Transfusion
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The rationale for intraoperative blood transfusion is often based on incorrect concepts and criteria. ⋯ The practice of intraoperative blood transfusion according to volume of blood lost is to be discouraged, and regular monitoring of the hematocrit is necessary to avoid unnecessary transfusion. The theoretical advantages of hypervolemic hemodilution warrant further testing of the model in a clinical setting.
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Most published reviews and audits of blood and blood component transfusion have focused on the issue of overtransfusion and on the inappropriate use of red cell components. There is growing concern that efforts to curb unnecessary transfusions may result in a trend toward undertransfusion of patients. There is little published information that addresses this issue or the magnitude of this practice. ⋯ Red cell and platelet transfusions were appropriately ordered for all patients who met the transfusion criteria. Undertransfusion is not a problem at this institution according to the criteria established. It is recommended that other institutions expand their blood utilization audits to include investigation for evidence of undertransfusion. Further research regarding the issue of undertransfusion is warranted and could be expanded to include other components.
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After the application of high volumes of high-molecular-weight starch (hetastarch), bleeding complications have repeatedly been observed. Later studies showed that the application of medium-molecular-weight starch led to far fewer disturbances of the blood coagulation system. However, the relationships among the degree of hydroxyethyl substitution, the rate of degradation, and the average in vivo molecular weight have not been investigated. ⋯ It is the intravascular and not the initial (in vitro) molecular weight that determines the properties of HES. Especially after repeated administration, a high degree of hydroxyethyl substitution leads to an accumulation of macromolecules that affect hemorrheologic measures and the coagulation system just as adversely as high-molecular-weight starch does. Depending on the degree of substitution, medium-molecular-weight starches can have widely differing properties.