited by 22 publications

References 20 publications

Subcutaneous Po2 as an index of the physiological limits for hemodilution in the rat

Subcutaneous Po2 as an index of the physiological limits for hemodilution in the rat

Gesellschaftsmitteilungen · Society Bulletins

Hemodilution: modeling and clinical aspects

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Subcutaneous Po₂ as an index of the physiological limits for hemodilution in the rat

Subcutaneous Po₂ as an index of the physiological limits for hemodilution in the rat