Gladys Martin July 2005
Indications for Blood Transfusions Goal of transfusing: Preserve oxygen delivery to tissues and avoid myocardial ischemia. One can do this by increasing the oxygen-carrying capacity of blood by raising the Hgb concentration of patients with acute/chronic anemia. Each unit will raise the Hct by 3 to 4 percent unless there is continued bleeding. Background: Transfusion trigger based on the 10/30 rule, give 2 units. However, with the discovery of transfusion-related HIV and other viral diseases, the safety of blood and the risks associated with transfusions led to a more conservative approach. • “The 1988 NIH Consensus Conference on Perioperative Red Blood Cell Transfusions suggested that no single criterion should be used as an indication for red cell component therapy and that multiple factors related to the patient's clinical status and oxygen delivery needs should be considered.” Transfusion Triggers/Indications • Acute Blood Loss: o Crystalloids should be used to fluid resuscitate hypovolemic patients along with inotropic agents to maintain blood pressure and cardiac output. o Oxygen delivery adequate because greater cardiac output, rightward shift of the oxygen-hemoglobin dissociation curve, and increased oxygen extraction can compensate for the decrease in arterial oxygen content. o Need for transfusion based on rate of blood loss. >40% blood volume loss has been shown to require rapid transfusion as well as 30-40% loss after initial replacement with crystalloids. •
Hemoglobin Concentration: o Hgb around 10 previously used as a trigger. Studies reviewing Jehovah’s Witnesses postop outcomes have shown that lower Hgb concentrations did not increase mortality. o Animal models and retrospective studies have shown increased mortality at Hgb levels of 3.5-4.0 g/dl. Notably, increase in the Lactate levels and the oxygen extraction ratio >50% were observed. o However in animal models with cardiac disease, the increase in mortality was...
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